Heathkit V-7A Vacuum tube voltmeter DC AC Ohm 1956-61 test teardown

contains two tubes, dual diode, and dual triode, and one selenium diode for the high voltage,
power consumption 10w (2watt is the bulb alone)
after fixing the meter mecanical issues, and calibrating it, it now measures very accurate,
front glass a bit broken, that is a bit sad.
this model is from 1956 to 1961
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#tube
#teardown
#heathkit
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I use auto generated subs, I go thru them my self, but i am far from perfect at finding all errors, so if you find errors worth fixing, please comment (or PM) with the TIME in the video you saw the error, i will be happy to fix it. This also apply to the Danish version.
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(Thanks to all my Sponsors / Traders / Swappers / Sellers / Buyers, without your support and constant flow of cool items in/out, none of this would be possible)

[@michaelchambers7691]

I have the same exact VTVM. I never turned it on until I replaced the capacitors, selenium rectifier, and light bulb. I also cleaned the switches. Get a mono plug for the DC lead. I built a very nice test lead for mine, a gold plated Switchcraft mono plug, a thin coax, and 2W flame proof NTE 1M resistor that tested within 1%. Buy replacement meter probes.

[@inse001]

I had a similar problem with a Kyoritsu VTVM, only after tapping on the glass, the needle would do the final move.
I figured out that there was too much friction in the needle bearing, so I released the adjustment screw a little bit-> perfect response of the movement.

[@TeardownOZ2CPU]

good idea, but this is not always easy to perform, you need a steady hand, and know what you are doing, and hold contra on the correct part, else it is very easy to brake it in 1 sec.
maybe i should try to explain this in a future video when i get one more unit in with sticky needle.

[@splitprissm9339]

@@TeardownOZ2CPU EDIT: Oh, you DID already what I was suggesting ... should have watched to the end. -- Original Post was: One tip I read - and tried with some success - to reduce some types of meter stickyness due to dirt is to wire the movement up to a function generator and exercise it... obviously, if it is abrasive dirt, can make it worse...

[@joramkalfa4038]

Fun video. Where can I get a schematic for this unit? Thanks.

[@TeardownOZ2CPU]

just put this into google : Heathkit V-7A schematic

[@twipsy2047]

Nice Meter, have the same one sitting in my pile of shame - waiting for repair.
Luckily the Battery in mine was already removed when I got it but the damage was already done and it looks way worse then yours.
Also someone decided to paint it yellow - wonder how I should clean that up😅

[@TeardownOZ2CPU]

oh no paint !! that is bad, i have no idea how to fix that, is your meter plastic perfect intact ? if that is the case, maybe use the plastic as a donor par to another one, this unit is not that rare, but a perfect intact plastic is !

[@twipsy2047]

@@TeardownOZ2CPU Yes, the plastic is intact apart from some minor scratches. Hope the internals are ok too, otherwise you might have a donor for your beat up plastic cover some day 😛

[@adrielrowley]

@@twipsy2047, depends on the kind of paint. Might be weak enough to remove with real white spirits (mineral spirits), the kind that isn't odorless. Maybe take it to the hardware store and see if the clerk has a product.

[@adrielrowley]

Just bought one off eBay for testing valve equipped HiFi, my Hammond spinet, and Dad's Beetle (my DVM is MIA after a move), hopefully good as the pictures show. Not much to go wrong, though really don't need another project.
What an odd telephone number, with a country code of 35, nothing comes up on the internet.

[@TeardownOZ2CPU]

be sure to double tell the ebay seller to super pack it, the display plastic is brittle and will crack, when ship and not packed for their type of handling

[@adrielrowley]

Wow, that was a quick reply, it is appreciated, thank you.
I didn't think to look and now too late to prevent damage, though if not as described, will get a refund. All I care about is after replacing the capacitor(s) (crucial a filter capacitor is replaced before mowing up a transformer as can cause severe damage) it is fully functional.
By the way, has all the leads, look to be useable (all wrapped up and tucked in the handle), if not, rather have something to rebuild then start from scratch, this will be my first electronics repair. Next up, use this to rebuild a Hammond amplifier, to practice before dive into the complete organ (my great grandmother's she bought new), the separate amplifier then be used for over drive (look it up, sounds amazing). Probably rebuild the console's amplifier first, being just one chassis.