Hi Grize,
TP509 = 5.06v
49mhz and 24mhz signals are alive.
I see the 24mhz on the filiment drive fets Tr501 and 502.
I pulled the GPIB interface adaptor to see if I could see the trace - the socket base is almost solid, so checked the continuity of the trace between the resistors to the IC socket - it goes to pin 18 which is the clock signal.
This is generated directly from the processor (pin 34 E) and is also to nand gates in IC118 which generated /OE and /WE
This line appears to be 3
to ground, so it looks like I've most likely fried everything connected to this signal line.
I think I will take out any IC that has direct connection to the E clock line which I think is the processor, the GPIB and the 74LS00 IC118 and see if that clears the short.
Then it's a case of a new processor and 7400 - I'll leave the GPIB out for now and see if it comes back to life.
So there might be still some hope left.
How does that sound as a plan?
What a muppet
Dek.