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Ten-terminal Quad-II output transformer
Ten-terminal Quad-II output transformer
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Old 4th July 2019, 04:15 AM   #1
Johan Potgieter is offline Johan Potgieter  South Africa
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Default Ten-terminal Quad-II output transformer

I have encountered a Quad II output transformer with a total of ten terminals instead of the usual eleven. It would appear that the secondary 'P' terminal (earth side of the loudspeaker winding) does not appear; the earth connection of the secondary must have been brought out directly by wire, attached to the output terminals close by.

I have unfortunately taken off and dismantled the OPT before realising this, so that the original connections are no longer available. I vaguely recall a picture of such a transformer showing the above direct connection, but very vaguely so. Unfortunately all lettering has been obliterated from the terminal plate.

Google search showed nothing relating to this, so I was hoping some member has some explanation/reference.

Thanks in advance.
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Old 4th July 2019, 06:02 AM   #2
jazbo8 is offline jazbo8
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Ten-terminal Quad-II output transformer
May be using the color codes, you can figure out which one is P?

E3C2139E-D4C4-4EB7-AEF2-6F266673ECB4.png
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Old 4th July 2019, 08:47 AM   #3
JonSnell Electronic is offline JonSnell Electronic  United Kingdom
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See which one is missing from the photos and maybe contact Majestic Transformers for advice.

Click the image to open in full size.
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Old 4th July 2019, 01:55 PM   #4
Johan Potgieter is offline Johan Potgieter  South Africa
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Gentlemen,

Many thanks for quick reactions!

Unfortunately any wire colours are obliterated by the 'pitch' potting material - this is an original Quad OPT. It is even well-nigh impossible to trace which lead came out where on the coil winding itself.

John,
The Majestic has all leads coming out to eleven turrets, thus might be a far cry for them to explain this old a original Quad OPT.
Still, will give them a try.

As you may have concluded this is a rewind on my side, so no real problem where to take leads in the end, even if I have to bring out a 'loose' lead directly to the loudspeaker terminals. I more wanted to find out what was done all those decades ago in order to duplicate as faithfully as possible.

Perhaps someone with the knowledge will still reply here.
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Old 10th July 2019, 02:33 PM   #5
johnm is offline johnm  United Kingdom
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Have you tried Rob Flain at Quad? Might be worth a shot. Or Keith Snook.

QUAD | the closest approach to the original sound
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Old 10th July 2019, 05:36 PM   #6
ejp is offline ejp  Australia
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The terminals on the Majestic are in the identical positions to the original. If that doesn't help I'm not really clear exactly what you're asking.
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Old 11th July 2019, 04:52 AM   #7
petertub is offline petertub  Sweden
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Ten-terminal Quad-II output transformer
Quote:
Originally Posted by johnm View Post
Have you tried Rob Flain at Quad? Might be worth a shot. Or Keith Snook.

QUAD | the closest approach to the original sound
The "new quad" seems unwilling to share important things like schematics etc. Buyer beware !
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Old 11th July 2019, 10:45 PM   #8
ejp is offline ejp  Australia
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Quote:
Originally Posted by petertub View Post
The "new quad" seems unwilling to share important things like schematics etc. Buyer beware !
That's not my exoerience at all, over the last 13 years of dealing with them as a serviceman. Very helpful indeed. They probably don't share schematics of current products except with their dealers, but they would hardly be alone in that.

To the orginal point, are there eleven wires?

EJP
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Old 12th July 2019, 04:51 AM   #9
Johan Potgieter is offline Johan Potgieter  South Africa
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Quote:
Originally Posted by ejp View Post
The terminals on the Majestic are in the identical positions to the original. If that doesn't help I'm not really clear exactly what you're asking.
Let me rephrase: I have two Quad IIs. The OPT on one is as per normal with 11 terminals: annotated P to Z. The other one's OPT only has 10 terminals: The usual three X, Y, Z at the outside (primary outputs), but an inner row of only 7 instead of the usual 8 terminals. (Unfortunately the annotations got 'erased' long ago). Also, I only became aware of the difference (not expecting it) after I had removed the core-windings proper from the casing, clearing away as much of the goo as I could and in the process cutting all leads off the terminal board for convenience. As said no wire colours were visible, all being covered by the tarry mess.

I vaguely recall a lead itself emerging from the casing through the terminal board, but the messy operation unfortunately did not put me in the mood for careful noticing. It was only after cleaning the terminal board and clearing away solder and wires from the terminals that I became aware of the discrepancy. (I did not look at the two Quads side-by-side; it was only the one OPT that was faulty; one cathode winding open). Then, the terminals themselves are of the same (larger) diameter as the power transformer (6,3 mm or 3/16 inch flange diameter), rather than the smaller 4,7mm (1/4 inch) terminals of the normal OPT. Apart from these, it does not appear to be anything but an original Quad product. The amplifiers are identical.

In reply to another post, I did trace all 12 secondary single wires (6 sections), some internally connected together. At that stage it was impossible to determine whether a secondary came out per 'loose' lead (as it must have for all secondaries to be accessible) - I did not find such. Neither did I find any reference to such an 'unconventional' OPT in any literature. (I have not yet tried to contact Mr. Flain as suggested; thanks for that!)

There is not really an insurmountable problem. I am rewinding the OPT and will just have to take connection 'P' out per loose lead (that appears to be the missing terminal) - there is hardly space to insert an extra terminal. My main interest is why/wherefrom this unconventional OPT - some 30+ QUAD IIs have already gone through my hands, all the others conventional. (I presume the winding data will be the same as per available information.)

Thanks for attention and responses.
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Old 12th July 2019, 01:16 PM   #10
ejp is offline ejp  Australia
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Still not clear whether you have ten or eleven wires coming out of the transformer, but there is only one possibility: the secondary has fewer terminals. The three terminals for HT and the valve anodes are a given, as are the three for the cathode windings. Output terminals is the only thing left to vary. Either there is an eleventh wire without a terminal, which would have to be P, or maybe T at the outside, or else R and S are elided into one to make a permanently 15ohm secondary.

Or it could be a BBC version with 100V output!!!!!
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