Test Equipment Anonymous (TEA) group therapy thread

[tautech]

Just a thought Vince for the +12V rail, check D1167 the 30V zener as I have seen old zeners drift outta spec.

[25 CPS]

Slow day so I decided to go ahead and test the Fluke 27.  No go.  I checked the 9 V Eveready battery that was included before installing it and it measured 8.6 V so I put it in figuring it’s close enough to get me through some quick testing and the meter didn’t start up up.

<snip>

 Putting it in the Fluke and trying to use it completely killed it. 

Did you get a service manual? If so, the fairness algorithm is at least trying  because the battery that I got with my 27 works.  Was yours calibrated and stickerized?

You know, I was wondering about the service manuals and packaging mishaps because mine came with two of them there complete with the one page insert.  I wonder if I might have gotten your service manual?

The Fluke box inside the shipping carton appears to have never been opened before it got to me and the 27 doesn't have any calibration stickers on it.

[Vince]

Just a thought Vince for the +12V rail, check D1167 the 30V zener as I have seen old zeners drift outta spec.

Yes I Could do that... now that I have  575 curve tracer ! 

According to the manual the Zener is there a safety device to protect the passe transistors from over voltage if things go really wrong.

I just replaced that +12V rail we are talking about, with my lab power supply. No improvement whatsoever as I thought... but at least I can see how much current it's drawing which can only be interesting right ? It draws only 320mA !!!  So this rail is no shorted at all, not even overloaded... the pass transistor is a beefy TO3 thing, it's bound  to be able to source much more than 320mA ! 

[mansaxel]

Slow day so I decided to go ahead and test the Fluke 27.  No go.  I checked the 9 V Eveready battery that was included before installing it and it measured 8.6 V so I put it in figuring it’s close enough to get me through some quick testing and the meter didn’t start up up.

<snip>

 Putting it in the Fluke and trying to use it completely killed it. 

Did you get a service manual? If so, the fairness algorithm is at least trying  because the battery that I got with my 27 works.  Was yours calibrated and stickerized?

You know, I was wondering about the service manuals and packaging mishaps because mine came with two of them there complete with the one page insert.  I wonder if I might have gotten your service manual?

The Fluke box inside the shipping carton appears to have never been opened before it got to me and the 27 doesn't have any calibration stickers on it.

The plot thickens!

Did yours contain a set of normal test leads? Does not look like it from the picture.

Other than that, was it complete with three probes and a bunch of small accessories in the pouch?

If you could consider parting with it, I'd pay postage for that extra service manual.  Let's call it my "enabler compensation" 

[factory]

Yeah I remember reading about this, hence why I immediately noticed it was branded IBM on the face plate and thought it was cool and added bit of historical value to it 

As for voltages yeah but I don't find obvious test points for them. Am trying to download the manual from Tekwiki but the download keeps failing ! Driving me nuts. So in the meantime I am doing it impro style, just looking around.

I noticed on a small board atop the main transformer, a dodgy looking axial electrolytic cap. Some nasty looking substance escaped from it, see picture...
I pulled it and measured it. Somehow capacitance and even ESR were still fine ! I replaced it anyway just to see if it would make any difference at all.
It's a 3uF 150V one. Plenty of 3,3uF but all low voltage. Closed I had with a high voltage rating was a 4,7uF 150V. Good enough for testing purposes I thought. So I soldered that in. Made no difference. Oh well...


......snip......

Now if I could bloody manage to download this freaking service manual !!!!! 

That capacitor is a Sprague 109D wet tant  they are well known for leaking the acidic electrolyte, following failure of the seal.

Oh, those again ?! 

I remember you telling me about these things, when I showed the two crusty one in the trigger rotactor in my HP 120B scope !

No, those in the hp 120B are not tants, the pair of crusty capacitors in series on the trigger switch (205, C206) are ordinary aluminium electrolytics, part no. 0180-0050, my dead-tree edition manual says they are 40uF but disagrees on the voltage rating on different pages, one states 500V & the another 50V.
The 120B unreadable-crap-editionᵀᴹ manual from Agilent only has 500V mentioned (no separate page for list of hp parts numbers). Don't suppose someone could clean off the originals and confirm which voltage rating is correct. 
Looking at your picture, I'm doubting they are 500V due to the size, they don't look big enough and other manuals such as the 3400A list 0180-0050 as 50V.

David

[mnementh]

There it is... the first scope ever on my new bench in the new place. Feel honored, Al. 

All home and inside; just sitting there while I make a place for it in the lowest traffic/clean & dry corner of the dwagon cave. Gonna be up on a empty bin, same room as the TV so you know it's safe.

mnem
Oooooh... I heard a screw rattling around inside... maybe I should open it up...

[tautech]

Just a thought Vince for the +12V rail, check D1167 the 30V zener as I have seen old zeners drift outta spec.

