Stuff That Lasts Forever.

What's pictured above is a Westinghouse fan that was built in 1914 and does service as a ventilation fan in the bedroom of our house.  It does not oscillate which is good because the oscillating mechanisms on these sorts of fans does not survive as well.

It was acquired at an auction in Newton, Iowa about ten years ago and thereby hangs a tale. It looked as if it had never been used due to the way the power cord had been coiled up, but we got it home in a series of misadventures that included a rainstorm and passing the ultimate Iowa citizenship test-hitting a deer.

I still have the National Sportsman accordion amp I bought later that day but that is a relative youngster, having been made in 1953..

The fan runs more or less continuously here in the warm months and I put my hand on the motor frame to see how it's doing. When it runs a little slowly and the motor housing gets a little hot I know it's time to give it some maintenance. This usually consists of some high quality compressed air to blow the lint out of the housing and a cleaning and inspection of the oilers.

There are two knurled cylinders, one beneath each bushing that unscrew. Inside the cylinders are two felt wicks and springs which keep the wick in contact with the bushing.

When maintenance is needed the wicks can be cleaned with some gasoline, dried and re-oiled with some 3 In 1 machine oil. The oilers should not be overfilled because that can cause some splattering on your walls and such. Once you've oiled the wicks and replaced them the fan can be run upside down to allow the oil to penetrate and lubricate the bushings, and it's good for another couple of years.

It's a homily on how well things were made in the past and how they soldier on and shrug off the ravages of time. At 104 years and counting this one has paid its way. It's also a homily on the abysmal quality levels of the junk that passes for consumer goods these days.

The Wen Chainsaw Has To Choose: Get Going Or Go To The Curb

Here's another diversion from the subject of guitar amps.

I've been busy fixing things around the house lately. I have a Wen Lumberjack chainsaw I acquired a few years ago to assist in removal of some of the bushes in front of the house.

They were a species of dwarf cedar and it was necessary to buy a low priced chainsaw to help cut the roots and stumps out of the ground. The Wen Lumberjack is about the cheapest one you can buy at about ninety dollars if I recall correctly. That task was accomplished and some general cleanup around the property done, the chainsaw was put away.

That was about four or five years ago.

When I went to revive it I found that the fuel lines were rotted away. They were some sort of inferior grade of vinyl or latex rubber and they'd crumbled into mush. I ordered a parts kit which contained a set of carburetor gaskets, three or four squeeze bulbs about which more anon, a couple of strainers and the all important fuel hoses of the correct size.

And there it sat for a couple of years until today. I'd removed the remains of the fuel hoses and tried some vinyl from the hardware store but that was a flop. While doing some general cleaning and vacuuming in the garage I figured that today had to be the day.

The squeeze bulbs are a sort of primitive primer and nearly everything with a 2 cycle motor has them. The kit contained a complete assembly and a few extra plastic bulbs as well-good things to have around.

So today I pulled it all apart again and proceeded to replace the lines from the tank to the squeeze bulb and from the squeeze bulb to the Walbro carburetor.

There's a trick to this. The fuel hose from the tank to the squeeze bulb won't push through easily but you can cut the end on an angle and put a little bit of grease on them and it will pull right through. Then you can cut the end square, install the filter and put it all back together.

It still wouldn't start. Pulling the plug and heating it with a torch was no better. Then, I mixed up some fresh fuel and spooned a bit down the carburetor's tiny throat after blowing out the jets and gave it one more try.

I said to it, Listen. It's either run, right now, or you'll get lugged out to the curb and some fellow who's probably not half as nice as I am will play hob with you. Now. What's it going to be, friend?

It gave a few half hearted coughs and the rancid smell of decaying petroleum convinced me that what was needed was to dump out all the old premix and fill the tank up with fresh fuel. After a few fits and starts it purged itself of all the old fuel and now runs satisfactorily.

I'm not sure yet what I am going to do with it, but maybe I'll use it to harvest some firewood for the winter. As it happens, this is maybe why my string trimmer runs like crap and why I should flush out the fuel system.

