ETN550
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- Knoxville, TN
I've been runniing a 701A and have noticed that after about 10 - 15 minutes of running the output voltage drops off. Starts out around 120 when the knob is cranked almost fully clockwise. Then, as it warms up the voltage drops off until it gets to around 106 or 108 at full clockwise on the dial. turning the dial counterclockwise can get it as low as 90. This seems to repeat once the machine is cooled off and then re-started. Load does not seem to make much difference.
So to get things moving along I swapped the entire A1V1 voltage regulator assembly with another I had in a complete and functioning control box.
Problem solved as it seems to be holding 120 and not at full scale on the dial.
Now I want to fix the bad A1V1 so my spare control box is back up to snuff.
Does this sound like the transistor is bad? And if so is the transister the component on the top with a dome the size of a nickel and screwed down with heat sink tape under it? Can it be replaced separately? Where do you get them? I know complete A1V1 is very pricey..
What else to look for?
Thanks for help.
So to get things moving along I swapped the entire A1V1 voltage regulator assembly with another I had in a complete and functioning control box.
Problem solved as it seems to be holding 120 and not at full scale on the dial.
Now I want to fix the bad A1V1 so my spare control box is back up to snuff.
Does this sound like the transistor is bad? And if so is the transister the component on the top with a dome the size of a nickel and screwed down with heat sink tape under it? Can it be replaced separately? Where do you get them? I know complete A1V1 is very pricey..
What else to look for?
Thanks for help.