Molar Mac no video no chime no led yes fan after cleaning PSU.

[Trekintosh]

So in order to replace the fan on my Molar, I took the PSU out and it was *filthy*, absolutely caked in dust. So I used a combination of paper towels, Q-tips, 99% IPA, and a small cordless vacuum to clean out most of the dust. While reassembling the molar after replacing the fan, I decided to also max out the RAM and install a VRAM SIM, and install a CD ROM player. Well, after reassembling all of that, I get no chime, no light, and the fan runs. No degauss either. Ok, don't panic, maybe it doesn't like the RAM. I brought it down to one stick and removed the VRAM SIM, no change. Removed the CD ROM, no change. I get good voltage on the +5 and +12v rails. I don't get any voltages of note on the neck board. Tried removing all the RAM, no crash noises or any other change. Tried random sticks in random slots, no change. Reseated the voltage regulator, ROM, and CPU a couple times. No change. Reseated all the PSU cables several times.

My guess is somehow the alcohol hurt something, the vacuum hurt something, or I damaged something with my aggressive Q-tipping, or the RAM or VRAM totally borked the logic board. I'm gonna try firing up the LB with an ATX power supply tomorrow, but I'll take any advice in the meantime. Any schematic for this power supply would be helpful.

 

[croissantking]

It’s probably something really minor, like you bumped something or forgot to reconnect something. Don’t panic - have a breather, then go back and look everything over.

 

[Durosity]

Make sure both the connectors on the personality card are connected, the AIO will do that if they’re not!

 

[Trekintosh]

Aaaand it's back. I have 3 guesses as to why

1: cracked solder joint and *this* reinstallation and cable reseating was the one that got it right.

2: some alcohol was shorting something out, maybe in transformer windings or under a component, and it fully evaporated overnight.

3: some capacitor was holding onto a charge for a setting it didn't like and it took sitting overnight to discharge despite me resetting the cuda chip with the button.

Ive since installed both the RAM and VRAM upgrades and it seems happy now.

 

[jovianartifact]

jsyk, vacuums can absolutely hose sensitive electronics- the immense amount of moving particles (air molecules, dust, etc) against the walls of the vacuum pump generate a shitload of static charge. i had to learn this the hard way after i absolutely murdered a pristine dell dimension that booted fine before i "cleaned" it.

 

[nathall]

I’m an electrician and electronic technician (specialized field) by trade, and it seems like I get at least one call of “my point of sale was running slow, so I opened up the server and vacuumed it out and now it doesn’t work” per year. For exactly that very reason. (As if dust bunnies cause a computer to run at a reduced speed.)

I always get a perverse pleasure in telling them that in an attempt to save $100 from calling someone to address the actual slowness issue by trying to “fix” it themselves, they now are going to have to spend $5,000+ in specialized proprietary hardware in order to get their business functional again.

My rule of thumb, NEVER use a vacuum on computer internals because of the static risk. Compressed air only.

Also, 99% IPA shouldn’t be conductive enough to short anything out. I’ve powered up boards with 91% still visible in wet spots on boards without issue.