So far the Toro mower and the elderly Snapper are up and running, but the Snapper is going into reserve status for national emergencies as the Toro does a better job of bagging. The pressure washer is up to par, the snowblower had its wheels and tires replaced, and the two leaf blower/vacuums are running nicely all by themselves. A new base was made for the drill press, I acquired a new circular saw and made enough parts for two or three amp stands, and all that's left is to cut up some steel and make a couple of bacon presses with the Miller welder. Plus, I cleaned up and organized a good part of the garage.

I think that a couple more workbenches are in my future as I do need a disassembly area and storage area for the amps. The garage floor is not adequate.

Not a bad two weeks for a guy who turned seventy yesterday.

Mowin' Down The Enemy: A Diversion

It is high summer here on the prairie and a young man's thoughts turn to yard work and how hateful a thing it is...not to mention it is mid July and that means mid October is only four months away.

A couple of things happened this week that were of interest and may prove useful in a technical sort of way.

Coming back from the grocery store last week I spotted a rather nice looking Toro walk behind mower parked at the curb. After we unloaded the groceries and put them away I got in the pickup and headed back and the mower was still there.

I knocked on the door and asked if the mower was unattached and the nice couple said "Take it, please." So I swung the tailgate down and off we went with a 2009 vintage self propelled walk behind mower. It appeared as if the recent heavy rains we had had briefly flooded the mower

I got it home and it did have compression which was good. After taking off the air filter so that I could dry it out I waited until after dark to see whether there was spark, and to my surprise there was.

Pull the spark plug out, then connect the plug to the wire and turn the engine over a few times by hand. If there's spark you'll see it. If not, you're going to have to get a magneto coil, but they're cheap enough on fleabay for the imported ones.

But it wouldn't start, so the next day I drained the fuel or what was left of it, pulled off the carburetor, blew out the jets and needle and seat, and put it back together.  It started on the first pull but  there was plenty enough emulsified oil and water in the crankcase to drain out and flush with a bit of gasoline. Then I put the air nozzle in and let it have a good proper blow job to air things out.

This is a pretty typical Briggs carburetor. It's got only three passage ways. Carefully detach it from the governor and choke linkage. Remove the bowl and clean it. Take some carburetor spray cleaner and blow out the main jet and idle jets and the fuel inlet passage where the needle and seat goes. check the operation of each passage with a bit of compressed air. Make sure the float is not sunk and the needle shuts off fuel when the float's up. Clean out the sediment well in the fuel bowl drain plug.

That's all there is to it.


Fresh oil-about a pint of detergent 30W- and fuel, and all seems well. I've got a good solid mower for nothing except an hour's worth of work. The drain plug is a 3/8 square pipe plug that sits in the bottom of the crankcase, or you can tip the mower on its side and drain the oil through the filler neck.

While all this was happening the other mower, the Snapper Ninja self propelled number that has been my workhorse for the last five or six years-it came out of an auction for twenty five bucks and it is at least 25 years old- started having problems with the transmission drive.

So I got out the parts manual and ordered some transmission bearings, a drive belt, an idler pulley and a drive disk from Snapper-which happens to be the cheapest source of parts I found.

After cleaning off the rust and dead grass and treating the deck with some rust stopping compound, I reassembled it yesterday and today with some new hardware, and while I was doing that I cooked up a good workaround that had never occurred to me before.

Clean off the corrosion and dead grease that coats everything. Buy your replacement carriage bolts at the hard ware store for a quarter instead of paying $2.35 for one plus shipping.

This mower has two springs that tension the drive mechanism components. Once the drive is assembled you gotta get the springs on but it proved difficult-until I wrapped some safety wire around one end of the spring and grabbed it with my safety wire twisters and pulled it through the hole. Nice.

Take a good look at the springs number 39 and 54. While you're at it look carefully at 73, which is a twisted piece of coat hanger wire that some people want twelve dollars for.

That went swimmingly, and the drive mechanism is functional and working smoothly.

Tomorrow I've got to see about changing both inner tubes on the snow blower's tires, change the oil and drain out the old gas and get it ready for winter. Then it's time for the pressure washer, the string trimmer, the chainsaw and likely the leaf blower too.

Converting a 50 watt Marshall Plexi From 6550s to EL34s The Right Way

A vintage Marshall "Plexi" arrived here that was in bad need of some refreshment. These are pretty much the ultimate rock and roll amps-loud, brash, edgy and in your face. So they are well worth the effort to bring them back to life.

