BWD 242A Dual PSU Meters Problem

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pykedgew
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Posted by pykedgew: Tue. Jul 21, 2009 - 07:06 AM
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Hi

I have scored a BWD 242A Dual Power Supply which still work perfectly.
The only down side is the aluminum needles on these meters has destintegrated due to aging & corrosion over a long period of time.
The meters are similar & are shown on these link below
http://s18.photobucket.com/albums/b131/The-Macservice-Group/TMG4/20-05-2009dscf5906.jpg
http://s18.photobucket.com/albums/b131/The-Macservice-Group/TMG4/20-05-2009dscf5908.jpg

Question is which of the following I do
1) anyone knows the manufactures of these meters
2) anyone knows the specifications of these meters
3) send it of to someone to get it repaired
4) can I do mechanical repairs? (means of need of rebalancing job etc)
5) ditch all the above & put in new meters of another brand & run with that

I do not have a service manual for this PSU unit either & where can I source for one of these?

Thanks
Ken

Tags:

Learning and Information, General Electronics
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Plons
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Posted by Plons: Tue. Jul 21, 2009 - 10:42 AM
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It will be very hard to find those meters in these days. You need lots of luck :)

This is the best source for those instruments I can find here in the Netherlands: http://www.baco-army-goods.nl/cat_21-1.html

I would go for option 5, Ken. LED or LCD meter modules are low-cost and much easier to find. Their price here varies between €4.- and €6.-

Nard

A GIF is worth a thousend words   They are called Rosa, Sylvia, Tricia, and Ulyana. You can find them https://www.linuxmint.com/

Dragon broken ? http://aplomb.nl/TechStuff/Dragon/Dragon.html for how-to-fix tips

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Kartman
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Posted by Kartman: Tue. Jul 21, 2009 - 11:38 AM
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They look like they were made by Master Instruments in Sydney. The company still exists, but I'm not sure if they still make meters.

http://www.master-instruments.co...

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Plons
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Posted by Plons: Tue. Jul 21, 2009 - 11:43 AM
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http://www.master-instruments.com.au/page/mi_analogue_meters.html

They do :)

A GIF is worth a thousend words   They are called Rosa, Sylvia, Tricia, and Ulyana. You can find them https://www.linuxmint.com/

Dragon broken ? http://aplomb.nl/TechStuff/Dragon/Dragon.html for how-to-fix tips

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pykedgew
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Posted by pykedgew: Tue. Jul 21, 2009 - 12:21 PM
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Hi Guys

Now you are talking, good find.
Master Instruments has the type I am looking for.
It's the FB50 series which I can change the back plates.
So I went to measured (duh) which I should have done in the first place. (127mm x 75mm bezel size)
I also did pull the meters out & measured the coil resistance & roughly 75ohms.(might be 50uA meter)
Tomorrow I will work out the ohms law to determine what type I need for V & I.

Nard, no.5, I was going to put LCD modules powered seperately in worse case scenarios.

Ken

ps Kartman, didn't you use to work at BWD?

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valusoft
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Posted by valusoft: Tue. Jul 21, 2009 - 11:08 PM
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Hi Ken,

I bought one of those BWD power supplies in mid 1970s at the Bureau of Met. I suspect it is still there ... but I am not :lol: I seem to recall there being a fault in the production that resulted in one T092 transistor being loaded incorrectly and it affecting the current fold back performance. One of our techs with too much spare time "sussed it out". Oh if only I had kept my notebooks ....

Cheers,

Ross

Ross McKenzie ValuSoft Melbourne Australia

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pykedgew
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Posted by pykedgew: Wed. Jul 22, 2009 - 12:52 AM
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Hi Ross

Thanks, hope this is not my model, you are referring to Ross.

Yes, they did come out in the 70's & were very robust in some models.
If I recall one of them if you switch them into parallel mode something started to cooked.

The only ICs in it is CA3054

Quote:
The CA3054 consists of two independent differential
amplifiers with associated constant current transistors on a
common monolithic substrate. The six NPN transistors which
comprise the amplifiers are general purpose devices which
exhibit low 1/f noise and a value of fT in excess of 300MHz.

Sent of an email "Master Instruments" for a meter catalog & cost.

Cheers
Ken

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Kartman
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Posted by Kartman: Wed. Jul 22, 2009 - 02:25 AM
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Did I work at BWD? Nope - just saw the MI logo on the picture and realised it was probably Master Instruments. They quoted me way too much money for some lithium batteries recently!

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pykedgew
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Posted by pykedgew: Wed. Jul 22, 2009 - 07:23 AM
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Hmmmmm, thanks for the head up on the costing, Kartman.

I got confuse it was another member & he is in Australia.

Thanks
Ken

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RickB
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Posted by RickB: Wed. Jul 22, 2009 - 02:25 PM
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I recently made a new pointer for a meter in a battery charger out of a very thin sliver of tempered aluminum foil. A bit painstaking! Made a jig to hold the pointer in alignment with the remaining fragment of the pointer and then addded a very small drop of super glue and let it cure.

Rick

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pykedgew
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Posted by pykedgew: Thu. Jul 23, 2009 - 09:44 AM
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Hi Rick

I will have look around or source for that sliver of aluminum foil.
Will google it or where to strip it out of something else.
Thought about drink cans & flatten to paper thin & go that way maybe.

Still waiting for reply from MI.

Ken

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