Test Equipment Anonymous (TEA) group therapy thread

[AVGresponding]

I get +/-0.0010V...

(2.5x0.02%) + (21x0.002%) + 1 LSD



EDIT: With everything warmed up, mine is within 7 or 8 counts of my 8840A (2.5VDC in 20V range)

That's because I'm an idiot and used  the actual reading instead of 2.5.    Either way it is a few mV  out spec after allowing for worst case temperature drift.

If I'm going to adjust it properly I need a few reference voltages and resistors and to spend money to warm up the house.

Just had a huge vet bill.  The .001% 10 V reference is out of stock at VoltageStandard as is the dmmcheck.    So the adjust will have to wait.

I suppose I could set it against the BM789.   It is closer.

Mine's been steady as a Fluke all day, 7-8 counts above the 8840A. I suspect yours has been adjusted by an "expert"...

[Vince]

TEK 7603 FAN rebuild


I received my new bearings this week. I just fitted them an hour ago.
The size is just perfect, so indeed it was imperial size.
They fit just nice, like the old ones : transition fit. Slight pressure with the fingers, and they go in.

So I put it all back together, now overall much quieter, scope can be used even in a quiet/music free lab (but I always put music on anyway), oooor maybe not.
It's not all perfect... the overall noise level is way down indeed, so from a quantitative perspective it's just fine, am very happy.
Problem is the qualitative perspective : there is a still a horrible rattling noise, like a ball bearing that's so shot it probably drove a million miles in your car, half of it without any lubrication.

So I can call the replacement a great improvement, but not a total victory, sadly.

I am not sure where that persistent rattling is coming from.
Once I had reassembled the thing, and before fitting it back into the scope, I did spin it by hand a few times to see how it was doing, and right there I could here a rattle every now and then.. weird.

Anyway, at least I tried. Was meant as a fun and educational / useful exercise, to elevate and diversify my restoration skills/techniques... mission accomplished.
I won't hesitate to do it again if the opportunity arises. But next time I will be more careful wen disassembling the "stack" of washers and clips, draw it down accurately, so I can put it all back together as it was... because sure as hell I had to improvise a bit here when I put that one together. I really didn't anticipate there would be that many washers everywhere....
So maybe that's why it's rattling, I don't know.

I think I will just buy a new fan now I know it's a standard 90mm fan. Will probably replace it with a 230Volts model rather than the OEM 115V, so as to get much more choice here

Metrix MX53C DMM

Seller was quick to send it, it's here.

Up close it is as expected in showroom condition in it's original box with original test leads, with its original 10A spare HRC fuse, and factory calibration report.
However I had no idea if it worked, or even turned on at all, so I was still a bit anxious test it.
So I spent some time sanity checking every range/function. Everything works fine, accuracy is there, and I don't get any wild "ghost" voltage in the mV range with test leads disconnected, like I do with many of these meters usually.

It's a winner, will put it in the "MX53s that work well, keep that one, sell the other ones" list.


That's all for now...


EDIT : might have an idea about the rattling fan. I noticed once reassembled that it had quite a bit of axial play. A little is required I guess, for proper operation, but now there is at least 1mm of it and it did feel to me a bit excessive. I don't recall how much play it had in the beginning, but I if I had to take a guess, I would say it didn't have  as much.
So maybe that noise is just the fan"bouncing" up and down the shaft...
I will try adding a washer under the final circlip that locks the outer bearing.I remember seeing there was a lot of empty space between the groove on the shaft, and the bearing. Another problem is the circlip itself... it looks tired and does not bite the shaft that well.. I had to use pliers, well, my tweezers here given the tiny size of the clip, to try to tighten it, but with limited success. Maybe a new circlip and a washer or two, might help. More to tinker with...


EDIT #2 : hmmmm yes, must be that. I think there should not be any axial play at all.. given that there is this springy-like stack of washers that the outer bearing is resting against. Surely this is precisely meant to take up any axial "slack"...  If there is any axial play at all, that means this spring is... not able to operate / do its job, and you might as well remove it...
OK... so washers and a new circlip I need....

