Quote:
Originally Posted by murphyv310
Hi.
Looking at the component side of the board I'd say the Diode across the relays coil is most likely short circuit, It's there to suppress the back EMF of the coil when the drive is switched off, if it goes short then its driver will pass too much current and cook, this is the one next to the diode I'd think, no doubt an NPN and I'd say shorted.
Virtually any Si NPN that is suitably rated would do. Snag is any transistor down stream of the driver could also be duff.
|
Well there only appears to be three smallish transistors, and perhaps one in the TO220 package attached to the heatsink.......
Given the crude simplicity of the circuit, it should be possible to repair that easily enough
Gary, if you check out the transistors with your meter on diode test, you should be able to identify which have failed, possible base emitter open, I should imagine they are being used in conjunction with the big boy on the heatsink??????
Brian