In no particular order it needed a fresh suite of electrolytics and some general freshening up before retubing and troubleshooting.

It was an ebay find I think.

As part of my standard procedure I noted that someone had "converted" it in a prior time to use EL34s but it didn't have any bias voltage, which makes me think that's why whoever had it gave up on it a long time ago. They didn't "convert" it either-just some half assed hack job.

Amps that were destined for the USA were equipped with 6550 power tubes by the distributor in the US which was, I think, Unicord. They changed the sonic signature of the amp, and it didn't sound very British any more.

There are four steps that must be taken to effect the conversion.

First, the bias splitter resistors should be changed from 150k to 220k metal film resistors. For some unknown reason the board was marked 82k.

This is relatively easy to desolder as all these things are by lifting up the board and putting a small light inside, like one of those LED lamps you strap on your forehead. Then you can see what you're doing.

 The 47k resistor should be changed to 22k. Don't bother with mickey mouse scabbing resistors on top of one another as some folks suggest.

It looks crappy. Do it right.

The two 10uf or 8uf 160v electrolytic capacitors need to be replaced. They do not last forever.

Now here comes the tricky stuff.

Install a 220k bias level resistor as shown on the schematic coming from the high voltage tap on one side of the power transformer to the  bias supply diode. Set the bias pot to the lowest setting. You can set up your bias checker with a set of power tubes, make everything ready and briefly throw the standby switch on, take a quick reading and then put it back on standby because you're probably drawing too much current.

Now, take two test leads and parallel the 220k resistor to reduce the bias level down to about half. Then you can see whether you're close enough to do a fine adjustment with the bias pot. If you are, measure the paralleled resistance and find something relatively close.  I ended up with a 100 k resistor. Or you could start with a 100k resistor, or you could fine tune it with a pot and then measure the total paralleled resistance.

The last step is to relocate the negative feedback wire from the 16 ohm speaker out[ut tap to the 8 ohm speaker output tap-which hadn't been done in this amp.

Once you've done all this check and check your voltages again before you button it up, and do a sound check.

You might find, as I did, that this amp has an oscillation problem which is likely how it got shelved to begin with.

If you're ready to button it up, clean off all the flux and schmutz with some anhydrous isopropyl alcohol and an acid brush cut off to about 3/8 inch. It makes a dandy cleaner.

Rock on.

What you should know about buying a tube amp

I am often asked for some opinions about what people should buy in the tube amp world.

Here are my thoughts.

First, the basic platform must be roadable-that is, rugged and durable, able to survive temperature extremes, odd voltages in dodgy ginmills, and one that can withstand being bounced around in the trunk of a car for hours.

Second, the amp must-MUST!-be free of unnecessarily complicated circuitry and gimmicks, because those doodads exponentially increase the likelihood of maintenance issues, breakdowns, and, for the technician, countless hours spent in chasing down intermittent faults. Some of the design features overwork the key components, which are the tubes.

For the most part this rules out Mesa Boogie amps and similar analogues such as Bugera, B52 and many others. They are complicated to work on, service information is closely held and not available to the trade, and that limits the number of people who can or will work on them. I have always thought that vertical information silos depend on key people to be available when you need them. On the other side, broad based systems of general knowledge do not depend on key people and are thus more likely to be available when you need them. I recently had a Dual Rectifier Road King II in the shop with failing muting jfets of which there are 15 or so. By my count it had 33 knobs and 22 relays.

This increases potential failure points in a geometric fashion. If the failure point is A, you have one potential failure point, but if you have five potential failure points you have AxBxCxDxE potential for failure of a critical component. The quality of the components used can only compensate to a certain degree.

This is directly connected to Bayes' Theorem, which applies to probabilities. You can read more about it here.

My math may be a little bit lacking but I think you can see that complication leads to failure at inopportune times.

This is not to say that Boogies are bad, or evil. They are fine in the studio if that's what you like to do.

This in general rules out all amps that have more than two channels and use channel switching via relays, optical couplers like Vactrols, and the like. They're troublesome.

What you can do here, when considering an amp for acquisition, is go to the best most respected amp tech you know and buy them a coffee. Ask them if whatever you're considering is a good buy from the standpoint of serviceability and roadability. You may be surprised at what you learn in a face to face encounter with a real person.

