Test Equipment Anonymous (TEA) group therapy thread

[Ice-Tea]

Probably older than me. But 0 dBm on the dot.

[extremgear]

Ok the job is done , and safely done, no cal lost , no burnt or electrical choc 
i hooked up a 3V external power supply.
i only goofed up with a leg of a capacitor left too long,  i was not able too insert the pcb inside the rail 

Let me just leave a couple of pictures of electrical burns here, for the complacent amongst you to contemplate.
And by the way these are some of the mildest of the pictures you find when googling electrical burns. Don't look at the others unless you have a strong stomach.

we had several accident in my company involving electricity ( no death in my country but in other countries...too much, maybe due to french regulation, i don't know) , you're perfectly right it is very bad to take bad habits with electricity !

[...]
So, just doing it the safe way all the time, one does not have to think about it.
Just as easy as putting on your seatbelt when you get into the car.

Ah, I see we are putting out the real controversial opinions now!

But on a more serious note, I agree: the shortcut will become a habit and might lead to an accident. Some say it's one of the most common ways...

To me, now only one question remains: if you use an external supply to support the Ram, is it a good idea to set the current limit low or high?
If it is high enough, an accidental short might be cleared momentarily by itself 

my supply was set with current limit to 100Ma , i don't think my supply can supply short circuit current and keep a voltage high enough for the ram.

[TERRA Operative]

Tonight's fun has been rearranging my 19" rack to take out some gear I don't use and fill it with gear I do and will use.

From top to bottom:

- HP 5445A Frequency Counter (1.3GHz and OXCO options, GPS referenced)
- HP 3325A Function Generator (High Voltage and OXCO options, GPS Referenced)
- Tek TM506 mainframe (To be filled with a PG506, TG501A, SG503, SG504, SG505, and maybe an RG501 or DC509 with OCXO option to fill the last slot)
- Tek TM5006 mainframe (To be filled with a PS5004 and SG5030 so far)
- HP 4276A LCZ meter
- Yokogawa 2558 AC Volt/Current calibrator
- Fluke 332D DC Volt Calibrator

I currently have the TM506 mainframe on the bench getting a spit polish. It needs new capacitors for sure, I pulled one and none of my meters can read the capacitance at all.....
One is bad, all get replaced.
Also, I tore it down and washed all the chassis parts, cleaned the fan, replaced the fan filter, replaced the mains filter capacitor with a proper X-class cap, replaced the one carbon composite resistor with an equivalent metal film, and removed the dirty old direct attached mains cord and installed an IEC C13 socket in its place.

Next on the bench will be the TM5006 for a going over and adjustment, and the Fluke 332D is in the last stages of repair (I hope....), just gotta replace a pass transistor or two in the power supply section.

Oh, I also ordered some carbon composite resistors from Hi-Fi Collective to replace some drifted ones in the RF Oscillator section in my SC504 that is getting a full rebuild (Including a replacement aluminium front plate to replace the shattered plastic piece). I ordered 10 of each value I need that I couldn't find in Akihabara, so I'll select the closest values after baking them to get any moisture out.


Once it's all up and running, I'll have a nice little cal lab to calibrate and adjust stuff, like the mountain of TDS600 and 700 series scopes I have sitting here....  

[Zucca]

Anyone with experience with XT150?

https://www.eevblog.com/forum/projects/are-those-xt150-connectors/

[McBryce]

Let me just leave a couple of pictures of electrical burns here, for the complacent amongst you to contemplate.

And by the way these are some of the mildest of the pictures you find when googling electrical burns. Don't look at the others unless you have a strong stomach.

I'm aware of the dangers, but it's no different to when I need to measure voltages when repairing mains powered or even tube devices. The rules don't change. Or how do you manage to repair such stuff without ever having to work on or near a live circuit?

McBryce.

[extremgear]

Hello,
i've received my 34465A, i get it for a very decent price, it's a 2017-2018 model, it works perfectly and is in a very nice condition, it only needed a software update, it still have the protective film on the screen but i think it's marketing bullshit from the seller because the inside was a bit dusty, i'll not complain given the fact this meter cost now almost 2400 euros new in my country !

[m k]

Earlier ROM copier addendum, a read/write board.
There Arduino D4-7 are multiplexed data and D2-3 are selectors.

KiCad comparison board was so quickly done that I had to check it few more times.
Wiring a circuit was even faster, picking stuff was the time consuming part.

[Messtechniker]

Hello,
i've received my 34465A, i get it for a very decent price, it's a 2017-2018 model, it works perfectly and is in a very nice condition, it only needed a software update, it still have the protective film on the screen but i think it's marketing bullshit from the seller because the inside was a bit dusty, i'll not complain given the fact this meter cost now almost 2400 euros new in my country !

