How to ID a PT (is it even possible?)

Discussion in 'Shock Brother's DIY Amps' started by Uffepungen, Jul 30, 2021.

  1. Uffepungen

    Uffepungen TDPRI Member

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    Hi all!

    As a naive 14 year old I built a 5E3 from scratch way back in 2004. It had noise issues and I decided to rebuild it a year later or so. Other projects came up and I never got off my ass to complete the 5E3.

    17 years and a few other amp builds later, this project is itching in the back of my brain. I would like to use whatever parts are still useable from this old 5E3 build and make something out of it.

    I don't have the spec sheet for the PT anymore. And I don't know how I had started to wire it in (so I don't "trust" the current connections that I made as a teenager).

    What I know: The PT (and everything else) was ordered in 2003-2004 from Weber. The PT was marketed as a "standard" 5E3 PT. And it's an export version (the way I remember it had taps for both 220 and 240 among other options)

    What I don't know: The colour codes for the wires. The current rating and voltage outputs.

    What I've tried: Emailing Weber and asked if they have the specs for this PT in their archives. I never got an answer (and I don't blame them, this is old stuff). Googling the code for the PT, haven't had much success yet.

    The wires are as follows:
    - 2 yellow
    - 2 red
    - 2 green
    - 1 black
    - 1 brown
    - 1 orange
    - 1 black/white stripe
    - 1 brown/white stripe
    - 1 red/white stripe
    - 1 green/yellow stripe

    I guess what I'm asking is does anyone have the same PT and the specs? Or does it follow a standard that I can trust? Or am I better off forgetting about this one and scrapping it in your opinion? :confused:

    Cheers peeps! ;)
     
  2. Uffepungen

    Uffepungen TDPRI Member

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    edit, delete
     
  3. Uffepungen

    Uffepungen TDPRI Member

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    [​IMG]
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    [​IMG]
     
  4. danlad

    danlad Tele-Meister

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  5. danlad

    danlad Tele-Meister

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  6. zeppelinofled69

    zeppelinofled69 Tele-Meister

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    There are some reasonable assumptions that can be made based on the colors and terminating locations of the secondary leads.

    **USUALLY** this is what you would see, but you definitely want to verify. Take all tubes out, apply mains power and measure the AC voltage at each secondary termination point. If it's got a standby, you can leave that off while measuring.

    green - green/yellow - green is your 3.15-0-3.15 (6.3VCT) Heater tap.
    red - red/white - red is your high tension/voltage tap.
    yellow - yellow is your 5V heater for the rectifier.

    I wouldn't expect the current ratings to be too far off from any other deluxe transformer on the market, so probably 3A on the 6.3V tap, 2A on the rectifier heater and maybe 90-120mA on the high voltage tap.

    As for the primaries, looks like you have brown and black/white stripe hooked up but its not clear from the pictures. Black, Brown-white and Orange all appear to be not hooked up, so those are your other primary side taps.

    More pictures of the rest of the circuit would help to see where the wires are going.
     
    Last edited: Jul 30, 2021
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  7. Wally

    Wally Telefied Ad Free Member

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    Orange is sometimes a frame ground to establish a Farraday cage, is it not? One could ascertain that with an ohmmeter.
     
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  8. Wally

    Wally Telefied Ad Free Member

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    That ‘605’ EIA code is the code for Lenco. Fwiw, that PT was built in 2005….the 18th week. 605 0518
     
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  9. schmee

    schmee Doctor of Teleocity Ad Free Member

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    I used to use Weber trannies. The color codes seem to be mostly standard. Weber often had two input voltage options, so there will be an extra wire there. I have a new international Deluxe PT here I didn't use.... I will see if I can find the codes for that.
    Most Weber trannies were Chinese made years ago.

    Here are the codes on the EU one I have, maybe it will help.
    [​IMG]
     
    Last edited: Jul 30, 2021
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  10. zeppelinofled69

    zeppelinofled69 Tele-Meister

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    Schmee, I think Weber has changed their transformer manufacturer a few times cause the one you listed a diagram for is definitely for one of the Chinese ones with the multi-voltage secondary. The one the OP has looks like it was made by Lenco and has only one HT secondary alongside the heater secondaries. The primary colors are different as well.

