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

[Cerebus]

Interestingly they've used the Linear Technology logo on the plastic caps.

The life cycle of a product like this is so long that it had to be in progress before the merger. Perhaps even to the point that they even had the tooling ordered for the printing fixture ordered before the merger.

[Specmaster]

Today arrival: 18 ADR1399KHZ
I've ordered them in Feb. 2022.
<snip>


Interestingly they've used the Linear Technology logo on the plastic caps.

What, they took 17 months to arrive

[Zenith]

There was a lot of supply chain disruption caused by Covid. Things you'd think were bread and butter parts, surface mount electrolytics, took 8 months to arrive from CPC. Through hole 1000µF 25v electrolytics took about 4 months, then they sent 4 470µF 50V caps by mistake, then they claimed they'd sent the four 1000µF caps but they had failed to be delivered - funny, the three orders had been broken into around 20 deliveries, all of which arrived with no problems, so I asked them to send them again, and they arrived. .

[25 CPS]

I made a promise to myself last night that I'd do something fun before going to work today. Afternoon shifts have the implied stopwatch ticking on the time earlier in the day before having to start the trip in that is really unpleasant.

Anyways, the initial power up and testing of a an HP 5261A counter:





I'm beginning to suspect a problem downstream of the internal timebase. This counter takes a 1 MHz reference input so I couldn't directly connect it to my 10 MHz reference distribution but I used a signal generator that is locked to it to generate 1 MHz out and it was still off. I got into the manual as far as the reference input was concerned but need to dig further into how the timebase is dealt with internally as well as the calibration of it. One thing that was fun to putter around with about using a signal generator to provide the reference clock was being able to arbitrarily change it and see how that affected the results displayed by the counter.

Also, in this, I discovered a cabling problem with the 10 MHz distribution to one of the counters in the back so I took the opportunity to fix that up and run 10 MHz to several more pieces of equipment. Then before I knew it, it was time to head to work. The highlight so far was being nearly run over by an Uber driver in a Tesla doing a high speed U turn into a condo driveway while I was walking back to work with a coffee from the Tim Hortons down the street.

[mnementh]

Oy. Waiting in the snack shop for the hospital to let me know where they put my dad; he had a slip in the shower and dislocated his cyborg hip.


mnem

[Specmaster]

Oy. Waiting in the snack shop for the hospital to let me know where they put my dad; he had a slip in the shower and dislocated his cyborg hip.


mnem

Ouch, I'm hoping that he is OK and not in too much pain, my thoughts are with you my friend.

[mnementh]

Finally here with him; he's got some pain meds in him, and we're waiting for them to shoot some pics of his hip.

Thanks for the well wishes; I'll be in touch.

mnem

[Cubdriver]

Yike!! Good thoughts inbound - hope it all goes well.

-Pat

[25 CPS]

Oy. Waiting in the snack shop for the hospital to let me know where they put my dad; he had a slip in the shower and dislocated his cyborg hip.


mnem

I hope everything goes well and he has a speedy recovery.

[BU508A]

Oy. Waiting in the snack shop for the hospital to let me know where they put my dad; he had a slip in the shower and dislocated his cyborg hip.

My best wishes for your father. I hope, he'll recover completely soon.
Take care, man!

[nixiefreqq]

Finally here with him; he's got some pain meds in him, and we're waiting for them to shoot some pics of his hip.

Thanks for the well wishes; I'll be in touch.

mnem

ouch! never heard of that before. is it a common problem after hip replacement?

[tggzzz]

Finally here with him; he's got some pain meds in him, and we're waiting for them to shoot some pics of his hip.

Thanks for the well wishes; I'll be in touch.

mnem

ouch! never heard of that before. is it a common problem after hip replacement?

Hmmm.

I did once see an old drunkard lying in he gutter. For some unknown reason I went over and found he wasn't drunk, but couldn't move due to severe pain in his hip. I found he had a hip replacement, called the ambulance, and he was taken the couple of hundred metres to the city A&E.

I've no idea what happened, but I've long hoped it was only a hip dislocation rather than something worse.

[mnementh]

Doc confirmed he has a dislocated hip, but the joint appears in good shape, so they gave him some muscle relaxants to help them put it back where it belongs. I wasn't allowed to be there for the procedure (I know from personal experience it can be a bit painful and even violent), so I went to to the cafeteria to get something to eat; I was making my lunch when this all happened and hadn't eaten anything since breakfast.

The procedure went well; they moved him to a room in the "ER Dept Observation Area" last night and kept him overnight for observation. They told me he may need to spend some time at a physical rehab facility to work on exercises and a motion modification program to favor those overextended muscles and ligaments until they heal.

