I just watched this video Dec 2021. My dad worked at IBM for 35 years and used one of these meters. He would replace it every few years. The old meter came home , I had several. Wish I would have saved one for sentimental reasons. The replacement was a Simpson 190 and a Fluke 8060A/AA. I still have them. Nice review.
I was going trough some old electronics stuff today and I found my old IBM 200c... I got that in the late 70'... thought I threw it away ages ago... and one of the batteries in there is still good, an old 1.5V Radio Shack Enercell Extra Life battery, must be at least 20 years old.
Nice meter ! I do not have info about the meter but I have a tip for viewers. I collect and restore analog meters and one thing I learned is that often long not used meters can have "problems" with the meter movement that make it seem that they are out of specs and the trimpots are not enough to get it right. Before you start to replace resistors or trimpots, first set it in resistance mode and make the meter swing a while by shorting and opening the testleads. So now and then test it on a voltage source (in V mode) until the readings stop changing. A meter movement is part mechanical and this way you most times get it running smooth again and within specsAnet A6 or within the range of the trimpots. Do not mess with the movement itself (spings, bearings etc).
Good eyes, steady hand and very good stainless tweezers to remove particulates in the movement. Above all, take your time. Any damage to these parts, you will pretty much scrap the movement.
My dad was a service technician with IBM Germany in the late 60's and through the seventies, maintaining the very electro-mechanical computer systems of the time (punch card readers, etc.). He was issued exactly the model you show here (with the fuse on top) with his tool kit. I was a little kid then but I remember playing with the multimeter. He also kept it, after he moved on to do other, non technical things at IBM.
@@joesmith-je3tq It sure did. In fact I ended up just buying one on ebay. It supposedly works (we will see about that). If it is decent, I may end up sending it to my dad, as his birthday is coming up soon.
I really have no need for an analog handheld meter. This thing will be a dust collector. I was going to leave the meter wired as it was originally built but I had it all apart anyway and the mod itself was fairly clean. Not to mention, the meter was certainly not museum grade. In the end, the designer in me won out.
I understand that the house it was in was falling down which is why they were brought in. They normally go through to check for hazards and saw this meter sitting there. The strange bit is a lady owned the home who had never married. She had passed on and the house was left. We may never know how this lady came to own this meter. It does not sound like she had worked for Big Blue or held any sort of technical job. Of course, when I am dead and gone, someone is really going to wonder about those funny looking sleeves. lol. When it comes to new handheld, you are not just kidding there!
If you like to collect old meters like this, I would guess that one I showed on eBay would be a good choice. I highly suspect it predates this one and looks to be in very good condition.
I don't do ebay anymore. When I find meters, I find them. I'm actually trying to cut back some. I seem to have a penchant for really cheap analog meters. They follow me home like puppy dogs. If I saw that IBM branded meter at a flea market for the right price I'd pick it up.
Hi, I have a TMK model 200 without the letter C made by TMK. I bought it 1972, and has been with me since then. It is a good meter and I can see why IBM modified probably for his field engineers. The diferences between the two models are. Where you or IBM put the fuse holder, mine has an input to measure audio power levels with a scale in decibels... ( probably IBM field engineers did not find that useful). It measure DC voltages up to 1200 volts DC. The meter has a scale to measure capacitance using the AC volts range using the 6 volts AC range. (The scale shows values from 0.0 till 0.2 microfarads.) . I remember the original manual that described how to make a setup do measure a capacitor in that range using a AC 6 volt transformer output ,conecting the capacitor as the load and reading that spetial scale you could measure its capacitance . I came across your video because I am trying to get a copy of the original manual. Love your video and I have had many digital testers, but this one has been my only analog meter. I guess someone will bury me with it..
Yes mine is exactly the one showed in the blog. Mine does not have a fuse holder inside 😮. What a I see are wire wound resistors that may get fried if you measure more than 600 ma.
Heres a tip. Get yourself an MF-47 in kit form and learn how all its functions work. For electronics repair and measurment this thing really has most of what you will use. As an additional bonus it measures 2.5KV using a seperate input. It can test for leaky capacitors, transistors and diodes. Its such a big meter that non of the traces come close to each other except at the selector switch. Pretty sure it would pass all of Joes robustness tests, just change the fuse for a ceramic.
