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Hoffman Amps Forum image Author Topic: Heaters  (Read 2392 times)

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Offline davidwpack

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Heaters
« on: August 09, 2020, 03:38:15 pm »
Ello. I had an abrupt problem with an amp that I've been playing for a while. Turned it on after having played it yesterday. It worked fine yesterday. Anyways, V2 and V1 suddenly have no filament voltage. I'm measuring 3.1 v  to chassis on pins 4/5 and 9 but nothing between. Shorted together somewhere probly? I'm going to rewire the filaments for V1, V2 starting at V3. I just wanted to run it by everybody because I've been playing through this for a long time with no issues. Thanks

Offline sluckey

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Re: Heaters
« Reply #1 on: August 09, 2020, 03:44:52 pm »
Probably a broken wire or bad solder joint between V3 and V2.
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline davidwpack

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Re: Heaters
« Reply #2 on: August 09, 2020, 03:51:33 pm »
That's what I was thinking. Thanks Sluckey!

Offline PRR

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Re: Heaters
« Reply #3 on: August 09, 2020, 06:49:07 pm »
> Shorted together somewhere

The heaters are a near-short 4/5 to 9.

Pull those tubes. Now one side may show 3V, and the other side not.

Offline davidwpack

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Re: Heaters
« Reply #4 on: August 28, 2020, 08:43:23 pm »
Sorry PRR, I didn't know I had a reply from you. I went ahead and put in new Belton sockets in all the preamp tube positions (V1-V4) because they were cheap. Out of a lack of aesthetic abilities or laziness I decided to do a straight Soldano style heater wiring job. At first it was noisy and sounded terrible. After a day of probing and tube replacements I found that the resistor leg on V1 connecting pin 2 to pin 7 was only soldered on pin 7. I went back and soldered pin 2 and now it's dead dead quiet. I thought I had inadvertently destroyed something else in the process until I plugged in a guitar but it's just that quiet. I think I'll try using that approach for wiring heaters more often. Anyways, thanks Sluckey and PRR..
P.S. Does anyone make tube shields for bottom mount sockets. I don't think they do but I thought someone might know something more about it.
« Last Edit: August 28, 2020, 08:49:52 pm by davidwpack »

Offline acheld

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Re: Heaters
« Reply #5 on: August 28, 2020, 08:55:08 pm »
Could you explain what a "straight Soldano style heater wiring" is please?  How is it different from the Fender style?

Offline davidwpack

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Re: Heaters
« Reply #6 on: August 28, 2020, 09:46:52 pm »
Wires are run straight as opposed to twisting them. Here's a pic from the internet.

Offline sluckey

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Re: Heaters
« Reply #7 on: August 28, 2020, 11:51:39 pm »
P.S. Does anyone make tube shields for bottom mount sockets. I don't think they do but I thought someone might know something more about it.
Get some of these collars...

https://www.ebay.com/itm/4-x-Tube-Socket-Collar-Base-For-9-Pin-J-Slot-IERC-Tube-Shields/293301400131?hash=item444a203243:g:5akAAOSws-xdtw5c
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline davidwpack

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Re: Heaters
« Reply #8 on: August 28, 2020, 11:59:11 pm »
I ordered 3 sets. I like the extra height the pins have from being bottom mounted. I believe I'll stick with that type. Thanks again Sluckey!

 


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