[frsimen]

Mark/Peter

I don't think there is anything untoward with those results, as far as they go. Moving the Tune control switch should change the voltage on pins 11,12 and 13 of IC10, so you will need to check that happens. There should be a position where the voltage levels swap.


The remaining mystery is where the 10V is coming from on pin 2 of IC15 when in the 5kHz position. 10V suggests a 2 diode drop, which could be a feed to the SZ line via the SX line. The SX line connects to the RP line via S2/2R on bands 1 and 4. The RP line goes to the phase detector board, but shouldn't connect to anywhere with a 12V feed on it.

A couple of suggestions to try.

1) Disconnect the wire from terminal 4 on the phase detector board. With 5kHz spacing and range 1 selected, what is the voltage on pin 2 of IC15 n the Logic board?

If it remains at 10-12V, reconnect the wire and try:

2) Disconnect the wires from terminals 9 and 10 on the phase detector board. Check the voltage on pin 2 of IC15 on the Logic board. If it is still 10-12V, reconnect the two wires.

If it is now 0V, measure the voltage on terminals 9 and 10 on the logic board. Note down what you find.

The above might identify where the unexpected voltage is coming from, but won't explain the cause of it.

Paula