Test Equipment Anonymous (TEA) : Discussion and Group Therapy Thread

[Cubdriver]

Very sorry to hear about Bindi - they always leave us too soon. My condolences.

-Pat

[mnementh]

Oh, Harley... come to the PC and have a little lesson...

mnem
balls.

He already knows all 3 moves. No additional lessons needed.

The spazz-attack in the middle still makes me LOL IRL...

mnem
*cat stalks off, tail all exclamation points* "you did not see that."

[mnementh]

Very sorry to hear about Bindi - they always leave us too soon. My condolences.

-Pat

@vk6zgo -

Same here. The holidays are a time to remember all family, furry or otherwise.

mnem
yes, even uncle Al, who looked like someone shaved a grizzly bear.

[25 CPS]

Sadly, my elderly cat, Bindi has done the "wandering off to find somewhere to die" thing that old cats are wont to do.
Millie, the girl dog, was looking everywhere for her the other day, with a puzzled look on her little furry face!

We are now left with a bundle of cat treats & food, but no cat, & as I am too old for another cat, we found a home for the goodies with an acquaintance who, at time of writing has no less than five cats (two are supposedly temporary, but I know how such things work).

I'm so sorry to hear your cat passed on. I wish there's something I could say that could make it hurt less but I'm glad your dog is keeping you company and the leftover cat supplies are going to good use with the person who has five cats though.

[vk6zgo]

Sadly, my elderly cat, Bindi has done the "wandering off to find somewhere to die" thing that old cats are wont to do.
Millie, the girl dog, was looking everywhere for her the other day, with a puzzled look on her little furry face!

We are now left with a bundle of cat treats & food, but no cat, & as I am too old for another cat, we found a home for the goodies with an acquaintance who, at time of writing has no less than five cats (two are supposedly temporary, but I know how such things work).

I'm so sorry to hear your cat passed on. I wish there's something I could say that could make it hurt less but I'm glad your dog is keeping you company and the leftover cat supplies are going to good use with the person who has five cats though.

She was a sweet old girl, but she was already an adult cat of indeterminate vintage when we got her, so we were expecting something like this to happen.
We were told "she doesn't take to people", but the first day, I was lying down reading & in came Bindi, jumped on my tummy, moved herself round to get comfortable, then started purring.
Whether she was my cat or not, I was her human!

We have both Millie & George, her brother, here with the latter "temporarily" with us, rather like the lady with the five cats, but in the "dog domain".
Bindi was around for the birth of the pups, so had a relationship with them since they were just "dog kittens".
I always thought she should have given them a swat across the ears when they were little, just to show who was boss, but she was always a bit maternal with them.

[nixiefreqq]

hey mnem

the other day swmbo asked about sizes of some rings sitting on my dresser. had to tell her that some are 10-1/2, and some are 11, and some are 11-1/2. but no idea which are which because we don't own any digital calipers.

so now i might be getting a set for xmas. do i direct her to harbor freight or the starrett catalog?

ps my only other use case would be a couple of drill bit index boxes with lots of loose bits stuffed in the bottom after spills. (too lazy to dig out a micrometer and figure out which go in which hole......those little ones can be tricky).

[Zenith]

The traditional way of measuring ring sizes is with a jeweller's mandrel or a trevel, I believe it's called.

I bought a digital calliper in Lidl, a discount supermarket noted for its special offers, for £8. It must be about 12 years back. Its metric or imperial and reads to 1/1000th of an inch. It agrees with feeler gauges. It looks like the Horror Fright $20 number. I think it's a generic Chinese design.

It was something of an impulse purchase, but I've been amazed how much I've used it. Some of them have a reputation for getting through Lithium batteries quickly but this one's been OK.

[Specmaster]

The traditional way of measuring ring sizes is with a jeweller's mandrel or a trevel, I believe it's called.

I bought a digital calliper in Lidl, a discount supermarket noted for its special offers, for £8. It must be about 12 years back. Its metric or imperial and reads to 1/1000th of an inch. It agrees with feeler gauges. It looks like the Horror Fright $20 number. I think it's a generic Chinese design.

It was something of an impulse purchase, but I've been amazed how much I've used it. Some of them have a reputation for getting through Lithium batteries quickly but this one's been OK.

I can also recommend the ones from either Lidl or Aldi, for the occasional user they are excellent value.

