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 Post subject: Triplett 60 type 2 questions
PostPosted: Feb Wed 12, 2014 2:50 pm 
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I inherited two Triplett 60 type 2 VOM's in very nice shape, show no signs of abuse, and are fully functional so to say.... amazingly to this point in my life, I have not owned a Triplett analog multimeter just bunches of Simpson 260's and 270's. These are the "ruggedized" Tripletts with the orange case.

First question- Why do these meters only read right when lying flat? If you try to use them with the handle tilted on the bench after re-zeroing, readings on the upper end of the scale are quite a ways off. For instance in the 10 VDC range 8 volts will read 8.4 V with it tilted, but they read perfect when lying flat. It almost seems like the pointer is so long and heavy that its own weight is pulling it down when tilted. This isn't an issue with the Simpsons, the 260's I have read right after re-zeroing if flat, at a tilted angle, or fully vertical. I guess one answer is to only use them lying flat, but this seems like a silly solution for what were expensive VOM's.

Second- Is there some way around the plastic meter face being so dang static sensitive? If I move my hand anywhere in front of the meter face, the pointer goes berzerk and the only way I can seem to remove the static is to dab the face with a moist cloth. What a PITA. Again, the glass faced Simpsons don't have this issue.

Thanks in advance for any comments or suggestions :)

-Mark-


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 Post subject: Re: Triplett 60 type 2 questions
PostPosted: Feb Thu 13, 2014 3:53 am 
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I don't have any advice for the first problem, but for the second you might try a Zerostat anti-static gun. They're expensive, though, but someone you know with a record collection might have one you could try.


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 Post subject: Re: Triplett 60 type 2 questions
PostPosted: Feb Thu 13, 2014 5:01 am 
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I've never tried it, but the advice I've read for static problems with plastic faced meters is to rub a drop or two of mild dishwashing liquid onto the meter face.

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 Post subject: Re: Triplett 60 type 2 questions
PostPosted: Feb Thu 13, 2014 6:25 am 
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Better yet is to remove the plastic face and dab the inner surface with a cotton ball wet with water and a drop of dish washing soap.
Let it dry, but do not polish or rub it, and re-install. Then do the same on the outside surface. Some sources say to use a drop or two of the soap straight, no water.

The purpose being to have a thin film that will dissipate static.

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 Post subject: Re: Triplett 60 type 2 questions
PostPosted: Feb Thu 13, 2014 4:17 pm 
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Thanks for the tips with the static, I'll give them a try. I'm not sure if the inside of the meter face will be accessible or not, but I'll check. I suppose everything has its quirks, these are otherwise very good VOM's.

-Mark-


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 Post subject: Re: Triplett 60 type 2 questions
PostPosted: Feb Thu 13, 2014 4:59 pm 
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MarkPalmer wrote:
Why do these meters only read right when lying flat? If you try to use them with the handle tilted on the bench after re-zeroing, readings on the upper end of the scale are quite a ways off. -Mark-

I had one on my service bench at the tv shop and I too noticed the same issue with the meter. Annoying as hell since I liked to move it around as needed for easy access but gave up on that... leaving it on the bench standing vertically. Was a pain since I had to squat at times to clearly view the meter's face. I remember disassembling the meter panel to check if the movement was loose- nope it seemed good. The digital Simpsons became available and I switched to that, with the Triplett now a standby analog meter. I also noticed the needle swing was slower... took a bit longer to settle on a reading when compared to a Simpson 260. Unfortunate, cause I always preferred Triplett over Simpson.

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 Post subject: Re: Triplett 60 type 2 questions
PostPosted: Feb Thu 13, 2014 5:23 pm 
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Since both of the 60-2's measure off by the same amount when standing up but are spot on when horizontal, I think that it's just the nature of the beast as the basic 60 VOM was designed as a down-and-dirty industrial field meter. I'm sure Triplett wanted customers to spend more for the 60-NA that included taut band suspension and temperature compensation if more sensitive and precise measurements were required. I'll just keep it in mind to use these meters in their cases lying down, I got them mainly for garage and outdoor tasks.

-Mark-


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 Post subject: Re: Triplett 60 type 2 questions
PostPosted: Feb Fri 14, 2014 5:13 pm 
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The Model 60 was designed and tested at the factory to read correctly in any position, flat on its back, using the tilt handle, or standing vertically. If this in not the case, then the meter balance is off. Balancing is done by moving some small spring weights on the "quad", the cross shaped piece which is connected to the torsion spring (taut band) and carries the pointer. The weights look like a coils spring (wire wrap?) on the quad. It is bent into three sections so that its position is held maintaining balance. There are three such weights requiring an iterative adjustment...time consuming but well worth it. At the factory, this was typically done under magnification by using a pair of tweezers and pinching the weight so that it is straight and can be moved on the arm of the quad. If you do a hundred of these a day it's quick. You do need a steady hand, though.

