Pc engine Duo-R one audio channel not working

[edomatic]

Hi Guys,

One of the audio channels has dropped out on my Duo R..

What i tried so far:
verified cable and measured the pinout from board till scart end of the cable, all good there
Verified cracked solder-joint, all good there
Even went with full re-cap but still only audio through one channel

Both channels worked fine but one suddenly fell out

Any sugestions as to where to start looking?

thanks appreciate all the help i can get with this..

[edomatic]

..so far i identified some 'possible' culprits of my failing audio channel but off course i can't know for sure :

Mitsubishi's M51131L (dual channel volume control)
IC's 4558 (Pre-amps) ,there's about 5 of those
one IC 4560 (Dual audio Amp)

The only way i can go at this is to change all these and hope this solves it but i wish there was some other way as this is rather shooting from the hip as i can't know for sure

[edomatic]

Guys ,

I really need your help with this..
I need to know where i can start to look to troubleshoot this one audio channel that is not working, as i understand after some more googling the HU C6270 is handling the sound but i have no pin out nowhere..
Is anyone here able to point me to a starting point for the audio channel troubleshooting on the duo R?

there are no visible problems, i have done full recap but still the channel does not come up
Where should i start looking
Please?

[ClodBuster]

http://lmgtfy.com/?q=huc6270+pinout



















































....just kidding. But that's basically the way I did found it.

Besides, sound is created by the Hu6280:
http://archaicpixels.com/HuC6280

[edomatic]

Thanks Clodbuster!

So it seems pin 17 is left out and pin 18 is right out
At work i have a scope i could use for signal tracing
Is it correct to say if either of these do not output the chip huc6280 is defective? This is where the audio 'starts' right? Before it gets sent to the various preamps and stuff i mean

[edomatic]

issue solved
was cable issue , i inversed 2 wires, the clue i got that led to the solution was from Clodbuster, i was able to trace the channels to the correct pins on the DIN conenctor, there i noticed that i inversed 2 wires, i wonder how i did not see this.. so embarrasing.. i actually made 2 new cables and the one i was using had the issue.... :oops:

Anyways fixed now and got a completely recaped duo R and even did the jailbar fix so future proof at the least ,so many thanks again to you Clodbuster!

Now on to the next issue, removing the high pitch noise noticed on games like ninja spirit and many others
the high frequency noise seems to be a know issue not only limited to the DUO R , but i have not seen solutions for it

i was thinking of trying something like a high frequency notch filter on the audio channel outputs to filter out  just that offending frequency

To be able to do that i will need to get the scope from work to determine first what frequency it is exactly

[ClodBuster]

You're welcome! And I'm glad you were able to fix the problem. Thanks for documenting your repair by letting us know what was wrong. I wish I had a scope, there are some things for sure I'd like to tinker with if I had such a device.