Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Sesh on October 11, 2021, 01:15:15 pm
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Hi there
Long story short, I'm converting a Bolex Paillard Sonorizer into a guitar amp. It's a device that was used to add sound 8mm film that also happens to have an amplifier and a guitar tube amp friendly complement of tubes (EF86, 12AX7, EL84).
In my infinite wisdom/naivité/newbness and with perhaps a bit of excitement-induced impatience (I know that trait of mine doesn't jive with electronics DIY and, at a later point, high voltages...), I took a few pictures of the original wiring and set to remove all of the circuitry intending to build from scratch. I thought, if all else fails I could use good ol' Uncle Doug's identification techniques:
Alas, the pictures are not clear enough for me to properly identify the leads, and since the power transformer looks quite different from the usual guitar transformer I've read about/seen pictures and videos of, I have a hard time continuing. Not to mention there's no schematic anywhere on the web.
Here it is: (https://i.imgur.com/rjGZeWl.jpg)
Here's what I have to go on: (https://i.imgur.com/yPY969R.jpg)
The left side is obviously the primary. The different colored leads are the different outlet voltages - It was set to 220 (we have 230v here now). What is the common, though? There's the striped wire and the black double wire.
Would it help if I tried to measure the leads/checked for continuity?
Would it be easier to identify it (a la Uncle Doug) if I removed the "distribution" turret boards mounted on the PT and used the wires straight from the PT?
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I'm not the big expert here, but I would want to nail down those leads with as much certainty as possible. Hence, I would disconnect the leads and start measuring resistances. The more senior folks here may have other ideas.
And -- there's nothing wrong with enthusiasm! Yeah, you'll make a mistake or two, but who's to know? Learning is best around these mistakes.
You do have to be careful when poking around high voltage, you bet.
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the filamant voltage leads will have 6.3VAC on them. You could start there and indentify those first. should be easy to tell which they are since their colored wires are probably still connected to the filament pins on the sockets.
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I learned from Sluckey when removing a PT from a chassis use the connections to help identify the wiring and mark them for future use.
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The distribution strips are a heap safer than a lot of high-voltage lashing about like snakes.
Yes, resistance tests. The highest will be your 300V-800VAC. The lowest is 5V or 6V. Something in the middle may be your 110V (220V?). How many voltages do you expect? Line, and loads?
I'd also prepare a 6VAC transformer with 10 Ohm 10W series resistor and a 60W incandescent lamp limiter. When you think you found the "110VAC" winding, feed 6V to it and see if all else is about 1/20th of expected (like 17VAC where might have been 350VAC). If it passes that, bring the 110V winding up on the lamp limiter.
LOTS Of Clip Lead!! Don't try to hold meter leads with fingers! With this many leads you will get tired, slip, and shock yourself.
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Check out Uncle Doug on YouTube. He has got a video that describes identifying the leads on a PT.
videos
Hope this helps
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Alright... my multimeter needed a fresh battery, but here we go.
It was pretty easy to determine high voltage and filament leads. The high voltage was 300ish something ohms, the other 2,5ish.
My main issue is the power outlet side. I know the small colored leads are the different outlet voltages. My issue is first and foremost - which is which and which one is the common?
Is there any systematic method I can use?
The measured resistances varied from 10-15ish to 50-60. I guess when the resistance is low, it means the voltages aren't too far apart (like 220v to 240v). Would it help if I recorded all the combinations?
Then finally.. the last question. The bottom left wires. What can those be?