[tggzzz]

The traditional way of measuring ring sizes is with a jeweller's mandrel or a trevel, I believe it's called.

I bought a digital calliper in Lidl, a discount supermarket noted for its special offers, for £8. It must be about 12 years back. Its metric or imperial and reads to 1/1000th of an inch. It agrees with feeler gauges. It looks like the Horror Fright $20 number. I think it's a generic Chinese design.

It was something of an impulse purchase, but I've been amazed how much I've used it. Some of them have a reputation for getting through Lithium batteries quickly but this one's been OK.

I can also recommend the ones from either Lidl or Aldi, for the occasional user they are excellent value.

I have some of those, but I tend to end up using the conventional mechanical calipers I bought in India. Faster and more reliable: no battery failures and no need to open the box and casing to replace the battery.

[mnementh]

hey mnem

the other day swmbo asked about sizes of some rings sitting on my dresser. had to tell her that some are 10-1/2, and some are 11, and some are 11-1/2. but no idea which are which because we don't own any digital calipers.

so now i might be getting a set for xmas. do i direct her to harbor freight or the starrett catalog?

ps my only other use case would be a couple of drill bit index boxes with lots of loose bits stuffed in the bottom after spills. (too lazy to dig out a micrometer and figure out which go in which hole......those little ones can be tricky).

Assuming you don't want to spend the dosh on Seiko/NSK or Mitutoyo, hands down the Titan/Star Asia 23175 (Not the 23173; it is decimal and fractions). Unlike most of the cheapies, it has "absolute measurement", meaning it "knows where zero is"; you don't have to re-zero it every time you turn it on, just like the "good name-brand ones".

It also "wakes up" and "sleeps" very well; you just grab it, move it a little and it wakes up... and battery life is years. Maybe once every 50 uses it'll have drifted a LSD and needs to be re-zero'd. I've had one of my Harbor Freight cheapies for close to 3 decades; this one is about $15 more than the current iteration of that, and definitely worth every penny.

https://www.amazon.com/Titan-23175-Elec ... 000B8XYV8/

Amazon is not the only place to find this tool; I got mine at Princess Auto in the GWN, but Summit Racing & Advance Auto Parts also carry it, and they do have their own tool website as well:

https://www.titan-us.com/default.aspx?p ... code=23175

Cheers,

mnem

[AVGresponding]

@BU508A in case you don't visit Discord and missed it on the EEVblog forum: https://www.eevblog.com/forum/buysellwa ... -with-qty/

[25 CPS]

I've had a bit of on again, off again test equipment activity over the last couple of months. My work schedule has been heavy as usual which gets in the way of everything, also as usual. Work started crying poor back in the fall and then started crying even more poor a few weeks ago and started laying people off. Hundreds and hundreds of people. So far I've been ok, but they always work people to death right up to the moment they hand you a redundancy notice and tell you that you're surplus to their requirements so being busy is no guarantee that you're safe. Anyways, here are the highlights of the test equipment:



After the success a few weeks ago getting the rolling cabinet swung into place where the oil tank used to be, I was able to get a set of shelves that I've had on hand waiting for the spot the cabinet used to be in to be freed up so I put those together. That finally allowed me to bring most of the equipment downstairs that on the main floor waiting for this shelf to be put together. This is great because once some more stuff gets moved downstairs, it'll represent a huge decluttering on the main floor of the house.



I also had a couple more small test equipment pickups. This is actually a Simpson 635. The reason why it's disassembled is because the lady selling it had been asked if there was battery corrosion inside so she took it apart and checked. It must've put off whoever asked because they didn't buy it and it was relisted for $20. I offered to buy it while I was having dinner with a friend and everything clicked into place so the two of us drove out to her place to pick it up. She mentioned that her ex used to be an electrician and this was his. When we got to her house to pick it up, it was waiting on the porch in the box just as you see in the picture. I hadn't realized that she didn't put it back together after checking so I have a reassembly job ahead of me. Even if the meter itself is a dud, the manual and case are still of value to me. The house had a "Sold" sign in front of it and between that and the mention of selling the ex's meter, I guess we can conclude that 2023 ended badly for that family too. A lot of people have been having horrible ends to 2023. I really hope 2024 is better for everyone across the board.



