53132A bad display

[uncle_bob]

There has to be a reason. When I pull mine apart to change the display board I'll check the temps on the SMPS. If the fan is indeed cooling off the supply I should  be able to see it.
Could it be that your supplies are going for another reason, are you sure it is the fan being off? I've been monitoring the fan all night with the instrument on and then off. I'm just not seeing any great variation in the temp, maybe a degree or two but several variables could be causing it.

I think Gerry's been running for awhile with his mod.

Rob

Hi

Once we started replacing fans, the supplies stopped dying.....

Bob

[Robaroni]

Replacing fans? Are you saying the fans went bad?

R

[uncle_bob]

Replacing fans? Are you saying the fans went bad?

R

Hi

Nope, the dirt and the like got them really noisy. I suspect they were not moving as much air as they should have. We started pulling them wholesale and that did the trick.

Bob

[Robaroni]

Uncle Bob,
Did these counters have any of the oven options?

Rob

[uncle_bob]

Uncle Bob,
Did these counters have any of the oven options?

Rob

Hi

Nope, we run them all of of external standards in multiple plants. They were purchased over at least a 10 year span, so no, we didn't get a uniquely bad batch. It took us a while to figure things out. A lot of 53181's bit the dust "donating" their power supply to the 131's and 132's. Yes, hanging on to the rest of the chassis (for the DISPLAY) would have been a really good idea.

Bob

[Robaroni]

Good to know, I'll make sure to check temps on the SMPS when I pull it apart to change the display.

You should have kept the displays!

We never throw anything out.... Sometimes this can work to our disadvantage!

Rob

[uncle_bob]

Good to know, I'll make sure to check temps on the SMPS when I pull it apart to change the display.

You should have kept the displays!

We never throw anything out.... Sometimes this can work to our disadvantage!

Rob

Hi

We tend to do the same thing. When it gets to the point that you are renting space in multiple locations to keep "stuff" the finance boys start to get into the act. Eventually an edict comes down. Unfortunately I do the same thing here at home. The space runs $550 a month. That's about $100,000 over the last 15 years or so. Want to bet I could buy a lot brand new gear for $100K? Same logic applies at work except their rent was running about 10X mine.

Bob

[Robaroni]

Uncle Bob,
Let me put this into perspective, my wife Nancy calls it the Robsonian!

Rob

[uncle_bob]

Uncle Bob,
Let me put this into perspective, my wife Nancy calls it the Robsonian!

Rob

Hi

My wife is far less kind when referring to my collection of "fine stuff" ....

Bob

[bitseeker]

I think if my stuff got a name it'd become part of the family. So, no naming here. However, the Robsonian sounds like a nice place to visit.

[BarsMonster]

Many of remaining 5313* displays will die... I hope I will get one that will survive.
To prolong it's lifetime - I am thinking about adding a switch to disable display when doing long measurements with logging. Did anyone ever did that and is there any hints?

[artag]

I have a number of instruments with VFDs. None of them seem to have degraded further while I've owned them, but some were quite faded when I acquired them. The oldest instruments are not necessarily those with the dimmest displays.

My assumption is that, if powered up only when used, they will last a very long time but if powered on all the time because they're part of a production or test bench, they will fade in a few years. I doubt that dimming the display during a long measurement will help much unless you do that all day, every day.

[Robaroni]

Many of remaining 5313* displays will die... I hope I will get one that will survive.
To prolong it's lifetime - I am thinking about adding a switch to disable display when doing long measurements with logging. Did anyone ever did that and is there any hints?

I remember that counter, I switched mine out for a Tektronix FCA3000. Doesn’t help you but from other Agilent/HP stuff I’ve had those displays last a pretty long time, My 34401A had a bad display and I changed it out, the new one lasted till I sold it. I replaced it with a NOS 34401A that does all the basic measurements on my bench now. You can leave it on doing testing but they go bad if you leave them on all day everyday for years. Usually when I have to leave a meter on for extended time I have the luxury of a Keysight 34465A which is a better measuring device.

