Left sound channel on A1200 gone
I recapped my A1200 rev 1D.4 with all new SMD caps (didn't change the through-hole ones), and exchanged the two sound caps with non-polarized ones... Now I only get sound in the right channel! I checked the solder connections like 25 times, and the polarity of the other SMD caps too...
Looks to me like the sound error is in the other caps somewhere, what caps should I check? The two non-polarized ones under the sound RCAs are already checked... :( |
@8bitbubsy
time to get mr multimeter out m8- firstly I would check if there is a ground issue with the left audio, then check before the cap, replace the cap if need be you may have a dud.. |
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I really think that the issue lies in the other SMD caps, but I don't want to spend one hour on each of them - therefore I ask: Does someone know which of the SMD caps (except the two under the RCAs) that's for the sound circuit? |
Take your multimeter and set it to resistance and put the leads across each cap.
It should start off with a low value and then increase to a few K or more. If it starts low & doesn't move, that means there is a solder short, probably under the cap. |
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Measured all the caps, they went from low to higher.. EXCEPT one cap, that didn't react at all - I guess it didn't get contact, I'll try to resolder it and tell you how it goes. :) |
:nuts
The cap makes the multimeter beep once, then it shows 1419 quickly, and goes down to 1... This is the ONLY cap (polarized) doing this! Is it destroyed? It was brand new :( No matter what pin I put - and + on, it does this... Weird! Tried to desolder it and measure as well, same... |
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If you have done everything correctly, then the capacitor is useless. This is not unknown with new capacitors. All it takes is poor QA. :rolleyes |
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EDIT: Still same, it measures like 1400, then fast down to 1 :nuts: ... I did still exchange it - no sound in the left channel still :( |
Small value capacitors will do this. They charge pretty fast.
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Perhaps the one that you grabbed from your broken A1200 actually has the same fault. |
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The A1200 have been playing a cracktro for like an hour now, it works very good, except for the lack of sound in the left channel. :crying |
check 1200 schematics and find paula raw outputs. solder some wires there and see if you got sound. from there check the routes till it gets to audio filter. eventually you'll find where it goes off.
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If I unplug the right RCA, I get sound in the left RCA! But only the right channel's sound, heh.. So that means that that problem is lying a bit before the filter/amplifier, I guess....
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Is that sound in the left channel all the time, but it's drowned out when the right channel is connected so you can't hear it?
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@8bitbubsy
you have a groudning out on the audio circuit... at this point I would pull all the caps, clean up and start again.... check at each stage m8. |
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Sounds like the issue is very early after the paula chip EDIT: When both RCAs are in, the sound in the right is high. If I unplug the left RCA, the sound in the right is getting lower o.O EDIT2: If I plug in my 030 acc, all I get is a blank screen... Seems like the caps are important for several things :crying |
I had a similar problem, with the problem i had was the trace from the left channel capacitor runs underneath the right channel cap. The caps leaked and wrecked that trace.
to check you can run a jumper wire from pin 1, U15 to the +ve input of C324 (the left channel cap. (pin 7, U15 goes to right channel cap) If when you run the jumper you hear the sound coming out and both channels sound equally loud then you will know that there is an open wire between U15 and the cap Edit... Be careful, shorting out this chip when attaching a jumper can destroy Paula!! |
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oh poop.... my apologies... you are talking about the 1200... Lemme look at the a1200 schematics sorry:shocked edit... K. the A1200 still uses U15, i'll locate it on the board for you... Rev 1D has it but i cant locate it on my Rev 2B ? thay must have made changes to the board |
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