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boobtoob
11-29-2006, 12:58 PM
Hello:

If I have an old amp PT that has no labels...how do I test the secondary for it's voltage output and amperage handling capabilities?

Thanks,
Dave Orban
11-29-2006, 12:59 PM
Bruno...?



































(Sorry, couldn't resist...) :rotflmao
Norse
11-29-2006, 01:14 PM
Bruno...?




(Sorry, couldn't resist...) :rotflmao


That would be Fender... ;)
John Ward
11-29-2006, 02:14 PM
You can easily test the voltage output of the secondary. First figure out which leads have continuity using an Ohm meter. I recommend using a lower voltage AC supply (rather than 120V). There are some useful tips from Paul Ruby here: http://paulrubyamps.com/info.html and if you don't know what you are doing, get some assistance. Messing with an unknown PT can easily generate >1000 volts.
John
John Ward
11-29-2006, 02:18 PM
I also wanted to add that you can estimate the max current capabilities of the PT by comparing its size and weight to other known PTs. But to measure the max current you need to put it under a load (not something I would want to mess with).
John
boobtoob
11-29-2006, 03:51 PM
I also wanted to add that you can estimate the max current capabilities of the PT by comparing its size and weight to other known PTs. But to measure the max current you need to put it under a load (not something I would want to mess with).
John

Thanks for the info.

If I power up the tranny and touch the secondary with my DMM, I get random voltages. I guess there needs to be a load attached to get correct readings??? Do I just solder in a huge resistor between the leads to get a load going???

And the amperage check, my DMM has a mA setting up to 10 amps. Could I just touch the leads with it set to this setting to get amps???
I admit, I am scared of frying things.
Old Tele man
11-29-2006, 03:56 PM
...I use the output from a 12.6VAC bell transformer to produce a "test" input voltage that's about 1/10th of the 120VAC line voltage.

...and I also connect a 100K/2W resistor across each set of output leads to provide a "light" load and give me something to "clip" my VOM leads to (don't like "open-circuit" readings).