Try it!!!! (Was - Re: One More PCB Dishwasher Question)

From: Bob Shannon <bshannon(a)tiac.net> soldered anymore). Older ones were effectively sealed units with a removable screw opening that was sealed with an O-ring. Those stand dishwaser just fine. Of course many computers never have anything like a TCXO on them. through the after its in This is to be expected with any sealed part or temperature sensitive part. Then again a reflow oven is far hotter than a dishwasher. mild like dishwasher, Actually caps like that are likely to have failed from age by now. Systems that used them are likely quite old and not of the easily dishwashed contruction for mechanical reasons other than components used. but there more common technology, any very real Modern as in PDP-8/11/ and vax series, flip chip and similar are certainly cleanable this way and likely were in the factory back then too. Older modular constuction of a more hand wired era may be not suitable. Then again most of the DEC wirewrapped backplanes would likely survive a dishwash but, it may be ill advised as they are mechanically fragile as those that have worked with them know. control. Is have been do know and allow Generally domestic hotwater never exceeds 160f due to scalding risks for the users. Some dishwasers have reheaters to compensate for low domestic water temps but they still only shoot for 160ish (F) max, and often that can be turned off by using the economy cycle. The bake dry cycle should be avoided if there is one (or too warm). One thing we ar not talking about is temps near boiling (212f) or water that hot. a heater Usually for dry cycle, sometimes powered to compensate for low domestic water temps. Econco cyle turns if off more often than no. bath water is maybe 105-115f (Very hot!) FYI. People are susceptable to harm with water over 130f. may have mechanical, No, internal bonds for the parts can take that shock and likely 10X that all day. External bonds??? We are talking soldered boards not wire wrap or really old MIL spotwelded. components here way, how can will be safe Most of the components are of the "open" contruction and not suitable or the problem of assuring they will dry needs addressing. The average printed circuit construction used in computers often does not contain them or they are designed to allow for that kind of cleaning. Parts I worry about and see: Pots (variable resistors of enclosed design) small relays of non hermetic design DIP switches (may need replacing anyway) Power upplies in general, (other than potted units). amplifiers, do (like safely, through your Soldering is high stress compared to 160f water. Also of they are socketed then by all means unplug them first then was the board. Most quartz crystals however are hermetic and can withstand significant amounts of heat. Again oen design parts have to be evaluated, most tolerate wetting well if properly dried before use. A core memory sense board fo the PDP-8e/f/m design and era tolerate this very well, then again they are of modern design. I have done it to several with at least one comming out working where it didnt' before! Cleaning prior to troubleshoot was to make life easier in that case but instead removed whatever debrie causing the inital problem. Something from the PB250 era would be more suspect, mostly due to a multitude of other reasons. I've done it as well to the PDP-8/f front pannel (rotary switch and many lamp sockets) with excellent results. It's still working well over two+ years later. dishwasher. If take the That first half is fair advice, be sure first. The second half is faulty however as there are just as many parts that will not tolerate IPA for extended times or the residue that may be left behind if not adaquately rinsed. It's fair to use caution but, to be a nelly maid over it is usually not warrented. Allison