Yes I Could do that... now that I have  575 curve tracer ! 

According to the manual the Zener is there a safety device to protect the passe transistors from over voltage if things go really wrong.

I just replaced that +12V rail we are talking about, with my lab power supply. No improvement whatsoever as I thought... but at least I can see how much current it's drawing which can only be interesting right ? It draws only 320mA !!!  So this rail is no shorted at all, not even overloaded... the pass transistor is a beefy TO3 thing, it's bound  to be able to source much more than 320mA ! 

OK good. 
IIRC there's a resistance spec for each rail that might be worth checking despite it only drawing 320mA.

[tautech]

There it is... the first scope ever on my new bench in the new place. Feel honored, Al. 

All home and inside; just sitting there while I make a place for it in the lowest traffic/clean & dry corner of the dwagon cave. Gonna be up on a empty bin, same room as the TV so you know it's safe.

mnem
Oooooh... I heard a screw rattling around inside... maybe I should open it up...

It would be just plain rude not to ! 

[Cubdriver]

No, those in the hp 120B are not tants, the pair of crusty capacitors in series on the trigger switch (205, C206) are ordinary aluminium electrolytics, part no. 0180-0050, my dead-tree edition manual says they are 40uF but disagrees on the voltage rating on different pages, one states 500V & the another 50V.
The 120B unreadable-crap-editionᵀᴹ manual from Agilent only has 500V mentioned (no separate page for list of hp parts numbers). Don't suppose someone could clean off the originals and confirm which voltage rating is correct. 
Looking at your picture, I'm doubting they are 500V due to the size, they don't look big enough and other manuals such as the 3400A list 0180-0050 as 50V.

David

40uF, 50V.



-Pat

[mnementh]

Eh ?! Since when does Dwagon have an interest in ancient glowing Tek scopes ?!    Had not gathered that so far ?! 

And... I thought another GWN fellow the other day talked about getting it ! You stole it from him ? Not nice !

No, I think this is a little coöperation between TE people. All will be well.

Ah OK cool, I prefer that. I was this close from swimming across the Atlantic ocean to go get the Dwagon and cut his tail off.

While I do love my 54645A,  I am still the resident 2465 poster-child. Just a small herd. As an aside, for the longest time my primary scope was a 454 inherited from "another Dave". That scope and that Dave and I had... history.  Bitseeker was kind enuf to give it a good home when I had to "thin the herd" prior to visiting Canada.

Now, now, now... despite what you may have heard from and/or aboot me... I may be a assh'o, but I'm not 100% a dick.  The ol' tinkerdwagon will belch a little fire if you get under his scales, but he's mostly harmless and well-intentioned.

Pack a lunch; you're gonna be at it for a while. And watch out; that thing might be loaded.

mnem

[mnementh]

...Anyway I am fucked now : I didn't like these scopes before, but now I have a brand new one on my bench, in the flesh, that I see how nice it is, I can't get myself to sell it ! Even for a profit.
Luckily cost me only 40 Euros and zero shipping  so it's not a huge expense.

As for fixing it, not sure it can be fixed, but I will keep it anyway....

Guy said he knew nothing about scopes, a 70+ yo chap, said he got it from his mother in law (which therefore must have witnessed the construction of the Titanic ! ). Said he powered it up, he saw a trace on the screen, then after 30 minutes or something the trace disappeared.

I tested the scope, you can get a trace no matter whzat you do. I guess the CRT HV transformer just gave up the ghost, probably, and good luck finding another one of those, never mind at a price that makes sense.  Will try and probe around a little just in case I get lucky and it's some discrete component instead, but I am not too hopeful !    Will only do it for the fun of working on it, but zero hope as far as I am concerned.... 

Oh my gars and starters... The 453/454 are quite possibly the best-documented of the Tek lineup, both from the manufacturer and resources on the www. No matter what's gone wrong with the one you have, someone has had the problem and posted a fix for it. I remember reading where a fellow rewound the HV multi by hand successfully!

Point being... google the fuck outta your problem, and be patient. You'll find the answers; you just gotta be willing to take the deep dive on research.

mnem
 

[Vince]

Yeah I remember reading about this, hence why I immediately noticed it was branded IBM on the face plate and thought it was cool and added bit of historical value to it 

As for voltages yeah but I don't find obvious test points for them. Am trying to download the manual from Tekwiki but the download keeps failing ! Driving me nuts. So in the meantime I am doing it impro style, just looking around.

I noticed on a small board atop the main transformer, a dodgy looking axial electrolytic cap. Some nasty looking substance escaped from it, see picture...
I pulled it and measured it. Somehow capacitance and even ESR were still fine ! I replaced it anyway just to see if it would make any difference at all.
It's a 3uF 150V one. Plenty of 3,3uF but all low voltage. Closed I had with a high voltage rating was a 4,7uF 150V. Good enough for testing purposes I thought. So I soldered that in. Made no difference. Oh well...