[TERRA Operative]

I made a few orders recently, stuff is on the way

- A second NI GPIB-PCII/IIA card for my test/cal PC for calibrating TDS600 and TDS700 series scopes, and for other retro computing and gaming stuffs. (I need to buy a period appropriate case next too...)
- A Sound Blaster Live sound card for the above PC, the original CT4620 gold plated one with additional addon IO board.
- PCI slot mounted CF card to IDE adapter for the above PC, will be used in place of a HDD, to enable quick OS swaps.
- A CY7C68013A-56 16 channel logic analyzer PCB from ebay, compatible with Sigrok (listed as Lcsoft Mini) so it'll be hopefully able to be used to sniff the GPIB bus for trying to figure out the Tek Field Adjustment Software.
- A couple obsolete chips for repairing stuff. Hopefully they aren't going to turn out as fakes.....
- ebay SMA torque wrench, can't be worse than doing it y hand, right?
- soon a Mouser order of parts for various projects.
- and also soon an order of machined aluminium faceplates for a few of my TM500 modules.

[Andrew_Debbie]

Mine's been steady as a Fluke all day, 7-8 counts above the 8840A. I suspect yours has been adjusted by an "expert"...

Mine is stable too, just a few mV wrong at 2.5V.   I opened it up.  From the date codes it is no older then 1995.  I found Minor rework.  Nearly all  parts appear original.  Overall the build quality looks good, but three resistor packs gave me pause.  They are SOT1, 2 and 3 on the schematic.   I suppose that is one way to adjust a value at the factory.   

The four tantalum caps are original as are nearly all of the other caps.  I dunno, I could replace them now but thing works.

[Specmaster]

I suppose the next question is do I send it out for adjusting???

I don't think it is too bad really, it is only 6mv out going by the 2 readings, here are results on my 1905A against a Brymen BM867s

As to sending it out to be recalibrated, why, when you have other meters that you can trust, and you can calibrate it yourself, using the readings shown on your trusted meters, even if they are slightly out, for the purposes of what we use them, it will be perfectly acceptable.

I have the calibration instructions and the service manual for the 1905A if you need it, just let me know.

[Peter_O]

snips:
...
my wife and I bought a house in 2021. We moved from the inner city to a rural village with nearly 1000 inhabitants and lots of Gegend* around it. (*- fields and grassland, sheep, cows, horses..)
...
We still have piles of moving boxes in two rooms and my TEA bench is not set up again. In fact it's still completely stored in the basement. 

We have ordered an individually built bookcase from a local carpenter and it will be delivered in May -I hope. That will give the space to setup my bench again. Shifting boxes and spaces..
...

Uri, maybe I missed something. But what's the point of moving from a city flat into a country house in the 'Gegend', when you need to tetris boxes and shelves to get a bench up and running? Normally the complete haul of a flat shoud trickle away into max 20% of the rooms of anything worth the label 'house'.   

I can only guess. Maybe the on wall fuse box has grown out of control and into several rooms while the electrician has been working off your wish list?

Guess II: What's the hobby of your girl? 

[m k]

I am not sure where that persistent rattling is coming from.
Once I had reassembled the thing, and before fitting it back into the scope, I did spin it by hand a few times to see how it was doing, and right there I could here a rattle every now and then.. weird.

Did you try different orientations?
Are there thin "spring" washers?

Maybe rotor is moving too much in depth direction.
Maybe some washers are finally so loose they are rotating against each others.

I've found that some silent ones are actually not so silent when they spin enough.

[Vince]

Replies are in my message "EDIT" sections... maybe you missed them.

[m k]

Yup, in my head it was strictly Metrix area.

[Andrew_Debbie]

I don't think it is too bad really, it is only 6mv out going by the 2 readings,

Yeah 6mV doesn't matter.   Knowing the meter is out of spec bothers me a little.  I decided to try to adjust against my BM789.   
Warmed up the loft.  Ran the meter for an hour and started through the steps.   

All the zeros were fine.  The next adjustment is 1.000V on the 2000mV scale.  I took the bottom off the case and tried adjusting  PR7 / A4.  PR7 fine tunes the reference voltage.    I ran out of adjustment.  There is a fault somewhere.

I suppose I'll start by checking the +/-15 Volt supplies followed by the reference.     After that maybe the 4016 that switches the reference voltage in the converter.

[Vince]

Philips PM 2440 VTVM

Been working on the thing this week-end.