[pqass]

Many of remaining 5313* displays will die... I hope I will get one that will survive.
To prolong it's lifetime - I am thinking about adding a switch to disable display when doing long measurements with logging. Did anyone ever did that and is there any hints?

I suppose you can add a pair* of low value resistors (5R or so) in-line with each filament lead (with DPDT switch shorting the resistors for full brightness). That should dim the display down; prolonging the phosphor.  I didn't see a "DISPLAY OFF" GPIB command like in the 34401A.

* it needs to be a pair (for symmetry) since the filament is driven by 5.5VAC whose center-tap is 6.2V above ground (via VR2 zener).

Service manual: http://www.ko4bb.com/getsimple/index.php?id=download&file=HP_Agilent/HP_53131A_53132A_53181A_Universal_Counter/HP_53131A_Universal_Counter_Service_Manual.pdf
DC/DC+AC converter used (HP:0950-2325 = ERG:E2577VF): http://static6.arrow.com/aropdfconversion/21bc2cafea0620cdaf462a249c08dfffcf094564/e2577vf.pdf  FYI: HP manual pinout seems to be off by one.

ALTERNATIVELY, if possible,
you can break the connection between U2 (SN75518FN) pin 21 and pin 24 (VFDSEN remains connected to pin 24), and instead connect pin 21 to the common pin of a SPDT switch. Then pin 24 is connected to the NC switch pin and a 10K resistor to +5V is connected to the NO switch pin.

Pin 21 is the STROBE and as per the datasheet: "When STROBE is low, all Q outputs are enabled. When STROBE is high, all Q outputs are low."  So, when "...all Q outputs are low" all segments and grids won't attract electrons from the filament; ie. blanking the display.  This shouldn't interfere with any ongoing pin 24 activity (latching data) and once pin 21 and pin 24 are reconnected via the switch, whatever the state of the latch will be visible.

SN75518FN datasheet: https://pdf1.alldatasheet.com/datasheet-pdf/view/546161/TI/SN75518FN.html

[BarsMonster]

I suppose you can add a pair* of low value resistors (5R or so) in-line with each filament lead (with DPDT switch shorting the resistors for full brightness). That should dim the display down; prolonging the phosphor.  I didn't see a "DISPLAY OFF" GPIB command like in the 34401A.

* it needs to be a pair (for symmetry) since the filament is driven by 5.5VAC whose center-tap is 6.2V above ground (via VR2 zener).

Thanks for detailed answer, this will definitely help!

[MaxFrister]

Back when this thread started, it was not possible to buy a replacement VFD for these counters.

A couple of years back I bought a 53132a with a dim display. At the time I was able to buy a new made-in-China display that is working great.

Price varies (I think I paid ~$120).  Currently someone has one listed at ~$80 and lots of people have them listed for $200 plus

https://www.ebay.com/sch/i.html?_from=R40&_nkw=%2853131%2C53181%2C53132%29+vfd&_sacat=0&LH_TitleDesc=0&toolid=20004&mkcid=1&campid=5338192028&kw=53132+vfd&LH_PrefLoc=2&mkrid=711-53200-19255-0&_sop=15

[RichardDiag]

Had someone ask me about an issue with a VFD (vacuum fluorescent display) on an HP/Agilent 33120 function generator.  The issue being a dot in the ';' always being on.  This suggested the driver chip, a SN75518FN was likely the issue.  It also seems that several HP/Agilent equipment uses this part.  Finding a replacement SN75518 was not looking good.  After a few hours of searching, I did finally find two parts that appear to be possible replacement parts.  I thought I would relay that info for someone else whom my be looking.

It appears that Microchip HV518 and Analog Devices MAX6934 are compatible parts for the discontinued SN75518; both available from Digikey.  This includes the PLCC package used in the HP/Agilent equipment.

Hopes this helps someone else out there.