    EDIT: Never mind, I see you were just posting this for reference. Sorry to add to any confusion.
     
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  11. Uffepungen

    Uffepungen TDPRI Member

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    Thanks everyone, really appreciate your time.

    @danlad Those links are something at least, I'll try Lenco and see if they can provide some info! :)


    @Wally First off, 2005 it is then! That agrees with where I went to school at the time. My memory is worse than I thought :D Regarding the orange wire, how would I determine if it is a Faraday ground with a DMM? Continiuity between orange and the cover of the PT?


    @zeppelinofled69 Awesome, that's really helpful. You're def right about the heaters, HT and 5 VAC wires. As those are hooked up as you describe and I remember it working (although badly constructed on my part). I'll get some pics later. The way I had hooked up the primaries after I started rebuilding the amp was apparently using the Black with white stripe and the Brown taps. I can't remember what I was aiming for, but I suspect that combo MIGHT be for 240 VAC.

    What I especially think about is what the other primaries might be supposed to do. Aren't some PT's supposed to be hooked up by connecting some of the primaries together for some voltages? On the other hand that might be for more "rare" wall voltages, like 100 VAC?


    @schmee Those trannies with the foil part seems to be the standard now? I'll keep that spec sheet for reference, even though it's different from my (probably older) PT. :)

    It seems not all hope is lost on this OT after all. I'll try contacting Lenco. Maybe I should view this as a reason to get myself a Variac so that I can determine the winding ratios of the taps... Although that would cost more than this PT and kind of defeat the whole purpose of using it I guess :lol:
     
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  12. Wally

    Wally Telefied Ad Free Member

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    Re: that orange wire. Yes, an ohmmeter can tell you if that orange wire has continuity with the transformer frame/ground OR with any of the windings. An ohmmeter will also let you ascertain how that primary is arranged. Some PTs have separate primary windings that can wired in various parallel or series arrangements for different voltages. Here is a link to a Hammond ‘international’ PT for a Deluxe that can yield any one of four voltages…and we can see the orange wire that establishes the Farraday shield.
    https://www.hammfg.com/files/parts/pdf/290BBEX.pdf
     
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  13. 2L man

    2L man Tele-Holic

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    Using an ohmmeter it is very easy to find input and output coils. Coil resistances are opposite of their voltage.

    Filament have usually less than one ohm. Then mains can have about 10 ohm and up. If primary has 110 and 120V inputs this section has about 1/10 of 0-110v section resistance. If thansformer is "international" there are two kind primarys. One coil which has 0-120-240 or 0-110-120-220-240. Or then there are two coils both having 0-120 or 0-110-120. They are connected parallel for NA and series for the rest of the world.

    Highest resistance is on HV secondary. Center tab is somewhere in the middle and if HV has bias output it is bit more towards the other HV AC output. CT tab transformer secondary coil half resistances are not the same because other half has less wire when it is wound first and second half has longer wire when it is wound over the first half.

    Then just input mains and you can measure outputs and it quarantees your resistive examination. Now center tab voltage comes very well between coil ends because voltage is a result of wound count and it is the same on both halves. But now you know what coil is for rectifier tube 5V and what is 6,3V. Without load their voltages can be even 20% more but there is no possibility not to know which is what!

    Search few valve PT "schematics" and you know what there usually is and what you need to find. Some manufacturers datasheet show coil resistances and it makes this essier.
     
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  14. schmee

    schmee Doctor of Teleocity Ad Free Member

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    Yeah, That sheet is for what Weber currently sells.
     
  15. schmee

    schmee Doctor of Teleocity Ad Free Member

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    Yeah, you never know with Weber. The PT I have unused I bought recently and came with wires exiting both sides of the tranny. (top and bottom) Was not shown that way on their site and still is not. How in the hell am I going to use that in a chassis? :mad: I could buy the "stand up" option and use it on something I suppose.. but Grrrrr......
     
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  16. mountainhick

    mountainhick Tele-Meister

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    Delete, my error. Dept of redundancy department.
     
  17. Uffepungen

    Uffepungen TDPRI Member

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    I gotta respond to this even though I don't have anything interesting to report yet. This is very helpful, I will desolder the PT and take readings as soon as I have the time. My plan is to make a spreadsheet of the readings of the different wires wrt each other, and then try to interpret the results :)
     
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