Test Equipment Anonymous (TEA) group therapy thread

[Martin.M]

I hope the instrument self is allready, the broken glass is no problem
I make my spare glasses from picture frames, they are low cost and the glass is 1,5mm only, easy to cut.

[factory]

I wasn't looking for another scope but this appeared yesterday, it looked complete, nice condition and in working order. I put in an offer then got a counteroffer of £60, I resisted for about half an hour but failed and ending up buying it.
(Attachment Link)

David

Looks good and I hope that you enjoy it when you receive it.

Well two weeks ago I didn't have a single non-sampling analogue CRT scope capable of more then 50MHz, I now have five.

Here is the first, the 275MHz HP 1725A that I won on evilbay.

It mostly looks in good condition, footless at the back as expected, a small bit a corrosion on the side of the case.
Channel B is good & the delayed timebase works , but I can't get a decent square wave on channel A, it's not the probe compensation, a forum search suggests reseating connectors & checking the attenuators.
This unit also has one of other common problems mentioned, the timebase switch needs re-greasing, possibly the time interval function needs looking at too, or I need to RTFM again.

David

I have that thing's "big brother", the 1727A storage scope. Very neat "little" scopes. I don't know how deep the 1725 is, but the storage tube makes the 1727A easily as deep as a Tek 7000 mainframe.

I don't know how deep the 1727A storage version is (or the Tek mainframes) but the 1725A is approx 20" deep, the tube doesn't stick out any further than the power supply heatsink, it's currently awaiting it's turn for repair, I've got distracted by the four non-HP analogue scopes that I picked up last weekend.

David

[factory]

I hope the instrument self is allready, the broken glass is no problem
I make my spare glasses from picture frames, they are low cost and the glass is 1,5mm only, easy to cut.

Hopefully the meter is OK, I remember having to clean lots of tiny bits of glass out, I got a replacement piece from a picture framing shop, but never got round to putting the meter back in the 428B, I'm not even sure where the 428B is stored at the moment.

David

P.S. If it is damaged then I do have that spare meter from the incomplete 428B I bought.

[mnementh]

Man oh man....all this hate for 7900 series regulators.  I've used them many times in circuits and never had any stability issues.  But it is absolutely important to have those 2 little tants mounted physically close to the input and output. But same also applies to the 7800 series too.   

I like them too; they’re robust & simple. For my quadcopters, I’ll use 7805s, 7808s & inverted 7905s (when I’m out of the other two) with a pair of 10-22uF MLCCs soldered side x side right across the legs. Oscillation seem to be eliminated with the equal value caps.  The main BATT and/or the ESC pads will also get a low-ESR 330-1000uF electro.

mnem
*unregulated-dwagon*

[BU508A]

Was that ‘Thank you’ for the content, or the fact I demonstrated a modicum of self-restraint...? 

Yes.

 

[FransW]

BU508A:
Looks log-log linear >> Pareto distribution

[bd139]

Man oh man....all this hate for 7900 series regulators.  I've used them many times in circuits and never had any stability issues.  But it is absolutely important to have those 2 little tants mounted physically close to the input and output. But same also applies to the 7800 series too.   

They usually screw you when you least expect it. Then they turn into power oscillators. Bastard things. Worst is the LM2940

[mnementh]

Was that ‘Thank you’ for the content, or the fact I demonstrated a modicum of self-restraint...? 

Yes.

 

And here we see a prime reason for confirming the originating address of a packet of information on the internet.

One might presume that this response was actually from the originator of the ‘Thank you’ in question, rather than a well and truly deserved goading from the peanut gallery. 

mnem
But wait, there’s more... Now how much would you pay...?

[BU508A]

Was that ‘Thank you’ for the content, or the fact I demonstrated a modicum of self-restraint...? 

Yes.

 

And here we see a prime reason for confirming the originating address of a packet of information on the internet.

