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Gday Bill, from Down Under,
Lets have a look at a few voltages first shall we,
What's the voltage at the base of the TIP31 that drives that pass Tran's,
it should be similar to the desired output???
When you adjust the YELLOW pot on the voltage reg board is there any
variance of voltage swing at the base of the TIP31?? , you may have to
remove this device if it is hosed to see voltage swing.
Having done that, no swing 1723 reg stuffed maybe, but I dont think
so..
Have you checked with a meter the pass transistors? i.e. diode check,
you should be able to do this in circuit see if their OK
WHY DIDN'T YOU HAVE THE THING FUSED YOU KNUCKLE HEAD!!!
The 2N5301's are a just a basic 10amp power transistor so if their
hosed don't worry too much a replacement is not all that expensive a 2N2955 will
suffice. and this lesson will teach you to have protection in place!!!
That 100R resistor that you replaced is part of an over
voltage CROWBAR circuit, it's there to protect your radios should the reg
circuit fail, not necessary but good insurance just about any SCR of reasonable
amperage will do here as you can see by the circuit it's driven by a zenor, when
voltage goes high volts are applied to the SCR and BANG should go something
a fuse would be good, there really should be a fuse between this and the pass
transistors.
I would say that more than likely you have hosed the pass and the driver
stage
See how you go with that,
73's Frank VK5MFW |
