Test Equipment Anonymous (TEA) group therapy thread

[TERRA Operative]

Those cans are much easier to remove if you have a slender set of side cutters to cut the legs one by one.

[Robert763]

Given the impact damage it could be a cracked solder joint or PCB trace at the capacitor.
Nice to see it has the readout board fitted. It was left off most R7603s.

Robert G8RPI.

[BU508A]

[...] make my b-day happy, as I've failed miserably with the tri-lug triax connector

You can get them at Mouser or Digikey (all are three-lug types):

Mouser:
Pomona: Pomona 5218 ca. 54 Euro / connector
Trompeter: PL75-55 ca. 41 Euro / connector

Digikey:
Pomona: Pomona 5218 ca. 55 Euro / connector
Trompeter: PL75-55 ca. 42 Euro / connector

Perhaps this thread is interesting for you: https://www.eevblog.com/forum/testgear/cheap-triax-connector/

I've attached the datasheets below.

(NAWTS)

[Neomys Sapiens]

Perhaps this thread is interesting for you: https://www.eevblog.com/forum/testgear/cheap-triax-connector/

That post made me wonder - what would someone, who thinks that a coaxial connector is below $1.- even want with a triaxial connector? He should have arrived at the point where it is obvious that those are utter crap looong before needing triax and the instruments where it is used.

[Neomys Sapiens]

I caught a compact Loop- and RCD-tester for a mere 20.- It is not my daily occupation, as I'm not in the installation business, but better to have one available than not. That way I can retire a far older and larger unit, which is languishing somewhere in my cellar in favor of one that will be available on short notice, because it can be kept within reach.

[Vince]

Tektronix R7603 scope repair



@Med : thanks for the offer !   
Tehg uy appears to sell internationally but costs a lot + need to add customs and taxes and god know what, and wait a long time probably.... and I hate blue ! I hate blue LEDs and LCD backlight, with a passion... seeing blue yet again, on a PCB, especially on a vintage TE where it looks so out of place...really eats the cake !
I would rather make my own board, if just to chose the colour... and ideally no colour at all, bare PCB, to match the existing PSU PCB.
However I am not yet productive enough to master doing even simple board like this... so for now I think my plan is to salvage the old can : saw the can say half an inch from its base, so I can reuse the base and be able to solder the new caps to the existing pins. Costs nothing.

I already need to make adapter boards to recap my rack mount Tek type (3)17, then some more for my type 575 curve tracer, some more for XYZ in the future... I really need to master this dance so I can make customs boards for any piece of TE I am working on, quickly/painlessly. It's a goal of mine...

Anyway, it's fixed !! 

I measured the old filter cap at only 2,000uF instead of the gigantic 18,000F it's supposed to be, so yet not quite good enough !
I grabbed an old salvaged 10,000uF cap from my stock, which tested just fine on the Chinese component tester... and hey presto it works !
First I simply held the cap by hand in contact with the pins of the old cap.. instantly the ripple was under control 
Then I tried soldering it so I can get my hands free and start testing the scope again.. but my modest ancient 50 Watt Magnastat Weller iron just doesn't cut even on the positive pin of the cap... so yeah, the 4 big ground pins, forget it. So instead, in  desperation, I simply connected the cap using crocodile test leads ! Gotta do with what you have eh !    With such long leads, ripple worsened a bit, but still plenty good enough for the 5V regulating circuitry downstream, to fdo its job -->  5V rail is not spot on , and ripple free, it works 

Then I turn my attention to the scope's CRT to see how things are going.... and the display is all over the place, garbage, very sick, a shit show.... 
So I thought maybe some other power rail just died on me. So I quickly check them all.. no, they are all good...
Then I turn back to the display.. and it's fine ! So it was only a temporary glitch... probably some cap reforming somewhere... so yeah really need to recap the entire PSU for starters..

So now that the 5V rail was fixed and the display behaving, I tested the scope again... and look at that ! Now it's all fine : I can display the 4 traces just fine, they look fine, stable, and as for sweep, all sweep speeds now work just fine, whereas last night most of the settings would lead to all traces disappearing from the screen !

So now I need to recap the PSU. But I need, absolutely... absolutely... a more power iron ! Mine really, reality doesn't cut it here, and I don't want to ruin the scope.
I can't afford to spend money on a proper iron, so I will have to resort to getting the cheapest chinese junk I can find, that's got enough grunt for the job... like, 30 Euros shipped...some old junk. Hell maybe not even an "electronics" grade iron... just an old unregulated iron, that you plug into the mains and has a massive tip and takes 30 minutes to heat up... that should do it. Power, thermal mass and cheap, are the motto  here !
I will se what I can find on-line...

