EF85 Valve Not Lighting Up. - UK Vintage Radio Repair and Restoration Discussion Forum

Jordan T · 11th Aug 2019, 10:26 am

Hi Guys,

Recently the all radio frequencies on my 1955 RGD 3-15 Radiogram have stopped working (however the record player still plays really well). I noticed that one of the valves (EF85) wasn’t lighting up, so bought a NOS Mullard replacement. The replacement Valve still doesn’t light up.

Does anyone know what could have caused this valve to have stop working? I don’t really want to go taking things apart until I know roughly where about's I should be looking.

Looking forward to your responses.

Jordon

Station X · 11th Aug 2019, 10:42 am

Unless you've got two faulty valves, the most likely cause is a bad connection twixt the valve and the valveholder.

Check the valves' heaters for continuity.

Check for 6.3 VAC at the valveholder.

http://www.r-type.org/exhib/aai0224.htm

'LIVEWIRE?' · 11th Aug 2019, 10:46 am

It may also be wise to check the valve socket, particularly if it is the type whose pins are like miniature forks. These sometimes break or weaken, resulting in no or poor contact between the socket and the valve's pins.

Jordan T · 11th Aug 2019, 11:52 am

All fixed!! Thanks folks. As advised above, one of the pins on the valve socket was slightly loose.

terrykc · 11th Aug 2019, 11:53 am

Quote:

Originally Posted by Station X

Unless you've got two faulty valves, the most likely cause is a bad connection twixt the valve and the valveholder.

Alternatively, it may be the connection to the valveholder beneath the chassis.

It is not unknown for a joint to be missed during the soldering operation in production but the wire may make perfect contact for many years without trouble. Another alternative is a dry joint caused by the wire moving during soldering. Again, it can work for years before giving trouble.

Ah, your post crossed with mine - glad to see you've fixed it!

Station X · 11th Aug 2019, 11:54 am

Quote:

Originally Posted by Jordan T

All fixed!! Thanks folks. As advised above, one of the pins on the valve socket was slightly loose.

Excellent news. We like happy endings!

crackle · 11th Aug 2019, 3:20 pm

Oddly enough this radio has 3 heater supplies on the mains transformer.
The ECC85 has its own winding (shared with the pilot lamps), the rectifier has its own winding, and all the rest of the valves share a winding.
Anyway it is working now so all's well.
Mike

toshiba tony · 11th Aug 2019, 5:49 pm

I assume the ECC85 is used on FM only, but why has it it's own heater supply. Or is it to lessen possible interference from the other stages. Never heard of it before, that's all. Thanks.

toshiba tony · 11th Aug 2019, 6:17 pm

Sorry, mistook it for an ECC85. Dementia bad today, sorry.

11th Aug 2019, 10:26 am	#1
Jordan T Triode Join Date: Oct 2018 Location: Telford, Shropshire, UK. Posts: 21	EF85 Valve Not Lighting Up. Hi Guys, Recently the all radio frequencies on my 1955 RGD 3-15 Radiogram have stopped working (however the record player still plays really well). I noticed that one of the valves (EF85) wasn’t lighting up, so bought a NOS Mullard replacement. The replacement Valve still doesn’t light up. Does anyone know what could have caused this valve to have stop working? I don’t really want to go taking things apart until I know roughly where about's I should be looking. Looking forward to your responses. Jordon Attached Thumbnails

11th Aug 2019, 10:42 am	#2
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,288	Re: EF85 Valve Lighting Up Unless you've got two faulty valves, the most likely cause is a bad connection twixt the valve and the valveholder. Check the valves' heaters for continuity. Check for 6.3 VAC at the valveholder. http://www.r-type.org/exhib/aai0224.htm __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

11th Aug 2019, 10:46 am	#3
'LIVEWIRE?' Rest in Peace Join Date: Mar 2006 Location: N.W. Oxfordshire(Chipping Norton) Posts: 7,306	Re: EF85 Valve Lighting Up It may also be wise to check the valve socket, particularly if it is the type whose pins are like miniature forks. These sometimes break or weaken, resulting in no or poor contact between the socket and the valve's pins.

11th Aug 2019, 11:52 am	#4
Jordan T Triode Join Date: Oct 2018 Location: Telford, Shropshire, UK. Posts: 21	Re: EF85 Valve Not Lighting Up. All fixed!! Thanks folks. As advised above, one of the pins on the valve socket was slightly loose.

11th Aug 2019, 3:20 pm	#7
crackle Rest in Peace Join Date: Mar 2011 Location: Basildon, Essex, UK. Posts: 4,100	Re: EF85 Valve Not Lighting Up. Oddly enough this radio has 3 heater supplies on the mains transformer. The ECC85 has its own winding (shared with the pilot lamps), the rectifier has its own winding, and all the rest of the valves share a winding. Anyway it is working now so all's well. Mike

11th Aug 2019, 5:49 pm	#8
toshiba tony Heptode Join Date: May 2006 Location: Accrington, Lancashire, UK. Posts: 978	Re: EF85 Valve Not Lighting Up. I assume the ECC85 is used on FM only, but why has it it's own heater supply. Or is it to lessen possible interference from the other stages. Never heard of it before, that's all. Thanks.

11th Aug 2019, 6:17 pm	#9
toshiba tony Heptode Join Date: May 2006 Location: Accrington, Lancashire, UK. Posts: 978	Re: EF85 Valve Not Lighting Up. Sorry, mistook it for an ECC85. Dementia bad today, sorry.