Taylor 65B Transformer to Rectifier Wiring Doesn't Make Sense

[Eddy_Stone]

Your circuit is different, it does not have two connections of the same winding shorted together by ground

[gezza123]

Hello Eddy.
Sorry if I may have missled you, as I said above they do connect to ground

Here is a better circuit,to show how its connected forget the 47uf. it is a 4uf .
cheers Gezza123

[AC/HL]

The other wire could be the screen, shown on the diagram in post 2, and not a centre tap at all.
It still leaves the transformer open circuit, though.

[ms660]

It all sounds confusing, maybe someone who has one of these that works could disconnect all the HT secondary connections and post up the unloaded voltage measurements across the winding(s)

Lawrence.

[gezza123]

HI Guys.
I dont know weather I have got time to take my transformer unit apart, but I have a copy of the circuit for mine.
so here you go it looks like they are just using half the transformer to do the job.
I have noticed that no external earth is applied the this unit, as the secondary of the transformer is connected to ground so maybe this unit cant have a separate earth and is left floating for safety.
Gezza123

[LittleDuckAlex]

I am now thoroughly confused. Is there actually a purpose in having a tapped transformer if it's wired up that way? And if it causes problems, then why would it have been done (and worked apparently)? Not sure on which way I should wire up a new transformer either; if there's a good reason to do it as it originally was, or if I should have it as shown in the schematic.

[ms660]

In your schematic it shows one half of the secondary winding shorted out, how does that work?

Lawrence.

[LittleDuckAlex]

Originally Posted by gezza123

I have noticed that no external earth is applied the this unit, as the secondary of the transformer is connected to ground so maybe this unit cant have a separate earth and is left floating for safety.

The original design of the signal generator meant that it would be floated until you attach the ground lead from the RF output socket to the chassis of the equipment under test; the chassis of the equipment would be connected to earth, and that's where the earth comes from (if of course you were to connect the chassis to earth).

Not sure if I've misunderstood what you're saying there, but that's the idea of the 65Bs earth connection, I think.

[ms660]

As far as the extra ground wire goes the suggestion in post #23 is the only thing I can think of.

Lawrence.

[Harry40]

I Think that I would go along with post 23. That centre wire could be a screen and the whole of the secondary windings are providing the feed for the rectifier. If not half of the secondary windings are definitely shorted irrespective of any earth connection. That centre terminal would need to be separated from earth and then see if it connects to the other tranny windings.

[Amraduk]

@Gezza123,

Does the transformer secondary consist of two completely separate 150V windings rather than one centre tapped 150V-0V-150V winding? If it does, it would explain the three black wires going to chassis.

Regards,

Dave.

[gezza123]

Hi, guys
Well I have taken out my transformer and measured it, the centre tap seems to be a screen and is connected as per your post #1.
As Harry40 says I would go along with post #23 as my transformer is not a centre tap but a screen

I have a secondary off 170v AC on dvm and a 6.5v heater supply.also had a look at the circuit of the taylor 65c and that is an updated circuit, with the 6x5 connected as a half wave I think when they were made they must have had problems with the 6x5's breaking down and burning out the transformers, so they put them on a halfwave and reduced the ht to the 6x5.
Only my Opinion.
I will now reassemble mine and put it on test.

Alex check your transformer again and see if you have two sets of secondary windings one for ht = around (600 ohm) and the other for the heater @ about 1.3 ohm.
There is no reading on the other wire, as it goes to internal shielding inside the transformer, note my transformer wiring was original and was very hard to get off and this is the first time it has been taken out.
Here is the circuit for the 65c with an earth point.

I don't think there is anything wrong with the circuit from the valve page, except they used a different transformer I/E 110-0-110V fullwave.good luck.
I now hope that mine still works when reasembled . Gezza123

[karesz*]

Hi all,
I agree with Gezza123`s and AC/HL`s idea. Check please the double Anodes of 6X5GT ie on Taylor 56B_No2: it must be a corrected drowing, but with a bug! :-( Over right-side Anode of these rectifier is an oversized "point" and some similar is to see on the leftside Anode, immediatly on the "tubecase"_they arn`t original lines and joints, they can`t be original ones...
Sincerely K.

[gezza123]

HI.Karesz*
Thanks.
I have now reassembled mine and its spot on Cheers Gezza123

[LittleDuckAlex]

Originally Posted by gezza123

Alex check your transformer again and see if you have two sets of secondary windings one for ht = around (600 ohm) and the other for the heater @ about 1.3 ohm.

Thanks for the info. I agree with your opinion, they probably had a big stock of 6X5s left, so changed things up to be more reliable without having to get different rectifiers. I measure about 0.8 ohms on the heater winding, but I can't get anything from the other winding.