Third-printed circuits. Are they inherently evil? The answer is no, if they're properly built with good components and proper engineering. They're a fact of life in this day and age, but they do require that the technician who works on them have a deft touch. They're less user serviceable than amps of an earlier era. They're also less damage and shock tolerant than traditional methods of hand wiring. Also, when troubleshooting down to board level faults, you may find the amplifier becomes uneconomic to repair.

Printed circuits have been around for a while now. The earliest one I have actually seen was in a Motorola table radio and it had a copyright date of 1956. At that time my father was working on a wave soldering project for Weston, so we've had them for at least sixty years. I'm informed that the first printed circuit boards with plated through holes was made in 1947.

Now, having said that, it is worth asking whether power tube and rectifier tube sockets are mounted directly to the circuit board. They generate heat-lots of heat, and the boards cannot withstand that forever. What happens is that the substrate gets carbonized to some extent, and as we all know carbon is what resistors are made from. That means that you start getting stray voltages and current leakage here and there. Ask the Marshall folks about conductive circuit boards in their DSL amps.

Also, circuit boards for guitar and bass amps are not generally available in the aftermarket, with very few exceptions. That means if the worst happens and a board needs replacement you may be out of luck. Occasionally some boards may be available in the secondary market or from friends in the trade but it is not something that can be relied on.

What this means is that you should spend all the money you are capable of getting your hands on and buying a hand wired amp built the old, artisan way.

Educate yourself on the methods by which your chosen piece of gear is built. Not all hand wired amplifiers are created equal. Learn about maintainability if you intend to take it on the road. Learn about after sale service and what you can expect from the builder.

Does that mean you should buy from a homebuilder who will assemble a kit for you? Probably not, unless you have seen examples of their work in the wild, and if the critics are satisfied.

All of this takes you back to the beginning. By far the best values for the money in the amp world are silverface Fender amps, some of the older Traynors, and some boutique-y amps such as Tungsten, Victoria, and Kendrick.

They're hand wired on eyelet boards and not overly complicated. With ordinary care they will last a lifetime of playing.

And last, do you like the way they sound? Do they speak to your style of music? Ultimately that should be the deciding factor.

The Cowpoke Forty, or, How I Stopped Worrying And Learned To Make My Own Bassman

You know sometimes how you get an idea and you just can't shake it? Gotta scratch that itch?

That's what happened here. The first Bassman 50 just didn't have any muscle, so I decided if I couldn't have a real Fender Bassman I'd have to build one myself.

The first step was to acquire a chassis and I was lucky enough to find a new production chassis on fleabay, the why pay more store. I already had, in no particular order, a Super Reverb power transformer from Pacific-nice stuff!-a Marvel choke, and a Classic Tone output transformer.

In short order I cooked up a circuit board from the usual stuff, punched out an extra hole for a rectifier tube, and commenced.

After some off and on work the Cowpoke as I called it was finished but still needed some fine tuning in the bass channel. Other than a tube rectifier it's pretty much all AB165 Bassman, and it was wired with traditional cloth covered pushback wiring, Omron octal sockets, and a mix of yellow poly and brown chiclet capacitors from China Inc-they were cheap at about ten cents apiece and do the job just fine, thank you.

For glassware it has a Raytheon 5V4, a pair of vintage Sylvania STR387s, a JJ ECC81 and a trio of JJ ECC83s. After trying it out I had to rectify a couple of mistakes I'd made with the wrong value caps in the bass channel.

That was all finished up today, the Bassman face plates were installed and in it went to make nice with the Weber Silver Bell that's in the J.D. Newell cabinet that I acquired a while ago.

You do not have to keep a Bassman power transformer in stock if you will but keep a Super Reverb/Pro Reverb power transformer. Just cap off the rectifier tube 5v winding if you don't like it. Stock one instead of two.

It's a good piece of kit and I will be experimenting with it and getting familiar with its Bassman goodness in the next two weeks or so.

The pictures.

Getting back to the basics of troubleshooting. Blackstar content.

After the contretemps with the dual rectifier road king which has 33 knobs and 22 relays by actual count, I worked on a nice old Bassman on Sunday and Monday to level my alpha waves for the next migraine, which was a Blackstar HT60  combo with dead overdrive channels that I tackled today. The overdrive channels were noisy but took no signal and they expired completely on the bench with the occasional pfffft! pffffft!.

