FT-7 Door Stop - Help

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FT-7 Door Stop - Help

Postby wa3yre » Sun Jul 23, 2017 4:33 pm

Greeting-

I just purchased an FT-7 from a fellow on QRZ.COM. He advertised it as being in working condition. When it arrived I hooked it to my TTFD and fired up on 40 meters. First call I got w9ims at the Indy Speedway with a 5-7 report. I was happy.

Then I checked the other bands and discovered 10 meters had no rx and no tx. I further checked the radio and discovered no CW only USB/LSB. When I contacted the seller he suggested reseating all the boards. So I pulled each board, hit them with contact cleaner, and reseated them. I also reseated the 10 meter (b range) crystal.

I will also mention that I reseated both relays and I cleaned the band switch. The cleaner I used was the same which I had used with good effect on my FT-101B which had been in the back of my closet for 22 years.

When I turned the radio back no now I have no RX on any band, no TX on 10 meters and no CW on any band. I know the problem is before the audio stage because the S meter is not even moving off the peg. I suspect a front end, IF, or mixer issue.

I have started to review schematics I found online, but have come to no conclusions yet.

I have very little in the way of a workshop being as I am in a small NYC apartment. My only test equipment is:

MFJ- SWR analyzer - doubles as a non-modulated RF signal generator
Watt Meter - 20 watt scale and 200 watt scale
DVM
Audio Function Generator - Program on android phone

I also have another working HF xcvr that goes 1.6-30 Mhz in 100hz steps.

If anyone can give me pointers I would appreciate it very much. I very much want to put this radio back into service. I have wanted one since I was first licensed in the 1970s.

73

-Brett
wa3yre
wa3yre
 
Posts: 6
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Re: FT-7 Door Stop - Help

Postby wa3yre » Sun Jul 23, 2017 8:20 pm

Another point of information the VOLTAGE REGULATOR on the CONTROL BOARD is getting hot as hell when the radio is powered on.

73

-Brett
wa3yre
wa3yre
 
Posts: 6
Joined: Sun Jul 23, 2017 4:14 am

Re: FT-7 Door Stop - Help

Postby wa3yre » Mon Jul 24, 2017 6:39 am

Well a test of the regulator on the control board while the board was connected to just power in shows that the regulator is blown. Looking close it seems this is a replacement regulator, so it has happened in the past with this radio.

So since the control board was pumping out 11V on the 8V line did I fry the rest of the radio? I have a 7808 on order to replace the blown regulator, but I sure would love to get to the bottom of why this happened and why the radio has no CW TX.

Clues appreciated.

73

-Brett
wa3yre
wa3yre
 
Posts: 6
Joined: Sun Jul 23, 2017 4:14 am


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