Re: Sony STR-AV19 Left Channel weak when quiet?
I finally figured out what the issue was. The speaker protection relay has bad contacts. I've by-passed it for now and will eventually order a new one to replace it since cleaning the contacts didn't help at all.
macjedimatt
Member
Last Activity: 01-11-2021, 03:01 PM
Joined: 05-25-2012
Location: Dracut, MA
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Sony STR-AV19 Left Channel weak when quiet?
I have a Sony STR-AV19 that works great when the music is on the loud side. But if things get quiet, I start to loose the left channel. It gets quiet and a little fuzzy sounding. It does the same thing no matter what the physical position of the volume knob is. It also seems to get worse if I have it running for a couple hours. I've had it taken apart and I don't see any visible damage. The service manual is available here:
Does anyone have any ideas where I should start looking? The volume knob sounds clean, so I don't think it's the potentiometer.
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Re: Peavey KB100 popping and thumping with humidity
Finally got it all fixed! Last night I discovered that one of the small NP caps in the EQ circuit was the culprit. It had a bad solder joint. I found it by poking the board with a marker while listening to it through headphones.
Thank you for all of the suggestions!Leave a comment:
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Re: Peavey KB100 popping and thumping with humidity
Yes. I'm going to have to get back to this tomorrow. 4AM comes awful fast. Thanks for the help so far!...Leave a comment:
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Re: Peavey KB100 popping and thumping with humidity
Ok, just discovered that flexing the pan that the board is attached to is causing it... So it probably has a bad joint or damaged trace somewhere that I missed.
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Re: Peavey KB100 popping and thumping with humidity
Confirmed. Signal patched in, headphones on the pre out, and a blank jack plugged into the pwr amp in. Thumped in the headphones. I think my neighbors like this test better :-) Now the question is, what the heck would cause this?...Leave a comment:
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Re: Peavey KB100 popping and thumping with humidity
Just put the meter on the 15v lines. -15 was -15.2 and pretty rock steady. +15 was 14.8 and also steady. Not sure if my meter just wasn't picking up the spikes though.Leave a comment:
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Re: Peavey KB100 popping and thumping with humidity
I did some more testing tonight:[LIST][*]Going straight into the PWR AMP IN = Clean with a couple faint clicks that could have been line noise.[*]Headphones on the PRE OUT = Heard thump in headphones and speaker[*]PRE EQ Patch in only = thumped, seemed to do it a few times also when messing with the EQ knobs.[*]Bypassing the reverb coil = still thumped.[/LIST]
I've attached an annotated schematic with what I have tested so far. At this point, I feel like the main power amp is probably fine. I'm not sure if it is...Leave a comment:
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Re: Peavey KB100 popping and thumping with humidity
So I have finally replaced all the capacitors and it doesn't seem to have gotten any better. It thumped a few times in the first minute or so of turning on. I hooked some tunes up to it and caught it in action on video: [URL="http://youtu.be/zjHkZr2dD54"]http://youtu.be/zjHkZr2dD54[/URL]
No combination of turning/pushing/pulling on the knobs seems to replicate it reliably. Also does it with no source connected.Re: Peavey KB100 popping and thumping with humidity
So I have finally replaced all theLeave a comment:
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Re: Peavey KB100 popping and thumping with humidity
I think the COMP led is "Compression" it lights up whenever it thumps on power on, or when it pops/thumps due to whatever is causing it to do that. I can't find a manual for this particular version. The one in the Peavey archive is for the newer version that has the XLR jack on channel 1, and no COMP light.Leave a comment:
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Re: Peavey KB100 popping and thumping with humidity
The attached PDF is the closest I could fine to my version of the amp. The COMP LED is connected to a 4558 amp on the lower left of the schematic.
Right. I think on this one it would be R111. I'll check it out tonight.
Thanks!...Leave a comment:
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Re: Peavey KB100 popping and thumping with humidity
A Canon EOS 20D. That one was using a fixed 50mm lens....Leave a comment:
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Re: Peavey KB100 popping and thumping with humidity
I've finally got it and taken it apart. I've gone ahead and pulled all the electrolytic caps. I'm going to start with replacing them and I plan on inspecting the solder joints while I put them in.
Some observations:
- The COMP. light is always very faintly lit.
- The power light isn't particularly bright.
- It thumps when turned on the first time.
- The PCB is a very cool design.
Pictures attached. Any other questions or recommendations welcome....Leave a comment:
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Re: Peavey KB100 popping and thumping with humidity
budm, That is the "newer" version of it. I have the 1984 which is slightly different. Hoping to get it apart and post some pictures Tuesday night.Leave a comment:
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Dell 2407Wfpb that is working fine... for now.
I have one of these guys that is actually working fine. Should I replace C605 just to prevent it from eventually killing the rest of the board? Anything else? Any recommendations appreciated. I've already "repaired" three of these by wiring in a Dell PA9 laptop adaptor. -
Re: Peavey KB100 popping and thumping with humidity
Well, it is still at the church. I hope to get it home this weekend and take a look at it myself. The shop that looked at it claims to have already re-soldered a bunch of it. We'll see about that.
I was able to get the schematic and the Peavey parts department has sent me a list of all the capacitors with part numbers and pricing. I doubt I will have to replace all of them. There are about 20 100pF and 0.1uF caps in there. I'm thinking that maybe the power filter caps (2200uF/50V) could be having a problem. But without...Leave a comment:
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Peavey KB100 popping and thumping with humidity
I have a Peavey KB100 keyboard amp that works great most of the time. However, for the past couple years, when things get humid, it pops and thumps periodically until it warms up. I have taken it to a musicians repair shop at the suggestion of my musical director but they can't find anything wrong with it. I'm wondering if I should just go ahead and re-cap it. Does this sound like something that could be caused by bad caps? It is at least 20 years old so I suppose it is possible that even high quality caps could be wearing out. Any other thoughts? -
Re: Dell 2407WFPb Monitor - Bad Cap
For those of you keeping track, I figured out what was wrong with it. The Dell PA-6 power adaptor I was using just couldn't handle it. The markings on it are very different from the other two I'm using so maybe this one just isn't made as well
I switched it out with a PA-9 and it works great. I also found a base for it
This makes three of these monitors I've fixed now. I have two using the PA-6 which is a 70W powersupply and one using a PA-9 which is 90W.
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Re: Dell 2407WFPb Monitor - Bad Cap
Hmm.. Ok that is good to know. I did this one the same way I did the other two I have done and they both work fine. One has been running everyday for over a year. I noticed that the PA-6 power supply cuts out when I connect the power board to the main board. The main board is fine. I tested with parts from one of the others.
It is good to know I didn't kill the board! I'll have to do some more testing. It could be the particular PA-6 I'm using. I noticed the markings on it are different from the others. Does anyone have a pin out...Leave a comment:
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Re: Dell 2407WFPb Monitor - Bad Cap
No. This was the same failure. After successfully fixing 2 of these, for some reason I thought it would be a good idea to cut the small wires on it. I thought it was connecting to the AC side of the board. As soon as I did it, I realized what that part was for
The damage is a little beyond what I can manage to repair safely. It doesn't look like something I can find easily without more information, which I haven't been able to get. I suppose it is just as well. This panel has a scratch on it and the stand is missing.
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