DIY Audio Projects Forum

Need help choosing right caps for amp
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Author:  Suncalc [ 22 Dec 2018, 16:46 ]
Post subject:  Re: Need help choosing right caps for amp

I'm just going to state the obvious here. This is something common. Therefore check everything common. This includes your test setup. Therefore speakers, speaker cables, input cables, and input sources are ALL suspect until each and every one of them has been eliminated as the cause (or part of it).

I have personally fallen down this rabbit hole in the past, spending days troubleshoot an amplifier when the root problem was an intermittent speaker.

Just a suggestion.

Author:  kitchi [ 22 Dec 2018, 19:41 ]
Post subject:  Re: Need help choosing right caps for amp

Don't swap channels around stick with one channel in one specific location.
Go though all that is common with all channels.input ,outputs, power supply. Re-solder all connections.Check grounds . I had a wire break once inside the insulation(mind you it was a solid wire ) that caused a bad connection. Also inspect the wiring to make sure that the insulation is intact and didn't rub though on something causing the wire to ground.
Recheck that channel only (ignore other channels as if they were not there)
If you still have the same problem then I would re-solder the entire board regardless if the joint looks good or not.
Pay particular attention when you re-solder the board if something looks odd remove the solder and inspect it.
If you are not sure of something snap a picture and post it.
Hmmmm here is a thought can you electrically disconnect all channels but one?
Better thought can you remove them from the case and still have the one channel working?

Author:  Yungman [ 22 Dec 2018, 22:28 ]
Post subject:  Re: Need help choosing right caps for amp

Pick a channel that seems to always have the problem. Remove all the rest of the amp module and just work on that one and try to make it fail. You don't have the schematic, It's time to check the voltages and get into the circuit.

Contact the manufacturer, plea to them to send you the schematic. You are going to need it at this point of time.

Author:  Yungman [ 23 Dec 2018, 02:11 ]
Post subject:  Re: Need help choosing right caps for amp

Hold on just a second. What do you use as the source and preamp before driving the power amp? I scan through the thread quickly, I did not see you talk about who is driving the power amp. What make you think it's the power amp's fault? You have another amp to try and see whether it gives you the same problem. Or you have another source to test the amp? You eliminated the speakers and the cable that caused the problem. You need to eliminate the source or whatever driving the amp also.

Did you follow my suggestion in the post on 12/16/18? About identifying a good channel, use that amp and plug into another slot and see whether it will fail. Read that post again. This is very important. 4 pages of talk and you have not move forward. Identify one good channel first, use that to test the other slot. You can use this idea, identify a bad channel, move that to another slot known to be good and see whether the problem follows.

You don't happen to have a scope? You have a multi meter? If you don't have any of these, it's going to get harder to troubleshoot. You need at least a multi-meter. At least get a cheap one: Even one that is under $10 is a lot better than nothing.

Author:  mtosh [ 23 Dec 2018, 11:08 ]
Post subject:  Re: Need help choosing right caps for amp

I am sending the amp signal from the pre-outs on two different receivers in two different setups. This is what makes me believe the problem is with the amp.

Home theater setup- Onkyo receiver, Oppo DVD player, Gallo speakers, good properly terminated speaker cables and interconnects etc.

Test setup- Yamaha receiver, Klipsch outdoor speakers, new RCA cables from the receiver to the amp, Sony SACD player.

Two different locations in the house, two completely different setups plugged into different power outlets etc.

The only constant is the amp, and I can produce the exact same results in both locations. This is why I'm not concentrating on cables and source components.

I am a total amateur who has never soldered a board, and I don't own any test equipment. I was considering swapping out the caps as this seemed like something I would be capable of doing. However, pulling apart and re-soldering the entire board is way out of my pay grade.

I may consider purchasing some of the test equipment you referenced, however my concern is that I do this and am still faced with replacing the solder in dozens of circuits/caps and may in the end destroy either my mind or the amp ;)

Author:  Yungman [ 23 Dec 2018, 13:01 ]
Post subject:  Re: Need help choosing right caps for amp

I hate to tell you, At this point, it's the amp that is the problem. I didn't realize you are this green. I don't even feel comfort to suggest you to go deeper. You might get hurt touching the live wires.

The problem must be common to all 5 module, look at the connection one more time from the AC cord connector, all the way to each power supply, use a wood stick to push those wires one more time. If you cannot find anything, that's pretty much the end of the road. Don't attempt to stick your finger into the amp if it is connected to the wall. Unless you can see an obvious problem, this is the end of the road.

Your likely choice is take it out to have people fix it, or dump it. It's going to be hard for people to help you without schematic, you without any knowledge and no equipment.

Author:  mtosh [ 23 Dec 2018, 15:45 ]
Post subject:  Re: Need help choosing right caps for amp

I figured I would give it a shot and if it was something that ended up being less involved than this I would proceed.

I suppose I could always get a decent starter kit and pull a channel to practice replacing the solder. The amp is too nice to dump, might be a fun project over time.

I hope I didn't waste anyone's time, I never take for granted all of the ideas and support you have all offered. Thanks, and if I ever get something figured out I will post the results.

Author:  mtosh [ 31 Dec 2018, 17:13 ]
Post subject:  Update**

Hi everyone,

I figured I would take apart the amp and check things over as I was planning on just getting something new. I noticed something interesting that I wanted to get your opinion on. I took several pictures of these (I don't know what) as several of them appear to be leaking or corroded. Could this be the culprit? I took a picture of one of them that appeared to be OK for reference. They are sitting just above the electrolytic capacitors.


Author:  Yungman [ 31 Dec 2018, 18:11 ]
Post subject:  Re: Need help choosing right caps for amp

It's a resistor, is the stuff dry? I don't think that's the problem if it's dry. If it is wet, then you need to look further.

Author:  mtosh [ 31 Dec 2018, 20:23 ]
Post subject:  Re: Need help choosing right caps for amp

Thanks, it appears to be dry. I will continue my quest. Have a great new years eve!

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