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Old 10-31-2021, 04:16 PM   #5
Join Date: Feb 2010
City & State: Ames Iowa USA
Line Voltage: 120VAC 60Hz
Posts: 69
Default Re: Motor control board

Originally Posted by R_J View Post
What are the numbers on the regulator ic's? especially the negative one. Doe the transformer only have 2 wires supplying the board or is it center taped?
you might want to indicate which one gets warm, is it the positive one or the negative one?
If you don't have a balanced circuit +15 and -15, you could see some positive voltage on the negative supply.
The two regulators which have heat sinks both have the following on them:
on the board they are labelled AVR1 and AVR2.

on the IC packages themselves, there is

on both. they seem to be identical, but only one is getting warm. The main transformer seems to have multiple taps.
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