Test Equipment Anonymous (TEA) group therapy thread

[TERRA Operative]

The blue Philips caps suck, but don't worry, you can replace them with new ones of the same type! They are made by Vishay now.

[Ice-Tea]

I've standardized on red (Würth) thank you verry much 

[med6753]

If you have a Tek DM501 and it has inaccurate DCV readings I have the fix for you. If yours still reads correctly I guarantee it will eventually lose it's cookies.

Mine before the fix. That's supposed to be +2.500V.



The issue centers around R10 which is a network/input divider.



It's a sealed unit with precision 0.1% resistors with TEK P/N 307-1015-00.



It even has it's own TekWiki page.

https://w140.com/tekwiki/wiki/307-1015-00

The internal 9MEG resistor reads 8MEG or less which is incorrect.



I cut it open with a dremel and it clearly says 9MEG/0.1%.



Measure directly across the resistor and still NG.



I isolated the resistor and now measures 9MEG as it should.

 

Between the 9MEG resistor and the others below it was this obviously degraded foam. Guess what? That foam had turned conductive and was shunting the 9MEG resistor.



The cleaned out the rest of the foam with 100% IPA and restored the 9MEG resistor in circuit and now reads correctly.



Installed the unit but I did not re-install the top that I cut off with the dremel. The DCV is now accurate across all ranges. Verified with 190mV, 1.9V, 19V, and 190V.

[Vince]

Had a day off today, had a go at cleaning the 502.

Damn, I've been looking for a reasonably priced Type 502 or 502A for a few years and nada. And you've got 2. Me jealous. 

I don't have two but 5 !     x2 502 plus x3 502A

It's strange that in Tek's homeland they would be even more difficult to find (at a decent price at least) than in some remote random small country like Frogland.
I guess that's my revenge for all the yanks that get 575 curve tracers with the 400V option and lots of cool HP gear for cheap.
No such things here 

[Vince]

Won't bore you with too many details and too many pics... I think I will soon create a new topic in the repair/restoration section, so I can have all the space I need for my write ups and lots of pics, and the restoration to come. I will try to do that this week-end hopefully and will post the link here for those who might be interested.

Here it is, fresh from the oven : https://www.eevblog.com/forum/repair/(classic)-tektronix-502-scope-repair-restoration

[m k]

Last BNC order is now settled.
BNC to RCA adapter was fine, gender changer female to female tube also.
None of T-adapter models were fine, some or all inner bottom metal shoulders were missing, triple female inner parts were also tilted.

Only mechanically good 3-contact adapter was Y-adapter with square center block.
That's the one where connectors of the other side are side by side.
(I hardly need more complex asymmetric adapters than RCA)

One problem with missing metal shoulders is that older connectors can start being loose because depth of the other side is too deep.
In my case new male cable ends were already loose.

All parts are unknowns from far away, maybe there are many makers with many different procedures.
RF is not tested and only some had any mentions.

[ftg]

The blue Philips caps suck, but don't worry, you can replace them with new ones of the same type! They are made by Vishay now.

Orange 47µF 25V Philips electrolytics are almost universally dead when I encounter them in equipment.
Those get replaced without even bothering to measure them.

[EE4all]

Picked up a broken 8340a sweeper. 

Now if I can fix it, I can use the TAM to do automated level adjustment calibrations to my 8563e analyzers (some hundreds of steps to do it manually). Somehow I ended up with 4 of these and and 3 are fixed now (need a YTO for the 4th still).

The 8563e's I got into because they were part of the automated calibration stack for my e4437b, and I took a liking to them.

Down the rabbit hole. No bottom in sight, send help.   

[TERRA Operative]

Down the rabbit hole. No bottom in sight, send help.   

No. You are stuck down here with us.

[wkb]

Down the rabbit hole. No bottom in sight, send help.   

No. You are stuck down here with us.

[tggzzz]

Down the rabbit hole. No bottom in sight, send help.   

Knowing the difficulties, there's a generous amount of help already prepared: see the previous 136834 posts. 

[factory]

Voltage de-rating is more important, modern tants are just as unreliable if you don't de-rate, YMMV.

In this case 50V tants were not available from my stock and I didn't know the expected voltages before replacing the first dead 1.5uF at 35V, which someone else smoked before I acquired it. The brown 0.47uF at 35V is still fine. The 4.7uF Nichicon caps were left over from the Tek 24xx series scope repairs. There are no more tants in this device.



David

Something at "the other plaice" reminded me of this, I never fully revealed what was hiding inside the Spannungsgeber box.







David

[EggertEnjoyer123]

I'm back with a high voltage insulation tester which I bought for $30

It was broken but the problem was pretty obvious: a ribbon cable fell out so the display and controls didn't work. After putting it back everything worked. (The voltage is still slightly off though according to my multimeter, so it might need cal).

