Remcon 12 Rx schematic needed

[jmendoza]

Don't ask me why I try to fix this stuff, especially old reed sets from the UK, but I get what I deserve by trying....a BIG headache!
I have a REMCON 12 receiver with a dead audio stage, very low (.5V peak to peak ) audio signal and so I need a schematic to figure out the circuit, and what types of transistors are used, and the electrolytic cap values.
I see it has Jap transistors, which are very hard to source here, as they were never popular and nobody ever carried a good stock of them at the retail level. Hopefully I can use a general purpose silicon transistor to substitute if the original is bad, but I need a schematic 1st. Of course now I'm really getting hopeful and would like a component layout, but that is probably a pipe dream!

Any help is appreciated lads,
thanks in advance,
Jay

[jmendoza]

I poked around and found an open winding on the audio transformer. How to find one of those?

[Phil_G]

M48 on the Archive page Jay
Cheers
Phil

[jmendoza]

Thanks Phil, I'll open it up and get back to work fixing the REMCON 12, will post pictures,
Jay

[jmendoza]

Transformer T1, 5:1 ratio, has an open primary, and the winds are not broken at the terminals, so it must be internal. I'll have to try and find a replacement, so if anybody has one I'm interested.

Thanks again,
Jay

[jmendoza]

I decided to abandon the transformer, so it was removed. In it's place I used a 10K resistor where the primary winding was, that added a collector load to the detector/audio amp. Then I connected a .47uF cap from the collector of the detector/amp to the base of the reed bank driver transistor at the point where the transformer secondary used to connect. Viola, it works really well and now, I have all four servos that came with it working. It started to get a little weird after repeated testing and that was the airborne battery getting low, so I put it on charge.
My inspiration came from looking at an Orbit 10-12 channel reed receiver; they do not use an audio transformer to couple the 1st audio amp to the driver, instead they use a 1uF for DC coupling of the stages. I hope Dunham and Mathes (RIP) don't sue me for copying their design

[Tobe]

I'm sure you have reached the limits for The statutes of limitations!

[Sparky1phillip]

Hi J Mendoza, That is very clever to iliminate the 5:1 ratio tx. I cant find the exact copy of the old d1001 Ardente or Henries radio anywhere. Thanks mate respect!