Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: yockoe on September 30, 2019, 10:29:00 pm
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I have an Export Model of the 1965 Fender Pro Reverb. I have not been able to find a wiring diagram for the Export Power Transformer that was installed in this amp. Anyone have any suggestions?
Thanks.
Jack
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More than likely you can measure it out and figure out the wiring based on the schematic, continuity/resistance between wires and, from there, figure out the voltages.
Based on the picture in the attachment, and the general 1965 schematic, you'll have 1-2 primary windings, and 3 secondary windings.
On the pictured layout, I'd guess the following, based on wire locations and color:
2 yellow wires - 5v rectifier secondary
2 red wires - HT secondary
1 red/yellow - HT center tap
1 red/blue - HT bias winding
2 green wires - 6.3v Heater secondary
1 green/yellow - 6.3v heater center tap
2 black wires - Primary winding
If it's an export transformer you'll likely have 4 primary wires. Two of them linked together, to bridge two 110-115v windings to make a 220-230v winding
What's the end goal here? You want to measure the voltages? Or is it totally disconnected and you need to re-connect it?
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The original transformer has been overheated in the past. There is oozing from the bottom. Not a lot and I don't know when it happened. I have owned since 1990 but don't know history prior. Has mostly been in closet since then. It was modified by someone prior with a 5U4 and huge output transformer (don't have the original but bought Classictone power and output replacements as well as a Mullard GZ34).
Want to return to closest I can get to original setup. I am old and don't need more power or loudness. I have replaced old paper caps with FT's and Spragues.
Yes, it still works.
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don't have the original but bought Classictone power and output replacements as well as a Mullard GZ34).
So why do you need the wiring diagram for the Export Power Transformer? Just put those classictone transformers in it and wire them as per the Fender schematic.
Maybe I'm not fully understanding? :dontknow:
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The original transformer has been overheated in the past. There is oozing from the bottom. Not a lot and I don't know when it happened...
Generally, when folks think that, it's just how the original potting material has set at manufacture.
These Fender PTs were potted with resin, not wax, it doesn't ooze out when the PT overheats; the PT can overheat to the point of billowing forth acrid smoke without any ooze happening.
I suspect that the 'ooze' is rock hard? If so it's been that way since the day it was made.
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The original transformer has been overheated in the past. There is oozing from the bottom. Not a lot and I don't know when it happened...
Generally, when folks think that, it's just how the original potting material has set at manufacture.
These Fender PTs were potted with resin, not wax, it doesn't ooze out when the PT overheats; the PT can overheat to the point of billowing forth acrid smoke without any ooze happening.
I suspect that the 'ooze' is rock hard? If so it's been that way since the day it was made.
You may be right, but the color is different than the rest of the transformer. Transformer dull, what looks like the ooze is shiny. Where the wires exit, it looks like a black goo is floating inside of transformer around the wires. May be just fine. I just want to be safe. If that's normal, I'll probably leave it as it is.
don't have the original but bought Classictone power and output replacements as well as a Mullard GZ34).
So why do you need the wiring diagram for the Export Power Transformer? Just put those classictone transformers in it and wire them as per the Fender schematic.
Maybe I'm not fully understanding? :dontknow:
I cannot find a Fender wiring diagram for the export version. The export model has a 6 position power selector switch wired to multiple wires from transformer. The wire colors of colortone vs original PT other than red, yellow, black, green, white are all different. Will get it traced in the next day or so.
The amp has been hot. The metal around the first 3 tubes is scorched. Someone in past changed GZ34 to 5U4 and added a huge OT. Could not find a name on OT.
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...I just want to be safe...
As with any newly acquired or put into service item of vintage mains electrical equipment, it would be best to take it a competent person for a proper appraisal of its safety and operation.
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I cannot find a Fender wiring diagram for the export version. The export model has a 6 position power selector switch wired to multiple wires from transformer.
Again, you don't need a Fender wiring diagram for the export version. When you successfully install that classictone PT IAW the Fender schematic there will no longer be any wires on that power selector switch. Just a power cord, convenience outlet, fuse, and power ON/OFF switch. Very simple. If this makes no sense to you then maybe let someone else do this job.
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I cannot find a Fender wiring diagram for the export version. The export model has a 6 position power selector switch wired to multiple wires from transformer.
Again, you don't need a Fender wiring diagram for the export version. When you successfully install that classictone PT IAW the Fender schematic there will no longer be any wires on that power selector switch. Just a power cord, convenience outlet, fuse, and power ON/OFF switch. Very simple. If this makes no sense to you then maybe let someone else do this job.
The USA Version power transformer (whether Fender or Classictone) is as you say and can be wired per the fender diagram. The Export Version has in order from left to right: power cord, 6 position switch (117/200/210/220/230/240), 2 way ground switch, fuse, ON/OFF switch. It DOES NOT have a convenience outlet. And yes, it came from Fender this way. On the original and Classictone, if you wired only as shown on the Fender diagram there would be 6 (7 on the Classictone) additional wires that should be attached to the switch to be able to select a different input voltage. Add a converter to plug into the socket in the foreign country and your in business.
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I'm still unsure about what you want to do. The only thing I'm sure about is that you have not been able to find a wiring diagram for the Export Power Transformer.
Does the amp currently have the export power transformer installed?
Does the amp work properly?
Do you intend to replace the current power transformer with a Classic Tone transformer?
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Is this like the voltage selector switch on your amp? And you want to wire the replacement PT to use this switch? If so I think I see your dilema if you are going to use the Classic tone equivalent tx to the 125-P5DX http://www.classictone.net/40-18029.pdf (http://www.classictone.net/40-18029.pdf) There are 6 positions on the V select switch but the classic tone pt wiring data only shows 4 possible voltage selections.. the classic tone pt looks like it is designed to be hardwired for one voltage and doesn't look to me to be a perfect replacement which will work with the switch and definitely does not have all the voltage combinations shown. :dontknow: The orange wire on the classic tone pt is a shield wire.. goes to chassis ground
(https://www.tdpri.com/attachments/dr-voltage-jpg.545171/)
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Bear in mind that there's been no evidence presented so far that the stock original PT in the amp is anything other than 'in full working order', the purpose of replacing it therefore seems to be beyond reason.
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Bear in mind that there's been no evidence presented so far that the stock original PT in the amp is anything other than 'in full working order', the purpose of replacing it therefore seems to be beyond reason.
You are correct in that the transformer is working properly. I was only concerned about what appears to have been leakage at one time or another. The photos shown by a previous poster is exactly like mine.
I want to thank all who have replied to my request.
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...
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The classictone 40-18029 can be wired for 100V, 120V, 200V, 220V, or 240V. But not with a single pole switch like Fender used. It looks to me as though you could only get 220V and 240V or 200V and 220V using Fender's switch.
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The last couple of photos was what I needed. Thanks to all who supplied info and comments. I really appreciate your help.
Thanks again.