exxos's Atari, Amiga & retro forum

stephen_usher wrote: 02 Feb 2022 10:05 The replacement PSU has arrived. It'll need some thought about how to secure it as, of course, the mounting holes won't line up with the originals. Also, I hope that the 'scope doesn't actually try to draw the full 20A@12V as I could only find a 16.7A supply in the right sort of form factor.

The original PSU board does look rather scorched, I take it that it's beyond repair?

I take it is CRT, so you might be right about it needing more than the 16.7A PSU you have. Could you test it with a bench supply or supplies, see if it'll give you an idea of the current draw?

Well, potentially it's fixable, if I knew what the values of the two toasted SMD resistors were next to the chip. There are a couple of fine traces on the main board which would need bodge wires too.

It's not a CRT, it's an LCD display with cold cathode backlight, so I don't know why it would be so power hungry. Hopefully 200W rather than 240W will be good enough.

I tried with my 5A bench PSU and that started to boot at that current but the limiter tripped.

It's a nice 4 channel, 50MHz 'scope with 16 channel logic analyser:

stephen_usher wrote: 02 Feb 2022 10:25 Well, potentially it's fixable, if I knew what the values of the two toasted SMD resistors were next to the chip. There are a couple of fine traces on the main board which would need bodge wires too.

It's not a CRT, it's an LCD display with cold cathode backlight, so I don't know why it would be so power hungry. Hopefully 200W rather than 240W will be good enough.

I tried with my 5A bench PSU and that started to boot at that current but the limiter tripped.

It's a nice 4 channel, 50MHz 'scope with 16 channel logic analyser:

Is there a schematic you could get the resistances from? Sounds all rather positive though, should be a pretty useful tool when you've got it running, having the integrated LA is nice.

No schematic, but there is a service manual, which is how I got the voltage and rating.

stephen_usher wrote: 02 Feb 2022 10:42 No schematic, but there is a service manual, which is how I got the voltage and rating.

I do hate it when there's no schematic!!

It's alive!

First tested with the PSU outside the main system to make sure everything was fine and I adjusted the voltage.


It took a bit of persuasion (with a hammer) but I finally got it inside and all back together and working.

Oh! This scope can do bus timings form the main channels and protocol decode too.

Big league stuff.

@stephen_usher Sounds like your luck was in with that one!

Yeah. I think this must have been close to the top of the range maybe?

It's now passed its internal calibration tests and self diagnostics. Woot!

The "info" menu shows that it doesn't have any module licenses installed. I'm not surprised as there aren't any modules supplied with it.