[salvagedcircuitry]

Call me crazy, but does it make sense to purchase a broken E5062A and repair back to it's former glory? The E5062A is definitely showing it's age, but it's realistically ~$500 broken and is a good value proposition for my personal lab. For about double a broken E5062A, I can grab a SSA3021X Plus and convert it to a SVA1032X, but I think the E5062A may be a more well rounded instrument.

What do you guys think? 

[EE4all]

I think if you get a E5062A, then it won't stop there. Will it be out of alignment once you fix it? Do you have all required devices to then align it? The whole endeavor of fixing broken gear can become the main aspect of the hobby. 

If you just need to get some other work done, then think hard on the Siglent.

[salvagedcircuitry]

I think if you get a E5062A, then it won't stop there. Will it be out of alignment once you fix it? Do you have all required devices to then align it? The whole endeavor of fixing broken gear can become the main aspect of the hobby. 

If you just need to get some other work done, then think hard on the Siglent.

So you're saying I should do the former. Hehehe. Got it 

[EE4all]

Of course! Then post here for therapy. 

[Vince]

Some more old Tek : the deal of the year my goodness.... a 556 for only 39 Euros ... ON OFFER at that !!! 

https://www.leboncoin.fr/ad/accessoires_informatique/2871101125

Local pick-up only of course...and of course as always it's at the other end of the country from me 

No I won't be trying to get that one, it's too big for me, but for whoever is local, it's incredible.

Seller of course sees no value in this thing and says "it's an ideal source of parts to build an audio amplifier " .
Well, me thought it would an ideal source of parts to build... a 556 eh ?! 

Anyway, boy I am frustrated I can't have that one ! 
But maybe it's better this way... if I had it, I would part it to restore my other Tek scopes. I have no love affair with the 556... maybe it's best that it goes to someone who will restore it and enjoy it for what it is.
Sadly we all know how it will end... it will get ripped of its tubes then the scope will go straight to the local junk yard 

[TERRA Operative]

That is one chonky boy...

[RolandK]

The 556 is the ulitmative 500 series scope. Go get it , you will not regret it  and you will not part it out  - you will love it on first view - believe me. 

[EggertEnjoyer123]

Call me crazy, but does it make sense to purchase a broken E5062A and repair back to it's former glory? The E5062A is definitely showing it's age, but it's realistically ~$500 broken and is a good value proposition for my personal lab. For about double a broken E5062A, I can grab a SSA3021X Plus and convert it to a SVA1032X, but I think the E5062A may be a more well rounded instrument.

What do you guys think? 

Get a LiteVNA

[Vince]

The 556 is the ulitmative 500 series scope. Go get it , you will not regret it  and you will not part it out  - you will love it on first view - believe me. 

Yes I hear you but really, really, it's too big for me. It's more than I can chew. It's just too big to fit on the bench, it would need a super large custom cart made, and I would not have space to have a cart sitting there. My lab is in the living room, I don't have the space. The scope would have to sit on a shelve, gathering dust, which is not the point is it...

Plus even if I could find someone to bring it to me, it would cost me 100 at least to pay for their service, so 139 total.. when my bank account is already negative and I need lots of money to fix the car, thanks to it failing the safety inspection last week, and I have only 2 months to do all the repairs...

My TE addiction does have some limits after all... the real gigantic massive boat anchors like the 556 just don't fit my TE "profile"... I am not " Paul Carlson's lab " with unlimited funds, a giant heated hangar dedicated to boat anchors, with 50,000 Euros worth of heavy duty shelving units, and literally a fork lift in the hangar to move the TE around ! 

It really hurts not to get it but I just would not be a good home for it. I am tempted to get it but only to rescue it from the tube hoarders and the junk yard... but then what would I do with it once I have it ? Who would want it from me ? Nobody, so it would just sit there unused, a tragedy.

Sadly I just don't see a good solution for this scope 

I have already saved / rescued 20+ of these old Tek scopes and went to great lengths to rescue that 502 just the other day... I just can't save them all sadly 


EDIT : remorse is eating me alive, trying hard to find a scenario for this scope now  ... maybe I can get it, to rescue it from the junk yard. Then once I have it, I will give it a good clean inside out, fix it electrically to make it all good, ready to go... then I can put it up for sale for a decent price, 150 or so, at least, so that tube hoarders don't find it economically viable/interesting to buy, but that it rather appeals to some collector somewhere.   I am trying hard, I am trying hard...

EDIT #2 : I just realised... with a 556, since it's got a dual beam CRT and two vertical plugins... one could feed the same signal to both beams, but one would go through a regular amplifier, whereas for the other beam it could go trough a spectrum analyser plugin instead, so you would get a display of the signal in the time domain and frequency domain at the same time... an MDO scope from the '60s, hollow-state !!!     

Hmmm..... that's quite something...

[TERRA Operative]

Just buy it already!

[Vince]

Buying it would be by far the easiest part of the story.... but then how would it magically traverse the country to get to me ? That's the hard, inextricable part....

[wkb]

That is of secondary importance