Test Equipment Anonymous (TEA) group therapy thread

[bd139]

Multi-region replication FTW... failed your due diligence there I'm afraid. I'm paid a fair amount to think of all of those things and make sure they can't happen. It's much more difficult outside of the cloud. Think what happens when Specmaster's secure offline hard disks are nicked by a Pikey...


Well something worked today

Code: [Select]

import pyvisa

rm = pyvisa.ResourceManager()

ins = rm.open_resource("GPIB0::3::INSTR")
ins.read_termination = "\n"
ins.write("DR SHITBALLS")


[BU508A]

Not that you NEED another scope    eBay auction: #154405003584

Already have one 1740A.  Do I need two?

Can I do stereoscopic traces??

Sure, and if you are doing it right, you'll see a nice 3D effect. 

[mnementh]

A very complete one for the AVO nuts out there too. eBay auction: #233944670135 $15 AUD post to me and on shipping at cost ENABLING available to non locals

 

This is starting to lose its appeal - even with no shipping and a cupful of fuel.  Four days to go and we have two bidders bouncing back and forth a couple of times.  Bound to be more bouncing ... and then there's the sniper unknown.

Anyone want to take a punt at the final price?

$134.50 Aussie pesos.  Way more than I would have thrown at it.

Not that you NEED another scope    eBay auction: #154405003584

For a collector price is a bit secondary. Some of my Manual Brewing Coffee collection was way to many $ for function but I just had to have the item 



I sold one of the two in front for $150. Makes one single cup at a time but more than a bit rare. Way better Coffee makers out there for way way less.

Looks like a crystal meth lab. 

mnem
Actually, in context, very similar role... at least in an existential sense. 

[mnementh]

Not that you NEED another scope    eBay auction: #154405003584

Already have one 1740A.  Do I need two? Can I do stereoscopic traces??

No, you don't need two. You need three.

mnem
...maybe four...

[Kosmic]

...

A snap of the workshop. Image quality is a lot better in real. Because the Bullard ITx is lacking a video out I had to grab a picture of the cheap LCD with my camera.


Next steps are, finding a suitable battery and adding a video out.

Found the video out. The Raytheon 300D core directly provide a NTSC signal in output.



Red == V+ (9-28VDC)
Black == Gnd
Green == Video +
White == Video -

I got one of those cheap video capture dongle. Windows 10 auto detect it and you can use the Camera app to capture. Then the Photo app to edit the video.



The Raytheon 300D provide a resolution of 320x240 but the capture dongle interpolate to 640x480. The result is not that bad. The focus point is a bit far though (around 1 meter).



This is 100% a thermal video, no superposition of a standard video in background.

[mnementh]

Multi-region replication FTW... failed your due diligence there I'm afraid. I'm paid a fair amount to think of all of those things and make sure they can't happen. It's much more difficult outside of the cloud. Think what happens when Specmaster's secure offline hard disks are nicked by a Pikey...
Well something worked today   

Code: [Select]

import pyvisa
rm = pyvisa.ResourceManager()

ins = rm.open_resource("GPIB0::3::INSTR")
ins.read_termination = "\n"
ins.write("DR SHITBALLS")


No, you don't have an excess of discretionary time... no... no... no.... 

mnem
"The devil's hands are idle playthings..."

[Specmaster]

I stumbled across this while we were offline for a few days, well which it then?? 

[Vince]

Yeah, I'd still want one of these inline with a variac, myself. A lot of the time you'll find that once things start turning on in a SMPS, especially the older designs, that's when a short appears. The scariac doesn't stop the magic smoke from coming out then, but rather encourages the switcher transistor to try and sink more current to make up for the lower voltage.

Oh, yeah, sure. I never meant to use a dim bulb tester and variac with modern SMSP stuff, only with old 60's/70's stuff with linear power supplies.
It's really only for the initial power up of old my old tube Tek scopes, so as not to risk frying the transformer and rectifier tubes, and wreckign the scope.. that's all.

For SMPS stuff I just rely on the circuit breaker I added in-line with my test power outlet on the bench.

