Amiga 2000 Power supply suddenly stopped working

[stj]

Re: Amiga 2000 Power supply suddently stopped working

it's 680uf in the foto.
and looks like a 10mm snap-in type

[roadrash]

Re: Amiga 2000 Power supply suddently stopped working

The 3 critical factors are that the replacements be 68uF or higher, 200V (or 250V), and the same lead spacing. Shorter is OK, 22mm diameter is OK if the leads fit. 100uF would just give you amazing hold-up time.

Like stj said, your originals are a good brand, and input 'lytics are less stressed. So they may be OK. What's the voltage across them when you apply power?

I havent applied any power yet as I am still trying to source 2 very large caps (200v 680uf) and nothing I can find online even comes close. They look in perfect order so I was hoping they are still OK. I have tested them on my component tester and here are the results: 672.7 ohms, Vloss=5% ESR=0.19 ohm. Do you think they are ok?

[Drack]

Re: Amiga 2000 Power supply suddently stopped working

That sounds about right for how old those caps are, are they 68uf or 680uf? 680 should be easy to find, I think you could use 820uf in case you don't find the other ones

[roadrash]

Re: Amiga 2000 Power supply suddently stopped working

That sounds about right for how old those caps are, are they 68uf or 680uf? 680 should be easy to find, I think you could use 820uf in case you don't find the other ones

They are Rubycon 680uf 200v. Is a ESR value of 0.19 good? and can i refit them or do they need replaced too. I'd like to bet a lot of those caps are OK actually. I just replaced them all in the hope I cured the fault. Ive attached the Rubycon data sheet for these but again no reference to a ESR number. Is there a rule of thumb like for instance if there ESR is less than 1.0 ohms they are good?

[Drack]

Re: Amiga 2000 Power supply suddently stopped working

Usually input filter caps don't need too low ESR, and for how old they I think it would be normal back then, but if you want to be sure order some new caps from farnell or digikey, it should be easy to find a replacement of a reputable brand

[roadrash]

Re: Amiga 2000 Power supply suddently stopped working

[QUOTE=PeteS in CA;713726]The 3 critical factors are that the replacements be 68uF or higher, 200V (or 250V), and the same lead spacing. Shorter is OK, 22mm diameter is OK if the leads fit. /quote]


Is the lead spacing really important? I sometime cant get the right caps with the lead spacing the same and have bent the lead on one leg with a step to make it fit well and not noticed any problems. iv's noticed some pcb's have drilling's for 2 different sizes of lead spacing It was like this on this Amiga PSU when I fitted new Polymer 0.1uf & 0.01uf X2 filter caps earlier today, which had slightly different lead spacing to the originals but fitted perfect having 4 holes to choose from.

[stj]

Re: Amiga 2000 Power supply suddently stopped working

those 680uf are 10mm snap-in - they use pins not wires.

[Drack]

Re: Amiga 2000 Power supply suddently stopped working

those 680uf are 10mm snap-in - they use pins not wires.

Do you think that he should use the old Ruby's?

[stj]

Re: Amiga 2000 Power supply suddently stopped working

if the uf reads good, yes.

[roadrash]

Re: Amiga 2000 Power supply suddently stopped working

Well got it back together and powered it up but still there is a fault even though all caps are are now Brand new except the big "Rubies" as you call them. When I turn it on connected to a PC PSU tester it makes a continuous tick tick tick sound and the LED's on the tester flash on/off. It wouldn't because I dont have a full load would it cos the tester has a different motherboard connection to the amiga so I could only connect up the floppy and hard drive connectors to the psu tester.

[budm]

Re: Amiga 2000 Power supply suddently stopped working

So what resistance do you get when measure the resistance between GND and each DC output wire with no load attached?

[stj]

Re: Amiga 2000 Power supply suddently stopped working

go back to what i said originally, and start checking the diodes for shorts.

[roadrash]

Re: Amiga 2000 Power supply suddently stopped working

So what resistance do you get when measure the resistance between GND and each DC output wire with no load attached?

There are two common main outputs Yellow & blue which are on every connector (probably 12v & 5v)


Multimeter set on 200 ohms scale gives:

All Yellow wires: 78.5 ohms
All Blue wires: 0.5 ohms

[roadrash]

Re: Amiga 2000 Power supply suddently stopped working

go back to what i said originally, and start checking the diodes for shorts.

Ok I will do. Which area is best to start?

[budm]

Re: Amiga 2000 Power supply suddently stopped working

There are two common main outputs Yellow & blue which are on every connector (probably 12v & 5v)


Multimeter set on 200 ohms scale gives:

All Yellow wires: 78.5 ohms
All Blue wires: 0.5 ohms

https://www.badcaps.net/forum/attach...2&d=1482431163
ORANGE?
I see Orange wires on the white connector beside the Blue and the Yellow wires.

[roadrash]

Re: Amiga 2000 Power supply suddently stopped working

The 3 critical factors are that the replacements be 68uF or higher, 200V (or 250V), and the same lead spacing. Shorter is OK, 22mm diameter is OK if the leads fit. 100uF would just give you amazing hold-up time.

Like stj said, your originals are a good brand, and input 'lytics are less stressed. So they may be OK. What's the voltage across them when you apply power?

Ok dont know if this is right. Is it still AC at these caps if so its showing 374 volts.

The strange thing is I just checked all the diodes in circuit just to get a idea if there were any possible suspects to remove and test and every diode checked as working ok. After this I turned it on again and its now working fine showing both 12v & 5v on the psu tester.

This lead spacing you mention is something I have read before and anwsered too but haven't yet followed up. I wasnt aware the lead spacing was critical to the integrity of the circuit I thought it was just a case of different spacing due to the diameter of the caps themselves. This board had 2 pairs of holes the cap could use and i used the pair that the spacing of the leads lined up to the best without bending them. Is this spacing critical. I still cant understand why this has now stopped the ticking sound and is outputting steady power.

[Drack]

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?

[stj]

Re: Amiga 2000 Power supply suddently stopped working

the main caps are receiving DC via the bridge rectifier / mains diodes.

[stj]

Re: Amiga 2000 Power supply suddently stopped working

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

[budm]

Re: Amiga 2000 Power supply suddently stopped working

"Ok dont know if this is right. Is it still AC at these caps if so its showing 374 volts." Using meter setting to AC and trying to measure the DC Voltage, the result is not going to come out right.