How to repair broken Brookstone Quad winders

[Rdenney]

The power supply regulation in these is in the wall wart. You’ll find no electrolytic capacitors on the circuit boards.

Rick “who didn’t attempt to reverse-engineer the PCB’s” Denney

[Rdenney]

Long-term report:

The belts I installed at the start of this thread are still in excellent condition.

But two additional things go wrong with these. First thing is the on-off switch for each position becomes flaky, causing a voltage drop to the motor and the loss of bias voltage for the switching transistors. Being unable to think of a compelling reason for the switches, I just moved one switch wire to the other terminal and soldered it down. I mentioned this before, but it was affecting four or five positions so I bypassed them all. That problem is solved. If I need to turn it off (such as to reprogram the timing), I’ll pull the DC plug out of the back.

The second problem is with the Mabuchi motors. Several of the motors started bogging down, and this is apparently just from gummy lubricant. I cleaned the motors by spraying just a bit of Deoxit contact cleaner into the motor to clean the brushes, and then put a drop of synthetic bearing oil on the shafts. They became quiet again and run like new. Any excess oil has to be rigorously wiped clean to avoid draining down onto the pulley.

The oldest of these is about 8 years old now, which is probably a record.

Rick “the adapters put out 3.3 volts” Denney