Congrats. Been using this beast for 7 years now. Has never let me down.

[Brumby]

Let me just leave a couple of pictures of electrical burns here, for the complacent amongst you to contemplate.

And by the way these are some of the mildest of the pictures you find when googling electrical burns. Don't look at the others unless you have a strong stomach.

I'm aware of the dangers, but it's no different to when I need to measure voltages when repairing mains powered or even tube devices. The rules don't change. Or how do you manage to repair such stuff without ever having to work on or near a live circuit?

McBryce.

In some cases, working on or near a live (mains) circuit is necessary - and at those times, you need to be careful of that risk.  However, when this is not necessary and you have the option of an alternate procedure, then you have the responsibility of weighing up the risks of personal injury, equipment damage and data loss.

How these risks are resolved is up to the individual.

Personally, I like to avoid mains risks - but I when I do, it is a measured approach.

[TERRA Operative]

So, it seems one of my TM5006 mainframes has had a fit and blown out two IRF840 transistors in its past life, I also had to replace a few popped resistors that died due to the dead-short MOSFET's, they put on a show when I replaced the fuse and powered it up..

The other mainframe that I'm keeping needs a new mains input filter/fuse holder/voltage selector, so I'll grab a freaking expensive Schaffner FN372-6-21 to replace it, it looks to be a direct replacement with all the correct terminals.
Hopefully this one wont pop in my face when I turn it on.... 


Time to get a Mouserkey order underway I think...

[Specmaster]

Let me just leave a couple of pictures of electrical burns here, for the complacent amongst you to contemplate.

And by the way these are some of the mildest of the pictures you find when googling electrical burns. Don't look at the others unless you have a strong stomach.

I'm aware of the dangers, but it's no different to when I need to measure voltages when repairing mains powered or even tube devices. The rules don't change. Or how do you manage to repair such stuff without ever having to work on or near a live circuit?

McBryce.

Yes, you are correct, but, there is always a caveat, you should only do so as a real last resort, and often there are other ways of doing the same thing in a safer manner.

[ch_scr]

The Solartron continues to entertain:
I've had it failed shortly after turning it on the second time this week. Its relays clicked continually and it showed "Failure 1" - no communication to floating logic. Snooping around inside yielded the insights that (a) the replaced capacitors are indeed good and (b) the 5V are spot on and low ripple. But the crystal oscillator for the 6801 was indeed not ok and stopped working when attaching a 10x scope probe. In this state the relay chatter fell silent, too. On it's div /4 clock "E" output the square wave signal was jittered and intermittent (when it was probed there exclusively). I've started by resoldering the crystals legs and these of it's associated resonant ceramic capacitors (C101 &C102). Which fixed it for literally a minute. In the next step I've replaced both ceramic caps with "new" ones harvested from an old radio pcb.

Which fixed it until yesterday evening, but letting it run through the night I woke up to an "Failure 1" again. I've resoldered the involved legs of the IC socket as well as re-plugged the IC into it's socket. Which seems to have fixed it, for now.

After letting it run over the day, I've also measured the noise on the internal 10V reference voltage.

As you can see it's pretty low noise but has 1uV(peak) spikes of switching noise from the AD converter (the spikes move with the multimeter reading, too).

For comparison I measured the noise from my homemade 9V reference...

...with the same settings on scope and amplifier. As we can see, it could use some improvement...


Edit: Also, This recapping job inspired by TERRA 

[AVGresponding]

Let me just leave a couple of pictures of electrical burns here, for the complacent amongst you to contemplate.

And by the way these are some of the mildest of the pictures you find when googling electrical burns. Don't look at the others unless you have a strong stomach.

I'm aware of the dangers, but it's no different to when I need to measure voltages when repairing mains powered or even tube devices. The rules don't change. Or how do you manage to repair such stuff without ever having to work on or near a live circuit?

McBryce.

Because when you're measuring something in a live circuit, you're using probes and leads and a DMM that are all designed to do this, and will (unless you are using the really cheap stuff) have the appropriate CAT rating, meaning it is designed not only to protect you from touching dangerous voltages, but to protect you when encountering voltages that may be much higher than you expect, and that if something does go wrong with the equipment, that it does so in a way that does not endanger the user.
Soldering irons are not designed with these considerations in mind, to the best of my knowledge.

