tag:blogger.com,1999:blog-6259385994368729849.post2349204557433817852..comments2024-01-14T00:27:13.233-08:00Comments on Judybox Revival: Service Review: The Blackstar HT40Robert Luedeman semi retired attorney and amp mechanichttp://www.blogger.com/profile/08184192807786983365noreply@blogger.comBlogger12125tag:blogger.com,1999:blog-6259385994368729849.post-36795555342570151352021-04-05T21:37:08.840-07:002021-04-05T21:37:08.840-07:00Just fired up a new HT 40 and the reverb switches...Just fired up a new HT 40 and the reverb switches itself on and off while I'm playing, it makes a huge crackling noise like it's going to explode, anyone else had the reverb problem?Shoulda known betterhttps://www.blogger.com/profile/07353429778331777558noreply@blogger.comtag:blogger.com,1999:blog-6259385994368729849.post-10203591137050521202016-05-05T09:47:03.539-07:002016-05-05T09:47:03.539-07:00Both r144 and r145 are 100 Ohms.
Greg R.Cranky'...Both r144 and r145 are 100 Ohms.<br />Greg R.Cranky'sAnonymoushttps://www.blogger.com/profile/10947309844985378642noreply@blogger.comtag:blogger.com,1999:blog-6259385994368729849.post-41030640944905788612016-03-06T09:58:30.091-08:002016-03-06T09:58:30.091-08:00can anyone identify r144 and r145 on the board for...can anyone identify r144 and r145 on the board for me? i have replaced a couple resistors that a shorted power tube took out but i cannot identify the value of r144 and r145 becuase they have been burnedAnonymoushttps://www.blogger.com/profile/01259855367875233234noreply@blogger.comtag:blogger.com,1999:blog-6259385994368729849.post-37935491385468912572016-03-06T09:56:00.118-08:002016-03-06T09:56:00.118-08:00can anyone identify r144 and r145 on the board for...can anyone identify r144 and r145 on the board for me? i have replaced a couple resistors that a shorted power tube took out but i cannot identify the value of r144 and r145 becuase they have been burnedAnonymoushttps://www.blogger.com/profile/01259855367875233234noreply@blogger.comtag:blogger.com,1999:blog-6259385994368729849.post-20470127095338174882015-10-04T08:10:46.428-07:002015-10-04T08:10:46.428-07:00I think all you could salvage might be the power t...I think all you could salvage might be the power transformer and output transformer. Probably best to gut it out and start from scratch. Maybe, say, a JTM45 or something.Robert Luedeman semi retired attorney and amp mechanichttps://www.blogger.com/profile/08184192807786983365noreply@blogger.comtag:blogger.com,1999:blog-6259385994368729849.post-73084498118787371632015-10-03T15:01:38.693-07:002015-10-03T15:01:38.693-07:00Great blog post, a lot of people don't realise...Great blog post, a lot of people don't realise how much of a gamble it is to buy a HT40 out of warranty. I really like your idea of using the chassis to build a Marshall clone. Would you mind sharing your thoughts on what kit would be suitable? Would any of the electronics from the HT40 be salvageable for such a new build? Anonymoushttps://www.blogger.com/profile/07555222752625128091noreply@blogger.comtag:blogger.com,1999:blog-6259385994368729849.post-51357096223078234882014-06-11T17:15:47.670-07:002014-06-11T17:15:47.670-07:00I'm having trouble too, changed the STK830 res...I'm having trouble too, changed the STK830 resistances.<br />I switched and audio still comes down.<br />Without the schematic is hard to run after the faultAnonymoushttps://www.blogger.com/profile/02650611407689103418noreply@blogger.comtag:blogger.com,1999:blog-6259385994368729849.post-77812679985698295182014-03-08T09:36:38.166-08:002014-03-08T09:36:38.166-08:00This post just saved me $300 and a headache. Thank...This post just saved me $300 and a headache. Thank you!smrbateshttps://www.blogger.com/profile/16363305312599445322noreply@blogger.comtag:blogger.com,1999:blog-6259385994368729849.post-3989686625070770482012-06-24T21:01:02.400-07:002012-06-24T21:01:02.400-07:00I understand that the programmed chip is involved ...I understand that the programmed chip is involved with the channel switching. I was able to get some sound out of it by completely bypassing all the surface mount solid state stuff, but there's olenty of room to build something interesting inside it. Best of luck.Robert Luedeman semi retired attorney and amp mechanichttps://www.blogger.com/profile/08184192807786983365noreply@blogger.comtag:blogger.com,1999:blog-6259385994368729849.post-60655888638005353092012-06-23T22:03:48.955-07:002012-06-23T22:03:48.955-07:00Thanks for the advice! I finally got some El34s in...Thanks for the advice! I finally got some El34s in it and fired it up. I am amazed that it even makes a sound. It seems like the diode gain stage(s) were KIA, among other things. I will let you know if anything constructive hapens. It would be ironic to build a Marshall out of it...Engineerintraininghttps://www.blogger.com/profile/00321825995182268782noreply@blogger.comtag:blogger.com,1999:blog-6259385994368729849.post-14844494657307700792012-05-24T06:08:16.375-07:002012-05-24T06:08:16.375-07:00I hope you got a good deal on it. There are three ...I hope you got a good deal on it. There are three problems here. One is getting technical information-i.e., a schematic, which Blackstar and/or Korg won't supply except to their service centers. A second problem is the programmed chip, which is made of unobtainium. Once you resolve those two issues, if you resolve them, you will then have to find out what was cooked in the preamp circuitry. Unless you have a pipeline into Korg, those problems will effectively prevent you from repairing the amp. If it was mine I'd throw the circuit board away and use the iron and the chassis to build something PTP like a single channel Marshall. There's plenty of room inside and the chassis looks strong enough. If you can fix it my hat's off to you-at which point you will have earned a guest slot here. I spent several weeks screwing around with it off and on and trying to get a schematic to figure out how the thing works. It was a money losing proposition all hte way around because I don't charge people if I can't fix what they bring me.Robert Luedeman semi retired attorney and amp mechanichttps://www.blogger.com/profile/08184192807786983365noreply@blogger.comtag:blogger.com,1999:blog-6259385994368729849.post-41860355990000318562012-05-23T19:52:12.921-07:002012-05-23T19:52:12.921-07:00I purchased this combo on craigslist for a good pr...I purchased this combo on craigslist for a good price knowing it was toast. I did some searching after i got it and found you had worked on it. I have some surface mount soldering experiance, any advice on how to get it going again?Engineerintraininghttps://www.blogger.com/profile/00321825995182268782noreply@blogger.com