Test Equipment Anonymous (TEA) group therapy thread

[AVGresponding]

It's better protected than the cheap stuff, if not quite on a par with a modern Fluke, but I expect it's comparable to contemporary Flukes. I wouldn't hesitate to use my Metrix MX57 at work instead of my Fluke 87V. Not sure I'd say the same about my Fluke 8060A!

It would be nice to have a pic or two of the inside of the bottom case, so we can see if there's plastic moulded to separate the fuses from the battery compartment etc.

[DC1MC]

One can have enough networkized serial ports 

https://www.ebay.de/itm/185693879793

[Vince]

That's super cool, I didn't even know such a thing existed...

[Vince]

It's better protected than the cheap stuff, if not quite on a par with a modern Fluke, but I expect it's comparable to contemporary Flukes. I wouldn't hesitate to use my Metrix MX57 at work instead of my Fluke 87V. Not sure I'd say the same about my Fluke 8060A!

It would be nice to have a pic or two of the inside of the bottom case, so we can see if there's plastic moulded to separate the fuses from the battery compartment etc.

Here you go AVG.

No special moulding around the fuses.  The battery holder has a some though, plus it's far away from the big fuse, at the other end of the meter.

[AVGresponding]

One can have enough networkized serial ports 

https://www.ebay.de/itm/185693879793

I shamelessly copied that link into Discord

[DC1MC]

One can have enough networkized serial ports 

https://www.ebay.de/itm/185693879793

I shamelessly copied that link into Discord

A lot of serial cables as well, I could have uses some a while ago for my Tek portable, thanks god for CatpBullsot that saved me with the RJ45 to DB9 cable.

 

[Vince]

Now for the next item in my haul.... as Factory said, it's the Philips PM2440 VTVM.

In good nick except cosmetically : the face plate is littered with small stains, leopard style, and I fear it's the kind that eats through the clear coat, so it's not gonna buff out... it's just a lost cause and I will have to live with them I fear 

Other than than, it's in good nick overall.

Set the vintage selector to 245V, easy to do. Power socket is a pain... one I have never seen before, quite chunky and perfectly rectangular.. if anyone knows what it is.  That did not deter me of course, because I like this TE so I had some motivation.... I popped the hood. The socket can be removed easily, just two screws and it lifts out of the chassis, with enough slack to let you comfortably solder a modern cable to it. So I did just that. Now we have a secure mains connection. Good.  Did the usual safety checks : good connection between earth pin of the socket, and the chassis. High-impedance between earth and live/neutral. Between live/neutral I get a few hundred ohms, good... neither shorted nor open circuit.

So I declared it good to be powered via the dim bulb tester. DBT didn't even light up at all.

Pilot light on the front panel does light up and I can see the heater glowing on some of the tubes (I counted 8 of them).

Applied some DC voltage to the input, using my lab supply.... no matter what I do, I can't see the slightest sign of life needle... so that's that.

Disappointed...

Dave, as you can see it's not the ancient style with prehistoric style caps. It's got mostly metal can caps, and a very few blue axial Philips.

Quite clean inside, no corrosion. A light but well cooked layer of dust on the tubes. You can just dust them off with a brush, doesn't do much. I would really need to take them all out to actually wash them. Gently of course, or else the markings would just come off as they like to do.

So I guess I am in for some trouble shooting then !
I hope there is a manual for this thing. Being a Philips, hopefully yes there is.

The construction is very service UN-friendly. Lots metal work bolted together with spacers and angles.
I hope I can fix it without too much dismantling.

I guess the first two things to check are the power rails of course, but also the meter movement. Maybe I can get to its wires and test it on its own to see if it works or not. Will see.

[Vince]

...

[Vince]

EDIT :   found the manual.... but I can only find it in GERMAN somehow !! 

Well at least I got the schematic, that's the most important for now.... so let's get probing...

[ch_scr]

EDIT :   found the manual.... but I can only find it in GERMAN somehow !! 

Well at least I got the schematic, that's the most important for now.... so let's get probing...

Oooh, that square thing in there looks like a mechanical chopper - do you hear buzzing when getting close to it?
High-tech of days long-gone! 

[AVGresponding]

EDIT :   found the manual.... but I can only find it in GERMAN somehow !! 

Well at least I got the schematic, that's the most important for now.... so let's get probing...

Oooh, that square thing in there looks like a mechanical chopper - do you hear buzzing when getting close to it?
High-tech of days long-gone! 

