Test Equipment Anonymous (TEA) group therapy thread

[factory]

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/

No they are original for the older ones, with the extra lamp fitted, see the circuit diagram where it's mentioned as being deleted after s/n 00736, is yours below s/n 00737?


Picture from the 1965 hp catalog.


Here are a couple of pictures of the oldest one I've seen, number 504-00115 or 00116 (hard to see last digit).



David

[mansaxel]

I AM calm ! 

Just don't have time or bench space to dedicate to that right now, so I buttoned it up for now...
Yeah sure would be cool if the transformer survived and I only needed to fix discrete components on the secondary side...

I was just thinking that you shouldn't veer off into some "repair until broken" tangent and start rewinding things unless verified broken from the start.

One of these days I'll get enough round tuit to test the hypothesis that my 5440 has tantalum disease. (the -30V is off, likely because shorted tant)

[edfarrington93]

  Yeah, I should have worded that better, I really like the 547. I just need to figure out how to calibrate it, the trace has a strange shape to it. When I get back to my place I'll take a photo and post it. I was wondering if I could calibrate it some other way, I'm new to all this and figured it would be a good way to learn while being able to play with cool vintage machines. I kind of want to make some sheet metal sides with glass or plexi windows so the gorgeous tubes can be seen whenever you want. I can't bring myself to hack the originals. Thanks for the info, I guess I'll have to keep an eye out for some calibration gear, not that I have a problem already or anything.

[med6753]

I'm not sure what the RC standardizer would be used for - that's not something I've encountered before, current or vintage.

It's used for calibration of the vertical inputs. Desirable but not absolutely necessary. I don't have one and really haven't seen a need as I can get good calibration without it.

[Cubdriver]

Type 453 CRT transformer rewinding : thanks to all who gave links and advise on this. I decided to at least give it a shot as nothing to lose and bound to be educational and fun in some way ! And hell if I am lucky teh rewind might go well and the scope might come back to life !

calme-toi!

Do read what mnem and med wrote; the primary will look like a short at DC! I have no idea what I'm talking about, as usual, but since the HV is created at not-exactly-50Hz, the transformer might not exhibit mains transformer behaviour either.
I believe it could be beneficial to examine the circuit more thoroughly.

And, a probulator might come in handy

I AM calm ! 

Just don't have time or bench space to dedicate to that right now, so I buttoned it up for now...
Yeah sure would be cool if the transformer survived and I only needed to fix discrete components on the secondary side...

Vince, I have a 453 that was functional when I last played with it a few months ago.  It will likely take a few days as my dance card is full at the moment, but if you can let me know what you measured on yours I will dig it out and take those readings on mine (after confirming that it's still working) and let you know so you'll have them for future reference.


-Pat

[Cubdriver]

Here are a couple of pictures of the oldest one I've seen, number 504-00115 or 00116 (hard to see last digit).



David

Damn - given that they started serial numbers at 00100, that's the 15th or 16th one produced for sale!  Seeing this pop up prompted me to dig the one I got a few years ago out.  Someone with penis fingers had been at it as several resistors on the range switch are disconnected at one end, and one is completely loose and has a much later date code on it, so I'm not sure what sort of buggery the poor thing was subjected to.  Finding that caused me to button it up and store it a few years ago when I first got it; seeing this makes me inclined to dig into it again.


Mine's a later eng rev, but still 65-ish for a time frame.


It's also missing the printing on most of the wheels in the counting dial.  That should be a fun fix...   

It doesn't appear to have led an easy life.

-Pat

[factory]

I'm not sure what the RC standardizer would be used for - that's not something I've encountered before, current or vintage.

It's used for calibration of the vertical inputs. Desirable but not absolutely necessary. I don't have one and really haven't seen a need as I can get good calibration without it.

How hard can it be to make one? from the description on another site*, it's a 1MΩ resistor with a fixed & variable capacitor in parallel, pretty much the same as the hp equivalent.



* https://groups.io/g/TekScopes/topic/7633934

David

[Neper]

What's the verdict on this one?

https://www.ebay-kleinanzeigen.de/s-anzeige/tektronix-analog-oszilloskop-2215-bandbreite-60-mhz/1890985713-168-1889

Description says good condition, checked, fully working.

[Vince]

What's the verdict on this one?

https://www.ebay-kleinanzeigen.de/s-anzeige/tektronix-analog-oszilloskop-2215-bandbreite-60-mhz/1890985713-168-1889

Description says good condition, checked, fully working.

FWIW : RUN AWAY !!! 

I have one of these... I paid 40 Euros for it vs 125 for that one.... even at 40 Euros it's still a waste of money !
I love the 2000 series scopes... but after having battled, and lost, my fight against my 2215.... I will NEVER buy one of these again !
People DID warn me on EEVBlog... I chose to buy one anyway... I should have listened.

