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sharp vcr vc AA-350 cassette loading problem.

Y

Yosief

Jan 1, 1970
0
Well I am an electrical engineer but an amateur repair engineer. A
friend of mine just gave me a sharp vcr VC AA-350, whom he previously
took to a repair center for it was a totally dead unit (power supply
problem). The technician changed a transistor in the power
supply.Currently there is power but the vcr wont take a cassette
(casette loading problem). I checked the mechanical parts it is ok. I
checked the motor, it works fine. I checked the power supply it seems
it works perfect. But there is no voltage coming to the motor. I just
can't isolate the driver ic. Can any one help me out there.
 
B

Bradley1234

Jan 1, 1970
0
If you connect up the vcr, does it "work" in that you get the channels to
change and a menu on the tv, or words on the tv when you push buttons?

If you plug the unit in, does a light kind of come on, then go off and
blink?

If it had a dead power supply, the supply might still have problems. The
way it loads, sometimes, is that it detects motion on the tape cassette
being pushed in, then it activates and loads

hopefully nobody touched the gears because there is an exact alignment
needed

So you push a tape in, and what happens exactly?

any noises?

Somewhere in the gear assembly is a master rotary switch that tells the cpu
where the tape is at, thats the thing that probably detects a switch change
and starts to load, but it is traced back to the cpu. They can go bad, but
its more likely the power supply still has a problem

Even though a transistor went bad, what was the original cause for it to go
bad?
 
Y

Yosief

Jan 1, 1970
0
Ok here is what happens. There is a light when you press any button on
the unit. when you first load the cassette the unit was designed to
activate a motor to load the casette. I checked the power supply for
problems, for i still think it is a power supply problem. Every thing
seems to work fine, the only thing i wasn't able to check was the motor
driver ic. there is no noise when you press any thing the belt is ok.
Some times the spindles rotate but it lasts only for a few seconds. In
short the whole system was designed to supply a 9 v dc voltage to the
motor. But at the terminals of the dc motor and it is also a loading
motor nothing comes, with power on. The multi meter reads 0 v. How do
you advise me to check the power supply.
 
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