PC Engine Duo and it's (ahem!) hot date with the dishwasher....help, please!

[agt_dale_cooper]

OK, got a PC Engine Duo whose board is about to go in the dishwasher.  I've replaced most of the caps on it and still have no audio-related Redbook or ADPCM love...had to refund my buyer for it this morning due to failure during post-switch install testing, and now I'm mega pissed.

To whomever has done this before, please suggest settings.....water temp, cycle length, etc.

From reading previous posts that mention this as a potential fix, I've gleaned the following:

1)  Don't run the dry cycle [excessive heat can turn your board into a 360-like nightmare [funny how the RRoD terminology/analogy has crept into our vocabulary!]]
2)  Use a certain bit of soap....7th Generation, due to it's apparent lack-o-crap ingredients...
3)  Remove laser (duh)
4)  Remove all previously reinstalled caps and try again
5)  Insure that all saves are backed up onto a Tennokoe, if desired...washing MAY equal loss.

Any other thoughts?  Any help appreciated....thanks!

[nat]

Only thought being you shouldn't have to remove any caps at all, regardless of whether they're original or not. Unless I'm misunderstanding your #4 there...

[agt_dale_cooper]

How about settings for the dishwasher?  [Not something I ordinarily use, or I wouldn't be asking..]  Hot water, I assume....cycle length?  7th Generation soap?

I'm gonna pull the caps on the general 'maybe something is cross-wired' principle, not to mention getting any electrolytic crap out from underneath the soldering job....a fresh set of caps are on the way to reinstall as well...

Further thoughts?

[spenoza]

You might not even need soap. Hot water at great force tends to clean pretty well on its own. Sure, the dishwasher's no pressure washer, but then you DO want to have something left on the board.

[Duo_R]

I took Nat's suggestion and used the 7th Generation - lemon scented (ahhhhh). I ran 1 cycle with soap, 2 with water only. Water was hot, but set to air dry.

After the soap cycle there was some soap residue stuck between some of the pins on the chips. It seamed to stick where there was alot of gunk. I busted out a toothbrush and dipped in mixture of rubbing alchohol and water. Cleaned that up really good, then ran with 2 water cycles.

Strange part is - I didn't lose my internal memory saves....

[agt_dale_cooper]

There we go...the voice of experience.  Thanks!  Will get this done sometime this week, see what's what, report findings.

[agt_dale_cooper]

No dishwasher-related love going on....have white funk caked inbetween the legs of some ICs.  NOT good.
Tried scrubbing with my new 91% and toothbrush, but this didn't do anything to it..
Gonna rerun through different dishwasher in the next day or so....
Anyone have experience running top or bottom rack?  I ran on the top, which I assumed was for more delicate things....if nobody sounds off, I'll try the bottom rack....
Thanks for continuing help, once we establish a good methodology, we should sticky this....[do we have this ability here?  I don't see any other stickies]

[Duo_R]

I had a couple of chips that white residue between the pins evan after 2 water only runs. I used a needle to carefully scrape out the gunk. Also I washed mine bottom rack. There have been other threads on how to do this, think one of them was "odd sound issue......." or something.

[nat]

That white stuff is harmless. It's residual traces of some kind of glue they use in the manufacture process. It was there before, it was just a different color (clear or slightly translucent brown).

[agt_dale_cooper]

Well, finally got the thing back together again.....one thing I learned along the way:  blow the power switch assembly dry with canned air so it doesn't rust itself closed.....mine did, and I had to clean with CLR then alcohol...seems to be working fine now, it's in the dish drainer drying out again...

Also, Nat was right about the white gunk between the chips on the backside of the mobo...it's just funk, clean if you're OCD.

[Duo_R]

Dale - based on the other posts that I read (mostly from NAT) I blew the board out with a compressed air can, got ALL The excessive water out (including the power switch). I then sat the board at an angle in front of a large box fan (like 3X3) and had it there for like 3 days. I rotated the board (flipped it over). Sucker was dry.

Yeah, when it comes to cleaning the PCB, I go OCD on the bitch. I want to be able to eat off the friggin thing after I am through! Go "like new", or go home! 

[Michael Helgeson]

The white stuff itself is actually due to hard water issues. The white stuff is due from water minerals primarily consisting of calcium, and magnesium  metal cations, and other dissolved compounds like sulfates and bicarbonates. Its not stuff you want to leave on a pcb. And yea it'll stick to other old dried up residue, ect. Ive seen people post pics too of it layering the bottom of the arcade pcbs, all the smooth areas, due to their water being so crappy. Its really bad if you use well water as your water source of water for your home and you try to wash a pcb. If you really want to get rid of it, get some distilled water, heat it so that it will be warm, and use it and a tooth brush and scrub away like there is no tomorrow along with alcohol in the scrubbing process. Thank god I don't have this issue with my water here, but evidently many others due it seems? I guess it just depends on where you are located,how good your city water is quality wise.

[agt_dale_cooper]

Yeah, water quality SUCKS here, I thought that's what the funk was.....but, apparently it doesn't conduct.

Anybody ever try CLR (C alcium L ime R ust remover) on a motherboard before?

I used it to unfunk my switch this afternoon, followed with a nice chase of 91% (and a good blowing off with the compressed air) in case any of it felt like sticking around......does not appear to have damaged the board in any way......may try scrubbing down these white bits with it and the toothbrush (if it's calcium/whatever deposits, it should burn right through them....), see what happens.

[Duo_R]

be really careful with these old boards. Using 90% alcohol on an old PCB like the Duo WILL start to remove some of the outer layers of the PCB (the green surface will start fading away, and you will see copper). That is why I recommend diluting alcohol with some water if needed. CLR is pretty strong stuff, it is not my recommendation to use that on a Duo PCB.