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Anybody have a repair for the MTH AG-0000062 PC board that drives the blinking light on the bridge?
i have two boards that have a smoked resistor. It is unknown if any other components are trashed, unable to determine that. I figure there is a repair/ mod for these as there are hundreds around.
i can replace the resistor, I just need its value to purchase, unknown what it was as you can see in the attached pic the color code got zorched. And, if any other component failed with the resistor.
New boards are unavailable.
Thanks in advance!



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  • A4224B7D-E217-46FD-8331-0BAA73384AC7: Ag-0000062 board
Last edited by Jim Battaglia
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OK, did some tracing.

Again, that resistor is taking the bulk rectified DC from the input, and then branches and feeds the 555 timer, and goes up towards the output transistors and appears to also be feeding the light?

So, one possible failure cause is load shorted- on the output.

Or, for whatever reason, the voltage coming in is high, and/or, the 555 or another component is failed and drawing current.

The Zener diode is reading 12.3V across when powered on a good board and that is the voltage regulation past the 150 Ohm resistor.

Again, quick tracing and measuring, AC power comes in, gets rectified by the 4 diodes. The larger 35V 470uF bulk cap charges up to whatever the peak voltage AC you were feeding into the board. Then the 150 Ohm resistor takes that high voltage, and jumps over to the 12.3V bus and that is regulated or kept at the max voltage by the large Zener diode.

If the 150 Ohm resistor burns and fails, it's because somewhere, somehow the load is shorted. Again, could be the 555, CD4093BE, maybe one of the smaller capacitors. Again, the 150 Ohm is part of the power supply regulation part of the circuit and if something fails, then it pulls higher current until the resistor smoke like a fuse.


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  • mceclip0

Thanks Guys!
An earlier parts search said last 50 boards were shipped in 2009 and inventory was 0. Seems the search was wrong as I able to order 2. Hopefully they have been modified. Looks like my old board could have used a heat Sink.
Now to find a repair person willing to take on repairing a pair of first gen Powermasters...

Again Thanks!

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OGR Publishing, Inc., 1310 Eastside Centre Ct, Suite 6, Mountain Home, AR 72653
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