Aiwa Mega CD CSD-GM1 Mainboard Repair

You bet there's issues! I've queued up four videos for YouTube before I crash for the night with various ideas and demonstrations of the problems and ways to try and fix them.
If I wasn't coming down with a cold or flu or something I'd do more but I just feel like sleeping for a few days / weeks.
Need to work out whether to put the power up or down and on which rail?
I reckon the 12V needs to be increased as when in Mega Drive mode the switch might activate more circuits than are used on normal battery mode.
If the 19-20V readings from the red power cable rail is supposed to be that high, it might explain why there are issues on the Mega Drive side of things when running at 12V.

Right? Back me up here! :loyal:

When I say I got the sound working, I mean at the Mega CD boot screen. Sound from Mega Drive games is still broken.
Capacitors are one idea. But there are so many capacitors on the Mega Drive board, the Aiwa mainboard is a bit less scary thankfully.
More pictures on my website as always under the photo gallery if anyone wants to see the inside of this thing in detail. Up to 2048 on the longest side!

 

Well this one has sat on the back burner long enough.
Was ordering some tantalum caps for another project and figured I should get some other bits and pieces.

Going off the 7806 voltage regulator specs, I should have 11V in and 6V out.
That's correct for one of the units. The other is dead. So I am getting one of those on order to test and hopefully resolve that.

I would have liked to have worked out which voltage regulator the B1064 is.
Using both mainboards with the (mostly) working transformer the outputs are reading as 19V, 8.5V, 19V. Form factor is TO-220.
That's a good thing because it means that both B1064 voltage regulators are outputting the same values...
But does anyone have any ideas what type / model of voltage regulator I am dealing with here?

Here's that video I promised but forgot to include on the last post after uploading completed. Can anyone validate my ideas?

 

Why am I always the last to know about these awesome combo systems!? Great job on the repair, mate! Keep up the good work!

 

They are a strange system aren't they. I couldn't resist picking them up when I saw them for sale.
Even in their bad states I knew they'd be a barrel of monkeys to play with :encouragement:
Thanks for the encouragement! I'll get there eventually, or end up with more char than Charizard himself! Hahaha!

 

Wow I've had these for more than a year now and I'm only just making real progress.

Could a mod change the title to "Aiwa Mega-CD CSD-GM1 Repair [Unit-02]".
I've got a Unit-01 and would love to keep these updated on here since burning my blog to the ground.

Anyway, progress wise, I've worked out how the boards are named.
The first two digits indicate the revisions of the PCB, while the second indicate which board it is.
This thread is now dedicated to the revision 02 unit.

01-01 (Revision 01, Board 01 - Mainboard)
02-01 (Revision 02, Board 01 - Mainboard)
01-02 (Revision 02, Board 02 - Volume Control)
02-02 (Revision 02, Board 02 - Volume Control)
01-09 (Revision 01, Board 09 - Mic Amp)
02-09 (Revision 02, Board 09 - Mic Amp)

I noticed that there was no amplified sound out of the Rev 02 Mic Amp when it was attached.
It seems that without the Mic Amp board there is no amplified sound at all. Perhaps it should be called the Mic / Amp board.
Anyhow, I spotted a few broken tracks while poking around with the old multimeter.
Have a peek and see if you can spot the broken tracks too!





Now I have two good working Mic Amp boards, but have discovered that my rev 02 volume control board isn't outputting sound on both channels evenly.
The left hand channel is fainter than the left and is missing a lot of bass. Solve one problem, move onto the next.
Currently I am testing these boards with the rev 01 mainboard as it has good sound output (but no game unit power).

 

I wouldnt have used wire. Personally I would have just used a fibre glass pencil, removed some of the lacque from each side of each break and just put some solder on it. Looks much tider and nearly stock.

 

While true I'm having a hard time seeing the break in the traces.

 

Believe me this 02 unit is anything but stock. I did remove some of the lacquer on some of the broken mainboard traces, but didn't know there was a specific tool - the fibre glass pencil made especially for the job. I'll add one onto the old to buy list now! Thanks! :loyal: I'll stick with wires for now anyway, it looks like whatever happened to it previously (either dropped heavily or overtightened screw... or both) caused the PCB to snap around the weakest point.

Oh they are there alright, check near the lowest screw hole, the two tracks on either side of it! Not surprising that I missed it really! :victorious:

 

There is a crack in the PCB running across the screw hole on the right - it seems to be crossing 4 tracks.

 

Or a proper conductive repair paint:

http://www.electrolube.com/docs/maintenancemain.asp?id=157

If you use a fibreglass pencil, be VERY careful. Those tiny filings are an irritant and they get EVERYWHERE and can even penetrate rubber gloves. You'll itch for weeks. Make sure you dispose of all the waste filings properly.

 

I dont like the paint on traces, it drys and flakes. I only use it on things where heat is an issue - keyboard membranes etc

 

Since the subject is trace mending, let me drop this H-BOMB here ...

lol
(edit: even I am amused with my lack of humility on this post :stupid:
But the point is show another technique for traces mending, where
a thin naked wire coated in solder is used to mend the trace)

 

Thats exactly how I do it for fine traces too. Larger ones like RJ's - id just use solder.