Odd behavior Pcengine DUO with original power supply

[adolobe]

I recently purchased a Pcengine Duo off ebay that was listing with sound issues. Knowing in advance that the most common audio issues are regarding the caps, I purchased a cap kit form Console5. I know I could of ordered my caps myself for probably half the cost from Digikey but I like to support places like Console5 and he has done a few customs bios programmings for me in the past so its money well spent in my book.

After I replaced the caps and inspected all the traces, luckily the corrosion was minimal. I fired up the Pcengine Duo with Dracula X. Audio was perfect but someone of the sound effects were missing and the system would occasional freeze up on me. So i double checked all my caps and all the chips to make sure there was no damage to any traces from possible leakage on the underside of the board. Nothing was found out of the ordinaly.

Out of a last ditched effort I tested the NEC power supply and it was putting out 15.8 volts at the plug. I checked mutliple locations on the board and everything was reading correct voltages after the regulators.

So I hooked up a $4  9.5v 1.5A power supply from china that Ive used in the past for Sega Model 1 and Atari Jaguar systems. I had a few tips that fit the Turboduo since I ordered a 10 pack a few years ago and tested this power supply on the PCengine Duo. Everything worked great, no missing audio and no freezing even ran the systems for 48 hours with out issue.

So my question to the experts here is do you think the NEC power supply is damaged and what is the voltage one puts out when not hooked up to a system drawing current?  Like I said earlier I only have issues with the PCengine Duo when hooked up to the original NEC power supply and none with the one I hacked together.

[mickcris]

Mine measures 14.06v (usa supply at 120v) with no load so yours is probably in the range of being normal since its a 100v supply. 

Not sure what the problem could be though.

edit,
Missed where you said you measured it with a load.

[SignOfZeta]

Power supplies don't last forever.

[bust3dstr8]

Those power bricks have caps in them as well. As they degrade the ESR shoots up and so does the AC ripple.


This is a common problem in Genesis as well. People will recap the Genesis and then feed it dirty power from an old power brick and still have problems.