Apple 24" iMac A1225 EMC2134 with a Delta ADP-240 AF B SMPS, won't start

[mkinn]

Slight click when power button is pressed, HD spins up for 1/2 a second, then shuts down. Obviously, it is trying to power on, because the HD spins up for a 1/2 second. I don't suspect any shorted diodes or semi's. I do not have a schematic, or I could do the troubleshooting myself. Please feel free to be very technical. I have an ESR meter, and a Hakko 880 de-soldering machine.

This is a 240W power supply, and has been replaced with a newer power supply, the APPLE 661-4478, an almost identical 250W version which includes a "pressure wall" which probably has to do with airflow.

[CapLeaker]

Re: Apple 24" iMac A1225 EMC2134 with a Delta ADP-240 AF B SMPS, won't start

Since you have an ESR meter, check them capacitors. I see a few that look like they ran hot. Are there more caps under these heat sinks? Maybe check the secondaries if they are putting out. Looks like they are two 12V rails and a 24V rail.

[mkinn]

Re: Apple 24" iMac A1225 EMC2134 with a Delta ADP-240 AF B SMPS, won't start

I took the power supply out.
I had to cut the heatshrink off the 2 33uf 35V caps with a sharp exacto knife.
I found the following ESR values:
33UF 35V (130°) X2 - 1.0 ohms
100uf 35V - 0.5 ohms
220UF 35V X2 - .25 ohms
820UF 25V - .25 ohms
470UF 16V - .25 ohms
1000UF 16V X6 - .1 ohms
150UF 50V - .25 ohms
120uf 450V X2 - .25 ohms
All caps are RubyCon 105° caps, except the 33uf 35V ones.

Seems like they are all within spec for these caps.
Meter: Electronic Design Specialists 88A In-Circuit DCR ESR Cap Analyzer

[stj]

Re: Apple 24" iMac A1225 EMC2134 with a Delta ADP-240 AF B SMPS, won't start

they dont sound in-spec to me.
what series are those rubycons?

[mkinn]

Re: Apple 24" iMac A1225 EMC2134 with a Delta ADP-240 AF B SMPS, won't start

33UF 35V (130°) X2 - 1.0 ohms - RX30
100uf 35V - 0.5 ohms - (PW)P
220UF 35V X2 - .25 ohms - (HD)P
820UF 25V - .25 ohms - ZLH
470UF 16V - .25 ohms - (PW)P
1000UF 16V X6 - .1 ohms - ZLH
150UF 50V - .25 ohms - ZLH
120uf 450V X2 - .25 ohms - BXA

[stj]

Re: Apple 24" iMac A1225 EMC2134 with a Delta ADP-240 AF B SMPS, won't start

there is no way a ZLH should have esr that high.
1000/16 for example, should be 0.029 NOT 0.1

[Stefan Payne]

Re: Apple 24" iMac A1225 EMC2134 with a Delta ADP-240 AF B SMPS, won't start

But is the ESR meter able to show anything below 0.1??

[stj]

Re: Apple 24" iMac A1225 EMC2134 with a Delta ADP-240 AF B SMPS, won't start

these need to be re-tested off-board too.
i suspect they are a bit cooked.

[mkinn]

Re: Apple 24" iMac A1225 EMC2134 with a Delta ADP-240 AF B SMPS, won't start

Complete recap, same problem.

[stj]

Re: Apple 24" iMac A1225 EMC2134 with a Delta ADP-240 AF B SMPS, won't start

make a list of the chips on the underside.
it could be an op-amp or voltage comparater on the way out tripping a false error.

[guruji]

Re: Apple 24" iMac A1225 EMC2134 with a Delta ADP-240 AF B SMPS, won't start

i am stuck with the same smps what i want to know the pfc boosting cap what is the voltage i get 334Volts generally should be 390V.on dap017 on pin 2 i get 3volts pin no 16 just 6.2 volts.Does anyone know the valuve for zd36 near d2 & Q2

[nassimhamdi]

Re: Apple 24" iMac A1225 EMC2134 with a Delta ADP-240 AF B SMPS, won't start

what a bout ic's voltages???