Resistance Checks for Terminals 47 & 48

[heavycowboy]

Hello,

Just finished my build. All resistance measurements are on the money except for terminals 47 & 48. The manual shows a *, but I'm getting 0 ohms for both. Any thoughts on what the problem could be?

Thanks in advance,

Todd

[Paul Birkeland]

Did you accidentally leave the amp plugged into the wall while doing these measurements?

Were you able to perform the power transformer voltage checks?

[heavycowboy]

Nope, the amp was definitely not plugged when I ran the resistance checks. And no, I have not performed any voltage checks yet.

[Paul Birkeland]

There are voltage checks on pages 27, and 31-32.  Were these checks performed? 

[heavycowboy]

Yep, per the manual I configured the wiring for an incoming voltage of 120v. It's been a while, but I'm pretty sure the subsequent voltage checks on page 32 were in the appropriate range.

[Paul Birkeland]

Well, if you have 0 Ohms on 47 and 48, that would tend to indicate that your incoming AC voltage is shorted to the chassis plate somewhere.  If, by chance, you accidentally measured with the power cord plugged in, then you would just be measuring that the neutral of your incoming AC is properly grounded at your breaker panel. 

Otherwise, there's just the wiring at the IEC socket, power switch, and those two terminals that is otherwise completely isolated from the chassis.  There isn't a whole lot to check here to verify that there aren't problems.

-PB

[heavycowboy]

OK. Much thanks for your help. I'll be honest, I'm not really sure how I should proceed. I'm assuming it's not wise to power it up and move on to the voltage checks, correct?

[Doc B.]

What PB is saying is be sure to check all of the wiring at the IEC socket, power switch and terminals 47 and 48, looking to see if a wire has been connected to an incorrect terminal or maybe some excess lead was not cut off and is touching the chassis plate. Do that before you power up the amp.

[heavycowboy]

Well, I went ahead and double checked all the wiring and then proceeded to power it up. To my surprise, all the voltages checked out. No idea, why my meter had trouble with the resistance on those two terminals. Regardless, it's alive and I'm loving it.

Thanks everyone.