You mean that thing that says "Chopper" on the side of it?

And you thought choobs were old-fashioned!

[Vince]

EDIT :   found the manual.... but I can only find it in GERMAN somehow !! 

Well at least I got the schematic, that's the most important for now.... so let's get probing...

Oooh, that square thing in there looks like a mechanical chopper - do you hear buzzing when getting close to it?
High-tech of days long-gone! 

Yes it's marked "Chopper" as AVG said. Below is a close up pic of it. It plugs into a round 7 pin socket. There are two wires coming out of it, at the top as well, I assume it's the coil that makes this thing spin.
Schematic attached below as a PDF. The chopper is about in the center of the page, marked " TR1 ".
The internal schematic looks like it's a relay inside... I don't know these things. Does it have anything to with a chopper amplifier, in spirit ? I see it's inserted between the attenuator and the amplifiers.

I can't hear it buzzing, maybe it does and it's just very faint. I can get too close to it as I do'nt wat to get zapped with HV, you see !   
However if I put my finger on it, I can for sure feel it vibrating, no doubt about that.

Looking at the schematic, I may have an explanation why I can see the heater glowing on some tubes but not all. Not all tubes are heated using the same winding on the transformer.

There is one that goes to 5 tubes + the Chopper + the pilot lamp. Since the chopper and lamp are alive, I guess this one works, though I need to make sure the voltage level is good, given how quiet the chopper is, and the bulb for the pilot light is very dim.

There is another winding that heats up tubes B1 to B4, and looking at the schematic, these 4 tubes are precisely the ones that do the grunt of the work, and drive the meter movement. So sure enough if they don't have a heater working, the needle will never move.....

So for now it looks like it might be a power supply issue...but hoping it's not a weak transformer, or I am toast 
I guess I could supply an external heater voltage to all the tubes to see if that improves things...

[ch_scr]

EDIT :   found the manual.... but I can only find it in GERMAN somehow !! 

Well at least I got the schematic, that's the most important for now.... so let's get probing...

Oooh, that square thing in there looks like a mechanical chopper - do you hear buzzing when getting close to it?
High-tech of days long-gone! 

Yes it's marked "Chopper" as AVG said. Below is a close up pic of it. It plugs into a round 7 pin socket. There are two wires coming out of it, at the top as well, I assume it's the coil that makes this thing spin.
Schematic attached below as a PDF. The chopper is about in the center of the page, marked " TR1 ".
The internal schematic looks like it's a relay inside... I don't know these things. Does it have anything to with a chopper amplifier, in spirit ? I see it's inserted between the attenuator and the amplifiers.

I can't hear it buzzing, maybe it does and it's just very faint. I can get too close to it as I do'nt wat to get zapped with HV, you see !   
However if I put my finger on it, I can for sure feel it vibrating, no doubt about that.

[...]

Excactly, it's a grandfather chopper amplifier, all discrete and with mechanical chopping. It sure is like a relay, too! See, you do know some of these things already, you just don't know 

[tautech]

Yep, electromechanical oscillator from days before active silicon componentry.
They even used then in the transformer primary of DC powered portable devices.

[Vince]

OK thanks... strange to find this antic chopper in this instrument, given that it does have some solid state stuff. There are transistors, small signal diodes, zener diodes... they could have made SS chopper I guess, if they could be bothered. I guess it was easier to take a know device that proved to work over the years.

OK I did some probing. Problem is that this thing as I said is not meant to be worked on.... you don't get to choose what you can probe.... so I probed what I could 

I measured the AC voltage that heats up some of the tubes, and the chopper and the pilot light bulb. It was rather low at only 5.45V instead of 6.7 (there is a table in the schematic that gives you a handful of voltages).

Also, on the board that carries the 4 tubes that do the amplification and driving of the galvanometer, I measrued voltage on all the pins of every tube, looking for high voltage... at least on the plate ! Plate voltage is.... 0.000V , not even a few mV.   Voltage on the other pins ? Highest I saw was 6 Votls or something IIRC.

So we definitely have a blatant power supply issue... unfortunately the power board is the one that's not accessible at all, neither top or bottom. It's a nighmare.

Also hoping the transformer itself is OK... but it's hard to check because it's in a box, you can't access it directly. You just have a wiring harness that comes out of the box and good luck with that.