I need to do it quick, because taking the PSU assembly out of the scope was a HUGE pain, lots of connectors all over the place. Took notes and pics but still, I don't feel confident at all ! I need to put this PSU back together before I forget how things plug where ! Actually there is ALREADY a brown two pin connector (there are two of them) that I am not so sure where it goes, and my pics don't tell me. 

The guy who wrote the TEk manual clearly was on crack ! He says the PSU slides out the back, comes out completely , with all cables still attached to it, enough slack, and you can operate the scope with the PSU out of the scope !  Come on ! You have to unplug half a dozen cables before you can even BEGIN sliding the assembly by one inch only... then you need to unplug some more cables to actually slide it out. And even once it's out... it's still has a short leash : there is 6 wire harness that's soldered directly the PUS PCB ! So there is no unplugging that one !!! 
It's worse than that but I make it short because I am trying not to vent al my frustration and anger on here... I am trying to spare you. Al lI can say is that I hope the guy who wrote such a monumental lie, got fired promptly afterwards, and die soon after, after a long suffering. Yes, I am THAT angry ! Taking this PSU out is a total disaster !
I guess it's made somewhat worse by the fact that servicing was probably optimized / designed for the bench top scopes not that rack mount.

Anway. Check both vertical plugins, they appear to work fine, not even dirty pots.
Only issues I found was with the time base plugins. One of them fails to tell the mainframe/readout when the time base is calibrated : even when I turn the little CAL red knob fully CW, I neither feel or hear any detent, as if there wasn't even a switch mounted at the other end of the shaft, strange.
Luckily the other plugins has a working detent, and it makes the readout happy.

However, I noticed two more issues, that somehow affect BOTH plugins ! So either it's not an issue and I just need to RTFM, or it's a common failure on these things and both have been hit by the same plague whatever that may be. So the two problems I notice are

1) The button to select triggering on positive or negative edge, appears not to work. NO matter if it's in or out, it makes no difference 

2) The delayed time base doesn't display the intensified portion of the trace. It all behave as you would expect, except the "zoomed in" trace does is not displayed.
so, if I pull the main sweep knob, then turn the "trigger delay" pot fully CW to the "run after delay" position, then as expected, the trace is intensified, and using the main knob I can vary the span/width of the intensified portion, and move it left and right using the vernier control. It all work normally that is, except the intensified trace does not show up ! 

I popped the two side panels on one of the TB plugins to have a quick peak inside to see if there were dipped tantalums in there. It's quite busy in there so I can't get to see 100% of the inner board component side. However I could see most of the components, and spotted no less than.... 21 red little devils !!!! 
So maybe there are a few more in there, say 25 total. Two plugins, that's 50 tants for these 2 plugins alone ! Getting expensive ! 
Lucky Terra can get them cheap... or as was suggested earlier, I can just replace them with cheap modern low ESR aluminium caps, with double the capacitance value.

Anyway, diagnosis has been made... it was just f ailed filter cap on the 5V supply.
So now I need to order the caps to recap the entire PSU like Papa Smurf did, and find cheap but beefy iron to handles those cans easily / painlessly.
That bloody boat anchor is using up my entire bench, so I need to do that real quick, not in 3 months.

[Neomys Sapiens]

As promised, the details from the Weinheim haul - with some photos. (without the coax adaptors and filters, as I have sorted those away directly)

The 'Spitzenwert-Messgeraet' (peak voltmeter) works perfectly, as I was told by the seller. When switched to a time constant of 5s, it takes 5s for a full deflection value to decay. In the switch position 'infinite', no noticeable droop occured during 20 minutes.  The little beast will find some uses, I'm sure.

The resistance box is, well, a resistance box. Values as labeled. Nice construction.

And a very elaborate variable capacitor from Siemens. With shielding hood, dial and pointer and a reduction gear. The movement of the pointer over the 180° on the dial take 5 complete rotations of the knob. The capacitor might have 2 systems, as there are 3 solder tabs on the rear. Have not looked into such details yet, also have not yet measured the range.

[factory]

Those cans are much easier to remove if you have a slender set of side cutters to cut the legs one by one.

I guess use a cheapo set of cutters if the capacitor pins are steel.

Tektronix R7603 scope repair



@Med : thanks for the offer !   
Tehg uy appears to sell internationally but costs a lot + need to add customs and taxes and god know what, and wait a long time probably.... and I hate blue ! I hate blue LEDs and LCD backlight, with a passion... seeing blue yet again, on a PCB, especially on a vintage TE where it looks so out of place...really eats the cake !
I would rather make my own board, if just to chose the colour... and ideally no colour at all, bare PCB, to match the existing PSU PCB.
However I am not yet productive enough to master doing even simple board like this... so for now I think my plan is to salvage the old can : saw the can say half an inch from its base, so I can reuse the base and be able to solder the new caps to the existing pins. Costs nothing.

