[SOLVED] PC Engine Duo - No disc spin: not pots and new laser?

[beepinghazel]

Since last week:

Washed the board in soap/water with full dry, system still behaves as before. Laser lights up but no focus attempt by laser.

Replaced several questionable-looking SMT resistors. They all tested fine once removed from the system, replaced with new SMT resistors. No change. Laser still does not try to focus.

It appears that whoever owned this system before replaced several resistors that appeared to be damaged - the stock resistors are marked 103, the new ones are blue and marked 1002 (both 10k Ohm).

Sanity check: What should R295 be? Should it be a 390Ω resistor?

I re-checked the board with my multimeter continuity checker still cannot find a single broken trace or bad contact.

Those missing are normal
The BA6290 is a current input chip, so you won't really see a voltage shift on its inputs
It's outputs go directly to the laser

Any suggestions on where to look for signals that focus the laser vertically?

Or is there anyone with a working PCE Duo willing to post photos of their motherboards? I wonder if the person that tried to repair the board before me replaced a resistor incorrectly. Hell, I wish there were a parts manifest.. something.. anything.

I'm not certain where to track down the signal that focuses the laser unit. I see the pulses for it (see my previous posts) but I don't know the system well enough to track down where the breakdown is..

Thanks again for your help.

[thesteve]

try replacing the BA6290 on top of the board
the one by the plugs runs the 2 motors and the other runs focus and tracking directly on the lens

[leonk]

Silly question:

How does washing the board might make it work? I recently did a cap kit on a Duo (cleaned all the pads from old solde; it was cleaned with qtip and alcohol). Added fresh solder and tacked down new caps. Everything worked except for disc.

Ended shipping it to theSteve and he said all he did was wash the board and all is well now.

[MNKyDeth]

The electrolytic fluid from the caps is conductive.

If you done get it all gone from the boars,  traces and thru-hole locations that go from the top and bottom of the board it can create shorts.

Very hard to troubleshoot until a good wash has been done. Usually after removing everything from the motherboard is when to give the entire board a bath. But washing with new caps should be fine as well as the caps are sealed. The old ones most likely not anymore from the leaking etc.

[leonk]

good to know. So you soak it to warm soappy water, use a soft brush, rinse it again and let it dry. correct?

What about the super cap for memory backup? It's got voltage stored there!

[MNKyDeth]

I have never cleaned a board with caps on it. So I can't say if or what are any bad effects of doing this.

I don't have a dishwasher so I literally give my boards a rubbing alcohol bath. I then go over the entire surface top and bottom with q-tips and an old toothbrush.

Once that is done and the board is clean any thru hole location that had corrosion around it or is black I then make sure to pay attention and clean them all put and sometimes even put cap legs thru them and solder them in place.

Then I put the new op-amps,  7805's and caps back on the board. Then any mods people want. 

[leonk]

why would you replace the op-amp?

[beepinghazel]

@thesteve - thanks, I've got a couple on order. Will reply once I have them in.

[thesteve]

the caps go through the wash without issue, i pull them first if replacing just to get a better clean under

[MNKyDeth]

why would you replace the op-amp?

There is usually a lot of leakage around three of the op-amps. When I take them off to clean under them I usually just replace them. 4558 op-amps are rather cheap so to me it's usually a negligible cost.

[beepinghazel]

AMAZING NEWS!

I got a pair of BA6290 and replaced the ones on the board. I can now play an audio CD (sort of)! It's definitely having some trouble dialing in the later tracks (it switches to "disc change" after a bit). The first tracks come up pretty quick though.

Edit: The laser lens started trying to focus immediately after replacing the two BA6290, which it had never done before.

I tested my copy of Valis IV, but no luck with that (not surprised). Going to work on the pots next.

THANK YOU thesteve! Not quite working but definitely an improvement!

[beepinghazel]

So far so good! Got Valis IV to load properly. Working on the gamepad at the moment. These pot settings seem to work more or less "ok" with the new HOP-M3.

[thesteve]

Turn VR103 about 90' clockwise and you should get better results

[beepinghazel]

@thesteve 90' turn seemed to help. The CD player seems to spin more slowly and at a constant rate. I was even able to use a CDR without any issues.

There is a slight whining coming from what I think is the motor that spins the CD. You can hear it here, but it's very faint ( http://sendvid.com/lqee7hsk ). Is there any way to lubricate or even replace this motor? Does anyone know the part# for it?

I didn't re-lubricate the metal rails after replacing the HOP-M3. I've read that white lithium grease works well, but others have suggested molybdenum disulfide grease or teflon grease works. Any suggestions on what to use?

I'm trying to make any final maintenance changes to the base system before moving on to RGB and region-free mods. Any other suggestions are appreciated.

[Keith Courage]

Turn V104 slightly (clockwise) or turn V103 (counter clockwise) to remove whine.