Test Equipment Anonymous (TEA) group therapy thread

[factory]

The second of the two crusty hp relics I bought a few weeks ago, the 3480B/3481A voltmeter, with option 004 (isolated BCD output).




Inside with shield cover removed from the 3841A plug-in and not much to see underneath.



Regulator board A1, with nice rusty RCA transistors and two internal layers, making it a four layer PCB, this board also contains the reference diode.



The clock & digital-to-analog memory logic board A2, no crystal reference for the clock of this DVM, just a simple transistor multivibrator and another early 1970's multilayer board.



TBC....

David

[factory]

....Part 2 of the crusty hp 3480B/3481A voltmeter.

The polarity amplifier board A3, this board has space for the ratio option A3 A8 (might not be compatible with the option 004, I haven't checked).



And the digital-to-analog comparator board A4, with it's colorful selection of adjustment pots.


A few pictures of the mainboard A6, this has the power supply capacitors, display logic and a spare IC, well that's a first  . Also a pair of rusty legged TI 7475 IC's and the display decoders are regular 74 series with a hp part no. & not a custom part for a change.



The last pair of boards are the option 004 isolated BCD output assembly A11, the manual mentions this can be used with the some hp 211x series computers and later on in the manual mentions use with a digital recorder, maybe it'll work with the 5055A (if I ever get found to checking/fixing it).
The isolation is pairs of inductors against that insulation strip between the boards.
These boards didn't want to come out, camera shy or hidden fixings?? 



TBC....

David

[Cubdriver]

Very cool.  I have it's brother, equipped with a 3485A Scanning Unit in my repair queue.  Interesting to see the innards, and the 3480 seems to be a pretty rare bird in my experience.

-Pat

[factory]

....Part 3 of the crusty hp 3480B/3481A voltmeter.

And finally the 3814A buffer amplifier plug-in, this seems to be quite an uncommon choice with only one range (10 volts), if fact there seems to be bugger all on the web, well apart from the catalog entry and the Jan 1971 Journal article; https://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1971-01.pdf



Unfortunately the plug-in didn't seem to want to come out, not sure why it's stuck and I don't want to break anything trying to force it out (the front & latching mechanism are plastic).
View from the top, with shield/cover removed, not much to see here. 


And the bottom cover removed, revealing quite a lot of transistors for a single range DVM plug-in, possibly making this set-up the largest digital panel voltmeter I've ever seen. 


The low serial number makes me think I'll struggle to find a service manual for it, possibly the third to leave the Scottish hp plant.


And a bit of testing after reassembly, oh dear my 4½ digit voltmeter has taken a downgrade to a 3½ digit DVM.



It zeros OK but seems to need some repair, as the 3.7V cell is reading a bit on the high side.
First things to check would be the PSU & +10V ref, then move on to a test plug (details in the crappy service manual from Agilent) to eliminate the plug-in, hopefully the fault is not with the plug-in.
This will have to wait, as I'm currently working on the 207A sweep oscillator.

David

[factory]

Very cool.  I have it's brother, equipped with a 3485A Scanning Unit in my repair queue.  Interesting to see the innards, and the 3480 seems to be a pretty rare bird in my experience.

-Pat

I've seen a couple of the 3485A scanner plug-ins in the past, probably a good choice for use with the 5055A recorder I have, they even supplied them as a set.


And you get lots of BD's favourite switches. 


Not seen a teardown as far as I know yet.

David

[cyclin_al]

*currently gusseting a bedframe for my son*

Just put a bottle jack under it and be done ... that is what I did.

Although I do have my bedframe in the garage from a previous lifetime (before kid, before marriage), but her antiques count more ...

Sounds like you need to upgrade in the Nixie counter dept.

Yeah, now I need one that counts higher. 
(in reality, I need to pull out that HP nixie counter and clean it up, and complete a lab so I have somewhere to put it)

[Cubdriver]

Interesting - yours has a burr.  Mine is mid '71 engineering rev, (1127) US made.  00103 is definitely an early one!!

-Pat

[mnementh]

Dave has a D'oh! moment... guess he shoulda done the daveCAD before he pulled a " 'ere, 'old me Foster's an'n watch this!"

mnem
 

[tautech]

Yeah definitely amateur hour. 

