h/p 204 Oscillator battery P/Supply conversion to AC question.

[Paceguy]

Hi, I have this battery option h/p 204 with dead batteries. Has anyone here converted a h/p 204's power supply from battery operated to AC only?. I looked at the service manual and see that there are two different part numbers for the power transformers but no voltages are shown on the schmatics. Can I use the original transformer in my conversion project? The power supply for AC only operation looks very simple and straightforward. Advice to how to go about it would be much appreciated. Thanks in advance!

[m k]

There are few versions.
For example 204C is quite a bit more transistorized than 204A.

[edavid]

Yes OP, tell us what version you have.

If it's a 204C or 204D, I answered this question in a previous thread:

https://www.eevblog.com/forum/testgear/oscillator-not-working-right-(hp-204c)/msg1226009/#msg1226009

P.S. Please stop writing h/p, that is just confusing.

[factory]

There are few versions.
For example 204C is quite a bit more transistorized than 204A.

It's not going to be a 204A, as the OP mentions a power transformer, something the "A" version doesn't have.
It must be either a 204B, C or D.

Attached below is the conversion someone else did to the 208A I have.

David

[TimFox]

I have an -hp- 403b voltmeter that used a string of Ni-Cd rechargeable batteries with an internal charger.
It could be run from the AC line or on the battery power, but the batteries were required to derive the internal supply voltages on AC-power mode.
The batteries were dead, so I replaced them with a series string of several TL431 shunt regulator circuits (with fixed resistors) to replace the battery sections between voltage taps, operating from the original charging circuit.
There was plenty of space in the battery compartment to hold the TL431s on perfboard.