Yes... dishwashers work fine for electronics and cases and well... everything that isn’t currently retaining an electrical charge.
The trick is making sure that you immediately remove water from every tiny spot.
While his method works, I prefer to flush the circuits with quick evaporating contact cleaner afterwards.
I’ve never used a hair dryer on circuit boards. Flushing with electrical contact cleaner that immediately evaporates seems more effective. If I can blow water with a hair dryer, that means I haven’t flushed it all out. I wouldn’t personally rely on a hair dryer being effective enough.
And I also tend to prefer using a shower sprayer instead for the water part. There really isn’t any need to introduce soap.
Usually I’ll dismantle cases and spray them separately in the shower with a shower wand.
And let them air dry. Hot water accelerates that. And I have used hair dryers. But on cases, I find automotive air compressors (industrial sized) with air spraying nozzles to be much more effective.
Keyboards are perfect for dishwashers. Just make sure you dry between the plastic sheets and rubber contacts they now use instead of old-school scissor switch contacts. Unlikely to be any harm, other than it registering the wrong key press until you actually dry between the sheets.
We’ve been using dishwashers and showers for decades behind the scenes.
Water only causes damage if left sitting to rust or if it’s in contact with a charged component. Never apply power unless you are sure there is not any water.
Also remember that some capacitors retain a charge long after power has been removed. Watch out if you get into old stuff with the quite dangerous “flyback transformers” (those are interesting enough without water).
And as always, anything you do is at your own risk. Better yet, don’t do anything.
Yes, the contact cleaner is nice because it flows through everything. And therefore can flush out the water you don’t see and then evaporates. Leaving nothing behind (except perhaps a smell).
Hair dryers push water away as it heats it to evaporation. The problem is you don’t know if you’ve actually gotten rid of all the water, or if you’ve just pushed beads of water into places you can’t see.
And those tiny little beads of water in tiny tight places can stay moist for days sometimes.
I have a pretty extensive history with vintage electronics. I used to do a lot of custom designs and circuit boards. I don’t have any remnants of old tech anymore since I sold my company.
I do miss it sometimes. And if you were closer, I’d enjoy working with you on some of your equipment. I love circuit work and soldering and customizing.