He's in good spirits, tho still having trouble putting weight on the hip. We're kindof in a limbo due to the weekend; no idea how we'll get him situated once he comes home. He can't come home right now... we don't have any way to do basic needs until he can at least stand reliably, preferably walk a few steps to the bath.

Had to have a revisit with the Discharge Coordinator; they were talking aboot discharging him home as soon as Sunday because MedicAid won't pay for that rehab center time unless he's actually admitted to the hospital (as opposed to ER care). Of course, there's a well-crafted hole in the hospital admissions criteria that makes sure a lot of people just like him won't be admitted, despite needing in-patient care.

That "ER Dept Observation Area" obviously exists as a DMZ between the ER and patients who don't have "Golden Ticket" insurance. But there has to be a plan for him to be safe for them to release him; and releasing him to our home simply isn't an option until a bunch of stuff gets placed there for him. Or we can pay out of pocket for a $5000-7000 minimum stay at any of dozens of rehab centers in the area.

Because the insurance lobbyists wrote the admission criteria/laws, that's why.
I guess I should just be glad he wasn't one of the dozens of patients I saw lined up in the halls all the way into the area where they were holding him...

mnem

[Specmaster]

Thanks for the update Paul, it sounds a real nightmare situation that you're in at the minute. That is just typical of insurance companies, they do the utmost to ensure that you can't tick all the boxes, even though you have been paying the often extortionist premiums for years.

Will they supply the required bits of kit to allow him to come home, or have you got to also fund those as well?

I hope it all gets sorted soon and that he is not in too much discomfort.

[mansaxel]

I'm beginning to suspect a problem downstream of the internal timebase. This counter takes a 1 MHz reference input so I couldn't directly connect it to my 10 MHz reference distribution but I used a signal generator that is locked to it to generate 1 MHz out and it was still off.

Check the supply crapacitors. I've read about more than one counter that had power rail ripple and added 50 or in your case 60Hz and its overtones to the result. Depending on the timebase trigger frequency the outcome varies, of course.

[bd139]

Outta here for a bit again. Need to escape this place again so off to Iceland with bd140 until the 18th. Going to do the entire ring road of 1800km in a crappy little van for 9 days. Not doing F-routes or off road - maybe next time. Will check in when I'm back. Have a good one everyone...

[mnementh]

piss off ye manky git.

mnem
bring back stories or we will cause you pain.

[mnementh]

Update:

Looks like I have no choice; they're sending dad home today. They're literally going to bring him via ambulance and stretcher to his bed.

I've demanded that at least hospital bed, hoist, commode, and wheelchair be arranged and in place prior; we'll see how our discharge coordinator does at coordinating that.

mnem

[tggzzz]

You have my sympathy, which is worth what you paid for it

Here in the UK there is an equal an opposition problem: bed blocking.

The lack of in-the-community social care means elderly patients can't be sent home, so they moulder in hospital beds and prevent new patients being admitted to hospital.

[mnementh]

Yeah, this DMZ area and the halls filled with patients in hospital beds is the only reason we don't have that; not because our in-the-community care is any better or even exists in any definable sense.


mnem

[Specmaster]

Yeah, I feel for you now, I know how that feels. Then way things are going here now, it looks like we are destined to become just like you with a for-profit health system

[25 CPS]

I'm beginning to suspect a problem downstream of the internal timebase. This counter takes a 1 MHz reference input so I couldn't directly connect it to my 10 MHz reference distribution but I used a signal generator that is locked to it to generate 1 MHz out and it was still off.

Check the supply crapacitors. I've read about more than one counter that had power rail ripple and added 50 or in your case 60Hz and its overtones to the result. Depending on the timebase trigger frequency the outcome varies, of course.

Thanks for the suggestion. I had been giving some thought to how the miscount is present whether the counter is running off the internal timebase or external 1 MHz because this implies pretty strongly that there's a problem taking place outside of the internal timebase. A noisy power problem would affect the whole machine for sure.

I did get a bit more playing time with this counter and I also wasn't able to adjust out the miscounting by varying the frequency of the external reference off 1 MHz either. I'll check the power supply performance on it next whenever I have another chance to play with it. The other possibility that comes to mind is the division and counting network downstream of the timebase source. It's possible something in there could be damaged; hopefully that's not the case because power supply components are much easier to source than difficult/unobtainable HP parts. The other thing I need to do is see if there's a better scan of the manual out there than the one on the Keysight website where the illustrations did not come through well at all.

Update:

Looks like I have no choice; they're sending dad home today. They're literally going to bring him via ambulance and stretcher to his bed.

