[Drake] TR-7 Digital Display Is Intermittent ??? Some Progress To Report

[w0ng at comcast.net]

Just wanted to take a moment to thank the many, many TR-7 owners who responded to my inquiry about my TR-7 having a digital display that just goes "dark" on its own seemingly for no good reason.

The concensus of advice I've received points to cleaning and re-seating ALL of the circuit board connector pins as they may have oxidized with time, removing the DR-7 board and cleaning all its molex connector pins and checking/replacing the 7805 5v regulator that powers the display.

I tried to thank each of you individually by return email for the specific advice each of you offered. This list is AMAZING in it's wealth of experience! If I inadvertently missed replying to one of you, please accept my apology.

So far I've carefully (and successfully) removed the DR-7 and am in the process of gently pulling each circuit board so I can clean the connector pins with a little Caig DeOxit.

The MC7805CT 5v regulators (obsolete) cross reference to a NTE 960. The spec sheets for both are identical and I can obtain the NTE 960 locally for less than $4.00 each. I think I'll do that. I did notice that the soldering job on the 5v regulator pins was very sloppy. Can't imagine it was the original Drake wiring. Also no heatsink grease underneath either 7805 regulator (???).

I've also noticed while inspecting each board that nearly all of them have had some mods performed (e.g., added resistors, caps, diodes, etc) on the component side. Especially the ALC board.

This rig also has the Digital Automatic Frequency Control (DAFC) mod with the added circuit board attached to (but insulated from) the foil side of the parent board.

Looks like it's going to be a fun journey learning about what makes this particular TR-7 "tick". Definitely not a stock radio, hi.

Once I get finished getting "back-to-the-basics" with this rig I'll post more info on what I find regarding the troublesome digital display. 

Thanks again & 73
Bill Pancake
w0ng
Fountain, Colorado