Need Resistor Value from PowerMac 7600 Power Supply Delta DPS-150GB

[powellb]

Rather the pinging an old thread about this power supply, I am asking broadly.

All, I am refurbishing the power supply on my PowerMac 7600. When replacing C2, I had to remove all of the white adhesive around it, and it turned out there was a resistor in there that was pulled from its leads: R41.

Does anyone have a Delta DPS-150GB open that could look (or test) what the resistance value is of R41? I haven't been able to find any schematics of it.

Thanks!

 

[obsolete]

Thanks to you, I know how filthy and dusty my 7600 power supply was inside...yuck!

I did not remove R41 from the glue, but I desoldered it and bent its leads away from the edges of the holes so I could measure it out of circuit. I got 838.6 kohms, which is right near the bottom of the range for the E96 (1%) value of 845k, so I bet that's what it is.

 

[powellb]

Thank you very much, this is a great help! I was tracing through the diagram to try to figure out what is was doing. The output of bridge rectifier goes into positive side of capacitor C1, but that also goes through R41 that then goes to R42, where I lose what is happening.

I really appreciate it, and I hope that your PS is now cleaned up!

 

[powellb]

Just to follow up: I ordered metal-film E96 845k resistors and put the PS back together. Everything is working perfectly. Nice to have that PS rebuilt. Thanks again for checking for me!

 

[obsolete]

I'm glad to hear that! Was this a preventative recap or a repair? Aside from the dust, mine looks pretty good inside, and the caps are good brands, so I'm inclined to leave it alone since it's working fine.

With R42 being 700k and in series with R41, perhaps they form a (very low current) voltage divider for some purpose.

 

[powellb]

I was replacing caps in a monitor and other things so I figured I would do the 7600 psu while I was doing everything. It was working before, but I wanted to refurbish it and check joints. All redone and should be good for the rest of my life!

im not a psu person, but the output from the bridge rectifier goes to those two caps to double the voltage (I think) for 110v supply. That resistor line actually goes from the rectifier off to something else…