One of my hobbies is restoring old test gear. What I usually do with VTVMs is build a tiny battery eliminator powered by the filament voltage. One side is usually grounded, so use the "hot " side. Any 1N400x diode and 100uF for DC, then an LM317 and a couple more parts for a 1.5 or 3 volt supply.
Another comment, if you don't mind, Did to change the probe switch to AC/Ohms before trying to calibrate for AC voltage? It will read about 9% low if you leave it on DC because the 1 megohm isolation resistor is in series with the meter's 6AL5 rectifier...And yes the resistors do drift in value and even the 1% resistors on the rotary switched do that. I usually have to replace 2 or three on the rotary switches to get the meter to calibrate on all ranges. They are odd values but can be made up out of regular value resistor combinations and checked with the ohms function of a good DMM. Don't forget to check the 1M ohm resistor in the probe handle used for DC volts.
I agree that almost all digitals have 10 megohm input. and a digital with a bar graph is helpful--so although a VTVM is not absolutely necessary on the workbench (especially now that new or used oscilloscopes are more affordable than they used to be in generations past), VTVMs are pretty handy. I have and use VTVMs quite often. They usually have a better AC voltage bandwidth for audio frequency voltages and beyond that digital meters don't have, (unless you have a high frequency rectifying probe for the digital and use DC volts settings).Looks like you have a good one there. Thanks for posting!
What cleaner did,you use to clean that spring ,my spring I had to clean off a leaky battery ,Mine clean now but your looks amazing,did you use vitamin c powered or some other cleaner .
What wire did,you use for your probe ,is it shielded,is there a number on it so,I can order it ,I just my 1 mega ohm resister in yesterday. with me having to different heath kit vtvm one a V7A and a I'M - 11,so.like any other vintage equipment you have to order parts ,and It's always a waiting game .thanks.for your video
WOW. Very impressed with the battery spring. What did you use for cleaning solution for that???? How and what did you use to clean the rotary switch wafers??? I just bought a Heathkit IM-18 VTVM on Ebay and I will be in the same boat you were. Any help or tips would be greatly appreciated. Thanx!!!! I finally broke down and got one because I can see the value in having a high impedance analog meter for specific applications. I almost got a vintage Simpson 260 but I figured I would add to my Heathkit gear collection.
+jp040759 the battery spring was cleaned with Bartenders Friend kitchen cleaner. It is very *slightly* abrasive which makes it excellent for cleaning but it wont actually scratch or eat away at the metal.
What type of resistors are used to replace the bad ones? Film, carbon, metal? Also do you make the values in parallel or in series? Very interesting and informative video Thank you
There are digital meter checks for tubes look it up I forget what two pin you check are for checking for shorts only .me I finally broke down and bought a tube tester on eBay .
Almost all digital multimeters are 10 meg input impedance anymore. I have owned all kinds of Flukes, Beckman, Viz, Micronta Agilent and others. Occasional cheapies are 1 meg. The Agilent U1253B kinda fudges at 5 meg above five volts or so. Kinda turned me off on that one.
+Mark Zacharias Yeah I have a few cheapies which have quite low impedance. I guess I never really looked at my fluke specs to see what it was. I just assumed because it was a digital meter it was lower. Either way I think this meter might be useful for working on some of the audio gear.
I replace ALL Caps. & Resistors on ALL old test equipment except for the precision resistors. And test the tubes. BTW- The Diode is OVERKILL! A 1N4004 would work just fine. At 6:57 that tube is used to balance the DC + & DC - In the early days, Daystrom designed a lot off the Heathkits. -- What a crappy solder job. The person that built this SHOULDN'T have been allowed near a soldering iron !!
It's amazing that a tool over 50 years old works so well. Great vid.
OK when digital meter was not availabled. Was always very unstable but nice look and friendly.
One of my hobbies is restoring old test gear. What I usually do with VTVMs is build a tiny battery eliminator powered by the filament voltage. One side is usually grounded, so use the "hot " side. Any 1N400x diode and 100uF for DC, then an LM317 and a couple more parts for a 1.5 or 3 volt supply.