Further, when you are measuring something, your mental focus is on obtaining a measurement of a potentially dangerous voltage; the dangers are at the forefront of your attention.
If you're soldering to a live board, your attention is going to be divided; you don't want to burn yourself, you don't want to damage the board or components by over heating, you don't want to get solder splashes on things, you don't want to short anything out with the soldering tip, you don't want to leave a dry joint. In this scenario, your brain defaults to habitual actions; you're soldering, so the soldering issues are the ones at the forefront of your mind, and not the dangers of the exposed mains voltages nearby.



I fail to see how it can be necessary in any way to work live like this. If the battery is so low that the TE can't be turned off without losing the data, how did you disassemble the TE? I own a 3478A, and I would consider it seriously dangerous to try to take it apart while powered up.

[McBryce]

Let me just leave a couple of pictures of electrical burns here, for the complacent amongst you to contemplate.

And by the way these are some of the mildest of the pictures you find when googling electrical burns. Don't look at the others unless you have a strong stomach.

I'm aware of the dangers, but it's no different to when I need to measure voltages when repairing mains powered or even tube devices. The rules don't change. Or how do you manage to repair such stuff without ever having to work on or near a live circuit?

McBryce.

Because when you're measuring something in a live circuit, you're using probes and leads and a DMM that are all designed to do this, and will (unless you are using the really cheap stuff) have the appropriate CAT rating, meaning it is designed not only to protect you from touching dangerous voltages, but to protect you when encountering voltages that may be much higher than you expect, and that if something does go wrong with the equipment, that it does so in a way that does not endanger the user.
Soldering irons are not designed with these considerations in mind, to the best of my knowledge.

Further, when you are measuring something, your mental focus is on obtaining a measurement of a potentially dangerous voltage; the dangers are at the forefront of your attention.
If you're soldering to a live board, your attention is going to be divided; you don't want to burn yourself, you don't want to damage the board or components by over heating, you don't want to get solder splashes on things, you don't want to short anything out with the soldering tip, you don't want to leave a dry joint. In this scenario, your brain defaults to habitual actions; you're soldering, so the soldering issues are the ones at the forefront of your mind, and not the dangers of the exposed mains voltages nearby.



I fail to see how it can be necessary in any way to work live like this. If the battery is so low that the TE can't be turned off without losing the data, how did you disassemble the TE? I own a 3478A, and I would consider it seriously dangerous to try to take it apart while powered up.

The battery wasn't so low that I couldn't turn the device off. I disassembled the device with no power connected, covered the parts that would be live when powered, then powered the device up to remove and replace the battery. There were no accessible live parts while I worked on it.

McBryce.

[Specmaster]

Let me just leave a couple of pictures of electrical burns here, for the complacent amongst you to contemplate.

And by the way these are some of the mildest of the pictures you find when googling electrical burns. Don't look at the others unless you have a strong stomach.

I'm aware of the dangers, but it's no different to when I need to measure voltages when repairing mains powered or even tube devices. The rules don't change. Or how do you manage to repair such stuff without ever having to work on or near a live circuit?

McBryce.

Because when you're measuring something in a live circuit, you're using probes and leads and a DMM that are all designed to do this, and will (unless you are using the really cheap stuff) have the appropriate CAT rating, meaning it is designed not only to protect you from touching dangerous voltages, but to protect you when encountering voltages that may be much higher than you expect, and that if something does go wrong with the equipment, that it does so in a way that does not endanger the user.
Soldering irons are not designed with these considerations in mind, to the best of my knowledge.

Further, when you are measuring something, your mental focus is on obtaining a measurement of a potentially dangerous voltage; the dangers are at the forefront of your attention.
If you're soldering to a live board, your attention is going to be divided; you don't want to burn yourself, you don't want to damage the board or components by over heating, you don't want to get solder splashes on things, you don't want to short anything out with the soldering tip, you don't want to leave a dry joint. In this scenario, your brain defaults to habitual actions; you're soldering, so the soldering issues are the ones at the forefront of your mind, and not the dangers of the exposed mains voltages nearby.



I fail to see how it can be necessary in any way to work live like this. If the battery is so low that the TE can't be turned off without losing the data, how did you disassemble the TE? I own a 3478A, and I would consider it seriously dangerous to try to take it apart while powered up.

The battery wasn't so low that I couldn't turn the device off. I disassembled the device with no power connected, covered the parts that would be live when powered, then powered the device up to remove and replace the battery. There were no accessible live parts while I worked on it.

McBryce.