......snip......

Now if I could bloody manage to download this freaking service manual !!!!! 

That capacitor is a Sprague 109D wet tant  they are well known for leaking the acidic electrolyte, following failure of the seal.

Oh, those again ?! 

I remember you telling me about these things, when I showed the two crusty one in the trigger rotactor in my HP 120B scope !

No, those in the hp 120B are not tants, the pair of crusty capacitors in series on the trigger switch (205, C206) are ordinary aluminium electrolytics, part no. 0180-0050, my dead-tree edition manual says they are 40uF but disagrees on the voltage rating on different pages, one states 500V & the another 50V.
The 120B unreadable-crap-editionᵀᴹ manual from Agilent only has 500V mentioned (no separate page for list of hp parts numbers). Don't suppose someone could clean off the originals and confirm which voltage rating is correct. 
Looking at your picture, I'm doubting they are 500V due to the size, they don't look big enough and other manuals such as the 3400A list 0180-0050 as 50V.

David

OK ! 

50V or 500V yeah not quite the same thing ! 

However when you look at the schematic, 500V is silly. Plus, given the size of these caps and their capacitance value, 50V adds up, 500V would defy the laws of physics of cap technology of the day ! 
Well even today it would still be a tight fit...
So as Cubdriver jsut said, of course they are 50V...

Anyway, have some news for the 453. Bad new, as I though the CRT transformer is toast. Actually it smells like toast as well ! Hoping the smell will go away if I open the windows.... but it's midnight and chilly outside here...


I removed the back cover of the cabinet, hoping to find some CRT related componentry hiding there. I was well inspired, components there were.
See the CRT schematic attached. The primary winding of the transformer is fed via 18V unreg or so, switched by a big TO3 NPN tranny, Q930. Supply is protected by a 2A fuse. So not the most complex thing to figure out eh ? Fuse was blown... great. checked if the tranny was short collect / emitter... Was not. Checked the winding of the transformer.... shorted !
In case it was a red herring of some sort, misprobing or getting confused one way or another... I decided to give it a chance. No, I didn't replace the fuse hoping for the best, please ! 
No, I hooked my lab power supply again, so I can watch current draw... thing was clearly shorted, it would take as much current as I would give it. I stopped before the fuse rating (2A). Think I went up to 1.5A briefly, then I heard some faint and spurious noise coming from the scope... turned it off and pulled the plug. It was the CRT transformer.. thing was smelling hot, and a horrible chemical like smell was coming from it. What ever that was.
So clearly the primary was shorted, and blew the fuse.

So unless someone has a cheap spare transformer, this scope is toast and just taking up space.... don't have the equipment to rewind it and never done it so not an option. That said since it's dead, I have technically nothing to lose, can't get worse, so might as well pull it and unwind it  ?! As good a pretext as any to get some hands on experience ?!  I don't know...

Well I am lygin, I have already unwound a transformer... the one from the SMPS of my Tek 2232 scope. MOSFET got shorted and 240V mains blew the primary  of the coil/transformer of the pre-regulator... I remember taking notes of number of turns, wire disaster and resistance. It's all there on EEVBLOG in the appropriate repair thread, somewhere... was a few year ago.

Anyway, at any rate there is no quick fix so I can button it up and put it in storage mode to free the bench.
Would still love to fix it somehow, and see a trace on the CRT. Just for smiles.

[Vince]

I remember reading where a fellow rewound the HV multi by hand successfully!

Ah.... there is hope then, I will send him mine ! 
hopefully he lives in Europe or shipping will be prohibitve ! 

[tautech]

I remember reading where a fellow rewound the HV multi by hand successfully!

Ah.... there is hope then, I will send him mine ! 
hopefully he lives in Europe or shipping will be prohibitve ! 

Check for its Pt# here:
https://www.sphere.bc.ca/test/tek-transformers.html

[med6753]

I remember reading where a fellow rewound the HV multi by hand successfully!

Ah.... there is hope then, I will send him mine ! 
hopefully he lives in Europe or shipping will be prohibitve ! 

It would be wise to check the HV rectifiers and capacitors on the secondary side. That could have been the reason the HV transformer smoked. 

[Vince]

I remember reading where a fellow rewound the HV multi by hand successfully!

Ah.... there is hope then, I will send him mine ! 
hopefully he lives in Europe or shipping will be prohibitve ! 

Check for its Pt# here:
https://www.sphere.bc.ca/test/tek-transformers.html

P/N 120-0360-00

Too bad, apparently they had a NIB one for only 35 dollars (canadian ?), would have been 25 Euros tops, could have been reasonable but then with taxes and import duties and shipping, would probably end up at 3 times that... Anyway, it's already sold so no point thinking about it....

