Solartron srs 153s - UK Vintage Radio Repair and Restoration Discussion Forum

thermion · 25th Sep 2023, 11:22 pm

Picked up this power supply on sunday from hack green rally, after curing a
Few silly faults its working.. sort of.. thing is i can’t turn the output voltage down to zero. Tested everything in the negative bias circuit, changed a couple resistors
That had gone high, & checked all the caps, but i still cant get it to turn down
To zero. The only thing i can think of are the two 5b/254’s in output are passing grid current & pulling the bias down. Removing one output valve at a time does reduce the minimum voltage quite a bit. They are connected in paralell..
It says 0-500v on the front panel so am i right in assuming it actually is suppoosed to go to zero?

Dave757 · 26th Sep 2023, 1:34 pm

Hi

The manual says 0-500volts, so that's my assumption too!

Kind regards
Dave

25th Sep 2023, 11:22 pm	#1
thermion Tetrode Join Date: Dec 2011 Location: Cheshire, UK. Posts: 50	Solartron srs 153s Picked up this power supply on sunday from hack green rally, after curing a Few silly faults its working.. sort of.. thing is i can’t turn the output voltage down to zero. Tested everything in the negative bias circuit, changed a couple resistors That had gone high, & checked all the caps, but i still cant get it to turn down To zero. The only thing i can think of are the two 5b/254’s in output are passing grid current & pulling the bias down. Removing one output valve at a time does reduce the minimum voltage quite a bit. They are connected in paralell.. It says 0-500v on the front panel so am i right in assuming it actually is suppoosed to go to zero?

26th Sep 2023, 1:34 pm	#2
Dave757 Heptode Join Date: Apr 2009 Location: Scratby, Norfolk, UK. Posts: 642	Re: Solartron srs 153s Hi The manual says 0-500volts, so that's my assumption too! Kind regards Dave