Test Equipment Anonymous (TEA) group therapy thread

[tggzzz]

The power supply circuit is the weirdest one I've ever seen. I'd like to shoot the guy who designed it

Oh, you lucky person!

You can look forward to the joy of understanding the Tek 1502 power supply.
Even when connected to the mains, it cuts out if the NiCd battery is missing.
Leaving the battery in causes the battery to be discharged in ~1month, thereby reverse-charging the weakest cell.
Leaving the battery on charge for >16 hours shortens the battery lifetime, probably due to the charging current's high crest factor.
Key component is a PUJT. Remember those?

On the plus side, it can be operatied in driving rain and stored under 1ft of water.

[EggertEnjoyer123]

After resoldering every joint in the power supply section, the scope now powers up.

There is still an arcing noise sometimes which causes the power supply to shut off. Also, the intensity seems to be high, and turning the intensity knob causes the trace to stretch horizontally (the trace becomes more stretched out at high intensity).

[Martin.M]

https://www.wellenkino.de/video/dsa-plot-4.mp4

it works ... 

[Neomys Sapiens]

https://www.wellenkino.de/video/dsa-plot-4.mp4

it works ... 

I can only see the progress bar...

[Messtechniker]

With firefox I get this:

[Vince]

No video for me either, I got only the sound track, whose beginning was like type writer / old cash register style...at first I thought it was the intro of " Money " from Dire straits....   

[Martin.M]

this may go better.

https://youtu.be/-vNA3So645Y

[Vince]

Works much better indeed, thanks !

Wow I just love plotters.... it's just so therapeutic to see them do their magic one bit at a time.
I got the scope, just need the plotter ! 
One of these days...

Only drawback is how freaking long it takes to plot.. makes you think twice before hitting that "Hard Copy" button on the scope ! 

[Martin.M]

makes Fun but this Tek can overheat the work room...
it was 2 hours running, then here was 29 degrees 
there are 3 fans at the rear, no tubes inside.

[Vince]

Yes I remember seeing pics of the back of the DSA with its 3 fans... it did scare me. You just confirmed that I was right to be scared....
I have its predecessor, an 11,000 series scope, and it's got only one fan and is pretty quiet for such a beast, so I actually wouldn't mind actually using it for more than a 5 minute test.
But first I need a cart to move it around, or build a new lab with much, much heavier duty shelves ! 

For now I think building a cart is by far the easiest, quickest and cheapest option. So I will start with that. Said cart will also be useful to play with all my 500 series hollow-state Tek scopes.

[Peter_O]

I stumbled over a manual for the HP 3457A in E$'s 'Kleinanzeigen'.
Always nice to have an original one.

[Martin.M]

and now you will make a scan from that for us? 

[TERRA Operative]

Scan it in colour at 600DPI, stick it on google drive/dropbox etc and I can automate it through Photoshop to crunch it down into a PDF. I have a workflow set up that makes it all pretty easy and mostly automatic to do.

[Peter_O]

and now you will make a scan from that for us? 

I've no scan equipment available to surpass the quality of the official keysigth scan. 

https://www.keysight.com/us/en/assets/9018-05670/user-manuals/9018-05670.pdf

And even the best scan possible cannot properly replace the haptic feeling reading the original manual. 

[TheDefpom]

If I had the time I could scan my one... I have a CZUR book scanner, but at the moment I am so damn busy.

[m k]

and now you will make a scan from that for us? 

I've no scan equipment available to surpass the quality of the official keysigth scan. 

Yes, you have.
Figure 1 of official scan is clearly a product of Cambridge five.

[Robert763]

He means microfilm....

[Martin.M]

3457A, a useful instrument with a rotten LCD display

[m k]

He means microfilm....

So the made available one is unofficial and official is kept secret?

Something else in the picture.

[wkb]

3457A, a useful instrument with a rotten LCD display

Not rotten, just not backlit. It escapes me why HP did that (I have multiple HP T&M boxes with this kind of display).

[GraXXoR]

Anyone have any experience with the GoodWill INSTEK GDM-8255A desktop multimeter?
I can't seem to find any information on it other than their own gumph and a few voiceless informercials... does seems unpopular...

Do you know if there is a "next gen" or "previous gen" device that was more popular with reviews or anything?

The reason why I ask is that I see one in mint condition calibrated until August '24 that was used at home during lockdown for what seems like a nice price. ($140).

I have been looking at the tried and tested Agilent/HP 34401A which show up daily but are often in really beaten up condition and their price can escalate quite a bit in auction if in anywhere approaching good condition... Moreover the 34410 which 'm really interested in blows up in the bidding at auction, so I end up bowing out every time.

Does anyone know if the 8255A can hold its own against the 34401A? I really don't need 6 digits of precision but my handheld multimeters' refresh rates leave much to be desired and watching the videos, the 8255 has a fairl decent update cadence.

The VFD on the device I'm looking at looks really bright, indeed factory fresh and the rubber bumpers are completely free from marks.

Final question, does it have a fan? If so, is it noisy? I intend to use this at home at night and ended up replacing my Rigol 832 fan with a Noctua...

Any help appreciated.

[factory]

GDM-8255A is 199999 count 5½ digit, not even close to a HPAK 34401A/34410A (6½ digit);
https://static.rapidonline.com/pdf/90-6195.pdf

A couple of other GW Instek bench DMMs on here.

GDM-8251A, 120000 count 5½ digit;
https://www.eevblog.com/forum/testgear/inside-a-gwinstek-gdm-8251a-bench-multimeter/

GDM-8341, 50000 count 4½ digit;
https://www.eevblog.com/forum/testgear/quick-gw-instek-gdm-8341-bench-dmm-teardown-review/

David

[GraXXoR]

Thank you for pulling those links.

Haden't seem them, since I was included 8255 in my search.
 
Very Interesting! But as I suspected, very little information on the 8255A itself. The 8251 appeared to be more popular...

But it seems the 8255A was more expensive and less popular.

One thing that is a positive, is that it looks a lot smaller with the guy holding in that I thought. Also, doesn't appear to have a fan.

Anyway, for half the cost of my GW121, I think I'm going to pull the trigger. I can always resell it on Yahoo if it turns out to be not my cup of tea.

[Peter_O]

3457A, a useful instrument with a rotten LCD display

Sure, I like the good old LED ones better, but it stands for a generation ...

[cosmicray]

Wow I just love plotters.... it's just so therapeutic to see them do their magic one bit at a time.
I got the scope, just need the plotter ! 
One of these days...

Only drawback is how freaking long it takes to plot.. makes you think twice before hitting that "Hard Copy" button on the scope ! 

I have an HP-7580B here. Was not aware that it could be interfaced to scope. Bought it used a long time ago, drew some house plans with it. Considering how seldom it's powered on, trying to decide if it needs a new home. This is an upright floor model that does up to D-size, and the pen carousel holds 8-pens, otherwise similar to what is in the video.