When I built my dim bulb tester, it was to try and not blow a hundred fuses as I was trying to repair the SMPS PSU in my Tek 2232 scope.
The MOSFET was shorted and sent the PWM controller to heaven, along with all the discrete components around it. Replaced everything but was not too hopeful as that was my first SMPS repair ever, first scope repair ever really. So since I had just leaned about this dim bulb tester thing, I thought hey, great opportunity here, let's build one !  The scope would not power up. The light bulb would literally blink, indefinitely, at a perfectly repeatable/stable frequency. Period of about 2 seconds or so. I though wow strange, what did I do wrong...  had no clue, so decided to cross fingers and power the scope without the bulb tester.... scope power up and worked just fine !! 

So I learned right away that SMPS don't like dim bulb testers ! 

[Vince]

Incoming DL1200A here by next week. 

Hmmm... are you a Yokiogawa lover, collecting them ?!

They aren't very common in France at the very least. Never everheard about them in my entire live. I became aware of them only recently as I was searching the local ads fr the keyword "oscilloscope"... a Yokogawa popped up, wondered what the hell that was. Looked like some medical gear or something...  was curious to play with one but it was not to be, since the sellers wanted a delirious amount of money given the poor specs of the scope.

Will do then a teardown of it.

Would be curious to see that. When you do, please post a link to it here, so I don't miss it 

[mnementh]

See my followup post.    https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg3544804/#msg3544804

That situation is precisely when you need something like the light blub tree, so you can add blubs to increase the max current. Doing so in smallish increments is your best means of successfully getting to a full-power state without having to replace the switcher transistor like half a dozen times.

Some SMPS can actually be powered from a CC/CV DC power supply... but ones which can provide adequate voltage and inrush current are expensive, and still oscillation can be very destructive on both the DUT and PSU.

I've learned this the hard way several times over the years, in several seemingly different scenarios. Sometimes the simpler tools simply are better.

mnem
 

[Cerebus]

Talking of OXCO's I've been putting one of my HP 10811Ds into a case and fired it up for the first time on Tuesday. Frequency was fine with No EFC and the mechanical trimmer untouched since it was removed ftom a 8922 cell test set abou 4 years ago and has been in a storae container for at least a couple of years the error to GPS was 0.052Hz.
Overall I'm pretty pleased. I made one difficult decision to use a DC-DC converter so it can run off mains or 9-18V DC. I'm seeing a little bit of nise from the DC-DC on the output. It goes up with the oven current and appears to be short bursts of noise. It's good enough as a frequency reference but not to multiply up to microwavs frequencies. I'll have to do a bit of work and see if I can knock it down a bit further.

Aye, there's the rub. Now I'm mucking about with building frequency standards I'm beginning to feel I need an SA.

Woe is me, it just looks like I'll have to start looking for one. 

I have a Marconi TF2370 available to a good home. Only 110MHz but digital storage and 5Hz resolution bandwidth make it better than a lot o SAs for looking at close in noise.

Tempting, and truthfully it would probably be a technically good fit for things I might practically need to do. But:



The bulk of that boat anchor would exceed both my available space and what little remaining store of WAF I have available to me. 

[Vince]

OK Vince, now with your keen eye you pointed out a tantalum cap in one of my pics of the hp E3611A - a trouble maker as you stated. That happens to be the only one in the parts list - a 6.8 uF 35V.

Now, that happens to be a 3-legged tantalum. Works the same as a 2-legged. They made them so that they couldn't be installed backwards. Although there are no polarity markings on it, I checked the schematic and the center pin should be positive. Also indicated by a voltage check too.

I'll let you decide, since you are appreciative of vintage test equipment - do you say it's OK to put in a 3-legged part in it's place, just to keep it original.

 

Wow, a 3-legged Tantalum, cool ! First time I see one 
Yes it's the usual trick of making a non polarized cap from two polarized one, sticking them head on.

I don't have the schematic, but if you are sure that they use a non-polarized one for "safety" but the schematics actually does not REQUIRE one for the proper operation ot the unit... well yes of course in this case you can do as you please and replace it with a 2 legged one of same value...

That said, I don't even know if you could replace it with a 3 legged one... I mean are these things still available these days ?!

