[Solved] HP 16500A Logic Analyzer Causes ELCB Tripping

[1Ghz]

Hello,

I recently bought second hand HP 16500A Logic Analyzer.
If I just turn on power supply switch, after ~70 seconds the ELCB tripped.
I removed all modules except power supply module and microprocessor module, but still same.

I checked my ELCB leakage current rating and it was 30mA.
Can 16500A leakage current reach more than 30mA?
If not how can I repair it?

Thanks,

[Armadillo]

The answer is NO and there is a unsafe leakage.

Did you remove the display board. I suspect the High Voltage section.

[free_electron]

Mains input filter. They have ero caps in em.

[DTJ]

+1 for the power filter.

[1Ghz]

The answer is NO and there is a unsafe leakage.

Did you remove the display board. I suspect the High Voltage section.

I did not removed color display module yet.
I'll do next try.

Mains input filter. They have ero caps in em.

+1 for the power filter.

If fault is power filter, should I replace whole power supply module? or replace some caps?
AFAIK, there's no schematic for HP 16500A power supply.

[DTJ]

Does it have one of those IEC power inlet filter modules?

https://www.google.com.au/search?q=iec+power+filter&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjGwIGlqPrRAhXCFpQKHbY9DK0Q_AUICSgC&biw=1920&bih=939

[TerraHertz]

Does it have one of those IEC power inlet filter modules?

https://www.google.com.au/search?q=iec+power+filter&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjGwIGlqPrRAhXCFpQKHbY9DK0Q_AUICSgC&biw=1920&bih=939

Yes, this is the likely culprit. Or, perhaps the power supply board has the filter there, as separate components. They will be right beside where the mains comes onto the PCB. One polyester cap between the A and N lines, and another two from the A & N to chassis ground (ie mains ground.)  Those have probably gone leaky. Replace all three (and any others of the same kind you can see) with mains rated polyesters (modern ones) of same values.

Btw, when those caps do go, they tend to burst into flames and produce the most god-awful stink, and an oily smoke that condenses on everything nearby and makes *that* stink too. It's a real bitch to clean.
I'd suggest not turning the power on again until you have replaced those caps and/or mains input filter.

[DTJ]

Perhaps as a test (if it does have the IEC style input filter), disconnect the filter and bypass it.

See if the unit then runs ok without tripping the ELCB.

[1Ghz]

Did you remove the display board. I suspect the High Voltage section.

I've removed color display power cable from power supply and still same.

Does it have one of those IEC power inlet filter modules?

Yes, it have IEC power inlet filter module.
I've attached photo of it.

Yes, this is the likely culprit. ... I'd suggest not turning the power on again until you have replaced those caps and/or mains input filter.

Thank you for your suggestion, TeraHertz.

Perhaps as a test (if it does have the IEC style input filter), disconnect the filter and bypass it.

See if the unit then runs ok without tripping the ELCB.

I'll test or replace it soon.

[1Ghz]

I've replaced IEC power inlet filter module and test again, but after ~140 seconds it's still tripping the ELCB. 
I'll replace whole power supply module next week.

[DTJ]

Bugger.

Is there a chance that the leakage might not be too high but the sum of leakage on that circuit is causing an issue?

Have you measured the earth leakage current? Is it high?

[1Ghz]

Have you measured the earth leakage current? Is it high?

No, earth leakage current not measured yet. I'll measure it next try.

[1Ghz]

I've replaced whole power supply module today.
It works like a charm.   

So problem is solved, but I was not able to repair faulty power supply module. 
I'll try to fix it later.

Thank you all for your reply! 

[DTJ]

Good to hear you got it going.