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Beamec CRT Tester

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Marc
 Marc
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Hi all,

A new toy to play with arrived today namely one.....

"Grünther Instruments"'  Beamec Cathode-Ray Tester and Re-conditioner..... Think i'll stick to 'Beamec' for short.

Any way at just £12.50 I thought it was worth a punt from our beloved vintage supplier 'eBay'. wink 

Condition wise it's filthy but complete except for it's rubber feet, it's fitted with the wrong knobs and the mains lead has perished but otherwise looks fine. I'm guessing that the caps will leaky and maybe a few resistor will be out of speck and the multi-pole switch will need some serious cleaning. I will also have to make a test lead for it to connect to CRTs.

Has anyone got any information available for this Beamec ? I've already spotted the data in the library but that is for the series 2 version.

Time to go cleaning me thinks.....hmm_gif

Marc.

DSCF4279-Medium.JPG

DSCF4281-Medium.JPG

DSCF4282-Medium.JPG

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Topic starter Posted : 05/10/2017 2:48 pm
Cathovisor
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Well, rubber feet are easy (I have some you put a screw through and they're real rubber) and I assume you have the base adaptor for it too. Knobs are standard Bulgin pointer ones?

Nice buy!thumb_gif

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Posted : 05/10/2017 3:00 pm
Marc
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Cathovisor said
Well, rubber feet are easy (I have some you put a screw through and they're real rubber) and I assume you have the base adaptor for it too. Knobs are standard Bulgin pointer ones?

Nice buy!thumb_gif  

Hi Catho,

I think I've got some feet that will do for now (stop scratching everywhere it's put down) but they are a bit weedy and I have a nice plug to make the lead from. Knobs, aren't they called 'Chicken Head' these days ?

Now to problem No1.... the voltage selector switch has a broken wafer to repair as you can see below.

DSCF4284-Medium.JPG

 

McMurdo plug seems just right for the job

DSCF4286-Medium.JPG

Marc.

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Topic starter Posted : 05/10/2017 3:15 pm
Marc
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Hi all,

I've checked and reformed the 3 electrolytic caps (2X16uf & 1X32uf) and they are all fine but the two 0.1uf wax caps were leaking badly and were replaced leaving just the single Hunts 0.05uf which was O/C so was also replaced. All resistors but one seem fine being within 10% tolerance, a 3.3MΩ was up at 4.8MΩ.

Next job is repair the wafer switch, it looks like it will glue back with epoxy. That's it for now.

Marc.

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Topic starter Posted : 05/10/2017 5:02 pm
Marc
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Hi all,

Fingers crossed the wafer switch has been rescued. after cleaning the breaks on the paxolin with IPA solvent the two parts of the wafer have been epoxied back together and a tie wrap has been positioned around the circumference of the switch to secure it and now all looks good.

Next job....find some suitable mains flex. hmm_gif

Marc.

DSCF4287-Medium.JPG

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Topic starter Posted : 05/10/2017 5:29 pm
Cathovisor
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marc said

Cathovisor said
Well, rubber feet are easy (I have some you put a screw through and they're real rubber) and I assume you have the base adaptor for it too. Knobs are standard Bulgin pointer ones?

Nice buy!thumb_gif  

Hi Catho,

I think I've got some feet that will do for now (stop scratching everywhere it's put down) but they are a bit weedy and I have a nice plug to make the lead from. Knobs, aren't they called 'Chicken Head' these days ?

Only if you're a Colonial who knows no better wink

Seriously - have you ever seen a chicken with a head that shape?

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Posted : 05/10/2017 7:44 pm
Marc
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Cathovisor said  Seriously - have you ever seen a chicken with a head that shape?  

Not in this house, there all cooked or roasted ! grin_gif

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Topic starter Posted : 05/10/2017 8:04 pm
Marc
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Hi all,

I found a nice piece of suitable mains flex that resembles the old rubber stuff before it had perished and it's now fitted.

Next thing to sort out is the CRT fly lead, I have a scrap B&K which I've pinched the CRT lead from and fitted an octal plug to it thus allowing me to use the B&K adaptors for now, I will in time make a dedicated Beamec style block connector once I source all the relevant sockets. I also need to order some better knobs for it too.

I've tested the Beamec on a couple of ropy Mullard round tubes and it all seems to be working as it should. 

 

The Beamec with it's B&K fly lead

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Emission from a well dodgy MW31/16

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Emission from an iffy MW22/14

DSCF4290-Medium.JPG

 

Marc.

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Topic starter Posted : 06/10/2017 4:58 pm
Cathovisor
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I have to say that the CRT base box I have with my Beamec looks identical to the one that comes with a Radar 202...

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Posted : 06/10/2017 5:46 pm
Marc
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Hi Catho,

If you take a look in the library under 'Beamec Technical' and scroll to near the bottom it gives the pin outs for it's block connector, you could compare it to your Radar block and see if they are the same. 

Marc.

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Topic starter Posted : 06/10/2017 6:53 pm
Nuvistor
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Are you going to try and recondition one of the low emmision crts?

