HP E3631 Readback problems

[dundee]

Hi Guys!

I bought a faulty E3631 Power supply here in the forum - Thanks to Peter! Very fast delivery
https://www.eevblog.com/forum/buysellwanted/uk-fs-hpagilent-e3631a-triple-output-dc-power-supply/

This device has some problems with it's readback voltages and currents.

I measured around the ADC and found R5 that was open.

After replacing with a 30K resistor the +-25V Ranges were working perfectly.

But the 6V range is still wrong. I made a little Video:


Sometimes the display shows values over 100V...

Any suggestions, where i have to look?

Steffen

[free_electron]

check the main board circuitry around the optoisolators.

[dundee]

You're right. The two left optoisolators are wrong...

Do you know where i can get these? Or an equivalent?

[rolycat]

HCNR200 optoisolators are still readily available, although not cheap.

For example, Farnell have them in stock: http://uk.farnell.com/avago-technologies/hcnr200-300e/optocoupler-smd-analog/dp/8549710

[dundee]

HCNR200 optoisolators are still readily available, although not cheap.

Is the HP2211 the same as HCPL2211?

I think the pinout of the HCNR200 is not the same.

[rolycat]

HCNR200 optoisolators are still readily available, although not cheap.

Is the HP2211 the same as HCPL2211?

I think the pinout of the HCNR200 is not the same.

No, the HCNR200 is the other optoisolator on that board which is often a source of problems.

I believe the HCPL2211 is the same as the HP part HP2211 - this Taiwanese website suggests that this is the case.

How is the repair going?

P.S.  Sorry about the long delay in replying - was hoping a more knowledgeable forum member would answer your query.