This is another Simpson wattmeter/appliance tester that's branded for Frigidaire. This one has a knob on the side to set the range instead of different terminals for the breakout cord's jumper connections. That spot at the top of the voltmeter's dial concerns me so I'm going to try to take this apart for some careful cleaning there and then spend some quality time documenting the 390, 390-2 and this one soon and then return to that small frequency counter that's miscounting.



One of these is not like the other. At Princess Auto, the tachometer that has the contact measurement function was on sale for $9 less than the one that's optical only which was at regular price. The website claimed they had three left at the store close to home but I only found two after digging through the shelves. The staff were convinced that both models were the same which is why I took a picture of the different versions side by side there and then sent it to a friend and called him to ask if he wanted one. I figure if I didn't call and ask right then, the second one would be gone by the time he or I would be able to get back there, and he did want it so I ended up buying both of them. We had a belated Christmas on Boxing Day at a local restaurant having breakfast and looking at tools both of us have recently acquired. Different, fun.

[systemCorruPti0n]

So imma try to get around and finally show the stuff I've been finding this last few months.

One of my favourites is this old fluke decade "tube":

d.jpg

e.jpg

Of course, while looking for issues, curiosity got the better of me and I had to open it up.

a.jpg

It was sealed tight and even had an oil? It was pretty hard to open to the point I broke a plastic pick/spudger and made a couple of small scratches T.T

b.jpg

Inside I think it only had 200 and 20k resistors (at least those were the ones that had the ref in the outer side) plus the 100R potentiometer

c.jpg

And the insides beautifuly covered in gold

It was announced as non working, but luckily the only problem it had was that the 100R potentiometer wheel had come a bit loose from the axis and it wasn't turning well. Apparently it was found by the seller next to some pots when they bought the house!

For now I have it as my reference resistors to check the meters, from all I've been learning it seems unlikely values will have drifted too much.

[Zenith]

So imma try to get around and finally show the stuff I've been finding this last few months.

One of my favourites is this old fluke decade "tube":

Welcome to the forum.

That's interesting. I see few decade boxes, but I can't recall seeing a cylindrical one like that. It's a neat design.

[tggzzz]

So imma try to get around and finally show the stuff I've been finding this last few months.

One of my favourites is this old fluke decade "tube":

Welcome to the forum.

That's interesting. I see few decade boxes, but I can't recall seeing a cylindrical one like that. It's a neat design.

Welcome indeed.

I have a similar ESI Dekapot, which also goes all the way up to 11 (actually 121.1ohms).

I also have an ESI DekaStat in the same form factor, a 1kohm Kelvin Varley Divider. And a JRL 7-decade KVD which is so heavy it will be difficult to ship.

[Robert]

TGGZZZ beat me to it. Looks like a licence copy of the ESI / Tegam Dekapot. As that one has a variable resistor for the lowest deacade it was probably robbed from a bridge. Unusually thes use a R/2R network and double pole switches rather than 10 identical resistors. This give the 12 step "decade".
I have two of ESI high precision decade boxes that use these. One is a DB877with two 4 decade units and one is a DB855with two 3 deades. These are the originals with 0.01% accuracy. The current Tegam models are 0.03%.
I also have one one of the KVD in this pattern (and a JRL VDR106-7 in an oak box)

DB877 Sch.jpg

[nixiefreqq]

was bored just before christmas.

so i threw out a low ball bid on a tek 1502 tdr. figured they would ignore me since it was listed with free shipping and my pittance was not worth their trouble. it arrived the day after xmas.

front panel looked pretty good. no missing or broken knobs. no battery....but that's ok. was gonna power it with a current limited 12V ps while checking it out anyhow.

opened it up and checked voltages on the main ps board. totally dorked. determined that the big switch transistor was borked. following the advice of a guy on eevblog.....you can replace parts on this thing from the top of the board with no need to pull it out. replaced the transistor with one from the junk box. but that didn't fix it.

checked some more and determined that the darlington driver was also borked. naturally did not have one of those. threw together two npn's that should make a darlington pair and bodged it onto the board. SUCCESS! its putting out all the right voltages.

but still no trace on the crt. that's strange. it almost acts like there is no HV. peeked under the main ps board to check out the HV board. son of a bitch, there is no HV board.....just some dangling connectors where it used to be.

guess i could just part out the tunnel diodes? maybe i should test them? oh shit! what are the chances they are still inside this poor raped instrument?

