Amiga 1200 sound issue

[sturulez]

I've recently purchased a ACA 1221 Accelerator for my 1200. I have had no issues with it so far until now.

The other day I was playing a game and noticed the sound wasnt very clear from one of the speakers in the monitor. My first thought was the connections either in my amiga or in the back of the monitor were not secure. I checked all of these and they seemed okay.
My next thought was maybe the speaker in the monitor wasnt working properly. So i purchased a audio cable adapter and pluged some PC speakers into the amiga. This had no effect and the issue was still present.
Next I plugged in my amiga 500 and loaded up the same game and there was no issue, I even tried it with the PC speakers and they worked fine.

So I pinpointed the issue was on the A1200. I thought I would remove the accelerator and load up the game. I then noticed the issue was no more.

So it seems the ACA 1221 is causing an issue.

Does anyone know how i can resolve this issue if at all possible?

Thanks

[Oldsmobile_Mike]

I think the accelerator is a false flag. Poor sound and erratic sound are a known issue with failing caps. Get those replaced first.

[paul1981]

Do you have another power supply you could try? What exactly do you mean by poor sound? Are there any fans or anything running off the 12V? The audio curcuits use the +12V and -12V supply rails.
What revision is your A1200? There's a video on YouTube I recall whereby the chap was investigating distorted audio on a 1A revision board and the problem was that the audio was too loud which was distorting the inputs to the amplifier/tv audio in etc. He discovered that the board had incorrect smd resistors fitted in the opamp circuit which he duly corrected. How does the volume of your A1200 compare with your A500?
Other than that, yes caps are a good start and the audio caps are known to have caused distorted audio on those machines where audio caps are leaking.

[StormLord]

As said above,
first check your power supply, and then recap the old beauty

[sim085]

I would also first check the power supply. I once had a sound problem and I traced it a disconnected wire in the power supply (I had a hack to convert PC ATX to amiga power in my case).

[Acill]

Even if you find it's  the power supply get it recapped. Lots of people on  your side od the pond do it.

[Pat the Cat]

First, bad +12 and or -12V supplies are known to affect all Amiga's  sound. Paula uses them, and as well as being a digital sound chip, Paula  also handles the serial port Tx and Rx pins. So checking those pins are really giving  out those supply levels from the power pack are well worth it.

Second,  A1200s have a few capacitor changes, originally from the days of CBM.  This has been tested and tweaked over the years, but was originally  intended for compatibility of accelerator cards.

http://ianstedman.co.uk/Amiga/amiga_hacks/A1200_Mobo_fix/a1200_mobo_fix.html

So  that could indeed be where the problem really started. It would also partly explain why CBM never released an "official" A1200 accelerator.