One might presume that this response was actually from the originator of the ‘Thank you’ in question, rather than a well and truly deserved goading from the peanut gallery. 

mnem
But wait, there’s more... Now how much would you pay...?

Or, it could be used as an example, why asking "or-questions" can be truly answered with "yes" with a probability of 75%. 

[Neomys Sapiens]

A follow-up and tear-down on the little video monitor:

This is what is inside:


(from the front)


(from the rear)
Yes, it is a tiny tube projected onto the curved screen behind the viewing window.
Originally, it is a Sony VIS-4000E module with only a few components added.


Showing a test pattern.


And another.
I have repeatedly made the decision to scrap this crappy digicam that made the pictures. And the, it performs again. But not today.

And I found out that my pattern generator has issues. Meh.

[med6753]

Man oh man....all this hate for 7900 series regulators.  I've used them many times in circuits and never had any stability issues.  But it is absolutely important to have those 2 little tants mounted physically close to the input and output. But same also applies to the 7800 series too.   

They usually screw you when you least expect it. Then they turn into power oscillators. Bastard things. Worst is the LM2940

Haven't used that particular one. But these two: LM337 and 79L12 are in equipment I designed/built 25+ years ago and get almost daily use with no issues. And the Fluke 8000A got an 7915 when the PSU was rebuilt and no issues there. Those are the ones I can think of at the moment. There have been others. We'll see how this one works out. If it self destructs you can all laugh at me.     

[mansaxel]

Another assembly problem with the 428B then, that's three different problems now. 
Hopefully you can fix it, that transformer looks different to the one in my good 1960's 428B and what may have been in the spares one (which has two small round holes in the chassis for the wiring), how late is yours?

Mine is current with the last revision of the manual; the serial number revision code is 0995A, meaning 1969, week 95 , USA built. (none of the sources explaining the -- hp -- serial numbers seem to mention years with week numbers going above 52, just some hand waving about "not always correct", well, yes, that is a reasonable caveat!)

It was possible to fix the cable, though first it broke off with only 1cm of free remaining cable sticking out of the winding. Can't really blame it; crushed as it was. Solder job was actually pretty easy. Shrink tubing and some careful routing to avoid repeating the problem, and 20 minutes trying to remember how the 115/230V switch was wired , and then smoke test via variac went well.

The +272V fuse was open circuit, but once I'd fixed that and let the instrument warm up, I was rewarded with a nice 270,1V bias voltage reading (in-spec, the manual says +/- 6V).

Testing the instrument in operation gives readings that somewhat correspond with my "reference"; a battery pack of 6 AA nicads shorted through a 100Ω resistor gave about 61,2mA according to the MetraHit  , and a reading of about 56mA on the 100mA range on the 428b. Looping the cable once more through the jaws brought the reading within 1,3% or so at 120,5mA, and another turn gave just about 183mA. Accuracy increases with range; this is not expected and reason for a full alignment.

But, the instrument works! 

[mnementh]

A follow-up and tear-down on the little video monitor:

This is what is inside:

(Attachment Link)
(from the front)

(Attachment Link)
(from the rear)
Yes, it is a tiny tube projected onto the curved screen behind the viewing window.
Originally, it is a Sony VIS-4000E module with only a few components added.

(Attachment Link)
Showing a test pattern.

(Attachment Link)
And another.
I have repeatedly made the decision to scrap this crappy digicam that made the pictures. And the, it performs again. But not today.

And I found out that my pattern generator has issues. Meh.

I used to have the Sony Watchman that thing is based on. I kept it and used it long after getting a similar-sized color LCD version; partly because it had a composite input and could be used for tuning satellite receivers, and partly because it had a phenomenally sensitive tuner that just sucked in any whisper of a signal that was out there, while the color one was pretty much a useless brick any time you were more than 10-15 miles away from the center of a major city. 

Oh, and that thing would run until the batteries were down to less than 1V/cell. It truly sucked every erg they had to give, while the color unit would go BLIP! & shut off the instant they dropped below 1.2V. 