I wanted one because it was one of the very few Tek scopes that had an "auto brightness" feature.  I thought it was cool, and wanted to see it for myself.
Turned out it was this very feature that was defective, resulted in weird  stuff... I have tried hard to debug this feature, to make it work, to understand it... I GAVE UP !!!   This supposedly cool feature is precisely what makes these scopes unreliable and impossible to fix. NEVER AGAIN ! 

Also, I recall someone saying they had dozens of them at work back in the day when the were brand new. Said they were fine for a few days... weeks... but quickly they all started  going haywire. Basically rushed to market, badly engineered, call it what you want.

This scope is also a very basic machine... there is absolutely nothing technically that you can't find in any other 2000 series scope.

So really, I would strongly advise to run away from it. Getting one in the first place is a bad idea, but paying freaking 125 Euros for it is pure folly !

For the same price right now there is a working 2232 here !!!!

https://www.leboncoin.fr/equipements_industriels/1985551178.htm

OK it's missing the skirt on the Channel #2 attenuator knob, bid deal, you can go get a new skirt/knob or just use it as is !


Also for 50 Euros the other day I found a working 2225 !!!

There is no reason in the world to buy a 2215, no matter the price.... unless it's free and you intend to just use it for parts rather than trying to fix it and use it....

I guess you can tell just how much my 2215 traumatized me !   

[Vince]

Vince, I have a 453 that was functional when I last played with it a few months ago.  It will likely take a few days as my dance card is full at the moment, but if you can let me know what you measured on yours I will dig it out and take those readings on mine (after confirming that it's still working) and let you know so you'll have them for future reference.


-Pat

Thanks Pat, that's very kind of you ! 

Let me know once you find the time to dig it out, drop me a PM or something ! 

[med6753]

Aw gee, Facebook is down. Has been down most of the day. Isn't that a fucking shame. 

NOT. 

[Bud]

Hoping it will never come back up 

[Bud]

The fallout also cascaded, because Facebook is used to sign in to many other apps and services. That led to unexpected domino effects such as people not being able to log into shopping websites or sign into their smart TVs, thermostats and other internet-connected devices.

Ha-ha-ha, no reminder from your fridge today that you are out of milk ! 

[https://www.nytimes.com/2021/10/04/technology/facebook-down.html

[Cubdriver]

Hoping it will never come back up 

LOL - it would be like when Obi-Wan Kenobi sensed the destruction of Alderaan - as if millions of voices suddenly cried out in terror and were suddenly silenced.  Well, we can dream, right?

-Pat

[mnementh]

People whinging that their primary source of income has gone down for almost a day... maybe you shouldn't have hitched your wagon to a shit-flinging star. Especially only to that and nothing else.

mnem
I pulled the plug on that unmitigated timesink years ago and never looked back.

[mnementh]

So... Deliberate Denial Of Suckage attack...? Or did they just piss off bd139 one time too many...?

mnem
 

[Wolfgang]

People whinging that their primary source of income has gone down for almost a day... maybe you shouldn't have hitched your wagon to a shit-flinging star. Especially only to that and nothing else.

mnem
I pulled the plug on that unmitigated timesink years ago and never looked back.

Did the same on twitter, instagram, reddit, linkedin, and many others. NOW i have some time for TEA. 

[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/

No they are original for the older ones, with the extra lamp fitted, see the circuit diagram where it's mentioned as being deleted after s/n 00736, is yours below s/n 00737?


Picture from the 1965 hp catalog.


Here are a couple of pictures of the oldest one I've seen, number 504-00115 or 00116 (hard to see last digit).



David

Interesting so the low profile one is the 'old' one and then the manual I have (1966) was updated with the graphics and pictures for the 'new' more proud square one. Mine is #1434. Bit surprising in some ways as the low profile looks like a more modern design and if replacing it was a supply/cost or performance issue 

New front cover added to my list of stuff to do 

[xrunner]

GPSDO Display Progress

I finalized the front panel and used my new roll of Atomic pine green filament to print it. The mounting method is simple - four pins or studs and Aleene's turbo tacky glue. Plenty good enough.

I also made a small change to the mounting plate for the processor, so that it would not interfere with the OLED display. Was the original design a mistake? No of course not! It was a normal and acceptable result of the synergistic interplay between competing physical dimensions in an evolving and improving system design. No - I only thought I made a mistake once (years ago), but that turned out to be an incorrect assumption on my part.

