Help with Murphy A130 radio lights - UK Vintage Radio Repair and Restoration Discussion Forum

MICK1985 · 31st May 2013, 10:07 pm

Hi guys.

Please can someone advise whether the U404 valve, which is blown on one side, would stop the display lights from working on one side? Either lamp will work in the right hand holder, but neither lamp will work in the left hand holder.

Many thanks, Mick.

matthewhouse · 1st Jun 2013, 1:09 am

If you don't already have the service manual I would highly recommend getting the manufacturers version, as it goes into great detail. You can purchase a copy from this forum by clicking the big box at the very top right of this page.

From what I can see the two bulbs are in parallel so if one works so should the other. I'd check for a broken or buckled contact in the bulb holder. The service manual mentions the importance of a rubber insulating sleeve fitted to the holders. The bulbs take their power from the same place as the PEN45 valve heater

Could you please explain: blown one side U404 valve? This valve is a single rectifier diode.

Steve_P · 1st Jun 2013, 1:27 am

An A130 is likely to be an AC version, but in the case of the A130 and the U130, they both use a half wave rectifier valve.

Sheet 994 has come to hand here, as my DVD has gone walkies! But anyway...

The A130 has an Auto Transformer and the bulbs are wired in Parallel. So I would check the sockets and the wiring.

The service manual is here.... http://www.service-data.com/product....75/5111/m13875 and it's jolly good value for money.

Does the set work apart from this?

Cheers,

Steve P.

MICK1985 · 1st Jun 2013, 2:04 am

Hi.

Thanks for the details. Yes the radio is working. What I mean by "blown one side" is that there is a black patch on the glass near the bottom right hand side. It does still light up, but not very brightly. This would not cause my problem would it?

Thanks, Mike.

Tractorfan · 1st Jun 2013, 9:48 am

Hi,
The black patch on the glass is probably perfectly normal. It is more than likely the "getter" which absorbs any stray traces of oxygen left after the evacuation process during manufacture. If the patch should ever become white on a valve, it means that the valve has lost its vacuum and is useless.
The dull glow is normal too.
Cheers, Pete

MICK1985 · 1st Jun 2013, 11:28 am

Hi.

As the valve's working fine I'm going have a look at the wiring to the lamp holders to see what's wrong resulting in only one side working.

Thanks, Mike

matthewhouse · 1st Jun 2013, 3:04 pm

Has this set been repaired? If the capacitors are original I would at the very least replace C40 (manufacturers manual). Do also be aware that although this set uses a transformer, it is a live chassis design. If live is connected to the chassis the chassis and bulb holders will be at full mains voltage. Do not handle the chassis or bulb holders with the mains lead connected, also ensure the neutral wire goes to chassis. Do not rely on the mains switch to disconnect the power, it is a 2 pole switch. If the live side is stuck closed the chassis will become live with the switch off even though the radio will appear dead. C1 and C3 need to be replaced with modern 'Class Y' types if this has not been done already.

MICK1985 · 1st Jun 2013, 8:44 pm

HI thanks for the advice so if i replace these parts it may bring both light working agien ?? sorry new to all this radio refurb stuff most caps have been replaced and both bulbs work just one side does not but wires are fine and so are holders seem ok given age but thanks for advice but i have noticed today that the bulbs fittied where not 6v 0.5a but 6.5v 0.5a would this had any effect on any parts do you think as i thought this radio bulbs would be 6v 0.5a or am i wrong ?? please advice cheers mike

Station X · 1st Jun 2013, 10:31 pm

The failure of a known good lamp to light on one side can only be down to faulty wiring between the lamp holders or failure of the lamp holder itself. Try doing some continuity tests with the set unplugged.

matthewhouse · 1st Jun 2013, 10:35 pm

Quote:

Originally Posted by MICK1985

HI thanks for the advice so if i replace these parts it may bring both light working agien ??

No C40 needs to be in good condition to prevent expensive damage to the audio output transformer, mains transformer and output valve.

C1 and C3 need to be safety rated as they protect the user from risk of electric shock from the aerial and earth sockets on the back of the radio.

This fault can only be a bad contact in the holder or faulty wiring at the holder.

MICK1985 · 1st Jun 2013, 11:15 pm

HI thanks so if i change the wireing first and if still no joy any ideia where im going to get replacement lamp holders from for this set as its an unuseal way of doing them as there enclosed in like a rubber ring can you advice also what bulbs should i be useing in this set would 6.5v 0.5a do any harm if used ?? many thanks mike

Station X · 1st Jun 2013, 11:34 pm

Don't change the wiring it may be OK. Test it for continuity.