Zero the meter flat (Always be sure to back the zero adjust screw a tad so that it does not contact the fork.) then hold it vertically with the pointer placed horizontally to the left. Adjust the tail weight opposite the pointer until the pointer rests on zero. Repeat this until both positions are zeroed. Then hold the meter so the pointer is vertical and adjust either the left or right weight to bring it to zero. Iterate as necessary. When done, the pointer should rest on zero regarless of its position.

We would drop every one hundredth meter from a height of of six feet onto a concrete floor in seven positions (twice one the top, handle up and handle folded) I never saw a meter go out of balance or out of factory spec for accuracy. I did have one which broke the torsion spring (taut band) and this was traced to a burr on the C spring. We reworked all the meters and had no more problems.

One thing that may be a stickler since I'm going from memory, the weights may have some varnish on them. It can be burnt off with a solding iron, but be sure to place a small copper sheet between the weight and the soldering iron to keep solder from getting in them. You should be OK because the varnish may have been done only on later models. Fred Scoles would probably have the docs on that.

While the meter is apart, make a mild soap solution with distilled (good city) water and gentle coat the inside of the window (outside too) including the black plastic frame. Let it dry naturally and make sure it is not blurry. Some meters (again, Fred Scoles would have the docs) used a small spring to contact the front and electrically discharge it to the dial. Again, going from memory on that one.

A good meter house should be able to do the balancing but I haven't had any experience with that in almost 20 years.


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 Post subject: Re: Triplett 60 type 2 questions
PostPosted: Feb Fri 14, 2014 7:08 pm 
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Jim- Thank you very much for the informative post! It's great to get this sort of information from someone who was there at the factory. I'll mess around with one of them over the weekend, I've worked on HP attenuators and other such very small stuff and have steady hands. The situation didn't seem normal for a Triplett to me, but I'm not familiar with them. I've read about meter balancing on some other topics, now I get to actually try it. Thanks again :D

-Mark-


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 Post subject: Re: Triplett 60 type 2 questions
PostPosted: Feb Fri 14, 2014 7:15 pm 
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Glad I could help.

Don't pull on the weights too much, you might over stretch the torsion spring (taut band) and break it. I did try balancing some of these when I was with Triplett and could not do it. The ladies on the production line would do it quickly, while talking to you and I don't recall too many be rejected at final inspection. Yes, this was specifically tested on each and every finished unit. You operate differently when you name is on the meter.


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 Post subject: Re: Triplett 60 type 2 questions
PostPosted: Feb Fri 14, 2014 8:27 pm 
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Off the direct subject but I just read that the old Triplett factory in Bluffton has finally been sold and will be occupied by a coatings company. They are going to demolish a few of the existing buildings but quite a bit of the factory will remain. The big Simpson plant in Elgin, IL was demolished a couple of years ago. They can't put anything on its ground due to a large amount of soil contamination, probably chemicals from all the bakelite :P

-Mark-


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 Post subject: Re: Triplett 60 type 2 questions
PostPosted: Feb Fri 14, 2014 9:09 pm 
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I have only adjusted a couple of meter movements, so I'm no expert, but I would suggest that before you touch the three tiny counter weights make sure that the needle is still straight with them.
I think that you can eyeball the needle to make sure it is still straight, and still in-line with the middle of the three 'arms' that have the weights.

I would love to hear from the experts on this; maybe I'm full of it?

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 Post subject: Re: Triplett 60 type 2 questions
PostPosted: Feb Fri 14, 2014 9:58 pm 
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Good point. The "needles" are essentially small tubes that friction fit (or sometimes use varnish) to hold them to the quad. If this adhesion is not sufficient, the needle can move. The knife edge is just a flattening of the tubing but it should still be a nice straight line. All these things can affect the balance.


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 Post subject: Re: Triplett 60 type 2 questions
PostPosted: Feb Mon 17, 2014 3:18 am 
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If an aluminum-tubed meter needle gets the least bit corroded, it can become significantly heavier and go out of balance to the point where even moving the bottom post counter weight to the bottom of the post may not balance out the heavier weight of the needle. In my experience, it usually was the larger meters with longer needles used in corrosive/chemical/lab areas that develop this problem. At work, we had ten Beckman 1966 "ZeroMatic" pH lab meters that had the Triplett 626 lance needles; all of them became too "heavy" to balance after about eight years. It drove our college students and instructors nuts, because they couldn't calibrate them when they were placed vertical, but were fine when horizontal. If a VOM was used or stored in a slightly corrosive drawer or room or had battery leakage, its needle can corrode. This may not be your problem with your TTT60T2, but slight needle corrosion can make it go way out of balance. One could calculate the change in weight/mass in their school chemistry course.

