Test Equipment Anonymous (TEA) group therapy thread

[BU508A]

HP 427A update. New power supply engineered and under test. Bog standard boring LM317 circuit. The positive things being that some of it is recycled from the HP PCM test set including the LM317T, the diodes, one of the capacitors and the heatsink and hardware.



Kicks out 24.56V which is good enough for the job. This will now be hooked up to the existing HP 427A voltage source and loaded with the peak of 13mA as per the HP427A's max load to make sure it doesn't drop out or exceed the differential voltage limits of the LM317.

Low tech mount - this will be taped to the bottom of the battery compartment with auto foam tape. Keeps it floating and insulated

Is 13mA enough to have the LM317 properly regulate? 

The datasheet (Texas Instruments) is saying yes.

[worsthorse]

What a long couple of years it has been; various SHTF events absorbed most of my free time and what I had left I invested in getting as far into the woods and away from things that beep and buzz as possible. While I have returned to building RF gear, I can't see myself doing a lot more test gear refurbishing, so I am selling the lot, other than the Tek TM gear (that will probably go, too, later), a couple of 485s (one works, one is a parts mule) and the 2465 (works but needs a complete recap) to a local hamfest reseller.  I won't get much for it, I am afraid, other than peace of mind and a lot of shelf space in my work area.

Once the weather gets wet around here again, I will refurbish the 2465 and the 485. I have used on my bench and they are fine scopes.  I am also going to start lurking around here again to watch what you all are up, too. 

Off to start reading the 2465 threads again and building the to-do list...

[m k]

So local is somewhere in the new world?

[worsthorse]

So local is somewhere in the new world?

 

local, as in "i will come by next week on my way to work and load my van with your gear"

[mnementh]

Ugh all that FR2 board. I keep getting flashbacks of that HP 54600 with cracked PCB 

And yet, my Hitachi V-212 has been dragged through the trenches & still works... and it is all Paxolin & off-the-shelf jellybean parts. 

BTW, bd... don't forget to PM me with your new meatspace addy once you're all settled in...

mnem
Oh, no reason... no reason at all...

[mnementh]

these are the voyages of the Valkyrie Saskia on her continuing mission to explore and eradicate gorillaism ...
(SNIP)
For fucks sake. Why did they not use a chain saw to break the lock ...   and 2500 for breaking the lock and fucking up the powerboard and the battery thingie on the CPU board ? Cut off their balls....

I think you need to apply your Bungard Press to the tenderest parts of their anatomy. Repeatedly. 

mnem
let the punishment fit the crime.

[mnementh]

What a long couple of years it has been; various SHTF events absorbed most of my free time and what I had left I invested in getting as far into the woods and away from things that beep and buzz as possible. While I have returned to building RF gear, I can't see myself doing a lot more test gear refurbishing, so I am selling the lot, other than the Tek TM gear (that will probably go, too, later), a couple of 485s (one works, one is a parts mule) and the 2465 (works but needs a complete recap) to a local hamfest reseller.  I won't get much for it, I am afraid, other than peace of mind and a lot of shelf space in my work area.

Once the weather gets wet around here again, I will refurbish the 2465 and the 485. I have used on my bench and they are fine scopes.  I am also going to start lurking around here again to watch what you all are up, too. 

Off to start reading the 2465 threads again and building the to-do list...

Welcome back! When you vaporized without warning, I feared the worst... but I was having my own "heavy doses of IRL" at the time and I guess I let it slide. 

I certainly am glad to be wrong. Hope you're still with that SO who so delightfully kept your home looking like a advert for Flowerama...

mnem
Tonight, the zeros 2465s were singing for you...

[Specmaster]

Oh great - my PL320 is starting to get flakey LED segments. Is intermittent. Comment problem on these but can't remember what the root cause was.

From across the room with my phone so please excuse crappy picture.



That's for the repair list then...

What is it with segment A on these LED's then?

[Specmaster]

I'm gob smacked, its not even blue, Plonking that on your bench is tempting fate, the Teks will be striking next 

Surprisingly everyone gets along without any fights. 

Get them to join this forum then and that might change 

[mnementh]

So local is somewhere in the new world?

 

local, as in "i will come by next week on my way to work and load my van with your gear"

If his advertised location is what I think it is, he's on the northwest coast almost to Seattle.

Of course, were I as "peoplephobic" as I recall him claiming to be... I dunno that I'd let folk narrow it down even that much.

mnem
"If you can see your neighbors, they're too fuckin' close."

[Vince]

No worries Vince, a fun adventure was had and now we know how not to do it. 

I'll have to see if I can figure out a way to pull the firmware without the tektools application. Once I get the PSU for my PC working......