MICK1985 · 2nd Jun 2013, 12:08 am

HI ok thanks i do that first if no joy its probly the wireing if not its probly the old lamp holder givein up the ghost after all these years saying that just takeing a look at the inside of the none working lamp holder there is sings of what looks like rust maybe this makeing the problem umm

thanks for all the advice guys im most greatfull to you all for helping me best wishes mike

ValveMan · 2nd Jun 2013, 12:21 am

Hi,

I had a similar problem with a radio I repaired. It turned out to be a bad contact in the lamp holder. Another simple thing is to check both bulb values. I worked on a radio in the past (bush dac90a) which had one light lighting and the other not. In the end I found one bulb was 1.5v and the other 3v. I don't have access to the service data but if the lamps are in series this may well be the problem, on the other hand, if they are in parallel it is most likely a bad lamp holder or as the others have said bad continuity.

Regards, Dylan

MICK1985 · 2nd Jun 2013, 12:27 am

HI ok thanks for that advice cheers mike

MICK1985 · 2nd Jun 2013, 6:12 pm

HI thanks guys sorted by changing a bad wire now both holders are working but what are the bulbs that would be required for this set as I've only got sets of 6.5V 300mA left. Would these be OK to use or would 6.5V 0.5A be better to use please can someone advise'

Many thanks, Mike.

wireful3 · 2nd Jun 2013, 6:31 pm

6.5V 300mA should be OK. In fact this is a typical value in many sets

matthewhouse · 2nd Jun 2013, 7:03 pm

The service manual states 6.2V 300mA, so the 6.5V 300mA ones will be fine.

MICK1985 · 2nd Jun 2013, 7:43 pm

Hi.

Thanks guys for all your advice and help with the problem I've been having with this set. I'm most grateful to you all for everything.

Best wishes, Mike.

31st May 2013, 10:07 pm	#1
MICK1985 Pentode Join Date: Mar 2010 Location: Clacton On Sea, Essex, UK. Posts: 184	Help with Murphy A130 radio lights Hi guys. Please can someone advise whether the U404 valve, which is blown on one side, would stop the display lights from working on one side? Either lamp will work in the right hand holder, but neither lamp will work in the left hand holder. Many thanks, Mick.

1st Jun 2013, 1:09 am	#2
matthewhouse Octode Join Date: Jul 2006 Location: Willand, Devon, UK. Posts: 1,023	Re: Re help with murphy radio lights If you don't already have the service manual I would highly recommend getting the manufacturers version, as it goes into great detail. You can purchase a copy from this forum by clicking the big box at the very top right of this page. From what I can see the two bulbs are in parallel so if one works so should the other. I'd check for a broken or buckled contact in the bulb holder. The service manual mentions the importance of a rubber insulating sleeve fitted to the holders. The bulbs take their power from the same place as the PEN45 valve heater Could you please explain: blown one side U404 valve? This valve is a single rectifier diode.

1st Jun 2013, 1:27 am	#3
Steve_P Dekatron Join Date: Sep 2003 Location: Bolton, Greater Manchester, UK. Posts: 6,644	Re: Re help with murphy radio lights An A130 is likely to be an AC version, but in the case of the A130 and the U130, they both use a half wave rectifier valve. Sheet 994 has come to hand here, as my DVD has gone walkies! But anyway... The A130 has an Auto Transformer and the bulbs are wired in Parallel. So I would check the sockets and the wiring. The service manual is here.... http://www.service-data.com/product....75/5111/m13875 and it's jolly good value for money. Does the set work apart from this? 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...?

1st Jun 2013, 2:04 am	#4
MICK1985 Pentode Join Date: Mar 2010 Location: Clacton On Sea, Essex, UK. Posts: 184	Re: Re help with murphy radio lights Hi. Thanks for the details. Yes the radio is working. What I mean by "blown one side" is that there is a black patch on the glass near the bottom right hand side. It does still light up, but not very brightly. This would not cause my problem would it? Thanks, Mike.

1st Jun 2013, 9:48 am	#5
Tractorfan Dekatron Join Date: Mar 2008 Location: St. Frajou, l'Isle en Dodon, Haute Garonne, France.(Previously: Ellesmere Port, Cheshire, UK.) Posts: 3,184	Re: Help with Murphy A130 radio lights Hi, The black patch on the glass is probably perfectly normal. It is more than likely the "getter" which absorbs any stray traces of oxygen left after the evacuation process during manufacture. If the patch should ever become white on a valve, it means that the valve has lost its vacuum and is useless. The dull glow is normal too. Cheers, Pete __________________ "Hello?, Yes, I'm on the train, I might lose the signal soon as we're just going into a tunn..."

1st Jun 2013, 11:28 am	#6
MICK1985 Pentode Join Date: Mar 2010 Location: Clacton On Sea, Essex, UK. Posts: 184	Re: Help with Murphy A130 radio lights Hi. As the valve's working fine I'm going have a look at the wiring to the lamp holders to see what's wrong resulting in only one side working. Thanks, Mike

1st Jun 2013, 3:04 pm	#7
matthewhouse Octode Join Date: Jul 2006 Location: Willand, Devon, UK. Posts: 1,023	Re: Help with Murphy A130 radio lights Has this set been repaired? If the capacitors are original I would at the very least replace C40 (manufacturers manual). Do also be aware that although this set uses a transformer, it is a live chassis design. If live is connected to the chassis the chassis and bulb holders will be at full mains voltage. Do not handle the chassis or bulb holders with the mains lead connected, also ensure the neutral wire goes to chassis. Do not rely on the mains switch to disconnect the power, it is a 2 pole switch. If the live side is stuck closed the chassis will become live with the switch off even though the radio will appear dead. C1 and C3 need to be replaced with modern 'Class Y' types if this has not been done already.

