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So I checked Q1 and it seemed to be ok. I cleaned up the bias pots with some Deoxit and turned them both counter clockwise all the way. Clipped the meter across the right channel emitter resistors. Plugged into the dim bulb and, after adjusting the settings a couple times, ended up with...

Grispato - That is what I was starting to do when I discovered the smoking resistor. I noticed that the protection was connected to the bias circuit as well. I probably should have zero'd out the bias pots prior to plugging it in. It stands to reason that they are way out of wack considering...

Ray - Got it. I'll check it. Thx!

Update: I have made some "progress" on troubleshooting this amp. Or perhaps its more of a lateral movement. I replaced the output transistors with C1695 and C4468 devices. Then I pulled Q7 thru Q10 on each channel and tested them. They seemed to test ok so I put them back in. Since the...

Jim, I saw in a post that you have an AB Systems 205. I have a bunch of these ABS & ABI amps and they are excellent performers. I just got a 205b that will need some work. Would you happen to have any info or an opinion of it's sound? It's much older than the other AB amps I have and I...

One more thing I forgot to mention. This unit does have, what looks like, a protection relay. I haven’t tested it’s function yet but it doesn’t appear to prevent it from self destruction even on the dim bulb circuit. Perhaps it’s stuck closed. I should probably pull it and test for function...

Thank you for the leads! That spreadsheet is a keeper grispato. I will check out those suggested replacements Hipocrates. (After a cup of coffee ;-). Thank you! I have a handful of these: Looks they are both one number up from the recommended replacement. This particular unit has a...

Made some “progress” on this today. Not sure about the prognosis yet though. Good news is the transformer work fine. Bad news is someone did some hack job repairs to a blown channel at some point. After testing the tranny I went ahead and replaced the burnt parts on each protection circuit...

Yea I’m thinking the parts business is a lot like fishing. Patience and luck are required. I certainly never meant to disparage the practice. I have a marantz that owes its life to a donor. It’s a piece that is very important to me for more than just audio reasons and I will never part with...

Thanks sansuiman! I hate parting things out and avoid at all cost. I see the parts listings on the bay and wonder how many of those donors could have been saved. If I know something is toast, I prefer to repurpose the parts for other projects rather than deal with shipping, etc. and maybe...

It’s definitely a discrete design and, at a quick glance, it looks like parts are still around for it. The last thing I need; however, is another system. I’m considering fixing it to sell as they are going for much more than what one would expect. My son and I are diy electronics hobbyist...

Hello! I got this amp many years ago and never gave it a second look except to move it around a few times. A guy threw it and the matching pre in with something else I was buying at the time. Well I stumbled across a couple on the bay the other day that had sold for stupid money. That got me...

Hello punker x. Thank you for responding. I started to post an update last evening but got side tracked and didn’t hit post reply. Turns out it was the capacitors although you are correct that it could certainly benefit from an alignment as well. It plays well now and is getting better as...

I hope this is the right section to post this... I'm trying to fix a radio for a friend of mine as a favor. He told me a switch was bad and it was cutting out. I figured it would be a simple deoxit and maybe recap while I had it apart. I took it apart and deox'd the switches and pots. The...

Hello gadget. I was thinking the same thing about the tone generator. I should hook it up to the scope and see what’s it’s putting out. I’m neck deep in a workshop make over right now so everything is tore apart. When I get organized again, I’ll post a pic of the sine wave. Thx!

Thanks for the insights. It’s been fun opening them up and checking them out although I will have to properly dispose of the old batteries. swechsler - I was wondering about the vibrasender. That’s pretty cool. Well I suppose they will be slowly integrated into various projects then...

I bought these on the auction site on a whim. I just liked the way they looked and figured I could always use the pieces and parts if nothing else. I like integrating old stuff into my projects. My son, for example, thought it might be cool to make a vintage looking game controller or MP3...

sregor - this is where i got my schematic from: https://elektrotanya.com/vector-research_va-1400_sch.pdf/download.html It's not the best but better than nothing. Brett

I recently acquired this amplifier in "as is" condition. All I knew is that it powered on. The price was right and I've always wanted a Vector Research piece for the "collection". They seem to be pretty well regarded around here. It arrived in very good condition so I powered it up on the...

JShaw3 - This is the listing from my cap order. I'd list the entire order but it was combined with a couple other orders to save on shipping. Keep in mind that I had to drill the board and solder on some tabs to make these work, as the spacing was not the same as the original. I used...

I’m actually more worried about my speakers than anything else. It would be tragic (and expensive) if the problem got worse over time and damaged my speakers. The xl280 is going to power the low end on a set of Polk rta-15c’s and I’m moving the p225 up to replace the parasound currently used...

I have heat sinks on them but I think they can still be be thermally bonded. I’ve seen it done on a build thread for the honey badger amp build I believe, so I’ll figure it out. It’s my understanding that this amp normally runs at 100mv of offset so the one channel may be ok. The one that’s...

Mondialfan - thank you for the reply. I dove back into this and here is what I’m seeing. Here are the values of the resistor in and around Q1-Q8. R5 is 26.9. I had replaced it at the same time as R4 & R6. I had previously pulled C3 out of circuit because I wasn’t sure I had it on the right...

mondialfan - thank you for that. It was very helpful while working my way through the process below. After I got through analyzing the board, I actually had a limited understanding of what you were say ;-). It is starting to make sense to me. Or at least I’d like to think it is... I’ve made...

So Ive made a little progress on this since my last post. Lowering the bias didn’t help at all. So I took measurements on one of the boards and compared to the manual. The voltages on the jfet sources were around +/-1 vdc and they should be +/-22v. There were a few other more minor...