I remembered something about the clean channel being solid state and the overdrive channels being tube driven, so I started with a set of preamp tubes which changed nothing.

Getting back to basics I started with measuring plate voltages and wouldn't you know, there was very little voltage on pin 1 of V2 which receives its plate voltage through R41. The resistor tested OK with my extra high quality Harbor Fright multimeter although not so well with my ten buck analog multimeter.

But the voltage was going in but not coming out.

It was a simple enough matter to snip the resistor and sweat out the cut off stubs without removing the circuit board, check underneath with a mirror to see that all was well on the underside, and solder in a new resistor which I could do because the holes are plated through. Cleaning out the lead free solder from the holes and using some good Kester 44 did the job. To be on the safe side I resoldered pin 1 where it merges to the circuit board. It looked like it could use it.

The overdrive channels sprang to life with all the bowel loosening feces tone Blackstar is famous for, and after checking and adjusting the power tube bias, away it went. I kind of like the idea of a bias balance and level set which these amps have. I mean, I had to say something good about them, didn't I?

The point is, start  with the basics-swap out for a set of known good tubes and then some checking to see that voltage appears in all the right places. As it happened no fancy schmancy tooling or scopage was required to set this amp right, and it was not the first time I've seen such things happen.

Unstacking A Terror Bass And Looking For Tin Whiskers

An Orange Terror Bass amp came in with a very strange complaint. The owner indicated that the treble control was inoperative.

At first I chalked it up to drama but when I got it back to the shop a couple of things became obvious-the treble control did, indeed not work and had no noticeable effect, and second of all the true genius of Leo Fender's designs.

For those of you who are unfamiliar with this amp it is a hybrid with a tube preamp that's (allegedly) the same as their AD200 bass amp, and a 500w Class D solid state power amplifier. I still haven't figured out how they do this Class D business or pack all that power into a lunchbox amp but nevermind. They say it, I believe it, and that settles it-more or less.

The tone stack in the tube preamp is a direct copy of the same section in the 5F6A Bassman as a gander here will show, with a few minor component value changes. Here's the Bassman.

Well. The similarities are there, and this combination of high and low pass filters does a very nice job. Particularly when you figure that this design is better than sixty years old, it speaks to the genius of the designer-one Clarence Leonidas Fender-that has not been surpassed.

It's homage in a way that Leo's designs live on in the newest amps-or relatively new amps.

So. After consulting with the Brain Trust and studying the schematic, an order was placed with Digikey for three pots of the correct size, value and termination points. No small thing when you start shopping for potentiometers I may say. Digikey's on line catalog is excellent because the graphics are clear and sharp, they let you see exactly what you're ordering, and they're only two days away, being in western Minnesota.

Also ordered at the same time were a pair of .047uf capacitors and a 470 pf ceramic disk capacitor to replace the 120pf capacitor as I figured it was not a bad time to revoice the amp for slightly better bass response. These had to be relatively small to fit in the space allotted to them, but at least the board is keyed to the schematic diagram so at least I knew what to remove and replace.

For that task I used my handy dandy ZD915 solder removing machine. It came from Marlin P. Jones Associates, and there is a good youtube review of this piece of gear on the EEVblog. It goes by the trade name Rhino in Oz, but it's the same piece of gear. It ran me about $120 US, and I ordered plenty of spare tips, filters, and a spare gun which was only $20.  I do not know how I got along without it, as the manual solder suckers I'd been using could lift pads on Fender boards quite easily with their recoil. Not a good thing.

Keep the ZD915 clean and you can use it on leaded solder or lead free as you wish. It helps to put a dab of leaded solder on the connector before you use the sucker-that or some flux is fine, but either makes the lead free solder's exit from the scene much more easy and a lot less drama to boot.



After reassembly everything worked swimmingly and it went back to its owner today.  I will likely autopsy the pots to see what went haywire. Some of my colleagues suspect that it was a case of lead free solder growing tin whiskers and shorting the treble pot out. I will do an autopsy with my 12x lamp and see what I find. Failure analysis is always fun stuff.

