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Old 4th Jun 2019, 1:16 am   #14
stahodad
Triode
 
Join Date: May 2018
Location: Halifax, Nova Scotia, Canada.
Posts: 11
Default Re: Marconi 2024 not powering up

Hello again. I got back to work on this power supply, after thinking over all of your advice for a few days. The capacitors seemed ok (none were shorted), so I started checking the resistors in the area after the 4 larger filter capacitors.

I tried measuring resistors in circuit, but the results were inaccurate. I had better luck unsoldering each of them and testing one by one. As luck would have it I found both R3 and R2 100 k ohm resistors were open.

The colour code was odd with the reddish brown resistor body made the Brown stripe look pink to me, but I have installed 2 new 100 k ohm resistors and the generator powered up just fine.

I tried measuring power supply output pins without the wiring harness installed, but the outputs were very low. I think that is because the rest of the generator circuity loads the power supply.

Once the new resistors were installed I also noticed the large capacitors no longer stored a charge after power was removed, and that would partly explain why I was getting shocks when I worked on it the first time.

I am not really sure why the resistors failed, hopefully it was just age related on this 20 plus year old power supply.

I did not locate the schematic for this power supply but it was nicely labelled, on the non soldered side, so that did help identify components like L4, a small inductor.

Once again, I would like to thank everyone for their help with this generator.

My confidence in troubleshooting has been given a little boost!. Cheers Chris.
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Last edited by stahodad; 4th Jun 2019 at 1:28 am. Reason: error in Resistor R1
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