I guess in the short term, for now best not to touch it if it tests good. Restore the unit first and then when it all works, worry about replacing the tantalum as preventative maintenance since sooner or later it will fail. But why bother replacing it if you don't even know if the unit can be fixed...

[Cerebus]

Code: [Select]

import pyvisa

rm = pyvisa.ResourceManager()

ins = rm.open_resource("GPIB0::3::INSTR")
ins.read_termination = "\n"
ins.write("DR SHITBALLS")


Literally not 15 minutes ago I had wished that I had done something similar myself. I've been manually taking down drift readings of the frequency counter every 30 minutes for the last 2 1/2 hours.

[Cubdriver]

Now, what was I saying before I was interrupted by someone sneeking off behind the generator shack for a quick fag? Oh yes, OCXOs.

So, my batch from what turned into a distributed group purchase took 9 days door to door. Ordered two and like BD, got twice as many for my money.

Desoldering turned out to be relatively easy for a part on a 10 layer board - just desoldered each pin with Chem-Wik (that stuff's good) and went around the board with a small screwdriver for a lever and gave each pin a lift while heating it with the old Metcal. No application of 60/40, chip-qwik or anything similar needed. All four survived the ordeal of having the board next to them violently cut and being desoldered.

Here's how they all performed:   

Sorry for the laziness of a screenshot, but converting to SMF's table notation is too much of a fag. Readings taken with my TTi TF930 that was last adjusted against GPS a year ago. All with enough range left to be steerable to 10.000 000 00 MHz at an appropriate EFC voltage with room to spare for future ageing (i.e. GPSDO fodder). None good enough to be used "out of the box" as a 10 MHz reference without trimming, unless you were more interested in stability than accuracy. I tried a few random selections for stability, using another known good uncalibrated 10 MHz OCXO as reference input to the TF930, and they stayed stable at the limit of the counter's resolution (10 mHz or 1 ppb) for as long as I was prepared to wait - several hours in one case.

Conclusion: £13.90 well spent.

Mine are still on the way; I too had a "Me three!!!" moment. As Canoodlian Post is the last mile carrier, we typically only get actual deliveries 2-3 times a week, so no idea when I'll actually see them.

mnem
 

The bunch I ordered arrived at the local P.O. yesterday according to the tracking info, but still show an expected delivery date of the 29th, so lord only knows what's going to happen.  I'd expect to see them in the next day or two, but have no idea how they handle shipments like that.  Time will tell.

-Pat

[bd139]

Code: [Select]

import pyvisa

rm = pyvisa.ResourceManager()

ins = rm.open_resource("GPIB0::3::INSTR")
ins.read_termination = "\n"
ins.write("DR SHITBALLS")


Literally not 15 minutes ago I had wished that I had done something similar myself. I've been manually taking down drift readings of the frequency counter every 30 minutes for the last 2 1/2 hours.

Yeah ... very easy this

Code: [Select]

import pyvisa
from datetime import datetime
import time

rm = pyvisa.ResourceManager()
ins = rm.open_resource("GPIB0::3::INSTR", read_termination = "\n")
ins.timeout = 50000

start = datetime.now()

while True:
    meas = ins.query("FU1")[2:]
    when = (datetime.now() - start).total_seconds()
    print("{0},{1}".format(when, meas))
    time.sleep(5)


Spot where I knocked it off the table 



This is comparing the built in crystal osc with the OCXO so I expect a lot of drift but it's not *that* bad actually (check the amount of zeros)

[Vince]

The 3 leg tant's are made for low impedance, not being reversable. Unless it has more then 25V DC on it I'd let it stay where it is.

Oh OK, thanks. Don't understand though why they don't just put two regular 2-leggeds ones in parallel then ?
3 legged on is a tiny bit more compact, but it's not an issue on that particular board.

[Vince]

The 3 leg tant's are made for low impedance, not being reversable. Unless it has more then 25V DC on it I'd let it stay where it is.

Oh OK, thanks. Don't understand though why they don't just put two regular 2-leggeds ones in parallel then ?
3 legged on is a tiny bit more compact, but it's not an issue on that particular board.

