Neonlampen voor Philips PM2421 gezocht

hello friends,

I have the restoration of 2 Philips PM2421 in Progress.

No.1 is now repaired and working, so I can test between them both to find the Problems in the other one.

[image]

It seems to be a bad neon bulb in the optical chopper device.
A hard Job to remove that box from the Instrument but I will do.
Inside are 2 neon bulbs, they must be changed to fresh.
Is there a way to find them anywhere? I have read that are direct soldering Little bulbs like the NE2 but with a integrated lens in the glas.

greetings from germany
Martin

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I'd go for LED's, simply put in series with the existing circuits
Nico

--
een kinderhand
is ook weer gauw leeg

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thank you,

I think this is not possible, that is a complicated design with signal feedback, not a simply 50Hz Chopper. I need 2 Neonlampen NE2-M with a lens in the front to repair that.

greetings
Martin

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Martin,

do you have a picture of the defective neon-bulbs?

best regards,
Johan

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hello Johan, thank you.

I think they will be destroyed by removing them from the metal block, Philips have put around them a lot of White gum like Silicone from bathroom.

I hope you know a simply NE2 Neonlamp with 2 wires. Exactly that, but it have a lens on the front.

I have removed now the complete coupler block, that have 2 wholes along,
from the one side there are 2 photo resistors in BC107 case, and from the other side the Neonlampe, also 2 of coarse.

The Neonlampe was shieldet with a thin copper mesh. I have removed that also from the side where the Photo R was putted.

Now I want to see how to remove the both bad Neonlampe but I think they will be break by doing that.

greetings
Martin

p.s. Pictures follow in some minutes

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Hi Wellenkino,
I once had a Fluke microvolt meter, also with a photochopper. The neonlamps of the dual bar type in this unit were pretty bad, but I could just see that only one of the electrodes produced orange light. This happened because the driving voltage was unipolar, switching between 0 and 100Vdc,always in the same polarity.
I simply reversed the neon connections, which solved the problem, the voltmeter can run now for another 20 years with light from the other electrode. :-D

So, if your neonlamps are of the dual-bar type, and driven with a unipolar voltage, reversing might help you too. :OK:

Good luck,
Koos Bouwknegt

--
Met buizen in de wolken

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[image]

this are the Neonlampe

greetings
Martin

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Martin,

I'll check what I have and come back to you.

johan

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Martin,

I checked my neonlamps but unfortunately I only have various kinds of 'traditional' neonbulbs. So with a concave and a ring shaped electrode. E10 socket+series resistor and lens.

Best regards,
Johan

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Hi Martin,

fyi. the same chopper unit was used in the Philips PM2436 . this is an analog meter for low voltages. But many of them have been sold second hand in not working condition. So might be more easy to find one of those for the chopper.

best regards

Kris

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Hi, Martin.

The Russian INS-1 Neon bulb seems like a suitable replacement. The outer diameter is said to be 6.5mm versus 6.35mm max for the NE-2E so you might have to drill out the module.

You can buy them off the famous auction site for about 50 cents/each in quantities. They can also serve as spares for the NE-2's in your tek's.

Kind regards,

Florick Wibier

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hello again.

I have replaced that neon bulbs by good originals with lens.
The chopper is lightning with correct 190Hz, that is allready.

But this instrument don`t like to work :-( still "overflow"
a test with a pair of russians INS1 was the same result.
I can not find the problem. So I think now, both ore one of the both light sensitive resistors are bad. They work at 190Hz, this is ultra fast for LDRs, and in a low light area, this neon bulbs will not load them full.
The replacement of this LDRs will be the next step.