[Amps] LK-800A
Will Matney
craxd1 at ezwv.com
Wed Jan 12 23:32:01 EST 2005
John,
Sorry about that. They were some manufacturers who wouldn't detail some
circuits on schematics fearing some would copy them. Thing is, it aint
hard to make a 555 timer so they didn't hide much. Shame it wasn't a
Amperex timer tube the way it used to be done. Just pull its tooth and
plug another in. There was a way though using that schematic to bypass
the timer as it showed switching +12 on to the switching circuit. You'll
see where the wire goes on and says + 12 V SW. Jump that to + 12 Vdc at
the lamp connection on the ready light. Most 555's use a 5 to 9 volt
supply so something may be open feeding the chip. If not, it could be an
electrolytic cap, resistor, or the chip itself which really is most
likely the case. They'll be a resistor and a capacitor forming the RC
network hooked to the chip to set the timing. Most likely one more
resistor from the chip to VCC. That's about all I remember on the 555
without pulling a book.
Will
Thanks for looking guys. The Bama site schematic is what I have and it
doesn't detail the 180 sec timer circuit and Omega wants us to send it
in for repair. I guess I'll try reverse engineering a diagram of it and
then troubleshoot the thing. I hate "shotgunning" parts in something
that needs a small .25 watt resistor. It is so easy to burn a circuit
board or destroy a good part and still not fix the trouble. I have a
feeling there were several version of this thing.
Thanks again
John, WA5BXO
http://www.qsl.net/wa5bxo
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