Circuit diagram for power supply Westfalia 267880 wanted

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pit

Joined: 05 Jun 2002
Posts: 219
Helped: 6

20 Jul 2006 8:47 l146 regulator

Hello!

I am looking for a schematic for the power supply Westfalia Technica no. 267880.
This is a dual adjustable power supply delivering at each output up to 40 V and up to 5 A, with adjustable current limit.

Apparently it was manufactured in Russia (or another country which uses cyrillic letters).

The problem with the power supply is that one channel delivers 60+ V at its output. So I checked the output stage first (consisting of 3 transistors KT845G in parallel), they are all ok. The driver stage is also working, so I suspect the regulator IC. It looks similar to an LM723, but I am not sure.

The circuit is somewhat weird, the secondary voltage and the electrolytic capacitors beyound the rectifier is 60+ V, the plus line is directly connected to the output, the minus line is regulated over the power stage. So the regulator stage is a low side stage, pretty uncommon.

There is also a 15 V fixed voltage regulator, which appears to be working.

I would like to have a schematic to speed up the repair.

CU

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Ante

Joined: 01 May 2004
Posts: 177
Helped: 4

20 Jul 2006 17:21 how does a lm723 work?

For a 40 Volt output as standard the regulator is probably an L146 (or RU sim) which is similar to the LM723 but for a higher input voltage. The LM723 has a maximum input voltage of 40V and the L146 has 60 or 80V. The pin functions are the same so you can work around the IC like it was a 723 to establish what’s wrong. I assume it has a tracking circuit as well since it has dual outputs, this circuit must also be considered as a suspect!

I hope this helps!

HSchwenk

Joined: 11 Aug 2006
Posts: 1
Helped: 1

11 Aug 2006 22:06 lm723 80v

Hi
I have a circuit diagram for Westfalia 26788.
But it is old and in bad condition.
If you are still interested I will tray to scan it.

Heinz Hschwenk(at)GMX.net