Quad FM3 - UK Vintage Radio Repair and Restoration Discussion Forum

mikes08 · 14th Aug 2022, 9:07 am

https://www.vintage-radio.net/forum/...d.php?t=170997

Just following up on this as had an issue with my FM3.
It would not lock onto stereo on turning on - I could coax it by tuning out and in again but after a few seconds the stereo lamp would go out. After about half an hour's running it would then lock in and then be fine for the rest of the day. Odd I thought and read back the attached thread and decided to change the decoder for new and also change out C103 - result.
Now locks in on switching on.
I guess i should have changed the components one at a time to see which was the problem but as i had them both to hand thought whilst i am in there - i was going on to look at TR101 but no need now.
Satisfying when you get a result for 10 mins work.

alanworland · 15th Aug 2022, 11:04 am

Bet it was the decoder, I had similar and haven't changed the cap.
Good tuners, had mine since the 70's!

Alan

Radio Wrangler · 15th Aug 2022, 11:17 am

Based on traffic on the forum, the FM3 seems to be quite a bit less trouble than the FM4. I seem to remember it's been decoder chips, the tuning indicator bulbs driver transistors and the mono/stereo switching. The stuff actually receiving radio signals just goes on and on.

Add small, neat, and stylish, and they're a little gem.

David

14th Aug 2022, 9:07 am	#1
mikes08 Pentode Join Date: Dec 2021 Location: Canterbury, Kent, UK. Posts: 135	Quad FM3 https://www.vintage-radio.net/forum/...d.php?t=170997 Just following up on this as had an issue with my FM3. It would not lock onto stereo on turning on - I could coax it by tuning out and in again but after a few seconds the stereo lamp would go out. After about half an hour's running it would then lock in and then be fine for the rest of the day. Odd I thought and read back the attached thread and decided to change the decoder for new and also change out C103 - result. Now locks in on switching on. I guess i should have changed the components one at a time to see which was the problem but as i had them both to hand thought whilst i am in there - i was going on to look at TR101 but no need now. Satisfying when you get a result for 10 mins work.

15th Aug 2022, 11:04 am	#2
alanworland Heptode Join Date: Feb 2011 Location: Southend, Essex, UK. Posts: 803	Re: Quad FM3 Bet it was the decoder, I had similar and haven't changed the cap. Good tuners, had mine since the 70's! Alan

15th Aug 2022, 11:17 am	#3
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,903	Re: Quad FM3 Based on traffic on the forum, the FM3 seems to be quite a bit less trouble than the FM4. I seem to remember it's been decoder chips, the tuning indicator bulbs driver transistors and the mono/stereo switching. The stuff actually receiving radio signals just goes on and on. Add small, neat, and stylish, and they're a little gem. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done