Cosmetics

The face plate was littered with spots/stains that's I thought were embedded underneath the clear coat, or at least a degradation of the clear coat itself, so I thought it was hopeless. But I gave it a try anyway and what do you know, I was wrong, the thing cleaned up just fine ! 
So then I removed all the stickers.

Looks quite decent now.


Electricals

1) Was reading low, 10 to 25%. Thought there must be tired tube in the 4 stage amplifier, or otherwise some troubleshooting required in that area. But I don't have a tube tester, no spare tubes to try out either, and neither can I do proper diagnosis/troubleshooting of that part of the circuit, because I am not clever enough to understand the details of it enough for that, and the service manual is all in German.

But, looks like resting for a few months was beneficial to this instrument ! It now reads much better, and I was able to calibrate it spot on, using the user controls on the front panel. It reads... just fine.

2) The two neon tubes that indicate the polarity of the measured signal. Well turns out tehy aren't just neon lamps, no it's much more refined than that. They are actually magic eyes/ tuning vacuum tubes. Model DM70. I looked at the datasheet for that... the pattern they display looks all the world like a big exclamation point. Weird. So I looked at these tubes up close with a torch light and sure enough I could see that exclamation point shape into them, interesting....

So I am not really sure how these things are supposed to behave relative to the input signal. Again, manual is in German so not much help. Looking at the schematic has me baffled more than anything else, as the feedback from the meter movement actually drives/modulates the anode voltage of these tuning tubes, rather than their grids. The grids are rather it looks like, subjected to a sweeping voltage / sine wave coming from the power supply section.
Anyway, I can't afford to buy a new tube to go try to fix this stuff, as it's an EF86 which is way too expensive.

So since it's not essential to the operation of the instrument, it's gonna stay like that.


So I think it's ready for sale, because I made the decision to sell it.

If someone wants to rescue it, it's free for you. Packing costs 15 Euros/ The meter weighs 12kg so shipping will need to be the 15kg rate = 21.60 Euros to Germany via "Mondial Relay".

Don't forget it uses a weird obsolete power cord which I don't have, so you would need wire a cable like I did, or fit an IEC socket.

[Neomys Sapiens]

@Vince: Those indicator tubes should indicate polarity of the input signal if deflection of the instrument is >=10%.
They are similar in concept to the small auxiliary indicator on the PM2503/2504/2505 multimeters.

[Vince]

Ah OK, so it's either lit or not light... so they are using them simply as a fancy light bulb then... might as well replace them with simple neon lights and call it a day... 

Had another look at the manual.... oops, looks like I got mistaken, it's not in German (some of the words look German-ish, got fooled), but it's in Dutch, which makes sense for a Philips product I guess.... 

It's also OCR'ed , so I copied the two paragraphs that talked about these indicators, into Google Translate and... miracle, I now am less clueless.

Confirms what you just said, indicators are triggered above 10% of full scale, and are either lit or not lit, no gradation.
The other paragraph describes how it actually works. Very complicated to me, but well I guess that's how they did it back in the day.

[PA0PBZ]

Ah OK, so it's either lit or not light... so they are using them simply as a fancy light bulb then... might as well replace them with simple neon lights and call it a day... 

Now I wonder why they decided to use this tube and not a simple neon indicator, but I guess it's too late to ask the designer...

[Vince]

With some luck, he wrote all his reasoning in his engineering logbooks of the day.
With some luck, Philips archived the log books of its engineers.
With some luck when the guy retired, Philips let him take all his books.
With some luck, he gave them to his son before he passed away.
With some luck, his son didn't burn them all down to ashes to make space.
With some luck he still has them and we could look at them....

So that would require a lot of luck, but the answer may still be accessible...

[URI]

snips:
...
my wife and I bought a house in 2021. We moved from the inner city to a rural village with nearly 1000 inhabitants and lots of Gegend* around it. (*- fields and grassland, sheep, cows, horses..)
...
We still have piles of moving boxes in two rooms and my TEA bench is not set up again. In fact it's still completely stored in the basement. 

We have ordered an individually built bookcase from a local carpenter and it will be delivered in May -I hope. That will give the space to setup my bench again. Shifting boxes and spaces..
...

Uri, maybe I missed something. But what's the point of moving from a city flat into a country house in the 'Gegend', when you need to tetris boxes and shelves to get a bench up and running? Normally the complete haul of a flat shoud trickle away into max 20% of the rooms of anything worth the label 'house'.   

