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Very Quite audio, TR396FCC

Posted: Thursday 25th Mar 2010, 10:31
by longhaireddwb
Radio Make and Model:
PCB Number:
PLL Number:
Test gear available:
Symptoms:

What is working:

What has been tried:

Did it suddenly happen ?:
Anything else that may be of help?:

Re: Very Quite audio, TR396FCC

Posted: Thursday 25th Mar 2010, 16:35
by longhaireddwb
I don't know what happened to my first post so I'll try it again.

I have a TR396FCC and the audio is very quite. If I turn the volume up all the way I get just a tiny bit of white noise. I hooked up 2 radios on my work bench and transmitted on the 396 then switched the antenna and got a reply on the second radio so I know the 396 is transmitting.

I have loud talk-back and PA. I've replaced IC8 and IC1 and four transistors trying to locate the problem. I've tested all the transistors and diodes (I think). I noticed today that when I turn the RF gain control all the way up or down it makes no difference. I did some more checking with my equipment which is a Huntron tracker, an o-scope, a signal generator and so forth and found that I had signal at TP3 but not at TP2. I than pulled IC2 out and checked it with the tracker. There is no connection internally between pins #6, 9 and 10. I have a feeling this might be the problem but I'm just not sure. Plus I don't have any of these around or in town I can get too.

If anyone out there can help me out I'd really appreciate it. I've been going over this radio for weeks now :banghead: (I'm new to radio repair :roll: ) and I've had nothing but headaches from it. Help!

Re: Very Quite audio, TR396FCC

Posted: Wednesday 31st Mar 2010, 17:33
by Uncle Ray
mate , i've had problems like this on an 858 chassis. Check the electrolitics ( caps ) feeding the input of the audio chip. I had one problem where the cap was open curcuit.
Infact , just replace the caps around the audio amp.
Hope it works for you.

Re: Very Quite audio, TR396FCC

Posted: Thursday 1st Apr 2010, 14:33
by longhaireddwb
Thanks for thew reply uncle ray but I sent it to a shop. I just couldn't wait any longer. If I can remember I'll post up what the problem was when I get the answer from the shop.