[Zenith]

You have several choices including:

Wait a month or two and re-list it on ebay as parts only.

Rescue, test and sell individually the hard to find parts.

Wait until you see another for a similarly low price, and buy it in the hope it can supply an HV board.

Make up an HV board.

Set it aside as a spares mine and really get into the 1502 TDR scene.

I have an idea that tggzzz will be along soon, to advise on the finer points of owning and restoring 1502 TDRs.

[tggzzz]

front panel looked pretty good. no missing or broken knobs. no battery....but that's ok. was gonna power it with a current limited 12V ps while checking it out anyhow.
...
checked some more and determined that the darlington driver was also borked. naturally did not have one of those. threw together two npn's that should make a darlington pair and bodged it onto the board. SUCCESS! its putting out all the right voltages.

but still no trace on the crt. that's strange. it almost acts like there is no HV. peeked under the main ps board to check out the HV board. son of a bitch, there is no HV board.....just some dangling connectors where it used to be.

guess i could just part out the tunnel diodes? maybe i should test them? oh shit! what are the chances they are still inside this poor raped instrument?

Persevere; they are nice instruments to the extent I have a fetish for them. I've sold several, still have one in excellent condition (with metric distance so there's no need to think in terms of decifeet), one mule, and one waiting to be resurrected.

Firstly, powering from a 12V supply is a good idea, since they require a functional battery. NiMH replacements aren't likely to survive given the crest factor of the charging waveform. Even pukka NiCds can be overcooked! Do realise that even when switched off, the current drain is ~1mA, so in a month or so one cell will start to be reverse charged.

Removing the unobtanium main TD isn't a quick process; it is seriously buried next to several air-mounted passive components. If the tunnel diode is present and the driver setup, connecting the output to a scope should show something like the attached image (horizontal scale probably 5µs/div). Two major features:

• "invisible" risetimes
• two different waveforms; one is used to determine/set the TD's threshold, the other is used for the measurement

You don't actually need the CRT to have a functional instrument: you can use the XY output driving a storage scope. (A YT plotter is almost useless, since it requires unobtanium perforated thermal paper) The major issue will be the slowness of the XY plot coupled with the difficulty of finding the distance 0 position (a function of the Zero and distance controls). Tip: put a 50ohm load on the cable connector, so you aren't searching for a very narrow 72mm pulse.

If you PM me with your email address, I'll send you ~12 documents I've scavenged, including two service manuals.

[Zenith]

I told you he was the main man for Tek 1502 TDRs and he hasn't disappointed.

[nixiefreqq]

hey tggzzz

thanks for the advice.

hooked the xy output to a scope and after lots of doodling got traces.

the first pic is around 7 ft of RG-58 solid with an open end.

the second pic is with an additional 3 ft piece of really crappy foam rg58 stuck on. (horiz setting was 2ft/div)

could have tweaked the horizontal sweep a little to exactly 10 divisions, but as is, it does seem to indicate the damn thing is working.

the third pic shows a bodged heat sink with fan on my junkbox switching transistor. it gets hot hot hot and without the fan the +25V being monitored starts to sag. maybe my transistor is too wimpy? or maybe something is sucking too much current? will investigate further when time permits.

do i really want to buy a junker hoping to snag a hv board? or should i consider that the fun of working on this thing has more than compensated me for a minor investment.......close the book on this experiment.......... and avoid the tdr rabbit hole?

everyone knows i do not have a compulsive or obsessive personality. (except for nixie devices)

thanks for the offer of documentation. will send a pm with my contact info.

[tggzzz]

Looks promising

Your next task is to have nothing connected to the BNC, so that its internal shorting bar is making contact. Then have 1ft/div and *0.1, and you should be able to see a 50ohm pulse corresponding to the 72mm internal distance between the sampling diode and the BNC connector. The trailing edge will be slightly slower than the rising edge, and marks the position of the BNC connector.

I like to have the 50ohms to 0ohms transition (i.e. the BNC connector location) visible on the first scope division, the one with the discreet arrow. (The picture below is not like that, since I wanted to show the pulse)

The flatter the top of that pulse, the better. The picture shows the best one I've seen (and sold). There is some serious black magic about making that as good as can be.