Maybe the easiest route would be to simply ask the guy who wrote TEKTOOL, if he would be kind enough to update it slightly so it can run on Windows 95/98.....

Or maybe at the very least, convince him to release the source code (But I am certainly not a software guy, so someone else will have to take it from there...)

Speaking of which, anyone got a spare TSM110CN or TSM111CN 'Triple Voltage and Current Supervisor) chip laying around?
https://www.st.com/resource/en/datasheet/cd00001698.pdf
I've tested almost everything else, and it seems the Current Mode Controller chip (uC3845B) that switches the main switching transistor isn't getting a signal from the TSM110CN, but the optocouplers seem to test ok.
It looks like Digikey have the TSM110CN chips in stock, but I need to make a $50 order to avoid the $20 shipping charge.......

https://www.ebay.com/itm/233603951155?hash=item3663e16a33:g:qiYAAOSwFohe0Qp5

Cheaper, 15 US dollars shipped..... or cheaper, since the seller is willing to take offers...
Direct from China. Japan is not that far from CHina so you would I hope receive them much faster than we do in Europe, in a matter of days rather than weeks or months.

Can't you just hack something to make use of a standard ATX power supply ? It's not like you needed to look pretty ion order to sell it or something... as long as it can power up the computer, GPIB will be happy enough....

China is an option I guess, but I'm always wary of fakes....

I do have a newer ATX PSU here actually, but the problem there is that modern PSU's don't have a -5V rail since there are no ISA slots any more... So even though a modern ATX PSU does physically fit, and repinning the power plugs isn't too hard, I still need to figure out how to get the -5V rail, and then we are back to it all being a harder process than just buying that chip for the existing PSU..   (Assuming that this chip is the actual fault in the first place...)

Oh, didn't know about -5V for ISA slots, interesting !

Well you can always supply your own external -5V can't you ! 

Too much work ? Too ugly ?

Well yes I know but your concern seemed to be money, so I was trying to trade money for hassle and uglyness.... trying to find solutions for you you see ! 

So 15 bucks for that chinese chip doesn't find your fancy so... well I guess next step is 20 bucks for one from Digikey, or order more stuff up to 50 bucks.
You all told me to do that the other day, laughing at me not wanting to do it... well look, even Terra doesn't want to do it now !
I am not alone...

Might be cheaper to get another PC, or another vintage ISA PSU...

[Vince]

Oh, BD revived his old avatar, phew !

I like it very much. The other one looked ugly and scared me somehow, brrr....

[bd139]

More Sunday afternoon 427A fun. Battery eliminator complete and working.

Hooked up the new power supply to the HP 427 battery terminals. The existing lugs and filter capacitor previously pictured have been snipped out here. 



A dummy load (resistor) was chosen and soldered across the supply to overload it by 200% the required current demand and the dropout checked. It's close but fine. This is with the 220 ohm series resistor from the original charge circuit in place still. Bottom trace DC out, top on AC in. Both 5v/div from bottom of graticule. Good enough!



The existing charge circuit was then modified. This is all on the slow/fast switch on the back of the unit. There are two branches from the charge circuit, the first of which goes to the battery connector that I've already shown in the first picture. The second branch goes to the power switch on the meter. I desoldered just the power switch wire and routed it back up through the chassis into the battery compartment and connected this to the output of the LM317 board. So the charge input is wired to the regulator input and the output is routed to the power switch on the front panel. This is the least amount of modification possible.

The board was then rested inside the battery compartment, its final resting place when Amazon finally deliver this bloody foam tape, and re-tested.



Battery indicator looks about right now as it's measuring the battery eliminator output rather than a battery.



And finally a quick check to make sure it's doing metery sort of things.



Happy so far.

To do:

1. Stick the battery eliminator down and possibly remove the heatsink because it doesn't even get warm anyway.
2. Clean up the unit a bit better.
3. Evaluate and possibly replace any rusty trimmers.
4. Calibrate.

[mnementh]

The divider network is designed to sink 7mA which is above the 5mA minimum regulation on the NS LM317T datasheet. The 13mA load is in addition to that

I saw that divider and guessed 5-10mA, plus load. But I do a lot more dead-bug fugly than most folk. Is the voltage differential enough that you even need a heat-sink at 20-25mA?

EDIT: Heh... you answered while I was asking. Sick minds think alike.

mnem

[bd139]

Oh great - my PL320 is starting to get flakey LED segments. Is intermittent. Comment problem on these but can't remember what the root cause was.

From across the room with my phone so please excuse crappy picture.



That's for the repair list then...

What is it with segment A on these LED's then?

Think they are probably crappy displays. Issue appears to have gone away again now. Will forget about it until it annoys me next time 

[mnementh]

Oh, BD revived his old avatar, phew !