There is something I don't like about all those adaptors, it's the clearance between the tracks, would like to see a bit more, especially for the higher voltage cans.
When I was looking at JCBPCB or whatever they are called  , they didn't have a bare/no color PCB option, though in some cases the solder mask would be better.

David

[Zoli]

A few PCB houses offer clear solder mask(even with black FR4); I you want no solder mask, add keep-out zone set for the solder mask layer.

[TERRA Operative]

Yep, make a keepout for the soldermask the size of your PCB, then add a note when ordering that it is intentional.

I did it for the high voltage option board I designed for my HP 3325A func gen. Worked out well and looked good and more 'original'.

(Bottom left corner)

[Zoli]

Yep, make a keepout for the soldermask the size of your PCB, then add a note when ordering that it is intentional.

I did it for the high voltage option board I designed for my HP 3325A func gen. Worked out well and looked good and more 'original'.

(Bottom left corner)

For me, it looks like clear solder mask; no solder mask should present the surface finish(HASL, ENIG, etc.) instead of plain copper   
/remember the days of Positiv20 and high pressure Hg lamps with broken envelopes...

[TERRA Operative]

That is ENIG plating on that board.

[Zoli]

That is ENIG plating on that board.

Well, you certainly should adjust the white balance of that camera(and maybe more), because it didn't looks like ENIG at all; or choose a better PCB house.

[TERRA Operative]

Looks gold to me on my calibrated monitor and in real life.. 

[Zoli]

Looks gold to me on my calibrated monitor and in real life.. 

ASUS ProArt PA278QV here, and still looks red, not yellow  Otherwise, I trust you(BIG MISTAKE) 

[BU508A]

Looks gold to me on my calibrated monitor and in real life.. 

ASUS ProArt PA278QV here, and still looks red, not yellow  Otherwise, I trust you(BIG MISTAKE) 

I think this red colour is a reflection of the red cable from above.

[TERRA Operative]

Dell precision 7520 with 99% Adobe gamut Sharp brand Igzo panel.

But I was probably wearing a red t-shirt which caused a colour cast.


Don't tell me we have an electronics version of that fkn blue/black or white/gold dress...

[Zoli]

...
Don't tell me we have an electronics version of that fkn blue/black or white/gold dress...

That particular picture was heavily overexposed. As result the recorded colours had nothing to do with reality; because of the colour distortions, it is impossible to determine the original colours. Memories of the chemical processing...
In the current case I think there is a big difference between the original HP board(above) and the later added board gold coating; add possible reflections to the situation, and here we are.

[Vince]

Back from work after 2h15min overtime... it's 19H30 and I am finally home ! 

Never mind... I will leave two hours early tomorrow evening ! 

I don't understand what's the fuss about Terra's picture... I have a very shitty monitor I guess (10 year old junk that I got broken and somehow managed to fix), and very shitty eyes for sure (even with my glasses on, I can't see squat), yet it all looks gold plated to me ! 
Different shades of gold, sure... but still gold 

[Robert763]

@DC1MC
On their way to you.

[DC1MC]

@DC1MC
On their way to you.

Holly-canolly on a stick, are they also gold plated as well !!!  , thanks a lot Robert, kindly please PM with expenses  !!!

Cheers,
DC1MC

[Robert763]

Genuine aerospace grade Trompeter.

[TERRA Operative]

Whoops...

Just won an auction on another TM500 module and mainframe... I see TM500, I buy TM500.....
This time it's an SG505 ultra-low distortion oscillator in a TM502 2-bay mainframe with a toolbox too. All for about US$40 plus shipping. 

One more to add to the list.

[Robert763]

Won a ebay auction for a broadband clip on current transformer. A ETS Lundgren 91550-1. 10kHzto100MHz up to 350A with 1uA sensitivity. In case you didn't guess it's for EMI measurements with a spectrum analyser. It arrived today and is clearly as new and unused. 

[Specmaster]

This calculator was delivered this morning as promised and when tearing it down for inspection, it had badly corroded Ni-Cad battery pack, corrosion on the main board and also on the keyboard PCB (on both sides).

Boards cleaned up nicely and in the process of cleaning, discovered that one track on the keyboard board had been eaten completely away, so that was repaired with a patch wire joining the bits together. Battery wires had corrosion creeping along them, coming from the battery connections, making it impossible to find a good piece of wire to solder to the new battery. Replaced the wires and also replaced 2 electrolytic capacitors and sorted out the clusterfuck of soldering at the connections.

Reassembled and tested, and horror of horrors another one with a duff segment in the LED display but is useable while I try and source another replacement module, making 2 of the 14 digit displays that I'm now looking for.

The case when it arrived had paint splodges on it, all cleaned off now after a struggle, as the case is textured.

I'd love to get a Commodore M55, big beast with 55 buttons and are rare, like hens teeth.