EM34 replacement?

[ted_ntsx]

Anyone know of a EM34 (near?) equivalent available at a reasonable price?
I have three Philips "vintage" sets with dead EM34's that I would like to replace. I don't mind rewiring the valve base or changing components if necessary.

I have seen NOS EM34's on Ebay for anything from £30 to £50+
Even "used" items seem to carry a silly price. Far more than the radios are worth!

Is there any way to revive a dim/dead EM34? (assuming it is not a terminal electrode failure). I have one that works but is VERY dim and only shows in a dark room, and two that have no visible display at all. I did wonder if overrunning the heater might get a bit of life out of them, even if only temporarily. Anyone tried this? Any other "tricks" known?

Ted.

[Steve_P]

Well you can try upping the Anode voltage...

There is a Russian version that you can try - just needs a couple of changes on the base. You can get them from here:

http://www.pasttimesradio.co.uk/index.html

Cheers,

Steve P.

[paulsherwin]

When EM34s are gone they're gone. Never buy an ex equipment EM34 unless you see it working or know and trust the seller.

A number of magic eyes can be subbed for the EM34 with minor wiring changes, but they won't look the same as the EM34 has a distinctive dual sensitivity display. Keep an eye open for the Y63, which was used in a lot of 1940s military gear and often turns up on eBay selling for about £10.

Paul

[ted_ntsx]

Originally Posted by paulsherwin

When EM34s are gone they're gone. Never buy an ex equipment EM34 unless you see it working or know and trust the seller.

A number of magic eyes can be subbed for the EM34 with minor wiring changes, but they won't look the same as the EM34 has a distinctive dual sensitivity display. Keep an eye open for the Y63, which was used in a lot of 1940s military gear and often turns up on eBay selling for about £10.

Paul

I do have a Y63, but it would not physically fit in clamp and space available.
I might have to do a bit of "metal work", which I was trying to avoid.

Ted.

[ted_ntsx]

Originally Posted by Steve_P

Well you can try upping the Anode voltage...

There is a Russian version that you can try - just needs a couple of changes on the base. You can get them from here:

http://www.pasttimesradio.co.uk/index.html

Cheers,

Steve P.

Thanks for that link. Looks like a possibility.

Ted.

[howard]

Hello Ted,

I went hunting for an EM34 for my Grundig 3028 around a year ago and as you say NOS valves are expensive and silly prices are asked for worn secondhand examples. You can replace the EM34 with the Soviet 6E5C or 6E5S valve with minor wiring changes but those valves have only 1 shadow angle rather than 2. There are several identical equivalents for the EM34 which include the US made 6CD7 (just as expensive), 6M2, 64ME, CV394 and MEM34. I eventually found a near perfect secondhand Mullard EM34 for £10, good luck and I hope you find a good one too.

Howard

[paulsherwin]

Originally Posted by ted_ntsx

I do have a Y63, but it would not physically fit in clamp and space available.
I might have to do a bit of "metal work", which I was trying to avoid.

The Y63 does have the classic 'coke bottle' shape, as do many other magic eyes. The display area is about the same size as an EM34 though. It's true that they can't be easily subbed physically in some radios.

Paul

[Keith]

A trick that I've used is to connect the anode to the reservoir capacitor (i.e. the first HT filter capacitor) rather than the smoothing capacitor. The few extra volts does give a slightly brighter display.

[Boom]

I have an ex-equipment EM4 here which came with a batch of valves a while back. Magic eye sets are not my area but I had a quick look around to see what it is and got the impression that it is sometimes possible to change the base of the valve itself rather than mess around with the sets valve socket wiring.

[kalee20]

Well, the EM4 and EM34 are the same valves on different bases (P and Octal respectively).

However, owing to the slight possibility of letting the vacuum out when removing the base, I'd be really cautious about any kind of surgery on an expensive valve. Far cheaper to replace the base, or make an adaptor, for the set! Especially as magic eyes are usually just mounted by clips and the holders not screwed to the chassis.

[rharness]

I have a used EM34 which is a bit loose on the base, and I don't know if it works or not, but you can have it if you want it. I need a spare 6v6 if you've got one to swop.

Robert

[Keith]

Actually I've found another cylindrical magic-eye on an octal base in my junk box. Unfortunately, all markings have been erased. It seems to have a 6.3V heater, but obviously not pin compatible as the grid starts to get hot when tried as a replacement. Anyone got any suggestions as to what it might be?

[LCTorana]

Originally Posted by Keith

Actually I've found another cylindrical magic-eye on an octal base in my junk box. Unfortunately, all markings have been erased. It seems to have a 6.3V heater...

Does it physically resemble any of these?
(Please click on the "Magic Eyes" link on the left hand column.)

[AlanBeckett]

Just as an aside, that's a splendid site, hereby bookmarked.
Alan

[Keith]

Yes, a splendid site indeed! I think it may be a 6U5G, which has the grid and target pins swapped compared with the EM34 (hence the glowing grid!) Having changed these over, it worked to some extent - but was about as dim as the original (sod's law) so I've put things back as they were for now. I have however, connected the EM34 target (not the anode as I mistakenly posted earlier) to the slightly higher voltage on the reservoir capacitor, which gives a useful improvement in brightness. Thanks for the link.