I later found a 5” color Sony “Beachcomber” (?) approx the size of half a loaf of bread; it was LCD but used “sub-C” NiCds & had a built-in inductive charger coil and charging base so the entire thing could be sealed against sand & surf. That also had an I/O port that was epoxy potted with composite in. It too had pretty exceptional tuning.

mnem
*So NOT ready for Pokemon*

[bd139]

I had one of the Casio LCD ones. Vile thing. TV400. Was my first expensive consumer electronics purchase and it was a bad one  . Got very hot and ate AAs rapidly.

[Neomys Sapiens]

As you commented, the catastrophe was already well underway.
The abovementioned pattern generator is (was?) from ELV (shame over me, but it was gifted upon me).
I am looking for one now. Also, I started wondering what would be the size (and make) of a comparable thing that could do colour (preferably multistandard).
AAAAAH!

Huh. I just remembered there is one sitting in my waiting room (for 'patients'). And it is a extraordirarely capable unit from Lucius&Baer, which lets you select about any conceivable format of video signal. Unfortunately, completely undocumented, as it was probably intended for internal purposes. I will look for a portable thing to complement the monitor and have a go at it as soon as the HP6825 has cleared my desk.

[Neomys Sapiens]

That digicam replacement is another story, with pondering and bothering in the size of the LCR-meter decision.
Unfortunately, I've got no first-born to sell and my parents are too old for the organ market. This limits the options severely, as otherwise, I would be going for a digital M Leica.
The Digilux2 is beautiful and quite reliable, but limited in terms of speed/low-light performance. The Digilux5 would be the pedestrian option, but where is the fun in that?
And I do not want a SLR, for reasons of weight/size as well as quietness of operation. It is no good if it is not when and where I need it, apart from home. Comes in the X-Vario.
Hmmm...
But then, I have some some ideas which they simply disregarded. They build in a lot of functionality into those things, but the ability for external triggering is sadly missing. Also, if using a digital camera in a externally triggered setup, in order to keep a manually adjusted focus it seems to me that you have to keep it in a mode where it will drain the battery quite fast. And the commonly available reviews do not adress such applications at all. Someone here an expert on those things?

[med6753]

Someone say Watchman? 

This was Jo Ann's (Lady Copper) Mother's. I inherited it when she passed and we cleaned out her apartment. It powered up but couldn't adjust the volume. Turns out the plastic shaft was broken. I was able to pull the knob and fix the shaft without disassembly. Which is just as well because I couldn't figure out HOW to get it apart. It's a real jigsaw puzzle.

It uses an inline 5 inch CRT and takes a basket load of D cells or AC mains. Obviously totally obsolete unless you utilize an digital convertor which is not in the cards. I did connect a VCR and it does have a decent B/W pix and sound. But other than that it's just a display.   

 

[med6753]

I wasn't looking for another scope but this appeared yesterday, it looked complete, nice condition and in working order. I put in an offer then got a counteroffer of £60, I resisted for about half an hour but failed and ending up buying it.
(Attachment Link)

David

Looks good and I hope that you enjoy it when you receive it.

Well two weeks ago I didn't have a single non-sampling analogue CRT scope capable of more then 50MHz, I now have five.

Here is the first, the 275MHz HP 1725A that I won on evilbay.

It mostly looks in good condition, footless at the back as expected, a small bit a corrosion on the side of the case.
Channel B is good & the delayed timebase works , but I can't get a decent square wave on channel A, it's not the probe compensation, a forum search suggests reseating connectors & checking the attenuators.
This unit also has one of other common problems mentioned, the timebase switch needs re-greasing, possibly the time interval function needs looking at too, or I need to RTFM again.

David

I have that thing's "big brother", the 1727A storage scope. Very neat "little" scopes. I don't know how deep the 1725 is, but the storage tube makes the 1727A easily as deep as a Tek 7000 mainframe.