Then you can have fun looking at the insides of inline terminations, or watching fingers move along coplanar waveguide. In the picture below the inductive peak at division 1 is the BNC/SMA connector, the fingers are the two capacitive dips at 3.5 and 4.5, and the open circuit end of the PCB is at 9.

Moving fingers and seeing the dips move is a great way to demonstrate its operation

[tggzzz]

Other points about the 1502's case: beware of the screws on the feet...

With most scopes, resting the scope vertically on its front panel will damage the front panel controls, whereas resting it on its rear panel is safe. The opposite is true with a 1502:

• when removing or replacing the case, rest the front panel on a flat surface. Unlike an ordinary scope, the “ears” (or case lid) will protect the controls
• when replacing the case, screw the rear bolts into the case thereby pulling the front panel onto the case. Do not push the bolts in, do not rest on the bolts, since internal captive nuts are peened onto the chassis, and can be dislodged.

To start the case moving, you will probably have to insert a screwdriver into the slot between the front panel and the case, and twist.

[nixiefreqq]

hey tggzzz

thanks for the documents. will read them tomorrow.

my shorting bar is not as pretty as yours. but it is still not bad considering the state of my unit.

am now going to ebay to look for a parts mule.

please take notice that you are now on my enemies list.


freqq


ps FYI.....what blows up on the low voltage board if you are tired, stupid, and you accidentally hook up 12v to a 1502 with the polarity backwards?

and the answer is......Q6557 & Q6547. fortunately my old man left me a boatload of real metal mil std 2n2222's. and to think i almost did not take them because "who needs a box of that old crap?"

[tggzzz]

thanks for the documents. will read them tomorrow.

You're welcome.

As you will see, there are multiple versions of the service manual. The content is pretty much the same but the Patriot Missile version has a different style and the schematics aren't very readable.

my shorting bar is not as pretty as yours. but it is still not bad considering the state of my unit.

That leading edge is tweakable. Theoretically it is 50ps risetime, so you need a fast scope, e.g. the built in CRT

The top looks pretty flat, and that's the bit that is difficult to tweak. It looks like there is a "new" document about that on the TekWiki, which describes how you "dress the components". Yes, that means tweaking their physical position until it looks right!

The other entertaining document describes how you waterproof it so it can be stored under 3ft of water.

am now going to ebay to look for a parts mule.

As I expect you are aware the 1502B/C/1503 are different beasts. Nonetheless, you might be able to take an HV board from a 1502.

An evil technique would be to spot a fleabay advert for a "used" item. If it doesn't show a trace then it is unlikely to work. And guaranteed if you can't see a battery box. Then claim, correctly, "not as described".

You could seriously lowball Solano Traders for item 402724794317. The 166peso shipping outside the US is a little bit high for me! Such traders sometimes want to move their stuff, hence I got my delightful Power Designs 2020 LM399-based PSU for $10+$50P&P.

The shock-mounted CRT is pleasingly robust, presumably because squaddies are nearby. My first 1502 had a long crack in the case and a bit was flapping, but it worked fine. Methylene chloride on a tiny paintbrush worked wonders; excellent creep.

please take notice that you are now on my enemies list.

Damn. I seem to have created competition.

Your next task will be to find a Tek 012-0482-00 precision cable to calibrate it, "The 012-0482-00 is a 50 Ω 1% BNC to BNC cable and is made from RG-223 50 Ω double-braid shielded coaxial cable (or equivalent) with special true 50 Ω BNC connectors made specifically for Tektronix, and is exactly 36" from end-to-end."

Or perhaps the cardboard nomogram

That should keep you out of my hair

ps FYI.....what blows up on the low voltage board if you are tired, stupid, and you accidentally hook up 12v to a 1502 with the polarity backwards?

and the answer is......Q6557 & Q6547. fortunately my old man left me a boatload of real metal mil std 2n2222's. and to think i almost did not take them because "who needs a box of that old crap?"

So far I've avoided that. I attach PSU via a flying lead and 4mm banana sockets to the connector buried in the battery compartment - with each terminal carefully marked with a + and -

My variant was to forget to check the transformer voltage wiring. Oops. I removed the ex-transformer and substituted a modern AC->12V brick. Job done.

P.S. I presume you do have an old school geiger counter based on dekatrons. Fun to get visitors to touch the exposed 500V and watch the neon glow whiz round.