Hi Joe, these TMK meters are relatively common over here in the UK. Sold from the 1960s through late 70s. A less expensive meter over the more usual professionally used AVOMeter (our equivalent of your Simpson 2xx meters). The model 700 has a 50k ohm pv movement. Andrew
I enjoyed this very much. I have one of these meters that I got while attending ASU (I graduated in 1970), with a serial # of K48396. The only difference in mine from yours is that instead of a fuse it has what appears to be a little light that would glow during testing. The main reason I watched this video was to confirm to my old memory the types of screws that holds the back in place, since I have long ago lost them. I thought they were nylon, and your video confirms this. I have been looking for replacements so that I can discontinue using black gaffers tape to hold the back to the front. Would you or any of your subscribers know where I might purchase replacement screw of the proper length and thread. I have been to several hardware stores and no metal screw (standard or metric) will work. The only screw that I was able to get to thread and hold was taken from a trashed computer hard drive, but it was not long enough to secure the back at the top-middle position. Any help would be greatly appreciated. Thanks, DH
Test the zero setting on the lowest resistance scale because the selector switch on these meters introduces some unstable series resistance with age. Unless you get some confirmation about the "IBM" branding, I am sceptical about whether that is genuine. While I am being picky, DEMOLITION is a noun; it is the act when you DEMOLISH something.
If you watched the entire video, you would have seen me adjust it in the low range, so not sure why you would ask me to do this. Was there some point during the video where the resistance was unstable? I am not sure what you would be skeptical about the marking. It seems like they may have been made for their service techs. They are fairly common.
@ about 3:00 I wonder if the "50uA VTVM" was a misprint. VTVM's don't draw that much from the unit under test as you know; I'm thinking that was a conventional VOM, much like yours. I've seen many Lafayette branded ones on eBay that resemble these.
I think you missunderstood what you saw and was lead on by me not reading the ad before I spoke. lol. This is what the ad states: "Consider this meter sensitivity on the low current scale, 50 microampreres will fully deflect the needle; just the thing when you want to balance discriminators in FM sets." The ad does not claim this to be a VTVM. To me, the ability for it to measure 5,000Volts DC is not something you see often in a handheld.
My dad worked as a Field Engineer for IBM in the 60s - 80s and I inherited this exact meter. However, the fuse is missing. What is the spec of the original fuse? It looked like there was a sticker on the inside of the meter that said "1A", so is it a 1 amp fuse? Thanks - great video - I know my dad would have really enjoyed it.
There was a lot of epoxy, sanding and polishing going on. That lens was in pretty poor shape and had to be wet sanded. I used that same polishing compound I showed in an earlier video. I also dyed the case black and mink oiled it.
I just found this same meter among my dad's things and was wondering if there was an owner's manual anywhere as a PDF or otherwise. Any help would be appreciated!
Google "tmk 500", third hit: www.vintage-radio.net/forum/showthread.php?t=80468 scroll down a few posts and you will find the manual. The internet is powerful.
People often question the 'usefulness' of an analog meter. Apart from 'nostalgia', they certainly had, and still have their uses. They don't understand about "Ohms/Volt", and loading. Often, in modern electronics, readings are WRONG without loading. With more modern electronic meters, you might need to ADD say a 50k ohm resistor as a load, before trying to measure the voltage etc. from a SWPS etc. It is a broad subject :-) EDITED...... Sometimes, this goes AGAINST you, and the 'Meter' itself is playing too much a part in the circuit being measured. THAT's when you need your 'modern' "Digital" :-) Also, most 'Analog' meters have 2 x 1.5v batteries, and so for 'resistance' measurements, as well as Diode checking, (at least .6v forward bias to test)that is OK. However, modern 'meters' use SUCH a low internal voltage/current for tests, that they NEED a special 'Diode' range, that puts enough voltage through them for the test to be realistic.... It's all 'horses for courses' xox
Many supplies I work with do have minimum load requirements and you are correct in that running outside of the manufactures limits can cause a significant error. That said, most of these that I work with require several amps of loading. And really, if you are running checks and not covering the basics, well dare I say you have bigger problems than your choice of equipment. lol. I can't think of any application I have worked on, professional or hobby, where I felt an analog meter would offer any advantage. If you look at that spreadsheet, you will notice there is more than one page to it. One page is for the continuity function. I started doing this after seeing so many people making reviews where they touch the leads together and call that their test. You would think people playing with meters would be a little more data driven than that. Anyway, that will give you some idea on the open circuit voltage and short circuit currents you can expect to see.
Interesting material, but very distracting that you kept moving the meter about in the field of view. It might have been better to leave it still and point with a thin pointer at things of interest, like the scale being used and what the expected reading would be.
It's always hard for me to know if once the video is in the final form if there will be enough resolution to see anything. With the scale on the analog meter being so fine and such a small area, I did not want to risk it. Other option may be to do a dry run. Or get a better camera.
It wasn't a resolution issue, it is that field of view continually changed. The shot at 13:00 is good. The shot at 15:00 is also good, although it could have been a little tighter. Then you start to constantly move the meter about. IMHO it is very distracting for the shot (and the focus) to swing between the scale and you showing that you've set the switch to the range you say. I'm most of us trust that if you say it's on a particular range then it is so. Watch from 15:25 through to 15:45, 16:25 to 16:50, 19:25 to 19:50. Constant movement and focus shifting.
Again, I had no idea until after I made the shot how readable it was going to be. After making the video, I think I would have left the two side-by-side and called it a day.
