Racal RS Thurlby Bench PSU Circuit Diagram Please


Adrian G4UVZ
 

I have a rather nice bench PSU with an intermittent fault ...Both displays indicate correctly and you can set the current limit.

but 99% of the time there is no output votage ,,,meter indicates zero as expected ...I have checked the back end and the usual 2N3055 and associated drivers are fine.

The drive voltage from the main board is what is missing ...have sweated joints etc etc and at one stage it started working ..put it all back together still fine...swithche on next day ...no volts!!

If anyone has any cct details or experience with this model psu it would be much appreciated ...I think that the RAcal RS Thandar Thurlby are pretty much the same PSU ..just rebadged

Many thanks 

Adrian


Jim Mcilroy
 

Hi

I don't have one of those but my bench PSU is a Maplin N93CX 20V 4A unit.

So far as I recall I had to turn the current control CCW and short the leads to get the PSU to engage with life. Some sort of sensing circuit. I then disconnected the leads, adjusted the voltage for what I wanted and everything worked fine.

Might be something a bit like that with yours.

Jim  G4EQX

On 24/04/2021 10:39, Adrian G4UVZ via groups.io wrote:
I have a rather nice bench PSU with an intermittent fault ...Both displays indicate correctly and you can set the current limit.

but 99% of the time there is no output votage ,,,meter indicates zero as expected ...I have checked the back end and the usual 2N3055 and associated drivers are fine.

The drive voltage from the main board is what is missing ...have sweated joints etc etc and at one stage it started working ..put it all back together still fine...swithche on next day ...no volts!!

If anyone has any cct details or experience with this model psu it would be much appreciated ...I think that the RAcal RS Thandar Thurlby are pretty much the same PSU ..just rebadged

Many thanks 

Adrian


Robin Szemeti - G1YFG
 

Mine did that, I replaced some electrolytics.

On Sat, 24 Apr 2021 at 11:29, Jim Mcilroy via groups.io <gts53=btinternet.com@groups.io> wrote:

Hi

I don't have one of those but my bench PSU is a Maplin N93CX 20V 4A unit.

So far as I recall I had to turn the current control CCW and short the leads to get the PSU to engage with life. Some sort of sensing circuit. I then disconnected the leads, adjusted the voltage for what I wanted and everything worked fine.

Might be something a bit like that with yours.

Jim  G4EQX

On 24/04/2021 10:39, Adrian G4UVZ via groups.io wrote:
I have a rather nice bench PSU with an intermittent fault ...Both displays indicate correctly and you can set the current limit.

but 99% of the time there is no output votage ,,,meter indicates zero as expected ...I have checked the back end and the usual 2N3055 and associated drivers are fine.

The drive voltage from the main board is what is missing ...have sweated joints etc etc and at one stage it started working ..put it all back together still fine...swithche on next day ...no volts!!

If anyone has any cct details or experience with this model psu it would be much appreciated ...I think that the RAcal RS Thandar Thurlby are pretty much the same PSU ..just rebadged

Many thanks 

Adrian


--
Robin Szemeti - G1YFG


Gary M1EGI
 

I managed to get one of these for free due to having no output, turned out to be the link bars to the sense terminals weren't making a connection...

So may seem a silly question (always worth checking simple things first), but are all four 4mm terminals tight on the link bar and making a connection?

73 Gary M1EGI