Tin whiskers are real, not fanciful, and they are microscopic fibers that grow out of the tin used in lead free solder. Some folks choose to believe they're not real, but I have seen microscopic images of them and have heard reports from other technicians who should know they're a real phenomenon in the age of RoHS compliant electronic products.

You can read all about them here

Straight Outta Linden

Mr. Brown, my Pawnshop Excelsior returned from its sojourn the other day. I guess the person who had borrowed it got tired of me whingeing and being a crying brat about it, but it was in a studio where they do some great work, and these guys are friends of mine so it wasn't like I needed it, mind you. Plus they do send me some interesting projects to work on now and then.

Thanks to Brandon and Micah-they're grand fellows and well connected.

Somehow or other the funky Gretsch footswitch took a powder but I had the makings of an Ampeg style footswitch here. If you recall, I detailed how to install a footswitch jack in this amplifier, although my simple but elegant solution to it was met with a certain amount of what passes for internet "commentary" but never mind.

The footswitch consists of about ten feet of zip cord-a large roll of which I acquired out of a defunct radio shop in Williams, Iowa, a right angle Amphenol jack, an on-off pushbutton switch as found in most of these things and a doorstop, which is a plastic or hard rubber wedge. You could make a wooden switch housing if you like.

I chawed out one of the ribs in the doorstop with my trusty Swiss Army knife, drilled a hole of the right size although here a note is important.

Do not do this with the doorstop resting on your leg. The results will be painful.

The other end of the zip cord is soldered to the switch terminals and then it is mounted in the doorstop. Attach the jack to the other  end in the usual manner.

If you've installed a jack in your Excelsior or other fine amplifier, then the last thing to do is plug in and play.

Come to think of it, I have a beautiful old Jensen P15LL that would be just the ticket for this amp to take some of the brightness out of it.

The Avalanche Project

A while ago I had a Deluxe Reverb Reissue come in with a blown power transformer, and of course they are made of unobtainium right about now.

The reasons why the power transformer failed were pretty simple. There is a small 22 ohm resistor in the bias supply and that failed open. With the loss of bias voltage, the power tubes red plated and died, bad smells came out and the power transformer primaries expired-no doubt it was the thermal fuse within, which is unrepairable.

 However, I did have an old style Vibrolux Reverb power transformer that's a drop in fit and it was a pretty simple thing to fix up all the burned stuff, add a couple of spade connectors , plug everything together and power it up. It worked fine, too, but I had the germ of an idea.

Now that I had a power transformer that was rated at 180 ma instead of 120 ma, what if I installed a more substantial output transformer as well? Then, I'd have a 35 watt amp in a 22 watt package with a pair of 5881 power tubes.

It also presented the opportunity to do some tinkering to make it all work together, upgrade that ridiculous 22 ohm grain of wheat resistor, and gave me a chance to try out my prototype vibrato roach (optocoupler) which I am calling the Doodle Bug.

There was the Surf Bug and the Black Widow roaches but they're out of production now and the maker of the Surf Bug has also passed off this mortal coil, more's the pity.

But there's the Doodle Bug.

 So Doodle Bug number one has been installed and it's a winner. Smoother than the original, it's more like a tube modulated vibrato than an optocoupler.

So the transformers went in in pretty quick order although the output transformer must be moved aft about half an inch to clear the speaker frame. It's tight but there's about 1/4 inch clearance which is plenty enough. You do have to drill a new hole for the mounting screw, and it helps to angle it a little bit because it comes up against the grommet where the wires go through.

I'd previously installed F&T power supply capacitors for tone and reliability. The bias supply resistor required some adjustment to increase the range to a usable level.

This amp has a 5A filament fuse which is OK for 6V6s but a little light for 5881s so I uprated it to an 8A fuse which should be fine given that most Deluxes didn't have a filament fuse to begin with and the Supersonic 22, which uses 6V6s has a 10A filament fuse. To be on the safe side I cleaned off the traces on the underside of the board where the fuse holder is attached and laid in a more thorough bead of solder. This was all because the 5A fuse failed after about three hours of service.

It's got a lot more guts than the DRRI, that's for sure.

The amp was donated by Matt Wellendorf, a local guitarist and also a great pal. I provided the brain power for this project.

