> Hey, I am having trouble with a Uniden PRO 535e and i was wondering if
> anyone would be able to help me with it. It seems that I blew one of the
> transistors, cause suddenly volume is very quiet, and the PA is pretty
> quiet as well. But, the behaviour is a little weird.
If the radio will transmit a carrier but no modulation
the audio IC might be bad.
> Anyway, is there a good source for info on fixing them, or should I just
> send it back to Uniden? (I would prefer no too, cause i have screwed with
> it, and i don't want to bother explaining to them what i have done.) If
> it is a transistor, then i can easily do that.
> Thanks for your time.
> Geoffrey Hoffman
Find the audio IC and check the signal at it's input and
output pins. The audio IC is a common failure point in
many modern CBs. You can find a pinout for it in the
replacement catalogs (NTE, SK, etc.). If the input signal
is missing or distorted isolate that pin on the IC (wick
up the solder and center the pin in it's hole) and check
again. If the signal is there and clean with the input
pin isolated the chip is probably bad. Two other verifi-
cation tests are: 1. Look for low supply voltage at the
chip's VCC pin. 2. Look for physical damage to the chip
itself. Often a chunk of the chip package will actually
blow out. If you find that the chip is bad make sure you
test all the pins where there are capacitors to ground for
shorts. Oftentimes a capacitor will short taking the chip
with it.
If these procedures aren't enough you can get service manuals
from Uniden. Here's a phone number: (317) 842-0280.
Good luck.
--
-=[Bill Eitner]=-
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