Next up is the rear panel with openings for power, USB, RS-232, and possibly an LED. As I noted a while back, the GPSDO sends a 1 pps signal free-of-charge to the RS-232 pin 8. I debated just mounting it on the front panel but that seemed too distracting. So I'll mount it on the rear because it's available. It gives  some semblance of operation of the GPSDO I suppose.

Beware! We had quite a few of these "always on" - after only a year a considerable number had gone bust; not only faded but missing lines and various glitches 
In general, blue OLED have the shortest lifetime of the "phosphor", yellow has AFAIK the longest.

In consideration of these concerns, I'm adding a code section to blank the OLED between certain hours. Might be between midnight and 6 am CST US (0500 to 1100 UTC). Could write a mini-screen saver ... wait that's feature-creep STOP!

[mnementh]

GPSDO Display Progress

I finalized the front panel and used my new roll of Atomic pine green filament to print it. The mounting method is simple - four pins or studs and Aleene's turbo tacky glue. Plenty good enough.

I also made a small change to the mounting plate for the processor, so that it would not interfere with the OLED display. Was the original design a mistake? No of course not! It was a normal and acceptable result of the synergistic interplay between competing physical dimensions in an evolving and improving system design. No - I only thought I made a mistake once (years ago), but that turned out to be an incorrect assumption on my part.

Next up is the rear panel with openings for power, USB, RS-232, and possibly an LED. As I noted a while back, the GPSDO sends a 1 pps signal free-of-charge to the RS-232 pin 8. I debated just mounting it on the front panel but that seemed too distracting. So I'll mount it on the rear because it's available. It gives a some semblance of operation of the GPSDO I suppose.

Beware! We had quite a few of these "always on" - after only a year a considerable number had gone bust; not only faded but missing lines and various glitches 
In general, blue OLED have the shortest lifetime of the "phosphor", yellow has AFAIK the longest.

In consideration of these concerns, I'm adding a code section to blank the OLED between certain hours. Might be between midnight and 6 am CST US (0500 to 1100 UTC). Could write a mini-screen saver ... wait that's feature-creep STOP!

Does the SSD1306 library support blanking fast enough to treat display output as if it were on a very low duty cycle PWM, so that the actual on time is very low? Lots of cheap LED digital signage does that to get long battery life while appearing very bright.

mnem
 

[xrunner]

Does the SSD1306 library support blanking fast enough to treat display output as if it were on a very low duty cycle PWM, so that the actual on time is very low? Lots of cheap LED digital signage does that to get long battery life while appearing very bright.

I don't know.

[ch_scr]

GPSDO Display Progress

I finalized the front panel and used my new roll of Atomic pine green filament to print it. The mounting method is simple - four pins or studs and Aleene's turbo tacky glue. Plenty good enough.

I also made a small change to the mounting plate for the processor, so that it would not interfere with the OLED display. Was the original design a mistake? No of course not! It was a normal and acceptable result of the synergistic interplay between competing physical dimensions in an evolving and improving system design. No - I only thought I made a mistake once (years ago), but that turned out to be an incorrect assumption on my part.

Next up is the rear panel with openings for power, USB, RS-232, and possibly an LED. As I noted a while back, the GPSDO sends a 1 pps signal free-of-charge to the RS-232 pin 8. I debated just mounting it on the front panel but that seemed too distracting. So I'll mount it on the rear because it's available. It gives a some semblance of operation of the GPSDO I suppose.

Beware! We had quite a few of these "always on" - after only a year a considerable number had gone bust; not only faded but missing lines and various glitches 
In general, blue OLED have the shortest lifetime of the "phosphor", yellow has AFAIK the longest.

In consideration of these concerns, I'm adding a code section to blank the OLED between certain hours. Might be between midnight and 6 am CST US (0500 to 1100 UTC). Could write a mini-screen saver ... wait that's feature-creep STOP!

Does the SSD1306 library support blanking fast enough to treat display output as if it were on a very low duty cycle PWM, so that the actual on time is very low? Lots of cheap LED digital signage does that to get long battery life while appearing very bright.

mnem
 

I think you can set the brightness in the library? Writing a full screen took a second or so if I remember correctly.

[Saskia]

the idea of facebook (and other crap) being down returns some brightness to my life.

If things were always that easy.

FWIW Hubby survived yet another stent implant ...

[Specmaster]

the idea of facebook (and other crap) being down returns some brightness to my life.

If things were always that easy.

FWIW Hubby survived yet another stent implant ...

You two are well-matched, you're both fighters, thats for sure, wishing him well.

[VK5RC]

@saskia - I was disappointed that they got it back up so quickly - I am sure it (along with a lot of the other anti-social media platforms) has contributed to the misery of a lot of people esp teenagers.
Bugger re the hubby stent - wishing you both the best 🙏