I've demanded that at least hospital bed, hoist, commode, and wheelchair be arranged and in place prior; we'll see how our discharge coordinator does at coordinating that.

mnem

Wow this sounds like it's been a nasty ordeal for everyone involved. I hope the return home recovery following that goes as smoothly as it can. As much as it might feel too soon for your father to come home, that's probably for the better. One of my friends in Philadelphia had a stroke and ended up in one of those rehab homes and it was a waking nightmare. There was no rehab or recover being worked on at that place and all they did was try to make sure that people's lives and financial resources both ran out at the same time so they could maximize their take. The whole thing was top to bottom a hellish nightmare and I strongly think it's for the best your father is not ending up in one of these.

[mnementh]

Well, it's supposed to be a simple matter of him getting the PT he needs in an environment that is safe for him in his condition; it's supposed to be in-patient medical care, not a old-folks home. This is pretty intensive health-care, so I expect no insurance is going to put up with him in such a place for extended timeframe.

But for now things are on hold; he's been complaining of pain in his foot and leg which is bad enough he can't put full weight on the leg. They're doing an MRI on him tonight to see if they can find some actual cause for the pain.

I spent the day seeking out grab rails and no-skid sticky flowers for the shower, then clearing stuff and making room for the hospital bed.

We'll see what happens tomorrow.

mnem
also, fuck you Firefox hotkeys... for like the millionth time.

[25 CPS]

I've been meaning to put this post together for a while and I just finished off doing some final testing this evening to conclude things.

One of the places I help out is a trolley museum in Baltimore. Sometime between 2019 and late 2021 one side of the interior lights inside of a 1948 Philadelphia streetcar went out and nobody was able to get them working again by swapping bulbs, changing fuses etc. I went down and visited a number of friends in November of 2021 three days after the border finally reopened and one of my friends and I visited the trolley museum. They'd asked us to dig into the dead lights since nobody was getting anywhere with it.

Here's a quick rundown on how the two main interior lighting circuits work: They each are energized off the 600 V traction power through a fuse and a switch at the front of the car and are composed of a series string of 32 V, 1.6 A street railway bulbs that start behind the destination sign, run down one on each side of the ceiling to the back, where they're grounded through a resistor sized appropriately to have it all add up to the nominal 600 volts. To avoid the series string of incandescent light bulbs pitfall of if one goes out, they all go out, the shell of each socket is sprung so that if a bulb isn't present, it connects to the tab at the bottom and the circuit has continuity and the remaining bulbs stay on. The bulbs themselves have a self shorting device built into the base so that if the filament goes open, the bulb short circuits so the rest of them continue to be lit and it's obvious which one needs to be replaced. This fault was interesting right from the start because given all this, it's unusual to have one whole string out unless the fuse has blown or someone has installed a regular bulb somewhere instead of the self shorting type and it's burned out and gone open and taken out the whole string.

We had all the tools and a good amount of the portable test equipment in my truck and we started digging into this, and it got messy quickly. The first thing was a disagreement in approach. My preference was to use a multimeter and take out a bulb about halfway down, switch the power on and see if 600 volts was present. If yes, the fault would be closer to the back. If not, we'd have to move towards the front to find the break. My friend wanted to ohm the circuit with the power off. That would be safer, and we did have the working circuit on the other side of the car to compare to, but we were getting wild readings. Low values that were plausible mixed with high resistance but not open circuit that made no sense - until June of 2023.



7.6 ohms is reasonable.



U1272A wedged into a standee window for hands-free use.



Clamp on the power feed to the working set of lights and DMM on the fuse holder in order to establish the parameters of the working side.



1.6 A at 578 V is pretty close to what we'd expect for a string of 1.6 A bulbs that's put together to operate on a nominal 600 V supply.



U1115A remote logging display with their readouts on the dashboard also good to tell at a glance if the dead side is energized or not by moving the DMM over to the fuse holder for that one. The OL was from the U1272A that we were using to ohm the circuit out.

One of the things we found in the 2021 session was that one bulb holder and bulb in the destination sign at the very top of the 600 V circuit had poor contact and arced which chewed up the base of the bulb. We were able to burnish the tab at the bottom of the socket and salvage that but the bulb's base was damaged pretty badly and had gone open.

Then, when while we were trying to get to the bottom of why it still wasn't working and trying to figure out why we were seeing such strange resistance measurements in places, we discovered this in the compartment under the very rear seat:



Sometime while the streetcar was still in Philadelphia, the resistors used to make up the balance of the voltage divider so the whole thing adds up to 600 V had been replaced by additional lightbulbs wired in series. Worse, the set of three alligator clipped to the fuse holder being used to hold these popped off. That would cause an open or potentially a very bad, intermittent ground path through the chassis of the car. Luckily this is at the ground end, not the 600 V end of the string so no arc welding took place.

