Mainline Power Transformer voltage check

[monteiro.sheldon]

Hi All,

As I got 121V accross 31U & 32U I followed the transformer wiring steps for "IF your voltage is GREATER than 115V AC and LESS than 130V AC"

Now when I do the voltage check, "Attach the red lead to terminal 12, and the
black lead to terminal 11" of the transformer. The manual says You should read 130-150 VAC.
I am seeing around 122V, is that a problem?

 

[Paul Birkeland]

Could you post a quick photo of your transformer wiring?

 

[monteiro.sheldon]

Attached pics, thank you

 

[Paul Birkeland]

I would reflow the solder joint at terminal 16 on the power transformer.

 

[monteiro.sheldon]

I reflowed all the solder joints on the transformer, still seeing around 120v.
Could it be a problem with the power transformer itself?

 

[Paul Birkeland]

What AC voltage do you get between 7 and 9?

 

[monteiro.sheldon]

Hi Paul,

I am getting 9.6V between 7 & 9.

 

[Paul Birkeland]

OK,  I would go ahead and continue with the build.

 

[monteiro.sheldon]

Thank you so much for all your help.

 

[monteiro.sheldon]

Hi Paul,

I proceeded with the next step to attach the power supply board.
The 6.3V measures correct.
I am only getting 48V DC on the board with the +-275V solder pad, not the 300-500V as specified in the manual.

I then measured the input AC voltage on T11 & T12 (red and white wires) and now its reading about 24V AC and not the 120V I got before I connected the power supply board.

Seems like something is going on with the power transformer.
The input voltage dropped down from 120V AC to 22V AC after connecting the power supply board.

I disconnected the red and white input AC wire and the transformer output measured 120V again, conencted the wires back to the power supply board and the same wires now go down to around 22V AC when measured accross T11 & T12 on the board.

Thanks
Sheldon M

 

[Paul Joppa]

Maybe your meter needs a new battery?  It's happened before ...  :^)

 

[monteiro.sheldon]

I put new batteries in the meter, getting the same voltages.
The AC input from mains and the DC 6.3V all measure correctly, so I dont think the meter is faulty.

Could the transformer section for T11 & T12 be bad, should I email for a replacement?

 

[Paul Birkeland]

With the board now installed, what AC voltage do you get between the solder pads on the PC board that say T14 and T12?

 

[monteiro.sheldon]

I am getting around 22V AC on T11 & T12.
It starts much lower and settles at 22V after a minute.

 

[Paul Birkeland]

You can go ahead and contact replacementparts(at)bottlehead(dot)com to request a new PT-11.  Be sure to provide your name and order number, as well as a link to this thread.  It's also very likely that we'd like the power transformer you have back if at all possible so we can return it to our winder.  I suspect that one of the wires coming out of the bobbin for that high voltage winding may be snapped off and making intermittent contact.  If you look at the little terminals poking up on the transformer, there are wires wrapped around the bottom that go into the power transformer.  Occasionally I have seen a break in one of those wires and could simply restore the connection with a little solder, though there isn't a lot of working room in that area!

 

[monteiro.sheldon]

I looked at the bottom terminals and dont see anything visibally broken.
I have sent an email to request a replacement.

Thanks Paul and have a great rest of your weekend.