I used Marvel Electric transformers which are plenty good and at a fair price. Currently the output transformer is a 4 ohm number  but the amp can stand the mismatch as all Fenders do. For a high end deal I'd probably install a Classic Tone Multi tap output, but the Marvel iron is good enough for proof of concept and some reliability testing. I see where Marvel is offering an 8 ohm output of this configuration which would allow a closer impedance match.

If this is something you'd like to try you can get in touch with me at all the usual places. At this point with all the parts added in about $350 should do it. If you figure that some routine maintenance and improvement should cost you $150 or so, it could be a good time to upgrade your 97 pound weakling.

Measuring Your Voltages: Why To Do It.

A relatively new Blues Junior III came in the other day because it wasn't making any sound....not a peep.

The first thing I did after testing the power tubes was get out my trusty multimeter I got from Horror Freight and started measuring voltages on the power tubes. Lemme see, plate voltage OK. Bias voltage OK...where the hell's the screen voltage?

Dave's not here, man.

It seems that  R47 (I think) the 2.2k 2 watt resistor in the power supply string had failed open kinda like a self activated standby switch.

From there it was a couple of hours work to crack it open, get rid of the Illinois power supply capacitors and replace the suspect resistor.

It powered right up and all is good.

The point is, measuring voltages is the first thing you do. Had I not done so I'd probably still be throwing parts at it in a random fashion hoping that something would stick or give me a clue.

When Vintage Was Vintage part III-Unobtainium Pots

I completed the Peavey Vintage today and surprise of surprises the reverb actually worked with a 4EB tank installed.

But first there was the problem of the pots. The volume, treble, bass and presence pots were all bad enough that the usual methods of cleaning were of no avail. There was a loud thump about half way up on the bass control, the presence control was pretty much jammed up with a bunch of Duco cement or other fine adhesive, and all this would cause some uncomfortable symptoms when monitoring current.

The pots were pretty conventional except for the method of attachment to the circuit board as these were some sort of primitive snap in controls. I thought about it for a while while I was pulling the board and then I had it,

I took a few resistors and cut the leads off them, removed the offending pots, cleaned out the holes, bent a right angle in the wire lead and soldered them to the board. Then, these leads could be inserted into a conventional Alpha pot of the proper value, soldered up, and then the surplus wire was trimmed off.

Perfect!

So if you're working on one of these old bombs, there's your fix.

Here's the rest of the innards with two nice new 6C10s.

How's it sound with a nice fresh set of JJ 6L6GCs?

Clean and loud. The reverb's not as wet and drippy as you might find in a Fender of similar age but it is reasonable enough considering. I think I may locate a set of new jacks and install them to lower the noise a bit-some nice plastic Cliff jacks might just lower the noise threshhold a bit.

Now all that's necessary is to scratch up the cash for a cabinet and this one can go in the Done file.

El Roacho, or, Secret Sauce Debugged.

I've been toying with the idea of rolling my own Fender style vibrato optocoupler devices for a while now, and a suitable test bed arrived the other day.

It's a Deluxe Reverb Reissue of the '68 Custom variety, and I have been trying out a couple of upgrade transformers to see if I could boost the output a modest amount. So I figured it was a suitable candidate for some roach research of the corksniffer variety.

What do I mean by corksniffer? Read on.

A while ago there was a fellow down in Texas who allowed as how he had discovered the secret formula after diligent experimentation and research into the subject.

He called it the "Surf Bug" and sold quite a number of them for about twenty bucks a copy, until he sadly passed away and, so 'tis said, took the secrets to the grave with him. He did business as Tonecraft Amplification.

After that there was the "Black Widow" bug that was being sold by Austin Amplifier, or so 'tis said although I do not have anything current on the situation.

According to the savants on the TDPRI discussion forum both these operations are out of commission-or maybe one, or maybe operating on some astral plane.

You can read all about the alleged secret sauce mojo here.

Well. I am about to rip the lid off this entire subject. The secret sauce dies here.

I autopsied a number of known working vibrato roaches, and did not learn much of great value. The dark resistance is so high that my multimeter couldn't measure it anyway. 

I obtained a number of GL5537 and GL5537-1 photocells.on fleabay the why pay more store, and a number of NE-2 neon bulbs. I made up a couple of test articles and put each one in the package with the relevant photocell. Of course they slipped out of the packages so I don't really know which was which.