Will investigate the rewinding route I guess, most economical, and most "fun" way as well... I guess you aren't a real man until you have rewound a transformer ! 

@MED, yeah will check... but it's not a problem since these are discrete components that can be replaced easily. Transformer needs rewinding any way so let's do that... one day 

[Neomys Sapiens]

@Vince: 'wire disaster' is the most appropriate typo in this context!
 

[xrunner]

@Vince: 'wire disaster' is the most appropriate typo in this context!
 

If it was the Tek 575 curve tracer's transformer he'd be converting an entire corner of his lab into a rewinding facility. 

[tautech]

I remember reading where a fellow rewound the HV multi by hand successfully!

Ah.... there is hope then, I will send him mine ! 
hopefully he lives in Europe or shipping will be prohibitve ! 

Check for its Pt# here:
https://www.sphere.bc.ca/test/tek-transformers.html

P/N 120-0360-00

Too bad, apparently they had a NIB one for only 35 dollars (canadian ?), would have been 25 Euros tops, could have been reasonable but then with taxes and import duties and shipping, would probably end up at 3 times that... Anyway, it's already sold so no point thinking about it....

An email will find out if they have more.......websites are not always up to date.

[mansaxel]

I remember reading where a fellow rewound the HV multi by hand successfully!

Ah.... there is hope then, I will send him mine ! 
hopefully he lives in Europe or shipping will be prohibitve ! 

Check for its Pt# here:
https://www.sphere.bc.ca/test/tek-transformers.html

P/N 120-0360-00

Too bad, apparently they had a NIB one for only 35 dollars (canadian ?), would have been 25 Euros tops, could have been reasonable but then with taxes and import duties and shipping, would probably end up at 3 times that... Anyway, it's already sold so no point thinking about it....

Will investigate the rewinding route I guess, most economical, and most "fun" way as well... I guess you aren't a real man until you have rewound a transformer ! 

@MED, yeah will check... but it's not a problem since these are discrete components that can be replaced easily. Transformer needs rewinding any way so let's do that... one day 

Have a look here: (if you haven't already, which I actually believe..)

https://w140.com/tekwiki/wiki/File:Tek_120-0360-00.pdf

[mnementh]

There it is... the first scope ever on my new bench in the new place. Feel honored, Al. 

All home and inside; just sitting there while I make a place for it in the lowest traffic/clean & dry corner of the dwagon cave. Gonna be up on a empty bin, same room as the TV so you know it's safe.

mnem
Oooooh... I heard a screw rattling around inside... maybe I should open it up...

It would be just plain rude not to ! 

        BWAHAHAHAHA!

I am tempted. But I think I'll hold off unless Al asks me to take some pics to whet his appetite for destruction. I have plenty to keep me off the street and out of trouble for a while. I had a 20% off coupon burning a hole in muh pocket. 



mnem
 

[mnementh]

I remember reading where a fellow rewound the HV multi by hand successfully!

Ah.... there is hope then, I will send him mine ! 
hopefully he lives in Europe or shipping will be prohibitve ! 

It would be wise to check the HV rectifiers and capacitors on the secondary side. That could have been the reason the HV transformer smoked.

Yes, IIRC that tripler circuit is the "well known point of failure" on the 454. Rebuild it and usually you can save the beast... provided it hasn't already take oot the multiplier/flyback.

mnem
 

[med6753]

There it is... the first scope ever on my new bench in the new place. Feel honored, Al. 

All home and inside; just sitting there while I make a place for it in the lowest traffic/clean & dry corner of the dwagon cave. Gonna be up on a empty bin, same room as the TV so you know it's safe.

mnem
Oooooh... I heard a screw rattling around inside... maybe I should open it up...

It would be just plain rude not to ! 

        BWAHAHAHAHA!

I am tempted. But I think I'll hold off unless Al asks me to take some pics to whet his appetite for destruction. I have plenty to keep me off the street and out of trouble for a while. I had a 20% off coupon burning a hole in muh pocket. 



mnem
 

 

[mnementh]

Ummm... maybe you missed the memo, Papa Smurf, but this old beast of a Tek isn't mine; I'm just doing my required TEA Missionary work, and enabling a fellow Canuck.

If it were actually mine, I'd strip the covers off it it so fast it sends octogen-stripper back in time.

Just for you.

mnem
 

[beanflying]

Why are the dial covers always missing on 735As ?

Not all of them have the plastic dial, below S/N 00737 have a different dial with an extra lamp fitted too.


David

Wondering if they haven't been retrofitted post manufacture either in this case if if the part below is the matching one? No date on this change from the original manual. That manual shows the more proud version on mine which is an early serial number.

Some more pics and serial numbers in this thread from others. https://www.eevblog.com/forum/testgear/hp-735a-dc-transfer-standard/