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Old 09-11-2020, 08:32 PM   #30
SolomonMan
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Join Date: Apr 2019
City & State: Deshler,Ohio
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Posts: 148
Default Re: DC Power Supply QW-MS605D

Quote:
Originally Posted by SolomonMan View Post
Back at it again....

....
So I am going to go forward with the KA7500B IC swap.
...
When I test the P75NF75 FET. I assume its best to get it out of the board.

Test (1)
Pin 1 to 2 or Pin 1 to 3 should not have continuity (be shorted).

Test (2)
Pin 3 (Multimeter Red Lead) to 2 (Black) should have continuity (shorted).

Test (3)
Reverse Leads should not have continuity.

Below is mouser datasheet for reference.
https://www.mouser.com/datasheet/2/3...71-1795852.pdf

Thanks in advance,
Chris

All,
Held off on KA7500B IC replacement....Went straight after the P75NF75 FET to test outside the circuit. It was simple enough to do and if I found an issue I hate to have the IC replacement play havoc in my troubleshooting. Not to mention I can do the KA7500B IC replacement if the FET tests ok.

RESULTS

Test (1)
Pin 1 to 2 or Pin 1 to 3 should not have continuity (be shorted).

This Tested as Expected no short between pins 1 and any other pin.

Test (2)
Pin 3 (Multimeter Red Lead) to 2 (Black) should have continuity (shorted).

SHORTED


Test (3)
Reverse Leads should not have continuity.

SHORTED


I have a Short regardless of lead choice between Drain and Source.

So I am going to order the P75NF75 FET.

Keep you all posted.
Chris
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