Re: [CAD_CAM_EDM_DRO] Westamp - PWM Servo Amp

I seem to remember that the transistors are selected on voltage drop and
gain at current as they are often used in parallel with other transistors.
The ident on the can used to be Westamps own and no help. I do not believe
(and I am plumbing the depths of my memory) that they used darlingtons. The
Westamp systems used a transformer coupled pulsed base drive to the output
transistors to simpify the output drive circuitry.

If you are in the Uk contact Ken Collins at this address and he may be able
to help you as he used to sell and service Westamp drives. tell him I sent
you !!

Collins Controls Servodrive
Sales & Service
Unit B1 Chasewater Indust Est
Chasetown
Burntwood
WS7 8XD
(01543) 672414

Regards Peter Seddon

----- Original Message -----
From: <bdoherty01@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Sunday, December 02, 2001 10:22 PM
Subject: [CAD_CAM_EDM_DRO] Westamp - PWM Servo Amp


> Hi,
> I have a Westamp PWM servo amp model no. 30060-3 ,(1981),with a
> faulty output stage.Details:
> Supply voltage: 100vdc
> Signal :+/- 10v
> Bias :15-0-15vdc
> Max output:20amp
> Cont output:10amp
> Motor HP : 1.1
> The output bridge uses four T03 packaged NPN silicon transistors
> which appear to have an internal 100r resistor across base-emitter
> and an internal diode across emitter-collector ,part
> no:29782w /c38123102.I am unable to locate replacements and both
> UK/US agents refuse to supply drawings or spares and quote $850.00
> and 30 working days for repairs!
> Can anyone suggest a replacement component, possibly with the
> resistor and diode mounted externally ? All help is greatly
> appreciated,
> Jim.
> Hi,
> I have a Westamp PWM servo amp model no. 30060-3 ,(1981),with a
> faulty output stage.Details:
> Supply voltage: 100vdc
> Signal :+/- 10v
> Bias :15-0-15vdc
> Max output:20amp
> Cont output:10amp
> Motor HP : 1.1
> The output bridge uses four T03 packaged NPN silicon transistors
> which appear to have an internal 100r resistor across base-emitter
> and an internal diode across emitter-collector ,part
> no:29782w /c38123102.I am unable to locate replacements and both
> UK/US agents refuse to supply drawings or spares and quote $850.00
> and 30 working days for repairs!
> Can anyone suggest a replacement component, possibly with the
> resistor and diode mounted externally ? All help is greatly
> appreciated,
> Jim.
>
>
>
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