exxos's Atari, Amiga & retro forum

The PSU had been working fine all morning, until I shorted the DC outputs out unlipping the cable clips.. now its "stuck" on 82V Its only supposed to go to 50V tops... my meter also says 82V so it is actually outputting 82V! Godknows whats up with the thing now.


EDIT:

So I put back the 741 I took out, and its gone back to the original fault, so obviously that had gone faulty... It must have blown the 5534 I put in yesterday.. so I need to see if I have a spare spare 5534....

EDIT2:

Nope same fault... oddly with what 741 in place, just touching pin 3 causes the voltage to shoot up.. there is only 1 probe connected, and its not pressing down on it at all, so its not a bad connection.. so like a couple of pF on the meter probe is causing it to go nuts ?!

I ended up putting back the 741... if I load it with 2 amps and turn the voltage to 35V, it drops to about 10V but powers my load... Before it was just tripping over current and dropping to zero volts. It seems the fault keeps on changing.. After spending all day on it, its going in the bin now. I think the whole thing is just a screwy design.

Back to the plot..

I had 3 PSU's with faults, just changing the chips on the 3rd one now ,so hopefully this one will work as well


EDIT:

Yep, all working

The UPSU saga continues...

After trying to calibrate it with the software, the battery just drops to zero according to the PSU & software and it won't run from battery. So I put some new batteries on just.. still not convinced the old ones are at fault as only 2.5 years old, which isn't really that old.



Just fitting the fuse...

Will let them charge up and do a re-test.. but I think this "new" PSU is faulty

Found that to do a "manual calibration" you load the PSU and unplug the wall power...

So connected my heater (about 800w per back IIRC ) which is about 30% load and let it run... its beeping like mad.. the battery voltage according to my meter isn't going down very fast either.. so I hope this isn't going to be beeping for the next 2 hours


EDIT:

Finally cut out at 19.2V So it ran for about a hour and half.. now to charge it all up again...

Interestingly,The power supply is turned off and now connected backup to the mains, so obviously the battery is now charging, and the fan is still running.. So it seems the fan runs when the battery is charging from a discharged state, which I think is a nice feature


EDIT2:
I tried running the heater on the PSU this morning and doing a self-test, and it still thinks the battery is flat

I have been plotting with the alt-ram pcb today.. I had a thought that if I use these pins...

..and chop the holes on the PCB In half, I should be able to solder to the large part of the pins to the half cut vias still allowing the thinner part of the pins to be able to push into a socket as normal. This way the CPU plugs into the header sockets as normal, but it in the effect it plugs on top of the PCB..



So at some point, should actually be possible to do the same with the SEC booster.

Finally fixed the reset switch

exxos wrote: ↑Fri Jul 12, 2019 6:11 pm Finally fixed the reset switch

Nice! and I see you have put two holes on the end plane for the MIDI sockets to cover off the two types out there.

Icky wrote: ↑Sat Jul 13, 2019 11:17 am Nice! and I see you have put two holes on the end plane for the MIDI sockets to cover off the two types out there.

Yeah, it was done a while back.