I never worked at the meter works, but I remember seeing the ladies balance and test the movements back in the '60s...more a learned skill&patience than science. One problem with the remaining eng files (some were lost due to the Bluffton flood & roof damages) I have is that they don't necessarily list the reasons (for the varnish on the weights) for something; but sometimes that was listed on a REA paper (request for engineering action form); the problem is finding it in the REA stacks. I suspect the varnish helped prevent the weights from moving on the posts during hi-g stop after a fall, but I'm only guessing.


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 Post subject: Re: Triplett 60 type 2 questions
PostPosted: Feb Mon 17, 2014 7:01 am 
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Regarding the static charge on the meter face, I seem to recall resolving it by using an anti-static sheet one would throw into a household clothes dryer to avoid "static cling".


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 Post subject: Re: Triplett 60 type 2 questions
PostPosted: Feb Mon 17, 2014 2:29 pm 
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Thanks for the tips- I discovered most of the static problem is coming from the leather cases the meters are stored in. I'm thinking maybe one of those Bounce sheets in the case will help. It's not so bad when the meter is removed from the case.

I balanced the one meter over the weekend. How did it go? Pretty good, I managed to correct the issue to get the meter to read within tolerance when at any angle. Not perfect mind you, but I got it as good as I could within reason in the hour or so I spent messing around with it. At that point I didn't want to risk damaging a perfectly good meter by being too anal about perfection. There was no corrosion or any problems to be seen on the meter movement. The weights are small springs, and they weren't varnished in place. Moving them and testing takes a LOT of patience, as Fred pointed out. One milli-micron of a movement of these springs makes a world of difference in the balance. I used jeweler's tools to hold the pointer in place and move the springs so I wouldn't ruin the band.

At least Triplett made getting at things very easy. I could do the balancing, while still being able to check the meter readings with a calibrator for accuracy. Thanks everyone for the help!

Image

-Mark-


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 Post subject: Re: Triplett 60 type 2 questions
PostPosted: Feb Tue 18, 2014 6:36 pm 
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My Triplett 60-2 (circa 1999 manufacture) needs to be mechanically zeroed for the position you will use. A weakness of an otherwise great instrument.
stevebyan wrote:
I've never tried it, but the advice I've read for static problems with plastic faced meters is to rub a drop or two of mild dishwashing liquid onto the meter face.

That works every time for me.


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 Post subject: Re: Triplett 60 type 2 questions
PostPosted: Feb Tue 18, 2014 10:05 pm 
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That would be indicative a a balance problem. The only technical reason for adjusting the mechincal zero provided the user is for accounting for small mechanical shifts due to temperature or mechincal shock. A manual excerpt (Model 60-M):

Quote:
METER MECHANICAL ZERO: Place the Model 60-M on its back on a flat horizontal surface. Set the Range Switch to the OFF position. (Refer to Figure 1 on page 11 for the location of operator Controls.) Examine the position of the Pointer on the Dial. If it is exactly on the "0" mark, then the Meter is mechanically zeroed, and no adjustment is necessary.
If the Pointer is not exactly aligned with the "0" mark, then the mechanical zero of the Meter needs adjustment. This is done by using a small, flat blade screwdriver to adjust the Zero Adjust Screw. Slowly turn the Zero Adjust Screw clockwise or counter-clockwise until the Pointer exactly aligns with the "0" mark on the Dial. Reverse the direction of rotation, turning the Zero Adjust Screw just enough to disengage it. This will reduce the affect that mechanical shock and vibration, and temperature changes, will have on the mechanical zero of the Instrument.


What you are doing will introduce an error, mostly at half scale. Full scale may not be affected as much.

Of course, it is possible that if balancing doesn't work, you may have a loose C spring which will slacken the taut band. Nothing you can do about that.

Also, if your meter was made in 1999, it is not a Type 2. When I started at Triplett in 1979, they were already on Type 3. The current Model 60 is Type 5. This will be important should you need to replace the meter movement. I do not know if the movements or meter modules are interchangeable between Types.


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 Post subject: Re: Triplett 60 type 2 questions
PostPosted: Feb Tue 18, 2014 10:36 pm 
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Balancing my 60 I know one thing for sure. They don't go out of balance due to movement of the spring weights, because they aren't real easy to move. Just taking a guess at the cause, the suspension band stretches a tiny bit over time and use.

-Mark-


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 Post subject: Re: Triplett 60 type 2 questions
PostPosted: Feb Wed 19, 2014 7:00 am 
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My guess: Each time the needle whacks into the stop, high end or low end, it may get a slight bend and not align with the balance weights.

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