KB ER30 problems - UK Vintage Radio Repair and Restoration Discussion Forum

Vespaman · 3rd Nov 2010, 2:57 pm

After many years of regular trouble free use this old box of tricks has developed a sickness. It has always performed perfectly; no loss of power, no crackles, no noisy switches-everything A-0K but now it will only go for about 10 minutes before it acts as if the volume control has suddenly gone down the tubes. The programme can still be heard faintly and some knob twiddling brings it back intermittently before it finally reverts to a whisper. I suspect it must be something heat-related.

Any suggestions from the experts out there?

Steve_P · 3rd Nov 2010, 3:16 pm

It could be a number of things, but the first thing I would do is replace THAT capacitor and any other waxies that may be left inside it.

Then check for loose connections and dodgy soldering joints which fail when warm. Then go round the valves you have and measure voltages before and after the fault occurs.

There is a sheet available here: http://www.service-data.com/product.php/3192/4145

Cheers,

Steve P.

gezza123 · 3rd Nov 2010, 4:08 pm

As Steve said change that cap+the waxies.before you do, you could switch the set to gram put a signal in the gram socket to test the amp,if it is the amp change (C 21 coupling cap to pin 7 6V6GT)very common in this set,and the circuit above is only £1.99 Email delivery is exellent.hope this helps Gezza

radiotircoed · 3rd Nov 2010, 6:38 pm

Should we be posting a sticky regarding 'that capacitor' ? Maybe we have and I've not seen it. Slap my hand if I missed it....

Bob W

Tim · 4th Nov 2010, 1:49 am

Also check valve top caps,audio amp valve (6Q7G?), and anode resistor thereof.

Vespaman · 4th Nov 2010, 11:15 am

Many thanks for all your erudite suggestions; now I just hope that I can get all those horrible knobs off so that I can get inside to do the operation!

Richard

Tim · 4th Nov 2010, 1:26 pm

They probably just pull off, but rotate and check for screw holes.
If the former you may have to resort to the string/handkerchief trick.

gezza123 · 4th Nov 2010, 11:07 pm

Yes they pull off,the best way I found was to use a long thin screwdriver and take of the clips off first, then push them off from the inside ,also make shure you have something or someone to catch them as they fly out,don't try to pull them from the outside as these knobs break very easy in the centre.and you may be looking for some new ones ,good luck.Gezza

3rd Nov 2010, 2:57 pm	#1
Vespaman Retired Dormant Member Join Date: Oct 2005 Location: Reading, Berkshire, UK. Posts: 21	KB ER30 problems After many years of regular trouble free use this old box of tricks has developed a sickness. It has always performed perfectly; no loss of power, no crackles, no noisy switches-everything A-0K but now it will only go for about 10 minutes before it acts as if the volume control has suddenly gone down the tubes. The programme can still be heard faintly and some knob twiddling brings it back intermittently before it finally reverts to a whisper. I suspect it must be something heat-related. Any suggestions from the experts out there?

3rd Nov 2010, 3:16 pm	#2
Steve_P Dekatron Join Date: Sep 2003 Location: Bolton, Greater Manchester, UK. Posts: 6,644	Re: KB ER30 problems It could be a number of things, but the first thing I would do is replace THAT capacitor and any other waxies that may be left inside it. Then check for loose connections and dodgy soldering joints which fail when warm. Then go round the valves you have and measure voltages before and after the fault occurs. There is a sheet available here: http://www.service-data.com/product.php/3192/4145 Cheers, Steve P. __________________ If we've always had it, why is the Car Boot open? You're not sneaking another Old TV in are you...?

3rd Nov 2010, 4:08 pm	#3
gezza123 Heptode Join Date: Mar 2010 Location: Eastham, Wirral, Merseyside, UK. Posts: 788	Re: KB ER30 problems As Steve said change that cap+the waxies.before you do, you could switch the set to gram put a signal in the gram socket to test the amp,if it is the amp change (C 21 coupling cap to pin 7 6V6GT)very common in this set,and the circuit above is only £1.99 Email delivery is exellent.hope this helps Gezza

3rd Nov 2010, 6:38 pm	#4
radiotircoed Pentode Join Date: Nov 2005 Location: Tircoed Forest Village - Swansea, UK. Posts: 193	Re: KB ER30 problems Should we be posting a sticky regarding 'that capacitor' ? Maybe we have and I've not seen it. Slap my hand if I missed it.... Bob W __________________ Radio Tircoed - Working for the Community

4th Nov 2010, 1:49 am	#5
Tim Dekatron Join Date: Jan 2003 Location: Bradford on Avon, Wiltshire, UK. Posts: 3,310	Re: KB ER30 problems Also check valve top caps,audio amp valve (6Q7G?), and anode resistor thereof. __________________ "Nothing is as dangerous as being too modern;one is apt to grow old fashioned quite suddenly."

4th Nov 2010, 11:15 am	#6
Vespaman Retired Dormant Member Join Date: Oct 2005 Location: Reading, Berkshire, UK. Posts: 21	Re: KB ER30 problems Many thanks for all your erudite suggestions; now I just hope that I can get all those horrible knobs off so that I can get inside to do the operation! Richard

4th Nov 2010, 1:26 pm	#7
Tim Dekatron Join Date: Jan 2003 Location: Bradford on Avon, Wiltshire, UK. Posts: 3,310	Re: KB ER30 problems They probably just pull off, but rotate and check for screw holes. If the former you may have to resort to the string/handkerchief trick. __________________ "Nothing is as dangerous as being too modern;one is apt to grow old fashioned quite suddenly."

4th Nov 2010, 11:07 pm	#8
gezza123 Heptode Join Date: Mar 2010 Location: Eastham, Wirral, Merseyside, UK. Posts: 788	Re: KB ER30 problems Yes they pull off,the best way I found was to use a long thin screwdriver and take of the clips off first, then push them off from the inside ,also make shure you have something or someone to catch them as they fly out,don't try to pull them from the outside as these knobs break very easy in the centre.and you may be looking for some new ones ,good luck.Gezza