I can only guess. Maybe the on wall fuse box has grown out of control and into several rooms while the electrician has been working off your wish list?

Guess II: What's the hobby of your girl? 

Simple reasons:
1. Volume of our flat: We lived in a 110m² 1930s flat with >3m high walls and we utilized all the volume we could. We had shelves from 2m to 3m above our heads that gave us a lot of shelve-meters.    Our house has normal 2,5m high walls and roof pitch on the first floor.
2.  We disposed a lot of furniture that we didn't want to or couldn't take with us. 2.8m high shelves don't fit under 2.5m ceilings.
3. Work pressure. My wife and I both have full-time jobs and after all the exhausting year 2021/2022 we decided to slow down a bit. (The kitchen is usable but still not finished)

We have to rearrange the storage of many things but we don't have no hurry. In the end we will have more space left than in our flat. 

I will split a room in the basement into two rooms, one smaller storage room and one bigger lab/bench room for me. 

For my wife's hobbies a whole room is reserved - No problem, we now have one more than before in our flat. 

[DC1MC]

Is it me, or the  EBAY and his smaller German cousin Kleinanzeigen are kind of dried right now, the little that's available is way overpriced. I wanted to get me a comfort TE,not expensive, but nothing on the radar 

Cheers,
DC1MC

[wkb]

No it is not you, Kleinanzeigen is quite depleted. Marktplaats.nl, its Dutch cousin is quite the same 

Wilko

[factory]

Not had any problems spending this week, won a lot of 8 HP inductors for £50* earlier this week and a Data Precision DMM for £49 tonight.



*I know the recent history of these inductors, they were owned by a forum member on the UK radio forum who passed away a while back, his collection ended up in a real auction, the inductors made £25 in that auction (picture is from the real auction, not ebay).

Just need to find one of the Boonton (HP) Q meters now.

David

[BU508A]

Related to Neomys Sapiens hint:

So, I would be very interested in the Telefunken lab books.

 

You're not the only one. This will not end cheap. Or should I forfeit them?

I was afraid of something like this. Actually, I don't want a wild bidding war, but this book set is extremely tempting. There is already a first bid.

The Telefunken lab books are on the way to me.
No, not these ones: https://www.ebay.de/itm/354626029537
 

These ones:


 

[AVGresponding]

Not had any problems spending this week, won a lot of 8 HP inductors for £50* earlier this week and a Data Precision DMM for £49 tonight.



*I know the recent history of these inductors, they were owned by a forum member on the UK radio forum who passed away a while back, his collection ended up in a real auction, the inductors made £25 in that auction (picture is from the real auction, not ebay).

Just need to find one of the Boonton (HP) Q meters now.

David

I was the other bidder. I'm sure I'll talk to you again. Eventually...

[m k]

If someone wants to rescue it, it's free for you. Packing costs 15 Euros/ The meter weighs 12kg so shipping will need to be the 15kg rate = 21.60 Euros to Germany via "Mondial Relay".

And me dummy have thought Mondial Relay is domestics only.

BTW,
I didn't skip the Metrix part, just stopped early.
Those subject lines are forcing them authorita.

[Peter_O]

Is it me, or the  EBAY and his smaller German cousin Kleinanzeigen are kind of dried right now, the little that's available is way overpriced. I wanted to get me a comfort TE,not expensive, but nothing on the radar 

It's not you. Seems to be low tide with TE. Only thing that my filter found interesting was a HP3325A, which I talked me out of, because I've a B already.   
And price ideas are ridiculous at the moment, yes. Should things really start to move at that high prices, I maybe should switch from buying to selling.   

[factory]

Also found a HP 3325A (not interested in that) listed on ebay.de, same seller also has a Solartron 7061 listed as defekt, but the seller is new to ePay, I tend to avoid new sellers, unless it's low value items, had too many problems in the past. 

The few cheap HP BINs I've seen the last week, have sold out within a hour or two.

Sorry AVG, sods law the only two bidders interested in the Data Precision DMM, were us TEA addicts.

Even auction items sometimes go a bit silly in price, such as this HP DVM. 


David

[HenryFeng]

 :-+Very good deal on the standard inductors, they works with HP 4342A Q meter, but Boonton Q meters will give different reading from the label.