Power Designs 6150 Repair

[hightest]

My Power Designs 6150 just failed.  The problem appears to be in the current regulation rather than the AC/DC conversion. Resistor R48 smoked and the current meter pegged. Resistor R48 is depicted in the portion of the main board shown below. I am desperately in need of of a schematic or a manual to assist in the troubleshooting.

[dave_k]

Have you checked any transistors for shorts? There are a lot of things you can check without needing a schematic..

[hightest]

The power transistors all appear to be OK.  I was going to check the transistors on the main circuit board, but to do that I think I need to unsolder them and that led me to request a schematic so I could determine which one (or ones) could take out R48

[coromonadalix]

  see this page, may help     https://www.barbouri.com/2017/11/30/power-designs-6150-universal-dc-power-source-restoration/

Maybe this one for an similar model the 6050 schematics, must be some similarities in design    : http://d112tss1dzpest.cloudfront.net/wp-content/blogs.dir/22/files/2015/10/Power-Designs-6050a-Schematic-and-Layout.pdf?x99172

[hightest]

Thanks for the links. Greg Barbouri, who restored a like power supply (1st link) did not have the schematic either, but has been helpful in supplying the values for R47 and R48.  The schematic for the 6050A is similar and I will try to use it to assist in troubleshooting.  Does anyone know if the transistors on the main circuit board can be tested in circuit?

[coromonadalix]

normally  pull them out to be really sure, the "circuit and connected parts" may interfere with the value you will read .... i would test them in diode tests and ohms test to see if there is leakeage etc ...

I do this even on the power output transistors since they are in parallel sometimes in powerful psu's, they have sometime reversed diodes between collector emitter pins to add protection ...

[hightest]

Thanks for the helpful hints on testing the transistors - I shall restart my troubleshooting next week and see if I can pinpoint the issue.

[kathy45]

I, too, have an influence designs 6150 in would like of repair. Consequently, I'm also seeking for a schematic for this provision. have you ever placed one and if thus, may you send me a pdf of it?

[hightest]

kathy45 - no, i have been unable to obtain a schematic for the Power Designs 6150.

[hightest]

I pulled and tested all 12 transistors on the main CCB.  Of them, Q23, a 2N2243A (lower middle of board in picture above) tested bad.  I ordered a new part from Mouser and a replacement for R48 from eBay.  When I get the parts, I shall install and see if this fixes the issue (fingers crossed).