Power transformer 453A


Fred Schumacher
 

I recently got a 453A with a shorted power transformer. This short is at the primary side to earth.
As the technical manual does not specify the secondary voltages, I am looking for someone who can inform me about this.
I know the 435 and 454 have similar dc power circuitry connected to these transformers, so I wonder if a transformer from these scopes could be used. I noticed the cooling fan is connected to the secondary side as for the two other models, it is connected to the primary 115V side.
Any help would be appreciated.
Thanks in advance.


Mark Vincent
 

Fred,

The voltages on the secondaries of mine with the input set on the high range at 120V mains input: Pins 21 and 22- 6,3V
Pins 12 and 13- 17,4V
Pins 10 and 11- 18,6V
Pins 13 and 15- 90V
Pins 16, 17, 18, 19 and 20- 71, 59, Gnd. 59 and 71V
With slight line variations, the voltages will vary slightly. Voltages were measured with the loads applied and the 6,3V with graticule set at minimum so the a-c voltage at these pins is higher than the nominal 6,3V. This is a 6,3V winding. I would guess the other power transformers you mentioned would work. The 454 type may have a heavier winding for the heaters in the older S/N types. That is fine. The only thing that may be the difference is the current and slight physical size difference. If you can get one, it should work fine.

Mark


Fred Schumacher
 

Mark,
Thank you for the effort to inform me about the secundary voltages. I expected this already.
If I decide to use a 454 transformer, which is identical to a 453 transformer, I have to do some cable dressing, as these transformers are horizontally arranged, with respect to the 453a transformer which is vertically arranged.
Anyway thanks again for your info.
Fred

On 18 jul. 2021, at 18:20, Mark Vincent <orangeglowaudio@gmail.com> wrote:

Fred,

The voltages on the secondaries of mine with the input set on the high range at 120V mains input: Pins 21 and 22- 6,3V
Pins 12 and 13- 17,4V
Pins 10 and 11- 18,6V
Pins 13 and 15- 90V
Pins 16, 17, 18, 19 and 20- 71, 59, Gnd. 59 and 71V
With slight line variations, the voltages will vary slightly. Voltages were measured with the loads applied and the 6,3V with graticule set at minimum so the a-c voltage at these pins is higher than the nominal 6,3V. This is a 6,3V winding. I would guess the other power transformers you mentioned would work. The 454 type may have a heavier winding for the heaters in the older S/N types. That is fine. The only thing that may be the difference is the current and slight physical size difference. If you can get one, it should work fine.

Mark