exxos's Atari, Amiga & retro forum

Hey guys,

I'd like some advice on how to diagnose the PSU for this device, and how to check if certain components are good or bad. Here are some photos:

So far I checked the fuses and also replaced one cracked capacitor but still doesn't work.

Well, I'm seeing large diodes, some transistors and probably MOSFETS and a bridge rectifier, oh and that IC.

You could check the diodes quite easily and probably get a datasheet for the FETs and make sure what input/output voltages they should have, tough you'd probably need to remove them to do so.

Do you have a component tester? they can be quite handy, though you'd need to remove the components from the board. You could also check the rectifier see if it's getting AC at the input and is pushing out DC, again, best get a datasheet.

The IC could probably be replaced quite cheaply too.

Whatever you do be damn sure to be careful and not get electrocuted?

I'm guessing you don't have a schematic?

Hmm yeah to be honest I am afraid to work on it because it is AC. I might contact Ultrawave and see how much it'd cost to just swap the board. I checked that IC and it's unobtanium, so the manufacturer of the machine is probably the only ones with stock.

Steve wrote: 24 May 2022 13:38 Hmm yeah to be honest I am afraid to work on it because it is AC. I might contact Ultrawave and see how much it'd cost to just swap the board. I checked that IC and it's unobtanium, so the manufacturer of the machine is probably the only ones with stock.

If you can get the maker involved that is a good plan.

You can work safely with AC, but if you're 'not feeling it' then safer to not do so :)

Steve wrote: 24 May 2022 13:38 Hmm yeah to be honest I am afraid to work on it because it is AC. I might contact Ultrawave and see how much it'd cost to just swap the board. I checked that IC and it's unobtanium, so the manufacturer of the machine is probably the only ones with stock.

I spend all day finding components for work so this was an easy one: https://www.switchelectronics.co.uk/cd4093be

It's just a cmos quad nand gate, other manufacturers than Fujitsu still make these.

Good luck with the rest of the repair process, I'm unable to help fix PSUs - I have enough of my own to play with!

Steve wrote: 24 May 2022 13:38 I checked that IC and it's unobtanium, so the manufacturer of the machine is probably the only ones with stock.

The 4093 ?

https://uk.farnell.com/texas-instrument ... dp/3120154

Steve wrote: 24 May 2022 13:38 I checked that IC and it's unobtanium, so the manufacturer of the machine is probably the only ones with stock.

Plenty of the 4093 ICs on eBay too as well as Farnell, that is if you can't stand their excessive delivery charges for small items.

Thanks guys! I was reading the part number incorrectly. Ordered myself a couple of these chips. I'm happy to just try a few easy/cheap part replacements. Thx.