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Posted : 06/10/2017 7:17 pm
Marc
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nuvistor said
Are you going to try and recondition one of the low emmision crts?  

Hi Frank,

Don't you just love Grünther's term "recondition" wink

The CRT with the lowest emission has already unsuccessfully been tickled and thumped before with my B&K many moons since and really should have been thrown away long ago so yes I don't mind bopping that one as a test piece but as for the other one I would rather let it simmer and see what happens after a few hours. I have a feeling that the old Beamec is rather a 'kill or cure' machine unlike the more gentle 'clean and balance' function of the B&K which I would rather use for any stronger intervention.

The main handy point about the Beamec is that it can test triode tubes which B&K can't do.

Marc.

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Topic starter Posted : 06/10/2017 7:38 pm
Marc
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Hi all,

Following on from Franks comments I decided to give the Mullard MW31/16 some 'treatment' on the Beamec with surprising results.

This tube, some time ago, had already been 'cleaned and balanced' and 'restored' using the B&K 467 resulting in absolutely no change in it's emission which was floating somewhere in the very low red area of the B&K's dial. After allowing the Beamec and the tube to warm through for about ten minutes this is the start point of the emission readings......    

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I then tried 'Process' which did nothing so I chose to 're-active' it using the No1 setting and got this......

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Now this is still low but it's certainly a big improvement to what it was. Next I put the tube through what Beamec call 'Aging' which lasts around 10 minutes and afterwards surprisingly the emission reading remained the same.

Next up I tried the B&K 467 to see how much the readings differ......

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The B&K emission reading is slightly lower than the Beamec but about what I would expect.

So the Beamec has beaten the B&K at improving emission with this tube. I'm still very cautious of 'bopping' tubes and will try any other more gentle means first but it's been interesting to compare both machines.

Marc.

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Topic starter Posted : 06/10/2017 11:43 pm
Nuvistor
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It’s usually a temporary improvement, we could get a few months at the most out of the CRT but that would be in use several hours a day and put off purchasing another CRT. After that time the customer may have decided to change the set rather than fit a new tube and it gave them some time to think about it.

Some CRT’s seems to work better and last longer with a 25% heater boost, but that involved some cost for the transformer.

With the amount of use these old sets will be put to, the CRT could last a long time after the “recondition”

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Posted : 07/10/2017 8:09 am
PYE625
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marc said

 I'm still very cautious of 'bopping' tubes and will try any other more gentle means first but it's been interesting to compare both machines.

Marc.  

Hi Marc, an interesting bit of kit welld_gif

Very wise to be cautious as it is  risky in that you can destroy whatever little cathode coating is left and end up with no emission.

Interestingly, when I worked at the co-op, the policy was to replace CRT's if defective and no such booster equipment was even owned by them. (It was used by other firms, that I do know). 

Obviously now, we do not have the luxury of readily available CRT's for replacements or re-gunning so have to do what we can to prolong life.

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Posted : 07/10/2017 11:01 am
Marc
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nuvistor said
Some CRT’s seems to work better and last longer with a 25% heater boost, but that involved some cost for the transformer.

With the amount of use these old sets will be put to, the CRT could last a long time after the “recondition”  

Hi Frank, 

If I remember correctly the set that the the MW31/16 came from had a boost transformer fitted in it and I still have it kicking around somewhere. With any luck a 'bopped' tube should last a while in collection usage.

Marc. 

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Topic starter Posted : 07/10/2017 1:16 pm
Marc
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PYE625 said

Very wise to be cautious as it is  risky in that you can destroy whatever little cathode coating is left and end up with no emission.

Hi Andrew,

With this particular CRT I had nothing to loose but interestingly I have actually gained from it, now that's unusual for me ! smile

Marc.

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Topic starter Posted : 07/10/2017 1:19 pm
Nuvistor
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From memory the Mullard CRTs would respond to a boost transformer, the Mazda ones not quite as much. Most faults I saw with Mazda CRT’s was an OC cathode, for me that fault was rarely repairable.

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Posted : 07/10/2017 2:00 pm
Anonymous
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Hi Marc,

I came across your post on this site whilst researching history about Grunther Instruments. My father, George Gurry, founded the company and produced the Beamec. He originally operated a CRT reconditioning service for the TV rental shops but then went on to produce the Beamec and sell it. The business he subsequently founded, CML Microsystems, is still flourishing today and is about to celebrate its 50th year - hence the research.

If you or any other posters here have any further information and/or pictures to do with any Grunther products then I would appreciate you letting me know.

Chris

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Posted : 04/09/2018 2:26 pm
Marc
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Hi Chris,

Now that's is very interesting to know about your father George Gurry. It amazes me how things come to light. I would be more than happy to send you some photos of my Beamec although it doesn't sport it's original selector knobs.

The one thing I would love to find it, if you could possibly help, would be the correct 'user instructions' for this particular model. The only instruction that I've found are for the later series 2 models.

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Topic starter Posted : 04/09/2018 6:27 pm
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