Carver MXR130 power supply

[merrylander]

Anyone ever see this on Carver's odd power supply.

Hook my Fluke 23 across the 60 volt supply and turn the VR to minimum. Power on and the voltage is at 25, advance the VR and it slowly climbs to 34V the the meter goes blank for an instant then comes back at 35 and rapidly climbs to 72V but VR has ne effect, shut down quickly as filter caps are rated at 63V. All transistors and parts near the TO-220 reg are good. Why could he not have just used a standard power supply?

[Chazb11]

Because he's Bob Carver!

[BrassTeacher]

The board doesn't look a little toasted anywhere in the area of the voltage regulator transistors does it?

Could be the VR is going bad too.

Or all of the above. The MXR130 was especially notorious for cooking parts of its circuit board, causing all kind of strange power supply behavior. I still have one in my "garage shop" that I'll get to "someday".

[merrylander]

Only toasted under those eight 2 watt resistors, like every other MXR130 I have seen.

[BrassTeacher]

Only toasted under those eight 2 watt resistors, like every other MXR130 I have seen.

If it's really bad, and I haven't looked in awhile, so I don't know how hard this will be, cut out all the toasted area under the four resistors on the main board.

If I get a chance, I'll go into the garage and have a looksie...

[mhardy6647]

On behalf of the owner of the Carver Rx in question... thanks, Rob, for your perseverence! ;-)