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Orange help, svp

:

6/21/1999 0:54 AM

Orange help, svp

I just got an Orange Overdrive Series Two, model# OR112M

I would really appreciate an schematic or url where I could find it.

I have to say that it is my very first valve amp, and allthough I know I

must be very carefull,

I would like to know how to adjust the bias for the power tubes.

It has two very similar variable resistors on the board...

The simpler, the better: something like --> red point of the multimeter

in lug #5 of the first tube... Something like that, if possible.

Thank you very much.

JohnC

6/21/1999 3:02 AM

Has the amp 2 or 4 output tubes ? Do you have any experience with methods of working on hi voltage equipment?

You should familiarize yourself with the routine of unplugging the amp, draining the residual voltages out of the amp with an insulated clip lead, one end clipped to chassis ground other end touched firmly to each plate connection or B+ or to the filter cap+ terminals themselves whenever you are gonna be hanging around an open chassis.

I have a schem for Orange but dont have my scanner working right now. You have one trim pot for the hum balance of the heater supply on the preamp tubes and one for the neg bias voltage on the power tubes- they call for minus 37 volts d.c. on the grids of the power tubes. Your neg meter probe will go to the grid (pin 5) your pos probe on the meter goes to ground (chassis) USE an alligator clip to attach your meter probe to the tube socket lug AFTER you have unplugged the amp and drained the charge off the main filter capacitors, then put one hand in your back pocket, use your free hand to touch the pos probe to chassis.

gotta run, good luck.

6/21/1999 11:51 PM

>Has the amp 2 or 4 output tubes ?

4

>Do you have any experience with methods of working on hi voltage equipment?

I'm afraid, no. But I try to learn fast.

>You should familiarize yourself with the routine of unplugging the amp, draining the residual voltages out of the amp with an insulated clip lead, one end clipped to chassis ground other end touched firmly to each plate connection or B+ or to the filter cap+ terminals themselves whenever you are gonna be hanging around an open chassis.

I'm sorry, but I don't know what is and how to recognize a plate connection. Nor a B+. I have two twin huge electrolithic caps near to the supply transformer on the chassis. Any of these three actions will drain the residual High voltages, or do I need to perform all of them?

>I have a schem for Orange but dont have my scanner working right now. You have one trim pot for the hum balance of the heater supply on the preamp tubes and one for the neg bias voltage on the power tubes- they call for minus 37 volts d.c. on the grids of the power tubes.

Will it be possible to measure current (-37 dc) even if the amp is unplugged?

>Your neg meter probe will go to the grid (pin 5) your pos probe on the meter goes to ground (chassis) USE an alligator clip to attach your meter probe to the tube socket lug AFTER you have unplugged the amp and drained the charge off the main filter capacitors, then put one hand in your back pocket, use your free hand to touch the pos probe to chassis.

(pin 5), is it, in tube socket, the lug marked with a number five?

>gotta run, good luck.

with your kind help...

thank you.

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