We ran out of time and I didn't get back for another visit until June this year. My friend and I resolved to get this sorted out and we went through it this time applying the 600 V and looking for voltage to disappear in order to find the break in the circuit. We got the test equipment and tools out of my truck and started working on it from the top of the circuit in the destination sign, beginning with the burned up bulb and socket pair we'd identified in 2021. Then we started dropping open lampshades and pulling bulbs and checking for 600V:



All of a sudden, with one of the bulbs out, the string came on minus a couple of burned out bulbs. Turn it back off, put the bulb back in, we got 3 V further down and no lights. This turned into a major headscratcher. 3V? Nothing? Take the bulb out and the functioning parts of the string came back up. At this point, I was standing in front of a light that worked and I had an idea: this was an example of a known good socket and a known good bulb that we could take the cover off this one and started cycling all the bulbs that weren't lit through it one by one and sorted them into good and bad bulbs. Then, take one of the known good bulbs and go through all the remaining sockets and identify any more damaged sockets.

The superdud dead bulb that took the whole string out wherever you put it in was the cause of the strange high but not open ohms readings we were getting in 2021 and the 3V as measured with the high impedance DMM when we were checking for voltage loss this year. The self shorting mechanism didn't short the bulb out the way it should have but it didn't fail completely open either and was the cause of the high impedance that was enough to break the circuit but had enough continuity to give strange ohms results.

Then, we had another damaged socket partway down the interior of the car where none of the known good bulbs would light up even though the rest of the string was on. This implied the socket itself was remaining shorted at all times, even when a bulb was installed. I figured this should be visible and possibly repairable so we cut the power and disassembled that light fixture:



Notice one of the brass screws is missing? It had worked its way loose and was shorting out the socket bypassing the light bulb that was in it. It was hanging down when I removed the bulb and fell out completely when the two of us disassembled the fixture to begin repairing it. Luckily we were able to find it on the floor and it hadn't rolled away and disappeared somewhere.



The culprit screw is about to be reinstalled. After we got that socket fixed up and the fixture reassembled, we replaced the burnt out bulbs with spares, reassembled everything and tested:







Full interior lighting and both sides of the destination sign lit up for the first time in years. The handful of lights in the middle of the ceiling are all 32 V regular bulbs wired in parallel along with the headlight and energized off the streetcar's low voltage power supply that's backed up by battery. You do not want a self shorting bulb anywhere in that circuit because as soon as it burns out and shorts out, it would be a dead short across the low voltage supply and pop the fuse for the headlight circuit.

For what should be a straight forward series string of incandescent bulbs, finding and fixing all of the faults that built up in this one was an adventure with:

- A couple of plain old burned out bulbs that needed to be replaced
- Burned up bulb/socket combo in the sign box
- Daisy chained string of bulbs that was alligator clipped in but fell off while being troubleshot replacement for resistors
- Shorted socket where no bulb would ever light up
- The superdud with the failed shorting device that would take out the entire string, unless installed in that shorted socket.

I took the superdud home and put it on the insulation tester just to validate that it was responsible for the bizarre measurements we were getting, which I finally this evening. For convenience, I was going to use a ceramic lamp socket to hold it and provide terminals for the test leads to clip on to and I measured the socket empty first to make sure it wasn't going to unduly influence measurements with the bulb in it:





I set the user defined voltages for the 50 and 500 V ranges to 32V and 600V respectively to simulate the in-circuit operating voltage this bulb should have across it and the 600 V open circuit voltage it had across it due to the malfunction. At 600 V, this socket can be pretty much considered an open circuit at >260 GOhms.





1.44 GOhm at 600 volts.



2.42 GOhm at 32 volts.

The 1.44 GOhms with the 600 volts open circuit voltage applied made the approximate 3 V we measured downstream from the superdud make a bit more sense given the value of the superdud, the rest of the equipment on the streetcar it was in series with, then the 10 MOhm meter to ground. The high impedance meter and very high impedance voltage source created an unintentional voltage divider circuit. Taking resistance measurements around the superdud in 2021 and going from low to very high impedance readings also makes sense now. Luckily it was a dud light bulb responsible for this. The resistance measurements we were getting in 2021 had me concerned that there was a metal fatigue break somewhere in the cabling in the ceiling of the streetcar that developed over 70-odd years of vibration in service. Replacing a faulty bulb was much easier than replacing wiring.

Anyways, that's a good example of some of my portable test equipment kit being used in the field for totally unrelated to work volunteer stuff.

[Cubdriver]

Nice job of troubleshooting! That one was for sure quite the head scratcher.

-Pat