Has anyone got a decent copy of the circuit diagram of the PBT/Reference Board for a Drake TR 7 ?
In particular I could do with figuring out what contacts / edge connectors relate to. At the moment I am trying to isolate a rather tricky fault. The symptoms are that the PBT (when selected) has no effect on the received audio, and switching between CW,RTTY,USB and LSB also has no effect on the pitch of any received audio. The RIT does effect the pitch. I have the voltages correct on the Power board. Receive wise its working OK with CW and demodulating SSB signals. The issue is the PBT / Mode switch does not appear to be selecting the correct Frequency off set in the 13.695MHz oscillator. I am wondering about the MC14016 CMOS IC (U1001 on the PBT / Reference Board) but can't make out the edge connector refernce numbers. Alternatively does anyone have any knowledge of how the wiring works from the mode switch back to the PBT / Ref Board? Thanks Adrian -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Adrian Rees Sent: 27 January 2010 16:09 To: [email protected] Subject: [Drakelist] TR7 Re-alignmnet Hello all I am trying to re-align my TR7. So far I have followed the Service Manual and am now trying to align the 8.05MHz Oscillator. (Section 3-5 in the Service Manual). I can't seem to measure a stable output on pin 40. It seems to be wandering around between 2 and 7 MHz. Additionaly on the 28MHz setting the display is showing 32MHz, which I guess is the VCO. Should I fault find the VCO problem first or the 8.05MHz Oscillator. Any help gratefully received ! Thanks Adrian MW1LCR _______________________________________________ Drakelist mailing list [email protected] http://mailman.zerobeat.net/mailman/listinfo/drakelist _______________________________________________ Drakelist mailing list [email protected] http://mailman.zerobeat.net/mailman/listinfo/drakelist
