Just bought this amp for £10. Reverb pot acts like a volume pot on both high and low inputs and treble pot has high pitch whine when turned up above half way, but only on low input. Any help would welcomed.
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I would clean the jack switches with DeOxit. You can pull a small piece of paper through the contacts to clean them as well.
See what signal you get at the effects-loop jacks, the Send and Return.
It might have no dry signal, only reverb signal and that is what you are hearing.
The schematic is half a page, where is the rest? -
Tested all the weird looking grey caps and didn't get any readings from these ones, in either direction c1 c11 c12 c13 c14 c17 c21. All the others gave a reading or started charging up. I cleaned all the pots and put it back together and all my problems went away. Don't know if I disturbed something or just got lucky. Thanks for your help, I will update if anything changes.Comment
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Crazily I happen to be working on the same amplifier; although mine is the mk1 (no green on the control panel ).
You can do me a favour, I need images of how the power amp links to the control panel pcb, and the power amp wiring generally, colours, etc.
. Regarding your amp, I notice the reverb output cable to pin 8 is missing (it's the reverb ground wire- there are 4 connections to the pcb from reverb tank, in out shield shield). That would account for the noise floor you're getting when reverb turned up. Those accutronics reverb tanks , they corrode bad, so flaky sig/ground connections can fuck up the reverb or make it sound ghostly quiet, etc, etcComment
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Thanks for the info, hope these pics can help you.Attached FilesComment
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I resoled the reverb output cable ground wire to pin 8 and now I've got the reverb pot acting like a volume pot again on both low and high gain inputs. Also the treble pot has a high pitch whistle on the low gain input at any setting, but is ok on the high gain input.Comment
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Yeah, mine does that too... ..and mine cost £20!! In the case of my cobra 90, this is probably due to the lack of proper power amp section. When the signal is sent to the power amp, there are smoothing caps and god knows what else, preparing the signal before it goes to the output. I don't have any of that, so it sounds like dirt.Comment
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also I found the suzz/gain and reverb controls all affect each other- even with a previous carlsbro amp which was fine. A bit unpredictable, you could sayComment
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Just took the reverb tank out and checked everything was ok, when I put it back in I reversed the input and out put connectors and everything works as it should now. Think someone must have put them the wrong way roundComment
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On this Vizio D65x, the volume will change on its own. I don't mean like during commercials where the volume will increase. I mean its like the (+) volume button on the remote is pressed and the actual volume dialog is displayed on the screen going up. It will do this, then the volume may start going down. It might go all the way to "0"or it might stop at a different number, then start going back up. The whole time its doing this, the volume dialog is shown on the screen.
It wont do it until it has been "ON" for 20 or 30 minutes, so it does seem to be heat related.... -
I have a strange fault on a Sony amplifier. The volume control varies the display from MIN, then 1 up to 30 and then MAX as expected. At MIN there is no sound. However, at 1 it is quite loud and increasing above 1 does not change the sound level.
I have tried a Cold Reset as per the service manual.
I have looked at the I2C clock and data to volume control chip IC501 (BD3499FV). Data is only sent to IC501 when the volume is set to MIN or 1. At any other setting no data is sent to IC501.
I have looked all the way through the service manual and tried many online... -
Hi,
I bought a used Marantz SR5007 and it's giving me some issues that I can't seem to really place. It functions well in most settings, ARC mostly works, it has no issues driving my speakers in any of the digital input modes, but I'm having issues running analog inputs in direct or pure direct mode. For some reason in this mode there's distortion for every volume increment I give it, but once the volume is stable it has no issues. Muting creates a loud pop, switching to another source also causes a pop and so does turning off the amp in that mode. Again, no issue in the digital modes.... -
I have this soundbar and when I turn it on it works until I turn the volume above 30.
Then the display show “PROT” protection and shuts off.
I can turn it right back on and it works until volume hits 30 again.
There is a little static on the surround speakers so I unplugged them but still have same problem. I tried unplugging all speakers also and when volume goes above 30 it shuts off.
I can turn the volume above 30 if nothing is playing but as soon as I play something it shuts off.
It will play fine for hours with volume... -
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