GEC BC 5442 repair project - UK Vintage Radio Repair and Restoration Discussion Forum

Ronners · 22nd Nov 2020, 12:05 pm

Hi there all
i have acquired a GEC BC5442 circa 1951 ish I have checked out the transformer etc renewed all the wax caps but still no joy works great on the PU side but no reception on any of the three bands any ideas please. I also have a second one of these in working order should I try swapping the valves over to see if that makes a difference? Best regards Ron H.

Simon Gittins · 22nd Nov 2020, 12:44 pm

Having a working example to compare with should be a great help. As you have changed all the wax capacitors, I would suggest checking your work carefully, perhaps comparing one set with the other; it's all too easy make a mistake.
Valve swapping should narrow the fault down (although you just might end up with neither set working if you are very unlucky). I would suggest checking whether the local oscillator is working by seeing if you can pick it up on a working set.

Ronners · 22nd Nov 2020, 1:05 pm

Thanks for that Simon one thought that has crossed my mind as I am a newby to this hobby in retirement is there a minimum voltage requirement on the replacement caps as service sheet only gives uF values. Best regards Ron H.

Cobaltblue · 22nd Nov 2020, 1:23 pm

You normally look at the highest HT and add a bit.

So in this case I would use 400V caps except for the fixed tone correction capacitor C17 on manufacturers sheet) where I tend to use 1000V but many use 630V.

You can of course use lower voltages for caps in the AGC and the Audio coupling (C13) but not C15, but in the end I just stock 400V types 1000V types and a few 250V types for Battery radios.

Unless there is a physical size constraint it makes little difference you can also be guided by the voltages on those you are replacing,

You need to be more careful with electrolytic they don't like being massively under run so don't replace a 12v Cathode bypass with a 400V type use a 25V type. (this set doesn't have a cathode bypass Electrolytic)

Cheers

Mike T

Ronners · 22nd Nov 2020, 1:36 pm

Thanks for that Mike i suspect through my naivety I may have used too smaller value caps I will re order and change very useful information. Best regards Ron H.

Al (astral highway) · 22nd Nov 2020, 5:18 pm

Hi Ron, try to establish a fault or a theory first. It’s very rare that valves fail in domestic sets.

Good luck and keep us posted!

Ronners · 22nd Nov 2020, 6:31 pm

Cheers will do Al thanks for your support. best regards Ron H.

22nd Nov 2020, 12:05 pm	#1
Ronners Pentode Join Date: Nov 2018 Location: Burnley, Lancashire, UK. Posts: 100	GEC BC 5442 repair project Hi there all i have acquired a GEC BC5442 circa 1951 ish I have checked out the transformer etc renewed all the wax caps but still no joy works great on the PU side but no reception on any of the three bands any ideas please. I also have a second one of these in working order should I try swapping the valves over to see if that makes a difference? Best regards Ron H.

22nd Nov 2020, 12:44 pm	#2
Simon Gittins Heptode Join Date: Jan 2006 Location: Cornwall, UK. Posts: 506	Re: GEC BC 5442 repair project Having a working example to compare with should be a great help. As you have changed all the wax capacitors, I would suggest checking your work carefully, perhaps comparing one set with the other; it's all too easy make a mistake. Valve swapping should narrow the fault down (although you just might end up with neither set working if you are very unlucky). I would suggest checking whether the local oscillator is working by seeing if you can pick it up on a working set.

22nd Nov 2020, 1:05 pm	#3
Ronners Pentode Join Date: Nov 2018 Location: Burnley, Lancashire, UK. Posts: 100	Re: GEC BC 5442 repair project Thanks for that Simon one thought that has crossed my mind as I am a newby to this hobby in retirement is there a minimum voltage requirement on the replacement caps as service sheet only gives uF values. Best regards Ron H.

22nd Nov 2020, 1:23 pm	#4
Cobaltblue Moderator Join Date: Dec 2010 Location: Exeter, Devon and Poole, Dorset UK. Posts: 6,859	Re: GEC BC 5442 repair project You normally look at the highest HT and add a bit. So in this case I would use 400V caps except for the fixed tone correction capacitor C17 on manufacturers sheet) where I tend to use 1000V but many use 630V. You can of course use lower voltages for caps in the AGC and the Audio coupling (C13) but not C15, but in the end I just stock 400V types 1000V types and a few 250V types for Battery radios. Unless there is a physical size constraint it makes little difference you can also be guided by the voltages on those you are replacing, You need to be more careful with electrolytic they don't like being massively under run so don't replace a 12v Cathode bypass with a 400V type use a 25V type. (this set doesn't have a cathode bypass Electrolytic) Cheers Mike T __________________ Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk Last edited by Cobaltblue; 22nd Nov 2020 at 1:27 pm. Reason: Electrolytics

22nd Nov 2020, 1:36 pm	#5
Ronners Pentode Join Date: Nov 2018 Location: Burnley, Lancashire, UK. Posts: 100	Re: GEC BC 5442 repair project Thanks for that Mike i suspect through my naivety I may have used too smaller value caps I will re order and change very useful information. Best regards Ron H.

22nd Nov 2020, 5:18 pm	#6
Al (astral highway) Dekatron Join Date: Nov 2006 Location: London, UK. Posts: 3,496	Re: GEC BC 5442 repair project Hi Ron, try to establish a fault or a theory first. It’s very rare that valves fail in domestic sets. Good luck and keep us posted! __________________ Al

22nd Nov 2020, 6:31 pm	#7
Ronners Pentode Join Date: Nov 2018 Location: Burnley, Lancashire, UK. Posts: 100	Re: GEC BC 5442 repair project Cheers will do Al thanks for your support. best regards Ron H.