I like it very much. The other one looked ugly and scared me somehow, brrr....

I saved a copy just for you, Vince...

mnem
 

[bd139]

The divider network is designed to sink 7mA which is above the 5mA minimum regulation on the NS LM317T datasheet. The 13mA load is in addition to that

I saw that divider and guessed 5-10mA, plus load. But I do a lot more dead-bug fugly than most folk. Is the voltage differential enough that you even need a heat-sink at 20-25mA?

mnem

I was over-engineering it to start with on the heatsink side of things. The thing has a 200 ohm dropper resistor in series with it which burns off most of the drop already so there was no need to make the LM317 drop it. I will remove it when I stick the regulator down. So yep, not needed. I'd rather not have it in there as it adds mass to the poorly mounted LM317 anyway which isn't great when it's not nailed down 

The actual HP 427A takes only 1mA of current on DC and AC ranges and up to 13mA on resistance measurements and most of the latter is the measurement current source. It barely sips the juice. Quality engineering 

[mnementh]

Oh great - my PL320 is starting to get flakey LED segments. Is intermittent. Comment problem on these but can't remember what the root cause was.

From across the room with my phone so please excuse crappy picture.      That's for the repair list then...

What is it with segment A on these LED's then?

Think they are probably crappy displays. Issue appears to have gone away again now. Will forget about it until it annoys me next time 

Translation: bd thumped it with his finger and it started working again. Fukkitt. 

mnem
percussive maintenance FTW.

[TERRA Operative]

Oh, didn't know about -5V for ISA slots, interesting !

Well you can always supply your own external -5V can't you ! 

Too much work ? Too ugly ?

Well yes I know but your concern seemed to be money, so I was trying to trade money for hassle and uglyness.... trying to find solutions for you you see ! 

So 15 bucks for that chinese chip doesn't find your fancy so... well I guess next step is 20 bucks for one from Digikey, or order more stuff up to 50 bucks.
You all told me to do that the other day, laughing at me not wanting to do it... well look, even Terra doesn't want to do it now !
I am not alone...

Might be cheaper to get another PC, or another vintage ISA PSU...

You already know, this is the only correct answer....     

[Vince]

Oh, BD revived his old avatar, phew !

I like it very much. The other one looked ugly and scared me somehow, brrr....

I saved a copy just for you, Vince...

mnem
 

[tggzzz]

Went to the Chippenham hamfest. Put some treasures in the car, but couldn't be bothered to try to sell anything in a field in the drizzle.

One bloke had a three Tek2712 and two Tek492 21GHz spectrum analysers. One of the former was shown working on a pure sine wave inverter; the display was just about visible. One 492 had a broken blue screen shield and was missing a handle, which is essential for that lump of metal. Said he would sell them for £300, but hadn't when I left.

Didn't get much. A couple of metal enclosures for £1 each, yet another Cropico resistance box (cal ran out in 2014) all resistors measure OK, and some banana plugs.

[Brumby]

Jaycar Electronics is moving their warehouse and they had a clearance last Thursday, Friday and Saturday.  I went on the first and last days.  Met Dave on the first day ... He's done a couple of videos about the experience.

To see what I scored - and the damage - have a look here: SYDNEY: Jaycar Relocation Sale

[Saskia]

FUUUUUUUUUUUUUCK 
The AWOL transformer waved at me. Now I have a spare.
But:
The ball launcher gun for my T2 which was freshly chrome plated and is absofuckinglutelydammit unobtainium went AWOL. As did my audio board for my T2.

I fucking hate moving.

 
Now I have a spare 300€ transformer
 

[bd139]

Went to the Chippenham hamfest. Put some treasures in the car, but couldn't be bothered to try to sell anything in a field in the drizzle.

One bloke had a three Tek2712 and two Tek492 21GHz spectrum analysers. One of the former was shown working on a pure sine wave inverter; the display was just about visible. One 492 had a broken blue screen shield and was missing a handle, which is essential for that lump of metal. Said he would sell them for £300, but hadn't when I left.

Didn't get much. A couple of metal enclosures for £1 each, yet another Cropico resistance box (cal ran out in 2014) all resistors measure OK, and some banana plugs.

I was considering having a day out down there. Glad I didn’t now 

[Brumby]

FUUUUUUUUUUUUUCK 
The AWOL transformer waved at me. Now I have a spare.
But:
The ball launcher gun for my T2 which was freshly chrome plated and is absofuckinglutelydammit unobtainium went AWOL. As did my audio board for my T2.

I fucking hate moving.

 
Now I have a spare 300€ transformer
 

Have an extra of something you don't need and lose something you absolutely do need.

Sounds familiar.

Here, have some more brick wall.....