[factory]

Interesting - yours has a burr.  Mine is mid '71 engineering rev, (1127) US made.  00103 is definitely an early one!!

-Pat

S/N 00103 is for the 3481A plug-in , the mainframe is a lot higher.

David

[beanflying]

Not one I have seen before (or have a NEED for ) eBay auction: #324821359264

Looking at the single photo it will likely be out of the Yokogawa Hewlett Packard Japanese production and likely match the Decade Capacitor frame I have - nope still dont NEED it 

VK6 side of the country and some other HAMmy type gear listed as well.

[Neomys Sapiens]

Not one I have seen before (or have a NEED for ) eBay auction: #324821359264

Looking at the single photo it will likely be out of the Yokogawa Hewlett Packard Japanese production and likely match the Decade Capacitor frame I have - nope still dont NEED it 

VK6 side of the country and some other HAMmy type gear listed as well.

So you have already an at least passable 600Ohm step attenuator? 

[beanflying]

Nope but I have 50 and 75  step attenuators - still not bidding 

[mansaxel]

No discord today. Am off to do some powerboatin' with the Middle Boy:



Then with Minor Boy to a boy scout night in the forest.

Missed a 5245L to a sniper the other day. Still too few Nixie counters (1) in the shop.

[Cubdriver]

Not one I have seen before (or have a NEED for ) eBay auction: #324821359264

Looking at the single photo it will likely be out of the Yokogawa Hewlett Packard Japanese production and likely match the Decade Capacitor frame I have - nope still dont NEED it 

VK6 side of the country and some other HAMmy type gear listed as well.

So you have already an at least passable 600Ohm step attenuator? 

I popped the covers off and took some photos of mine (unbalanced version) earlier, but still need to upload and post them.  Neat little thing, and, unsurprisingly given its provenance, quite well built.

-Pat

[Neomys Sapiens]

Nope but I have 50 and 75  step attenuators - still not bidding 

Oh my, that is a sorry lot! You really, really need to do something about that! Although you might very well start with the impedance not covered at all,,,

[Specmaster]

Dave has a D'oh! moment... guess he shoulda done the daveCAD before he pulled a " 'ere, 'old me Foster's an'n watch this!"

mnem
 

Yep, saw that one the other day, just goes to show we all have our days when Murphy gets yeh 

[beanflying]

Nope but I have 50 and 75  step attenuators - still not bidding 

Oh my, that is a sorry lot! You really, really need to do something about that! Although you might very well start with the impedance not covered at all,,,

At $5AU pesos for the pair or about 3 Euro I reckon I am still in front 

[vk6zgo]

Not one I have seen before (or have a NEED for ) eBay auction: #324821359264

Looking at the single photo it will likely be out of the Yokogawa Hewlett Packard Japanese production and likely match the Decade Capacitor frame I have - nope still dont NEED it 

VK6 side of the country and some other HAMmy type gear listed as well.

Nah! my days of precision 600 Ohm measurement are long gone!

[beanflying]

Carrots are healthy ergo those and my other Vegan Beer snacks tonight are healthy too as I have seen the data

[mnementh]

3 fried eggs, 4 local product breakfast sausage, huge cuppa coffee with 3 heavy cream : 4 grams carb, 630 kcal.

Also quite yummy, and jump-starts my heart. I'd post a pic, but it's all gone.

mnem

[med6753]

Carrots are healthy ergo those and my other Vegan Beer snacks tonight are healthy too as I have seen the data

My spidey sense is telling me cooked via that method they are not all that healthy. It looks good which means that it ain't no good for you. 

[tautech]

Carrots are healthy ergo those and my other Vegan Beer snacks tonight are healthy too as I have seen the data

Healthy enough to get you out of the scratcher bright and shiny for Discord in the morning ? 

[beanflying]

Carrots are healthy ergo those and my other Vegan Beer snacks tonight are healthy too as I have seen the data

Healthy enough to get you out of the scratcher bright and shiny for Discord in the morning ? 

Depends 3am and 5am were last nights unscheduled awakenings I actually got some sleep circa Discord time this morning. 

[mnementh]

Meh. Been all sorts of out of sorts the last week or so; too much to do, too little time... 4am-5am up & making breakfast... then a nap til 10 or noon has been the last couple nights. 

mnem
whu-we-talkin'-abooot...?