Re: [ATM] My Mototrak V stopped working... what will I do?

[Ken Hunter <atm_ken_hunter@yahoo.com>]

First off... I'd suspect the transistors are not making the noise. More likely a step-up transformer inside the unit is making the noise. It's possible that the transformer has developed a shorted winding. If that' the case, the transformer must be replaced. It could also be that the mount has developed a "sticky" drive which requires more horsepower to move the mount.Fortunately the transformer is usually a simple filament transformer run backwards to generate the operating voltage for a synchronous motor. The transistors are not so special either... the trick is to determine which is the problem.
   
  First thing I would do is unplug the mount and let the unit idle for a while then check the temperature of the unit without the load. It should run cool without a load and not make strange noises. If it fails this test, there is something wrong inside the unit and we can go from there.
   
  If it passes this test, check the mount for binding. You want to be able to move the mount very easily by turning the shaft that the motor drives. You may have to remove the motor to make this test... That's OK, as you can then reconnect the motor and run the unit without a load on the motor. It should make slightly more noise and get slightly warmer but not by very much.
   
  This should get you started.
   
  Ken Hunter
   
   
  

Christopher Dalla Piazza <dalchri@hotmail.com> wrote:
  I'd hoped that it would last forever but...

It does not appear to be producing enough power to start my RA drive 
anymore. I have noticed that two of the transistors are getting very hot. 
These transistors were pointed out to me earlier by JMI in determining if I 
had the 5W or 10W model. Because these transistors were small, I had the 5W 
model.

The drive corrector also emits a buzzing sound that increases/decreases with 
the frequency of the current as I press the east/west buttons. It's hard to 
isolate but it seems to be coming from the transistors. It has been making 
that noise for awhile and I can't be sure that it hasn't always made that 
noise.

I am praying that the problem is one of the simple components and not any of 
the smarts that is built into it.

The reason I am so set on fixing it is because I don't know where to get a 
drive corrector anymore!! My mount is not integrated with a corrector. All 
I need is E-W AC, and N-S DC control with an autoguider input. No one seems 
to sell one. So, faced with having to possibly build a replacement, it 
can't be harder to fix what I have.

Does anyone have any ideas? I am completely dead in the water for imaging 
until I find a solution. Any pointers to products I don't know about or 
basic electronics troubleshooting would be greatly appreciated!

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