Anyway, I know which direction to go now.... but it's midnight and I am yawning badly, going to bed. 

Thanks for watching. Please click like and subscribe and hit that notification bell. More videos to come soon. You can donate on Patreon or Paypal. I take cheques and Mastercard as well.
I will open a charity soon as well : " Let's save the old junk ", tax deductible.

[Messtechniker]

I've had mostly a bad experience with these blue Philips electrolytics.
Maybe a starting point.

[TERRA Operative]

@Vince, to make things happy with the safety of that multimeter, just stick this to the front:




Also, if you want to retain period accuracy if those Philips caps need replacing (They do...), Vishay now make them and can be had from Digikey and Mouser.

[Vince]

PHILIPS PM2440 VTVM REPAIR


Stop knocking on those poor axial blue Philips. Every time I had a TE to fix, they were not the problem...

Good to know that Vishay makes them again though ! Well, hoping they make better spec ones, 50 years later....
I hope they are affordable.


Anyway, I am glad to report some significant progress !  Still not fixed, but made huge progress none the less.

Worked on the power board. The most difficult board to access. You only have partial access to the solder side, and even then access is scary, it's not reasonable to stick probes in there to play with HV...
But I am motivated, so I did my best, and it paid.

Se schematic. I trimmed it to leave only the power supply part of it. The stuff I coloured in blue can be ignored for now. From what I understand it must be some auxiliary negative supply to get the chopper amplifier going. I concentrated on the positive HV.    We have 240V and 85V.   Both measured.... dead zero, not a sausage.

- So measured Ac voltage at the output of the transformer. Got 285V IIRC, good.

- Then measured at the output of the rectifier tube, got 370Vdc with low ripple.... excellent. So the juice is there, and smoothing cap is good.

- So the pass tube, that PCL82 pentode, is not working. Is it dead, or just not getting proper grid voltage ?

- Could not see that tube glowing, and it was dead cold hmmm...

- Measured filament voltage, right at the pins / solder joints of the tube socket. Got 15.5V.  Schematic says should be 17V. Pulled the datasheet for that tube, says 16V. OK all good.

- So the filament of the tube must be failed open circuit then ? Surely ? Pulled the tube, measured filament resistance... no, not open circuit, I got 8 ohms or so hmmm.... strange.

- Powered the filament with my lab supply. Gave it 16V, it drew 300mA, exactly what teh datasheet says it should !

- Filament glows, easy to see, and a couple minutes later tube got real hot.

- OK so the heating is fine on this tube, so why doesn't it glow when it's in place in the instrument ? Bad solder joint ? Loose socket ? Corrosion ? a mix of all that ?

- Tube socket looks OK-ish to me, no blatant defect. So for good measure I put some contact cleaner and exercised the tube in its socket a few times. Did the same with the voltage regulator tube while I was at it.

- Result ? Tube now glows and heats up, and filament voltage dropped from 15.5V to 14.5, further indicating that indeed the filament was not drawing any current before.

- Voltage ? We have juice now ! 240V rail reads 252.4 with low ripple. The 85V rail measures at 84V and low ripple.

SUCCESS !!!!! 

So I tested the instrument again.... still no luck, needle stuck on zero no matter what range I use and what voltage I apply. Snif....
HOWEVER, I DID see life in the needle ! NOT when measuring something, but when I turn the instrument on or off. When I do that, the needle briefly jumps a good buit, about 20% of full scale deviation, the immediately drops down to zero.
We didn't have that before !
So that's cool, means the meter movement is working, big relief (and one more step ticked off the diagnostic procedure.... ) !!! 

So quite happy, made big progress here, let's continue !!!!   

[factory]

I've had mostly a bad experience with these blue Philips electrolytics.
Maybe a starting point.

Don't think they would stop the heaters from working, it's got to be either a open connection somewhere (wiring loom, PCB joint, etc.), or the transformer winding for those vacuum bulbs has failed, or much less likely all four vacuum bulbs have open heaters.

I'm sure a small replacement 6.3V transformer at 800mA-ish wouldn't be too hard to find, if that is the problem, unlike some of the multiple different winding ones that I've had fail. Be sure to check the power consumption first, to make sure it's not got shorted turns.

Re: the rectangular power connector used on old Philips test gear, thought I had seen another recently, it was this thread: https://www.eevblog.com/forum/testgear/trying-to-find-a-vintage-philips-specific-test-gear-mains-connector-plug/msg4438555/#msg4438555
The OP was asked several times to confirm the size, pin spacing, etc, but never did update the thread. 

