Author Topic: Duo music/cd volume  (Read 147 times)

8bitplus

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Duo music/cd volume
« on: June 11, 2017, 07:13:47 AM »
Hello. I'm trying to fix a black PC engine duo. The sound is working correctly for the HU card games, but very faint for the CD background music.

I have done a complete re-cap, and initially everything worked. Then the next day NO SOUND at all.
After days of poking around I fixed a couple of traces and replaced the 2 op-amps under the board, and the one at the AV jack.

I reassembled and found the CD volume is very low on both the AV and headphone jack.

Can someone tell me which caps and amps are for the CD drive?
Thanks
www.8bitplus.co.uk Retro gaming projects and console repairs

8bitplus

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Re: Duo music/cd volume
« Reply #1 on: June 11, 2017, 08:47:37 PM »
After more reading it sounds like the problem may be related to the M51131L. I have a second fully working Duo and its getting 5v to pin 8 of the M51131L when playing CD music, but this Duo is getting less than 1v.
I'll take the board out of the case again and inspect that area closely...
www.8bitplus.co.uk Retro gaming projects and console repairs

8bitplus

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Re: Duo music/cd volume
« Reply #2 on: June 12, 2017, 09:15:18 AM »
Fixed.
Turned out the OP-Amp at IC521 wasn't getting correct voltage. I linked it to a 5v line on pin3 and the cd music is nice and high again.
www.8bitplus.co.uk Retro gaming projects and console repairs

SonicBlastMan

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Re: Duo music/cd volume
« Reply #3 on: October 08, 2021, 09:17:30 PM »
Sorry to necro but I had this EXACT problem and there was a hairline break in a trace going to pin 3 of IC521, also voltage drop on the same pin

I never would have found that without this thread, a million thanks 8bitplus!!