DEK AC Generator Low AC volt Part III

ErnieD

Member
Tore into the generator end and removed the stator. Found what appears to be a diode, marked plus and minus on the bottom, which is shorted out. The other diode is potted in green, and tests ok.
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No sign of a automatic voltage regulator (just a capacitor) and this diode wired into the rotor. Rotor coils each have a resistance of 3.8 ohm.

No part number or other marks than plus or minus.
 
Some of those gensets are not ment to be repaired. I have seen some with no parts support. And no information on them. Some the parts cost so much. It is cheaper to buy a new unit.
 
Yeah, that is what I am fearing. The component was soldered in. More research calls it a varistor.
 
Hello ernied,

Ha! Variable resistor...... That could be the invisible regulator?
Can't believe how many parts are no longer avaible, not that old



Guido.
 
Hey Guido, I'm old enough to know. They came in all kinds of different voltage values. The SK book was full of them. You know those little LED voltage gauges that Radio Shack sold so many years ago. I built one of those from an electronics magazine even before RS sold them. Was just after those diodes came out. Good gravey half the parts in those projects you can't even get anymore.
 
If it is a Varistor, it might be just fine. Put a digital ohm meter across the leads and warm it up with a hair dryer. If it shows change it might be just fine! Jim
 
That is the conclusion I have arrived to. The tan circular coil creates a mag field around the end of the rotor, the diode varister rectifies and regulated the field. One diode varister is shorted both ways, the other blocks one way and ohm varies the other. Well I will call tomorrow and continue the quest.
 
A shorted diode conducts both ways with little resistance. An open diode does not conduct at all. A diode coupled with a heat sensitive resistor does what you are indicating. Jim
 
Hello jeffcat,

When I get a chance I will dump my box of old electronic components on the bench, and post a picture for you. Ceramic caps witb a color code? Many power resistors, eproms and eeproms, transistors, and more. Still have my tack and dwell meter, I built as a kit. Remember heathkit? The timing light finally smoked out. I think he found the way the gen set regulates power out,

Guido.
 
Some learning needed fellows.
"A varistor is an electronic component with an electrical resistance that varies with the applied voltage. Also known as a voltage-dependent resistor (VDR), it has a nonlinear, non-ohmic currentvoltage characteristic that is similar to that of a diode. In contrast to a diode however, it has the same characteristic for both directions of traversing current."

My 2 cents says it is a simple diode/rectifier, but press on!
 

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