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Old 10th Feb 2019, 4:24 pm   #1
The Philpott
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Default Record 'Minor' Insulation Tester

A Wee Megger in everything but name, for £10 this appealed to me as a solid piece of engineering. Slightly taller than the E&V equivalent, and with enclosed gearing, I understand E&V bought out Record in the 'fifties, and this one appears to be late 'forties...?

Problems: The crank sits on a dog clutch so that the handle is free to reverse to it's parked position, but there is no spring action to pull the dog into engagement for cranking. I wonder if there should be a washer/spring combination sitting on the visible end of the shaft (see pic) to hold the dog sprung to it's closed position.

The crank handle sits hard against the case when the dog is engaged and has chafed the bakelite- it's as if a shim or washer is missing or broken up inside the mag.- I am hoping there is some adjustment in the mag. mountings.

The output struggles to get over 50v, but frankly for the price (and being a trade sale) I was quite pleased to see a sign of life.

I cannot yet see a capacitor- does anyone have a circuit diagram?
Thankyou.

Dave
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Old 1st May 2019, 10:27 pm   #2
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Default Re: Record 'Minor' Insulation Tester

For info, i have removed the scaleplate, on the reverse of which is a date- March 1943.
This instrument being larger than a wee megger, has more space inside and may well be simpler to dismantle and diagnose.. 2 of the screws which hold the mag. in are accessible from underneath, but have never been disturbed- black composition is over them with a tamper evident logo (I will sketch this logo and try to get a photo.)

It seems the mag. is the source of the 'undervolt', so i will check for shorted windings as and when i remove it.

No service data or circuit diagram has come to light, but it all looks quite simple inside.

Dave
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Old 7th May 2019, 10:32 pm   #3
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Default Re: Record 'Minor' Insulation Tester

This has resulted in a total stripdown, which was quite easy. I have found no electrical fault other than a blackened comm. which cleaned up with metal polish and is very smooth and now unblemished. The gearbox is nicely made, all brass and steel inside a bakelite housing. The only way to stop the crank handle fouling the case without courting disaster trying to dismantle the crank, will be to move the gearbox/mag. assy closer to the end of the casing, courtesy of slotted mounting holes. Up to about 25 thou extra clearance will be available but only by dremel attack to the case- since the gearbox bushes sit hard up against the case and will require a recess in which to sit. This is less than ideal but the crank and crankshaft give every indication that they wish to stay exactly where they are, and the bakelite around them will probably just give way if force is used.

The part of the case which i intend to dremel internally already has a hairline crack which i will superglue.

Although rather well made overall, the crank handle scraping the case looks likely to be an issue that would affect other Record Minors, particularly at this late stage in the game. (Should you wish to actually use one!)

Dave
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Old 14th May 2019, 8:25 pm   #4
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Default Re: Record 'Minor' Insulation Tester

- Factory wax seal in very dark brown.
- Magneto casing with magnet that has to be inserted!.
- Brush box.
- Armature & movement

No insulation failures found anywhere! - disappointingly output remains low but never mind- the crank no longer hits the casing, and there are design quirks that are worth noting. The brass housing has slotted radial fixing holes to account for irregularity in the set-up of the armature end-float. As the VERY TIGHT casing is pressed back onto the gearbox, end-float for the armature is set as and when the gearbox hits the edge of the magnet. The location for the magnet in the brass case is a bit pathetic; i am surprised the armature is able to spin without hitting the magnet. Some jiggling was required to set the brass case parallel in order that no horrible noises emanated during cranking. The springs in the brush boxes are (almost) captive, as their ends are wound round the brass contact peg and soldered to it.

Dave
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Old 14th May 2019, 9:28 pm   #5
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Default Re: Record 'Minor' Insulation Tester

-Gearbox (steel gears 18 teeth, brass gears 52 teeth)
Oil is applied to the bushes via strategically placed galleries in the housing.
-Assembled magneto. Outer housing was so tight that i wonder if it was fitted rather hot at the factory then allowed to shrink on...?
- Made in 1943. A war veteran (if only it could talk)
- Cranking end of gearbox.

I was able to prevent the crank arm hitting the bakelite casing by aforementioned grinding of the case, allowing the mag. to move closer to the end. The holes for the mag. mounting screws also had to be elongated slightly to allow this. Nasty, but better than damaging the exterior of the case.

Nominal brush length .375"
Brush width/height .1215"
Coils on armature 2.73kohm and 2.41kohm
Resistance from winding to winding, and winding to shaft, at least 60Meg.
Discrete coils (both) 80.3kohm

Output on a high impedance voltmeter 130v, but on a lower impedance voltmeter this voltage plummets to perhaps 40v. Current 1.5mA (Compared to my wee megger which pumps out 5mA)

There is no capacitor in the Record "Minor" Tester.

The accuracy of the movement is quite good; 3Meg is spot-on, open circuit reads 20Meg, 200k reads 220k, 40k reads 50k, short circuit reads 5k or less.

One more thing to note- the combination of smells inside this tester is quite pungent- my other half asked me if i had trodden in something when i came indoors after putting this thing back together!

Dave
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Last edited by The Philpott; 14th May 2019 at 9:37 pm.
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Old 14th May 2019, 11:22 pm   #6
Phil G4SPZ
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Default Re: Record 'Minor' Insulation Tester

Hi Dave, it looks like you’ve been talking to yourself for a while! I don’t have a Record Minor (or Major - I bought one once, described as ‘working’ but had an o/c movement so it went back for a refund) but I thought I’d chime in to say that I rebuilt a Record Bond Tester a while back and was impressed with the standard of its construction and especially its Bakelite mouldings. However I could find almost nothing about Record, despite diligent searching.

It certainly sounds like the magneto has some shorted turns in it if the output voltage is so low. Good luck with fixing it.
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Old 15th May 2019, 9:38 pm   #7
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Default Re: Record 'Minor' Insulation Tester

Yes Phil, i remember your (four wire?) Bond Tester.
I think you're correct, shorted turns it must be. I can't imagine the magnet deteriorating to that extent. I think i will call it 'as fixed as it can be'. There's always the possibility of one with a damaged case turning up, in which case i would consider re-visiting it.

Dave
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Old 21st May 2019, 10:43 pm   #8
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Default Re: Record 'Minor' Insulation Tester

- Just discovered the vestigial little bosses adjacent to the main terminals (See pic in Post No.1) are for a carrying handle, which mine has lost. (I thought they were cable guides to reduce stress on the input leads)
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