Dean markley signature series head

[FIREBIRD]

I would like to install new power tubes. I have located the trim pot for adjusting the bias but i cant seem to locate the hot test point!
Anybody out there familiar with dean markley SIGNATURE SERIES 60 tube heads?

[Enzo]

Hi, welcome.

Good form would be to post or link the schematic for your amp.

I don't know that there is a test point per se. Often "test points" are just places in a circuit. Many adjustable amps have no official test points. We use a shunt method across the OT primary, or we add or find a 1 ohm cathode resistor, or even use a bias probe.

[pdf64]

Or measure the resistances of the OT primary, CT to plate, and then the voltage dropped at idle across those resistances.
To prevent oscillation when probing power tube plates, remove the phase splitter tube.

[Chuck H]

Schematics for that amp seem to be unattainable. I believe the model is T60? And general/collective schematics may exist for the T60, T120, T60-R and T120-R (R designates reverb models). But I have only been able to find a smattering of unconfirmed circuit diagrams and unconfirmed reports that the power amp is the same as the CD amp line.

In this light I think learning about how bench techs measure bias is the only solution. Enzo and pdf64 have touched on what to search and learn. Also read about working in high voltage tube amps and safety precautions before going in.