1st Jun 2013, 8:44 pm	#8
MICK1985 Pentode Join Date: Mar 2010 Location: Clacton On Sea, Essex, UK. Posts: 184	Re: Help with Murphy A130 radio lights HI thanks for the advice so if i replace these parts it may bring both light working agien ?? sorry new to all this radio refurb stuff most caps have been replaced and both bulbs work just one side does not but wires are fine and so are holders seem ok given age but thanks for advice but i have noticed today that the bulbs fittied where not 6v 0.5a but 6.5v 0.5a would this had any effect on any parts do you think as i thought this radio bulbs would be 6v 0.5a or am i wrong ?? please advice cheers mike

1st Jun 2013, 10:31 pm	#9
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: Help with Murphy A130 radio lights The failure of a known good lamp to light on one side can only be down to faulty wiring between the lamp holders or failure of the lamp holder itself. Try doing some continuity tests with the set unplugged. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

1st Jun 2013, 11:15 pm	#11
MICK1985 Pentode Join Date: Mar 2010 Location: Clacton On Sea, Essex, UK. Posts: 184	Re: Help with Murphy A130 radio lights HI thanks so if i change the wireing first and if still no joy any ideia where im going to get replacement lamp holders from for this set as its an unuseal way of doing them as there enclosed in like a rubber ring can you advice also what bulbs should i be useing in this set would 6.5v 0.5a do any harm if used ?? many thanks mike

1st Jun 2013, 11:34 pm	#12
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: Help with Murphy A130 radio lights Don't change the wiring it may be OK. Test it for continuity. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

2nd Jun 2013, 12:08 am	#13
MICK1985 Pentode Join Date: Mar 2010 Location: Clacton On Sea, Essex, UK. Posts: 184	Re: Help with Murphy A130 radio lights HI ok thanks i do that first if no joy its probly the wireing if not its probly the old lamp holder givein up the ghost after all these years saying that just takeing a look at the inside of the none working lamp holder there is sings of what looks like rust maybe this makeing the problem umm thanks for all the advice guys im most greatfull to you all for helping me best wishes mike

2nd Jun 2013, 12:21 am	#14
ValveMan Retired Dormant Member Join Date: Apr 2013 Location: Edinburgh, UK. Posts: 16	Re: Help with Murphy A130 radio lights Hi, I had a similar problem with a radio I repaired. It turned out to be a bad contact in the lamp holder. Another simple thing is to check both bulb values. I worked on a radio in the past (bush dac90a) which had one light lighting and the other not. In the end I found one bulb was 1.5v and the other 3v. I don't have access to the service data but if the lamps are in series this may well be the problem, on the other hand, if they are in parallel it is most likely a bad lamp holder or as the others have said bad continuity. Regards, Dylan

2nd Jun 2013, 12:27 am	#15
MICK1985 Pentode Join Date: Mar 2010 Location: Clacton On Sea, Essex, UK. Posts: 184	Re: Help with Murphy A130 radio lights HI ok thanks for that advice cheers mike

2nd Jun 2013, 6:12 pm	#16
MICK1985 Pentode Join Date: Mar 2010 Location: Clacton On Sea, Essex, UK. Posts: 184	Re: Help with Murphy A130 radio lights HI thanks guys sorted by changing a bad wire now both holders are working but what are the bulbs that would be required for this set as I've only got sets of 6.5V 300mA left. Would these be OK to use or would 6.5V 0.5A be better to use please can someone advise' Many thanks, Mike.

2nd Jun 2013, 6:31 pm	#17
wireful3 Retired Dormant Member Join Date: Sep 2003 Location: Bristol, UK. Posts: 808	Re: Help with Murphy A130 radio lights 6.5V 300mA should be OK. In fact this is a typical value in many sets

2nd Jun 2013, 7:03 pm	#18
matthewhouse Octode Join Date: Jul 2006 Location: Willand, Devon, UK. Posts: 1,023	Re: Help with Murphy A130 radio lights The service manual states 6.2V 300mA, so the 6.5V 300mA ones will be fine.

2nd Jun 2013, 7:43 pm	#19
MICK1985 Pentode Join Date: Mar 2010 Location: Clacton On Sea, Essex, UK. Posts: 184	Re: Help with Murphy A130 radio lights Hi. Thanks guys for all your advice and help with the problem I've been having with this set. I'm most grateful to you all for everything. Best wishes, Mike.