I don't know how deep the 1727A storage version is (or the Tek mainframes) but the 1725A is approx 20" deep, the tube doesn't stick out any further than the power supply heatsink, it's currently awaiting it's turn for repair, I've got distracted by the four non-HP analogue scopes that I picked up last weekend.

David

FYI: Typical Tek 7000 series mainframe is approx 25+ inches long. That includes knobs, etc.

[Specmaster]

I had one of the Casio LCD ones. Vile thing. TV400. Was my first expensive consumer electronics purchase and it was a bad one  . Got very hot and ate AAs rapidly.

Ditto I got mine free with a mobile phone, it wasn't the TV400, but I can't remember what one it was but it could chew through a set of 4 AA's in about 90 minutes.

[Neomys Sapiens]

Some tool-info that might be useful for some of you:
https://www.eevblog.com/forum/reviews/technical-use-of-surgical-instruments-some-info/msg2727250/#msg2727250

As before, I decided to post it in the offcial category instead of hiding it here.

[xrunner]

Yea saw it, I was unaware of the two different kinds tools, always thought hemostat was a hemostat, thanks.

[0culus]

I wasn't looking for another scope but this appeared yesterday, it looked complete, nice condition and in working order. I put in an offer then got a counteroffer of £60, I resisted for about half an hour but failed and ending up buying it.
(Attachment Link)

David

Looks good and I hope that you enjoy it when you receive it.

Well two weeks ago I didn't have a single non-sampling analogue CRT scope capable of more then 50MHz, I now have five.

Here is the first, the 275MHz HP 1725A that I won on evilbay.

It mostly looks in good condition, footless at the back as expected, a small bit a corrosion on the side of the case.
Channel B is good & the delayed timebase works , but I can't get a decent square wave on channel A, it's not the probe compensation, a forum search suggests reseating connectors & checking the attenuators.
This unit also has one of other common problems mentioned, the timebase switch needs re-greasing, possibly the time interval function needs looking at too, or I need to RTFM again.

David

I have that thing's "big brother", the 1727A storage scope. Very neat "little" scopes. I don't know how deep the 1725 is, but the storage tube makes the 1727A easily as deep as a Tek 7000 mainframe.

I don't know how deep the 1727A storage version is (or the Tek mainframes) but the 1725A is approx 20" deep, the tube doesn't stick out any further than the power supply heatsink, it's currently awaiting it's turn for repair, I've got distracted by the four non-HP analogue scopes that I picked up last weekend.

David

Yeah, that thing is tiny comparatively.  As med said, the 7000 mainframes are >=25" deep. The 1727A will sit comfortably on top of my 7904A and use up all the space. [edit], yeah the 1727A is all of 24 inches deep including the protrusions on the rear panel and the knobs + tilting bale (in the propping position) when it's sitting on the bench.

[Neomys Sapiens]

Little Joy of the day:
looking for a implement of unknown location, I crept under a table and dug into a box (probably packed by my loving ex-SWMBO in our moving frenzy) and there it was:
An unregistered triaxial (3-lug) measurement cable. I did not know that I had this one, so I enjoyed it like newly aquired.

[worsthorse]

I did some more work on the multiscope today. Decided to post a regular old teardown thread over in the RF section...

https://www.eevblog.com/forum/rf-microwave/yo-901-yaesu-multiscope-teardown-and-repair/new/#new

Today's bonus prize: going through one of the boxes of cables I picked up a couple of months ago, I found two of the fabled "5nsec" cables used with the 191 and 106 sig gens. Both still in the original bag.  Now I just need to find a voltage pickoff and a couple of GR 50 ohm terminations and I will have all the goodies. 

[tautech]

Little Joy of the day:
looking for a implement of unknown location, I crept under a table and dug into a box (probably packed by my loving ex-SWMBO in our moving frenzy) and there it was:
An unregistered triaxial (3-lug) measurement cable. I did not know that I had this one, so I enjoyed it like newly aquired.

Bit early for Christmas isn't it !