Another comment, if you don't mind, Did to change the probe switch to AC/Ohms before trying to calibrate for AC voltage? It will read about 9% low if you leave it on DC because the 1 megohm isolation resistor is in series with the meter's 6AL5 rectifier...And yes the resistors do drift in value and even the 1% resistors on the rotary switched do that. I usually have to replace 2 or three on the rotary switches to get the meter to calibrate on all ranges. They are odd values but can be made up out of regular value resistor combinations and checked with the ohms function of a good DMM. Don't forget to check the 1M ohm resistor in the probe handle used for DC volts.
I agree that almost all digitals have 10 megohm input. and a digital with a bar graph is helpful--so although a VTVM is not absolutely necessary on the workbench (especially now that new or used oscilloscopes are more affordable than they used to be in generations past), VTVMs are pretty handy. I have and use VTVMs quite often. They usually have a better AC voltage bandwidth for audio frequency voltages and beyond that digital meters don't have, (unless you have a high frequency rectifying probe for the digital and use DC volts settings).Looks like you have a good one there. Thanks for posting!
What cleaner did,you use to clean that spring ,my spring I had to clean off a leaky battery ,Mine clean now but your looks amazing,did you use vitamin c powered or some other cleaner .
You did a good job on this but a correction to something you said. The more accurate part of the scale is to the left (or full scale).
What wire did,you use for your probe ,is it shielded,is there a number on it so,I can order it ,I just my 1 mega ohm resister in yesterday. with me having to different heath kit vtvm one a V7A and a I'M - 11,so.like any other vintage equipment you have to order parts ,and It's always a waiting game .thanks.for your video
Did you replace any faulty resistors?
WOW. Very impressed with the battery spring. What did you use for cleaning solution for that???? How and what did you use to clean the rotary switch wafers??? I just bought a Heathkit IM-18 VTVM on Ebay and I will be in the same boat you were. Any help or tips would be greatly appreciated. Thanx!!!! I finally broke down and got one because I can see the value in having a high impedance analog meter for specific applications. I almost got a vintage Simpson 260 but I figured I would add to my Heathkit gear collection.
+jp040759 the battery spring was cleaned with Bartenders Friend kitchen cleaner. It is very *slightly* abrasive which makes it excellent for cleaning but it wont actually scratch or eat away at the metal.
+Adam's Workshop Thank you
What type of resistors are used to replace the bad ones? Film, carbon, metal? Also do you make the values in parallel or in series?
Very interesting and informative video
Thank you
There are digital meter checks for tubes look it up I forget what two pin you check are for checking for shorts only .me I finally broke down and bought a tube tester on eBay .
Did my stop running the D.C- and D.C+ scale, would you have a clue what it can be?
Almost all digital multimeters are 10 meg input impedance anymore. I have owned all kinds of Flukes, Beckman, Viz, Micronta Agilent and others. Occasional cheapies are 1 meg. The Agilent U1253B kinda fudges at 5 meg above five volts or so. Kinda turned me off on that one.
+Mark Zacharias Yeah I have a few cheapies which have quite low impedance. I guess I never really looked at my fluke specs to see what it was. I just assumed because it was a digital meter it was lower. Either way I think this meter might be useful for working on some of the audio gear.
I have the Heathkit V7 vtvm.
@@adamsworkshop7182Good idea on using that electrical insulation much better than using shrink tubing.👍
Looks like age made that wire brittle
Which is the reference of the large valve. I need to buy one for mine, but the numbering is off.
Its a 12AU7.
Adam's Workshop obrigado
I replace ALL Caps. & Resistors on ALL old test equipment except for the precision resistors. And test the tubes. BTW- The Diode is OVERKILL! A 1N4004 would work just fine. At 6:57 that tube is used to balance the DC + & DC - In the early days, Daystrom designed a lot off the Heathkits.
--
What a crappy solder job. The person that built this SHOULDN'T have been allowed near a soldering iron !!