Amiga 2000 Power supply suddenly stopped working

[roadrash]

Re: Amiga 2000 Power supply suddently stopped working

btw, what make & series caps did you buy, and where from?

I fitted rubyconn ZLS Caps The correct value but about 20% smaller than the originals as these were the closest i could get from Farnell.

[roadrash]

Re: Amiga 2000 Power supply suddently stopped working

The spacing is not critical in this case, if they are right on polarity there should not be a problem, I don't like when things just start working again because it will probably die soon, sure you didn't touch anything? Soldering maybe?

I know what you mean about things just suddenly starting working. I all I can do is see if I can get it to fail again by moving things a bit. There is no way surely that the reason this psu suddenly shut down after all these years could be down to a dry/bad joint and I changed all these caps for nothing.

[stj]

Re: Amiga 2000 Power supply suddently stopped working

hardly, those caps were way off original spec.

[Drack]

Re: Amiga 2000 Power supply suddently stopped working

Check the solder side, that might be the trouble.
Those caps where too old to trust, so you did right changing them

[roadrash]

Re: Amiga 2000 Power supply suddently stopped working

hardly, those caps were way off original spec.

Are you saying that I have put caps in that are the wrong spec?. I just went to Farnells website and searched for the closest they had of the same value & voltage and size wise nearest to the originals. I spent ages searching online & tried Ebay, RS, Mouser, Digikey & others and these were the best good brand caps I could find. Where is best to find Caps like this?

[Drack]

Re: Amiga 2000 Power supply suddently stopped working

He was talking about the old caps, the ones you bought are good quality ones and you looked at the right page, farnell have original caps, not that Chinese things that you find on eBay

[stj]

Re: Amiga 2000 Power supply suddently stopped working

exactly, the old ones are well past it - they are only rated for about 2000 hours use.

[roadrash]

Re: Amiga 2000 Power supply suddently stopped working

exactly, the old ones are well past it - they are only rated for about 2000 hours use.

Phew! I thought I done stupid. Still to find out what this intermittent fault is now. I turned it on this morning and again it made a ticking noise and the LED's on the psu tester flashed on/off. I disconnected it and try a few more times and still it wouldn't work then I turned it over solder side up reconnected it and it started working. Since then I disconnected and reconnected it turning it back over component side up and its not failed since. I am going to have to look into this a bit further but at least its working so just got to track this down.

[stj]

Re: Amiga 2000 Power supply suddently stopped working

sounds like probably a bad solder joint.
check anything bolted to a heatsink, and any coils or transformers - the weight causes stress.

[roadrash]

Re: Amiga 2000 Power supply suddently stopped working

What a disappointment its not working at all properly. That PSU tester is lying & useless. When I connect a Hard drive and a floppy to it its still pulsing on/off and does not give a stable output. So the original fault is still there.
To sum up so far ive changed all the electrolytic's and Ive checked all the diodes and can't find any faulty ones. Now I am mystified. I wish I could find a service manual for this one.

[stj]

Re: Amiga 2000 Power supply suddently stopped working

sounds like it's falsely detecting an overload.

too bad it's not a month or 2 from now.
i have one i intend to rebuild soon.

infact, i have 2-3 A500's
1 B2000
1 A1200
1 A1200 fitted in a B2000 case with an 060 card!
and some other stuff.

i'v been slowly buying gotek drives & stuff ready for a big rebuilding session when i get time!

[roadrash]

Re: Amiga 2000 Power supply suddently stopped working

sounds like it's falsely detecting an overload.

too bad it's not a month or 2 from now.
i have one i intend to rebuild soon.

infact, i have 2-3 A500's
1 B2000
1 A1200
1 A1200 fitted in a B2000 case with an 060 card!
and some other stuff.

i'v been slowly buying gotek drives & stuff ready for a big rebuilding session when i get time!

When I get this B2000 PSU fixed I still have the PSU from my original A2000 to fix as well and its different to this one. I remember when the fan was connected and I turned the computer on the fan jerked round a mm at a time just like the power being turned off/on. It does sound like a overload I must admit so I better look for short or high resistance somewhere I suppose.

[roadrash]

Re: Amiga 2000 Power supply suddently stopped working

Hang on I put those 2 680uf 200v rubies back in. It wouldn't be one of those would it because Ive just found a couple at Farnells that would do the job so will be getting a pair on my next order.

[stj]

Re: Amiga 2000 Power supply suddently stopped working

didnt you test them in your component tester?
btw - make sure they are discharged first!

[roadrash]

Re: Amiga 2000 Power supply suddently stopped working

didnt you test them in your component tester?
btw - make sure they are discharged first!

Yes I did it earlier and each cap was 672.7 ohms, Vloss=5% ESR=0.19 ohm

[roadrash]

Re: Amiga 2000 Power supply suddently stopped working

Just seen another post on the web about a computer SMPS that is doing the same as mine after replacing all the electrolytic's and it was eventually traced down to a 0.01uf capacitor neat the thyristor according to its Schematic. Isnt that low value a Tantilum cap?

[stj]

Re: Amiga 2000 Power supply suddently stopped working

no, probably ceramic

[roadrash]

Re: Amiga 2000 Power supply suddently stopped working

Just read something else from another forum where someone was replacing a Amiga PSU with a PC ATX supply. In that article it was mention that there is a timing signal between the standard PSU and the motherboard. That got me to thinking, hang on I wonder if this PSU cannot be tested without being fitted up to the motherboard so I did just that and quickly put it together enough to test and "Bingo" the Amiga fired up. Thank goodness for that I was starting really scratch my head as everything all the diodes etc I checked were OK.
Thanks everyone for you help and especially you STJ. Ive got the older A2000's power supply to look at yet and its different & simpler in design to this one.

[stj]

Re: Amiga 2000 Power supply suddently stopped working

Just read something else from another forum where someone was replacing a Amiga PSU with a PC ATX supply. In that article it was mention that there is a timing signal between the standard PSU and the motherboard.

forget about that inacurate post.

forstly you can only use an AT or *early* ATX1.0 psu on the amiga.

second, the timing signal is not ATX, it's on the amiga psu and only needed by the motherboard.
and only if you set the "tick" jumper to "external clock" because it does not even need it.
it cant shut down the psu.

[stj]

Re: Amiga 2000 Power supply suddently stopped working

That got me to thinking, hang on I wonder if this PSU cannot be tested without being fitted up to the motherboard so I did just that and quickly put it together enough to test and "Bingo" the Amiga fired up.

i didnt know you were trying to run it alone.
*most* switchmode psu's wont run without a load connected!