They both worked fine, and the results are a slightly smoother and less choppy vibrato that sounds a bit more like a tube modulated vibrato. Attached are a photograph of the first article and a shop sketch.

In addition there is a photograph I found of what are supposed to be five new Surf Bugs.

I can't tell the difference.

I fully expect that I will be lambasted by people who just want to believe the magic sprinkles and the existence of secret sauce.

Perfectly all right says I. Bring on the bashing

When Vintage Was Vintage, Part II

After a thorough recap and some fresh tubes the Peavey Vintage is up to its old tricks-loud and clean.

Power supply capacitors and all the small electrolytics on the board were replaced, as were all the film caps except two tone caps which are pretty low voltage stuff and not excessively overworked.

To get it running and test everything and set the bias all I had in the way of compactrons were a pair of 6K11s which drop in but don't have much gain in the right places. I will have to hunt up a pair of 6C10s or 6AD10s. Also on the shopping list will be a volume control, bass control, and presence control. I may just replace them all if I can find suitable replacement stock.

 I'll post some pics and internals  and an extended commentary as I do not think anyone has written anything about these rarely seen amps.

Tube pin cleaner.

If you take a stainless steel pot scrubber or a copper sponge and stick it to the inside of a plastic cup with a dab of hot melt it makes a fine tube pin cleaner.

Take your tube and jab it into the scrubber a few times and all is good.

Reverb Resuscitation

A friend of mine brought over a nice old Fender 6G15 outboard reverb unit today and as I had my nose slightly out of joint over other matters (social media drama) I hid out in the laboratory.

This friend has a knack for acquiring stuff on the cheap and this was no different. It had a bad habit of blowing fuses, and when it was brought up on the variac it was drawing about three times the normal current.

The fix was simple, and this seems to be my week for dodgy old electrolytics in power supplies.

A refresh of all the consumables and a new power cord and all was well.

I did find that it is susceptible to ground loops as it developed the granddaddy of a hum in the living room. I soon figured out that it was on a different circuit in the house. Plugging it into the same outlet as the Cowpoke quieted things down and it'll go home tomorrow or the next day.

When Vintage Was Vintage.

What you see here is the progress so far of a two or three year quest.

I'd been reading a piece by Hartley Peavey, the Mississippi amp wizard, and in it he discussed the 5F6A Fender Bassman and how he was inspired to cook up an all tube, 100 watt tweed Bassman with reverb.

Here's a page where he discusses that. I do not think he will mind.

"So" says I to me, "What could be better than an all tube 100w tweed Bassman with reverb?" and the search to locate one started.

In between all that I built a high power tweed twin knockoff which I am still not entirely happy with and I will get to it presently.

So I'd been searching on Craigslist and fleabay without ever finding a good all tube Vintage. There were a couple but one was pickup only in the great state of Oregon, and one was a wreck in Tennessee that the owner still wanted a lot of money for. And then there was the Peavey faux tweed, which is something nobody wants.

Anyway....this amp showed up on fleabay as a bare chassis, no tubes, and it seemed to be in pretty decent shape. A deal was made and it arrived here Saturday, no glass, power cord cut off, the whole works.

It's in good enough shape cosmetically although a few of the resistance welds are broken, but that is what me and Mr. Miller are made for.

Mr. Miller is a Miller MiG140 welder that runs on household current and is good enough for everything up to 3/16 steel plate.

But the overarching consideration was to do enough to power it up and see if it held up or whether one of the transformers was finished, and that required a recap with some of the good stuff from the House of Fischer and Tausche in the great nation of Germany.

But never mind that for now.

I just finished that job and installed a new power cord, fuse holder and strain relief and flipped the switch-running through the variac of course.

It held, by G-d. The plate and screen voltage without power tubes was about 525v and the filaments look happy.

So there it is. The plan now is to repair the cracked welds on the chassis, and order up a head cabinet in blond tolex with a wheat grille.

Stay tuned.

UPDATE: I  decided to try repairing the cracked chassis spot welds with JB Weld epoxy. I cleaned everything with alcohol and an emery board, mixed up some JB Weld, spread the chassis where the welds had come apart, fed it in with a cut off zip tine and then clamped it tight. I'm letting it sit for a few days while I attend to other matters such as figuring out what sort of cabinet to order and polishing up the faceplate.

Stay tuned.