I would still call this action to be ill-advised. There are methods of replacing the said battery without losing the cal data, that does not require the adoption of live working, and accidents can and will always happen. Accidents don't let you know beforehand that they are going to happen, they just happen, and unlike when you are trying to measure something, the fact that you are trying to measure voltages on equipment, it means that you have to be working on "live" equipment because there is no other option, but to change a battery  Come on, you have to admit that is a bit extreme, there are ways of doing so without the loss of the data, but there is always a small risk of something not going to plan, be it solder bridges, dropped solder or tool on the PCB etc, and then having to calibrate the meter again, not a major problem, I have recalibrated a 3478A myself before, just consumes a bit of time. Working live if an accident was to happen it could potentially be the end of the meter and or seriously harm you, every electric shock has the potential to kill you, and people don't knowingly give themselves electrical shocks so why put yourself at risk 

[TERRA Operative]

If one is well versed in safety procedures and working with elevated voltages, then what McBryce did isn't so bad, especially after covering the bits that bite.

However, I would hesitate to recommend it to someone without knowing their electrical competence first. There are processes and safety considerations that we take for 'common sense' that less experienced people may not be aware of.

[Brumby]

My first idea for when I swap out the battery in my 3478A involves an 18V battery from my cordless drill with suitable interface.  Mains will not be connected.

[McBryce]

If one is well versed in safety procedures and working with elevated voltages, then what McBryce did isn't so bad, especially after covering the bits that bite.

However, I would hesitate to recommend it to someone without knowing their electrical competence first. There are processes and safety considerations that we take for 'common sense' that less experienced people may not be aware of.

I worked for many years on live equipment (diagnosing and repairing running factory equipment that couldn't be powered down) and later on with much higher DC voltages on HV car batteries that for obvious reasons can't be switched of either. So I have a lot of experience working in this environment, but of course I wouldn't recommend it as the best way to tackle this particular task.

McBryce.

[wolfy007]

Bought a Fluke 1912A counter, thought I bought one without batteries, but alas after opening I saw the image below. 

Not sure how bad it will be, but will try to restore it, after further pull apart and giving the board a good soak/wash to clean and neutralise the dead nicads fluids.

PS: Hope the varnish on the transformer protected it... 
PPS: Sorry the batteries were in there, but I cut them out first, then took the photo.

[med6753]

Since we're talking safe working practices and safety. Under the category of "What were they thinking?". Fluke LCA-10 Line Current Adapter. I wonder how many DMM's met their maker, possibly in explosive fashion, when this was in line with a high in-rush current device such as an A/C compressor? Yep, Fluke attempted to cover their behinds with all kinds of warnings. But who reads safety tags? As far as I know Fluke discontinued this adapter many years ago which is no surprise. I think I used it once and it does work but there are much safer methods.


 

[vk6zgo]

The battery wasn't so low that I couldn't turn the device off. I disassembled the device with no power connected, covered the parts that would be live when powered, then powered the device up to remove and replace the battery. There were no accessible live parts while I worked on it.

McBryce.

I'm afraid I have a bit of a "two bob each-way" feeling, here.

Although in post #132741, I commented that someone might feel the need to solder in an active circuit, & pointed out that you could do so with some versions of Weller WTCP, I have really only once ever soldered on an active circuit.

Out in the middle of nowhere, in a place called "Turkey Creek", there was a longline repeater station for a very long open wire pole route.
A mod had been done to this to add a bit of additional cooling in the form of a couple of fans running off the local 48v DC supply.

As it happened, one fan had failed, so I was given the job of installing a replacement one.
The connection was directly soldered, so I had to unsolder it, which was connected by a red & black wire.

I unsoldered the red one with no problems, & from that, & not being familiar at that time with the propensity of Comms people to ground the positive leg & make the negative "hot", assumed from that the old Adcola iron I was using had an isolated tip.

Nasty surprise when I touched the black wire---nice little "zap" & the whole thing dropped off, generating a very loud alarm.

It wasn't a really big deal---I had just knocked out a 12-channel phone, & 24 channel telegraphy system, but it was in the bush!
While it was down, we finished the job, the Phone bloke reset the supply, & went off to do the "paperwork"!

[TERRA Operative]

Bought a Fluke 1912A counter, thought I bought one without batteries, but alas after opening I saw the image below. 

Not sure how bad it will be, but will try to restore it, after further pull apart and giving the board a good soak/wash to clean and neutralise the dead nicads fluids.

PS: Hope the varnish on the transformer protected it... 
PPS: Sorry the batteries were in there, but I cut them out first, then took the photo.

Oooh, nasty! A good wash down, and removing the solder mask to get out any crap that seeped underneath should have most of it fixed. (A small flat bladed screwdriver gently used as a chisel will flake off any soldermask that has been lifted by junk underneath).
I usually end up scrubbing the affected traced with a fibreglass pen, then dousing with flux and lightly 'scrubbing' with my soldering iron and a blob of solder. Suck it off as it gets dirty, clean with alcohol, rinse and repeat until it's clean and retinned.