David

[Vince]

Thanks David for looking the socket up. So it looks like it's yet another pain in the butt of a socket then.... here comes the IEC socket....
I don't have a passion for a million different vintage cables with impossible to find power cords. I rationalize on the more modern IEC 3 prong.

Well I don't know yet if I am gonna keep this one or sell it, so it's way too early to talk about details like power socket replacement.

Anyway, I  worked some more on the thing. Seeing as contact cleaner in the tube sockets brought the power rails back to life, I did the same treatment to all remaining tubes in the instrument.

That would be 5 tubes. x4 EF86 and one E80F. 
Each time, I pulled the tube, gave it a good clean because I like sparkling glass.
Then tested the heater on the lab supply to see if it works, and how much current it draws versus what the datasheet says.
Then some contact cleaner in the tube sockets and exercise the tube in its socket for like 20/25 cycles.

Applied power....tested the thing, using my lab power supply to sweep voltage, and my chinese Vref to make more accurate assessments and.... it works !!! 

Yes... there is now life in the needle. it moves smotthly as I sweep the input voltage, and is stable, no jerkiness like the Ballantine TRMS VTVM.
In the lower ranges, the most sensitive ones, 10 and 30mV, it does what you would expect : needle goes haywire just by touching the input jacks with my fingers.
So that's good.

See ? Those blue axial caps were not at fault, told ya ! 

So it's now back to life, yeah !

But it's not perfect of course. We are now in the second pass of the troubleshooting process.... now that we got the big problems out of the way, there is now the second wave of problems, the less severe ones....

So, I see two main problems that need addressing now :

1) The needle reads way too low. At first it read 15% low, but then I let it cook for 30 minutes and when I came back, it had worsened and was now 25% off ! Grrr...  EDIT : 10 minutes later it improved a bit and is now 20% off...

Way too much to be a calibration issue, especially since it moved in the course a few minutes, so dramatically.
I maybe have an idea / suspect : look at the schematic. In green I circled the amplifier section, the part that does the hard work. 4 tubes. x3 EF86 whose filaments drew 200mA as per the datasheet. However there is also an E80F, coloured in yellow. This one, its filament was drawing only 200mA but datasheet says it should be 300mA, 50% more ! That's quite significant. So maybe that tube is tired and has low emissions, and since it's the front-end tube so to speak, the first to see the input signal... I guess having a low gain here is not good. Might explain my very low reading ?!

However this tube is quite expensive. Not crazy expensive, but expensive enough to wonder if it's worth investing that money in the old boat anchor, especially since I am skint.

So I would rather want to troubleshoot the problem more precisely to be really sure that the tube is the problem. I wish I had a tube tester...
Unfortunately to do more detailed troubleshooting, the schematic is not enough... I now need to be able to read and UNDERSTAND what the manual says, theory of operation etc.... and it's just not possible with this bloody manual that's in GERMAN !!!! 

I am not so good at German...

IF someone can find me that manual in French or English, that would be soooo helpful....


2) Problem #2 : the two indicator tubes on the front panel (coloured in magenta at the bottom of the schematic), that indicate the polarity of the input signal... neither of them ever lights up, it's so sad.
Might have a clue here as well : there is a tube / triode nearby (coloured in blue) that maybe is related to these indicator tubes. The filament of this tube is strange, it draws MORE current than expected.... it's an EF86 again, so should be 200mA like all the others, but this one happens to draw.... 300mA, 50% more !  By what phenomena is that even possible ?!    MAybe this is my problem... but just a shot in the dark and again, I need the freaking manual ot help me understand how this circuitry works so I can troubleshoot it precisely and avoid wasting money on a tube that does not need changing...


That's it for today... made good progress just this afternoon, quite happy. Now hoping I can find the root cause of these two remaining problems...

[Vince]

2) Problem #2 : the two indicator tubes on the front panel (coloured in magenta at the bottom of the schematic), that indicate the polarity of the input signal... neither of them ever lights up, it's so sad.
Might have a clue here as well : there is a tube / triode nearby (coloured in blue) that maybe is related to these indicator tubes. The filament of this tube is strange, it draws MORE current than expected.... it's an EF86 again, so should be 200mA like all the others, but this one happens to draw.... 300mA, 50% more !  By what phenomena is that even possible ?!    Maybe this is my problem... but just a shot in the dark and again, I need the freaking manual ot help me understand how this circuitry works so I can troubleshoot it precisely and avoid wasting money on a tube that does not need changing...

