[Amps] SB220 plate meter question

[gudguyham at aol.com]

Warren, well it could be a bad solder joint.  The SB-220 plate meter has a PLUS red wire and a MINUS black wire coming off the meter going to the rectifier board.  You must check the solder joints at the meter side and at the board side.  Then you have a 3600 ohm resistor as a series resistor for the plate meter reading on the board, that resistor could have an issue or the solder joints associated with that resistor and also the 1 ohm shunt resistor as well, that needs to be looked at as well as solder joints on that.  That is the metering circuit in a nut shell.  Unless there is some problem with the meter itself you should find your problem in that area.  Do you have a stock Heathkit meter board or some aftermarket one?  Lou



-----Original Message-----
From: Warren Volz <warren at warrenvolz.com>
To: Amps <amps at contesting.com>
Sent: Tue, Nov 7, 2017 3:41 am
Subject: [Amps] SB220 plate meter question

All, 

My SB-220 is sick again. The plate meter works fine after start up but
then ~15-20 minutes later it starts to show lower and lower values.
Eventually it doesn't show any plate current, but the amp still produces
full output. It doesn't look like I have loose connections. I suppose it
could be a poor solder joint? Anyone have any other ideas? 

-Warren KD5YPH
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