Switchable Output Transformer?
Moderators: pompeiisneaks, Colossal
-
BonesMachine
- Posts: 35
- Joined: Fri Jan 28, 2022 2:28 am
Switchable Output Transformer?
Looking to switch semi quickly between 2 OTs. I think one i have might be damaged and breaking up early. I would like to compare against a new OT. Any way i can solder up both OTs at the same time i guess that would be in parallel, and have 1 wire of each OT on a separate switch. So that would be a 2 switch (one off / one on) kinda ghetto setup. Then I could power off the amp, unload caps and switch the OTs? Could a standard 1 pole household switch handle the dc voltage if switched while the amp is off etc?
Re: Switchable Output Transformer?
Yes it will work, once at least. The overvoltage might cause arcing so if you stick to your plan to cold switch it it should be fine.
The suspect xfmr can be trouble though.
Did you check it for a shorted coil? Aside from early breakup, any other symptoms, like getting hot?
The suspect xfmr can be trouble though.
Did you check it for a shorted coil? Aside from early breakup, any other symptoms, like getting hot?
Tube junkie that aspires to become a tri-state bidirectional buss driver.
-
Stevem
- Posts: 4601
- Joined: Fri Jan 24, 2014 3:01 pm
- Location: 1/3rd the way out one of the arms of the Milkyway.
2 others liked this
Re: Switchable Output Transformer?
With a Fender amp here’s a easy way to tell if the OT is good while it’s wired into the amp.
This test assumes your output tubes are atleast halfway good.
Two things are needed for this test.
1) a way to drive the amps input with a test tone of 150 mill volts or about -10 db.
2) a voltmeter.
With the amp hooked up to a speaker open the volume pot up to 3 1/2 to 4.
With your meter set for ac volts and hooked across pin 5 of a opposing pair of output tubes you should read around 49 volts or more .
This will be the signal from the PI section that drives the output tubes.
With this much drive signal hitting the output tubes if the OT is good the the volume of the test tone should be killing you, in fact 49 volts of drive signal should be darn close to pushing the amp into clipping if you where to look at the output wave form on a scope.
If this does not take place then the OT is shorted in some
Way.
This test assumes your output tubes are atleast halfway good.
Two things are needed for this test.
1) a way to drive the amps input with a test tone of 150 mill volts or about -10 db.
2) a voltmeter.
With the amp hooked up to a speaker open the volume pot up to 3 1/2 to 4.
With your meter set for ac volts and hooked across pin 5 of a opposing pair of output tubes you should read around 49 volts or more .
This will be the signal from the PI section that drives the output tubes.
With this much drive signal hitting the output tubes if the OT is good the the volume of the test tone should be killing you, in fact 49 volts of drive signal should be darn close to pushing the amp into clipping if you where to look at the output wave form on a scope.
If this does not take place then the OT is shorted in some
Way.
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
-
Kagliostro
- Posts: 533
- Joined: Wed Dec 30, 2009 12:09 am
- Location: Italy
Re: Switchable Output Transformer?
To give a look to your old TU
Franco
Franco
You do not have the required permissions to view the files attached to this post.