OK, I managed to figure that one without the manual, phew.

That tube is definitely bad, sure 100%....

I forgot to mention that it's starting to build a bit of a white residue at ithe top.....

Then had an idea... tube is an EF86 and there are 3 others in the instrument, all in the amplifier section.

So I swapped the suspicious tube with one from the amplifier. Result ? VTVM is now dead, needle stuck at 0 no matter what.
Swapped the tubes again.... meter back to life !

That's enough evidence for me....

So that's money here... not going to change this tube since the polarity indicator is a luxury.... I won't spend money on that until I have diagnosed the low reading issue, hoping it's not that E80F tube that needs changing because it's not cheap.

[m k]

For Labor I ordered T727 something, from China also.
Not exactly sure how it fits since there seems to be different inserts.

T727 is here.
It has wrong width, too narrow but not a problem.
Depth seems to be correct, same with prong width, holes are too thin though.
So finally it can be used since ceramic part is correctly sized.

Two options then.
I think I'll try China side and try how their male part fits to the machine.

https://www.superbheater.com/materials-and-fitting/high-temperature-plugs/aluminium-connector-2-pin-high-temperature.html

I'm surprized any of it fits, given the 35A rating  (which I find hard to believe knowing the usual over-inflated ratings on china stuff).
Guessing it's one of the old connectors on here (which has probably already been mentioned); https://www.plugsocketmuseum.nl/PowerCord2.html or here: https://www.plugsocketmuseum.nl/ApplConn_classic2.html.

David

Local and old service shop has a whole cable, NOS or not but it's available through their net shop, I'll visit their brick and mortar part next week with the connector and do some compares.
Machine side slot is ~40mm wide, no idea what the old grill and stuff around here had, but the guess is that all were DIN 49491.

For amperage I guess China uses those same new physics the EU also have.
On the other hand, had anybody really thought the 16A Schuko can really handle that for longer period.
If memory serves it's specsed for 10h, that's 38kWh.

[tautech]

@Vince, to make things happy with the safety of that multimeter, just stick this to the front:




Also, if you want to retain period accuracy if those Philips caps need replacing (They do...), Vishay now make them and can be had from Digikey and Mouser.

Our neighbor and friend operates a fleet of excavators for driven building pile installation and every machine has this warning plainly on the door to remind his operators to keep their mind on the job when using them. 
Jobsite incidences have reduced dramatically since the the addition of these door stickers ! 

[Brumby]

I am always accused of dramatizing.... I think this time it's you dramatizing. If you think electricians risk their life with a reputable brand, just think what of the millions of people that use dirty cheap chine meters. They are much more at risk than all the pro electricians using their Chauvin-Arnoux mete day in day out for a living.

I am sure I can find videos of Fluke meters failing in nasty ways. If you search long enough, you can always find a counter example to anything...

I do appreciate though, you showing interest in my well being. It's heart warming. Must be the X-mas effect.

I'm sure there are thousands of people measuring mains voltage every day with $10 mutlimeters - and they get away with it because nothing nasty has found its way to them.

The problem with such meters - and any with less than adequate safeguards - is when something nasty DOES come along.  This is where things get dicey.

If you're lucky, only the meter will suffer - but if you are not, then you could have a high energy explosion where your last concern will be with the damage to the meter.

These things are not commonplace - but they are not impossible.  The more frequently you make such measurements, the greater the probability you will encounter the uncommon - thus it is expected that professional gear would have appropriate levels of safety.  However, this does not mean the casual hobbyist is ok to be blasé about such things.  They are only at lower risk because they (typically) have less exposure to those circumstances.  Should they actually experience a high energy event, the quality of the protective systems built into their equipment can be the difference between inconvenience and medical intervention.


In full disclosure, I will admit to having used a $10 meter to check 240V mains, but those measurements were quick - no more than 2 seconds - and done at arms length, with the expectation it would disintegrate at any moment.  Also note, that this was done ONLY when a more appropriate meter was not at hand.  I did not like it.

[oz2cpu]

my latest score
HP 5245L electronic counter 1968 8-digit nixie 50MHz
it is the one with oven osc
https://youtu.be/5X0MLTsO_7g