It has worked well for a few of my HP boat anchors that had leaky batteries. They still work well after a few years. I do the same for ECU's from cars, usually 90's Toyota's, never had a return yet.

Although, that vertical PCB, might be better to draw something up in your PCB software of choice and get a replacement made in China... 

Since we're talking safe working practices and safety. Under the category of "What were they thinking?". Fluke LCA-10 Line Current Adapter. I wonder how many DMM's met their maker, possibly in explosive fashion, when this was in line with a high in-rush current device such as an A/C compressor? Yep, Fluke attempted to cover their behinds with all kinds of warnings. But who reads safety tags? As far as I know Fluke discontinued this adapter many years ago which is no surprise. I think I used it once and it does work but there are much safer methods.

Oh my, I do very much want me one of those!! 



As for tonight's work, I just calibrated my Tek 2445 scope. I had already done a bit of work on it ages ago, maybe even have a video on it on my Youtube channel. Just a usual fan repair and Rifa replacement. Didn't bother with capacitors etc beyond that.

It adjusted perfectly and works really well. I am happy, should be easy to sell this one as fully working and calibrated/adjusted.   

[factory]

As for tonight's work, I just calibrated my Tek 2445 scope. I had already done a bit of work on it ages ago, maybe even have a video on it on my Youtube channel. Just a usual fan repair and Rifa replacement. Didn't bother with capacitors etc beyond that.

It adjusted perfectly and works really well. I am happy, should be easy to sell this one as fully working and calibrated/adjusted.   

I would be weary of buying one that hadn't had a PSU recap, someone on another forum bought one that had only had the X2 caps replaced (sold as recapped), it didn't last long before the PSU failed causing lots of damage. Casualties were the HV board, various op-amps on the A5 board, two CA3046 transistor array and the U950 hybrid and few others I can't remember. This took several months to fix, I ended up repairing the A5 board & confirming the defective U950, don't say you weren't warned. 

David

[Specmaster]

If one is well versed in safety procedures and working with elevated voltages, then what McBryce did isn't so bad, especially after covering the bits that bite.

However, I would hesitate to recommend it to someone without knowing their electrical competence first. There are processes and safety considerations that we take for 'common sense' that less experienced people may not be aware of.

I worked for many years on live equipment (diagnosing and repairing running factory equipment that couldn't be powered down) and later on with much higher DC voltages on HV car batteries that for obvious reasons can't be switched of either. So I have a lot of experience working in this environment, but of course I wouldn't recommend it as the best way to tackle this particular task.

McBryce.

Exactly my point, given that we cannot be certain that a relative newbie does not read our posts and attempt to do the same and end up in all kinds of problems. There is a huge gulf of difference between what we might be tempted to do with all of our years of experience behind us and what someone just starting out in their career should be attempting to do. This is something that we all should try and remember that we cannot control who reads our posts.

[xrunner]

Jason of Siglent NA received my email and is sending me a new probe. So, I'm impressed with customer service. 

Jason is a top dude and does all the NA Siglent videos.
We chat about things often as he visited NZ a few years back before we got to know one another.

Received a new replacement 200 MHz probe for the SDS2202X-E today. It does not have any noise issues when wiggling the cable. So I decided to take apart the original one to see if I could find any problems inside.

I disassembled the original probe. After inspecting the guts with a microscope, I failed to find any obvious issues. I really was certain that the cable connection was going to be the issue. Once taken apart, I placed it in a plastic 3D printed vise, and connected it to the calibration signal with a test lead. I could not get it to exhibit the original issue - the noise issues when the cable was wiggled (although it did pick up mains noise which was to be expected with the shield taken off). Perhaps some component was touching the metal shield that the PCB slides into?

Put it back together and it again exhibited the noise only when the cable was wiggled or pulled. I now thought it may be the connector at the end of the internal PCB. It connects to the probe pin inside the metal shield, which is not making good contact. That is why when it is connected to the signal via the clip lead the noise does not appear when wiggled.

Removed the plastic probe tip assembly from the metal shield. When I pushed it back onto the PCB end connector, it does not fit tight at all. The PCB end female has two small dimples in either side that are supposed to clamp to the male pin - they are not formed correctly and do not grab the metal as they should. This is what is wrong with these probes (that hopefully the sub-contractor has fixed).

I did notice that the inner conductor of the probe cable is solid wire - not stranded wire. I would have expected stranded wire used for something that had to take being moved around quite a bit over its lifetime. Hmmm ...