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Old 12th Sep 2021, 9:10 am   #1
khunmoo2
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Default Record MegOhms AC generator

I have fully restored a circa 1960 Record MegOhms insulation tester. The unit was pretty tired and battered after spending decades in outback Western Australia with more than a few sparkies. It has come up really well and working very well.

Question: this unit has a built in AC powered 50 0VDC generator and built into a wooden instrument case. Does anyone know the period Record made this version (allegedly around 1960) and if they are quite rare versus the much more common hand crank generator versions?
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Old 12th Sep 2021, 8:25 pm   #2
The Philpott
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Default Re: Record MegOhms AC generator

Lovely. I am going to take a punt at 1960-1964. It seemed to me there is a lot less data around concerning old 'Record' equipment than there is for old 'Megger' equipment.
When i was tackling a 500v hand cranked Record insulation tester i had to wing it, there didn't appear to be anyone current on the forum who had dismantled/serviced one. Ultimately a bit disappointing as it would only push out 50v and a very tiny current sub 1mA- shorted turns presumably.

I would estimate that what you have there is quite rare.

Dave
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Old 13th Sep 2021, 12:59 am   #3
khunmoo2
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Default Re: Record MegOhms AC generator

Tks Dave, my experience is the same. I had to study up on megger and resistance testing theory then reverse engineer the schematic. But Iím very happy, it now looks good and works just fine.

I plan to offer it for sale in UK, USA and Australia.

Khunmoo2
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Old 13th Sep 2021, 10:13 am   #4
DMcMahon
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Default Re: Record MegOhms AC generator

It does look lovely, first time I have heard of Record.

David
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Old 13th Sep 2021, 10:25 am   #5
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Default Re: Record MegOhms AC generator

I have an old Record DC voltmeter,in a well made wooden case. 0-300 volts in ranges selected by terminals down one side. I bought it for my father from Patrick and Kinney,London Rd,Romford in the 70's.Les.
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Old 13th Sep 2021, 10:02 pm   #6
Bill
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Default Re: Record MegOhms AC generator

I have two Record "Cirscale" meters now installed in a boat, Voltmeter and Ammeter. When restoring them, I noted hand written on the backs of the scale plates, dates in 1923 and 1924. They have steel cases with a beaded alloy bezel to retain the glass, about 7ins in diameter. The movement has a large horse-shoe magnet.
Record Electrical, Broadheath, Altrincham Nr Manchester. My father in law worked for "The Record" many years ago.The business is still going and supplying "Cirscale" meters.
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Old 14th Sep 2021, 1:39 pm   #7
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Default Re: Record MegOhms AC generator

-Here's a Record Minor insulation tester next to a contemporary 'Wee Megger'. I think that i bought the former as a back-up in case of failure of the latter, but it turned out to be more of a curio. The Megger came back to life with replacement of the capacitor, but the Record is rather frail in certain areas (and for some reason does not use a capacitor..?)

As you can see it's quite large by comparison. The commercial success or otherwise can be judged by the Record s/no being around 7,000 and the Megger 700,000! They both date from mid WW2.

As far as the Record goes, apart from not generating proper voltage/current, the dog-clutch is iffy, the hand-crank chafed against the case in the past, which had a sizeable crack in it. No adjustment is available so i ended up sanding away the flange/lip of the bakelite where the two halves of the case meet, to avoid further damage! The lugs on the end of the case are where the carry handle was, apparently.

Dave
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Old 16th Sep 2021, 11:52 am   #8
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Default Re: Record MegOhms AC generator

Got a pretty low serial number for my AC powered Record MegOhms. They probably did not make too many. Ser No G1954/A1
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Old 22nd Sep 2021, 10:04 am   #9
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Default Re: Record MegOhms AC generator

My Record MegOhms AC generator has the restoration completed. I will give you guys first bite of this rare cherry by listing it for sale exclusively on this forum for a week or three.

Khunmoo2
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Old 22nd Sep 2021, 11:53 pm   #10
trobbins
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Default Re: Record MegOhms AC generator

Does it maintain a 500V supply down at 1Meg ?

As an aside, that resistor likely wouldn't be rated for 500V.
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Old 30th Sep 2021, 12:03 pm   #11
khunmoo2
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Default Re: Record MegOhms AC generator

I tested the Record Megohms with a range of resistors of varying quality.
Voltage readings about 400V at 1 megohm up to 550V across a 10 megohm resistor.

I had put new capacitors and silicon diodes in the generator.

Its list for sale at present on this site.
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Old 30th Sep 2021, 1:22 pm   #12
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Default Re: Record MegOhms AC generator

I have a 250 volt Megger that had an O/C hand crank generator and I replaced the generator with an inexpensive inverter chip with a 9 volt input. It delivers 239 volts when measuring a 1 Mohm resistor and the meter reads spot-on.

Peter
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Old 30th Sep 2021, 1:59 pm   #13
The Philpott
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Default Re: Record MegOhms AC generator

-Could that upgrade resurrect my Record Minor...? Do you have details of the inverter chip Peter?
Dave
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Old 30th Sep 2021, 2:10 pm   #14
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Default Re: Record MegOhms AC generator

This lovely big wooden Megger found its way home with me from the flea market a few years ago.
There was no problem with the generator apart from me not being able to find the handle.
There was just a pair of terminals.
The accuracy is good over quite a wide voltage range while I was finding an inverter and battery that could be stacked on the terminals without mechanically overloading them.
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Old 30th Sep 2021, 3:37 pm   #15
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Default Re: Record MegOhms AC generator

Quote:
Originally Posted by The Philpott View Post
-Could that upgrade resurrect my Record Minor...? Do you have details of the inverter chip Peter?
Dave
Hi Dave, It's quite a few years since I fitted the inverter and I can't find a record of me buying it. Unfortunately I also can't find one that looks similar. It is a very simple board 9v dc in 240v dc out. I can't easily extract it from my Megger but have taken a photo from the side.

More recently I did buy a higher voltage inverter for CRT testing. The hyperlink is not the same seller but is the same item. For CRT testing only very low current output is needed so I don't know how well this will work in an insulation tester.

Peter
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Old 30th Sep 2021, 4:19 pm   #16
peter_scott
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Default Re: Record MegOhms AC generator

Sorry Dave,

I've found me describing what I used for a power supply and it wasn't the type of inverter that I thought. https://www.vintage-radio.net/forum/...ghlight=Megger See post #15.

I still can't think what I actually did. I guess I was switching my 9 volt dc into the secondary of the bell transformer and rectifying the 240 volt output at the primary.

Peter

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