OK, progress is being made! I discovered that the +10T line was hot, and that the unit was in transmit mode when it was turned on (this wasn't the case a few days ago, because I specifically checked the +10T and +10R lines, and all was well). At any rate, I discovered a diode soldered on the underside of the parent board, between pins 11 (PTT enable) and 13 (+5V) of the tx exciter board, anode side on pin 13. I don't know what was intended by this (it looks like the PTT line would always be pulled high), but I didn't see it in the schematic, so I removed it.
So, I'm now receiving! However, I'm only receiving on two bands: 2-3MHz and 4.5-7MHz. The other bands are completely dead (no audio, no S-meter deflection). Earlier, I tested the DR-7 with an external signal source on the CNTR terminal (switch to EXT), and all was well. With the switch to NORM, the display starts out at 51950.0, and slowly morphs to 11110.0, where it stays. I can tune across the working bands, but the VFO display never varies. I appreciate all the suggestions at this point...anything else that might seem obvious that I'm missing, please let me know. --Brian/WA3ITE On Mon, Jul 05, 2010 at 11:46:00AM -0500, Brian Koontz wrote: > I inherited a TR-7 (serial #4388) from my father (SK). Fortunately, > I was also able to locate the service manual and extender boards. > After repairing a shorted cap on the IF/audio board, I discovered that > the receiver is dead. The VFO displays "11100.0," and doesn't change. > I suspect the audio portion of the board is OK. _______________________________________________ Drakelist mailing list [email protected] http://mailman.zerobeat.net/mailman/listinfo/drakelist
