technics cd repair

[James]

Right, this is my problem. I have a technics hi-fi system, the ch-550 range.
Im having problems with my cd player. Lately its started jumping so i have
done the usual and cleaned the lens, manually, lubricated the runners etc
and the problem still exists. I have measured the voltages on the unit and
found that when the cd has been playing for a short time the voltages on
the power supply start to drop. When they get to a certain level the cd
jumps and skips. After this it settles down again for a short while and
then it repeats itself. Does anyone, or has anyone had the same problem
with this. The model of the cd player is sl-ch550. I dont have a diagram of
this so im at a loose end. I was wondering if it were worth my while
changing the 3 transistors on the power supply and the caps to see if this
is the problem.

Could anyone help me here please? Being an electronic person id like to sort
this myself but without a diagram its pretty tough.

--
James

To e-mail me direct, remove the 123 from my address

[CJ]

I had a similar problem with an AIWA cd that skipped at a certain point on
some cds. The problem was due to a small amount of plastic trim that had
been left on a gear wheel. This caused a tight spot in the gear train which
only showed up at cetain spots. Its just a chance but if you do have a tight
spot caused by some wear or dirt in the gears it could cause the motor to
take more current and drop the output volts.

Chris John
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[Jerry G.]

Check to make sure that the laser assembly can move along its track
without any obstruction, or hard resistance to move.

The next step is to verify the laser's output to make sure that its
emission is up to specs. You will require a CD laser checker to do this.
If the laser is weak, then it will have to be replaced. The tracking
alignment will then be necessary to redo. The service manual and proper
test gear will be required.

If the laser is good, then you will have to follow its signal path up to
the processing area to see if this is in specs. If this compiles, then
the problem can be in the processing area, or servo control area. You
would have to follow this from the information given in the service
manual.

We found that if the problem was not simple in these players, it is more
economical in the end to replace them. The cost of servicing them for a
complex problem is too high in relation to its replacement value.

Please note that it can be dangerous to eyesight to look at the laser
output while the player is running.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
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WebPage http://www.zoom-one.com
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Instruments http://www.zoom-one.com/glgtech.htm
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