[Cerebus]

A very complete one for the AVO nuts out there too. eBay auction: #233944670135 $15 AUD post to me and on shipping at cost ENABLING available to non locals

 

This is starting to lose its appeal - even with no shipping and a cupful of fuel.  Four days to go and we have two bidders bouncing back and forth a couple of times.  Bound to be more bouncing ... and then there's the sniper unknown.

Anyone want to take a punt at the final price?

$134.50 Aussie pesos.  Way more than I would have thrown at it.

Not that you NEED another scope    eBay auction: #154405003584

For a collector price is a bit secondary. Some of my Manual Brewing Coffee collection was way to many $ for function but I just had to have the item 



I sold one of the two in front for $150. Makes one single cup at a time but more than a bit rare. Way better Coffee makers out there for way way less.

Looks like a crystal meth lab. 

mnem
Actually, in context, very similar role... at least in an existential sense. 

In that vein, this situation:



made this:



a very welcome sight when the postie came earlier. Talk about an existential crisis....

[bd139]

The 3 leg tant's are made for low impedance, not being reversable. Unless it has more then 25V DC on it I'd let it stay where it is.

Oh OK, thanks. Don't understand though why they don't just put two regular 2-leggeds ones in parallel then ?
3 legged on is a tiny bit more compact, but it's not an issue on that particular board.

It's for installation, not impedance. If you wanted impedance you'd use a tant and ceramic in parallel.

Specs are same as the two legged ones.

Says so on the datasheet! https://www.vishay.com/docs/40044/299d.pdf



Really this is about making them even more of a bastard to get out of a board 

[mnementh]

Code: [Select]

import pyvisa

rm = pyvisa.ResourceManager()

ins = rm.open_resource("GPIB0::3::INSTR")
ins.read_termination = "\n"
ins.write("DR SHITBALLS")


Literally not 15 minutes ago I had wished that I had done something similar myself. I've been manually taking down drift readings of the frequency counter every 30 minutes for the last 2 1/2 hours.

Proof that sick great minds think alike. 

mnem
 

[med6753]

Well, I thought I had some 7586 Nuvistors in stock but I can't find them. I must have used them up. I did have a few flaky ones in other projects. Yep, drift issues. So off the Ebay. Got a few coming next week.

The Mouser order did indeed ship this morning. And yes, delivery Monday.

Not doing much today just going to relax. Tomorrow is the big day.....I finally get rid of this cat. 

[Vince]

The 3 leg tant's are made for low impedance, not being reversable. Unless it has more then 25V DC on it I'd let it stay where it is.

Oh OK, thanks. Don't understand though why they don't just put two regular 2-leggeds ones in parallel then ?
3 legged on is a tiny bit more compact, but it's not an issue on that particular board.

It's for installation, not impedance. If you wanted impedance you'd use a tant and ceramic in parallel.

Specs are same as the two legged ones.

Says so on the datasheet! https://www.vishay.com/docs/40044/299d.pdf



Really this is about making them even more of a bastard to get out of a board 

Ah great, thanks for that datasheet ! Final word it is then, it looks...  I will tend to trust Vishay 
So it's indeed just for convenience and nothing else...

[Cerebus]

The 3 leg tant's are made for low impedance, not being reversable. Unless it has more then 25V DC on it I'd let it stay where it is.

Oh OK, thanks. Don't understand though why they don't just put two regular 2-leggeds ones in parallel then ?
3 legged on is a tiny bit more compact, but it's not an issue on that particular board.

It's for installation, not impedance. If you wanted impedance you'd use a tant and ceramic in parallel.

Specs are same as the two legged ones.

Says so on the datasheet! https://www.vishay.com/docs/40044/299d.pdf



Really this is about making them even more of a bastard to get out of a board 

Ah great, thanks for that datasheet ! Final word it is then, it looks...  I will tend to trust Vishay 
So it's indeed just for convenience and nothing else...

Oh I don't know, those three leads form quite a useful little fin which will help stabilise its trajectory when it ultimately explodes and comes winging off the board. 

[mnementh]

...For a collector price is a bit secondary. Some of my Manual Brewing Coffee collection was way to many $ for function but I just had to have the item 



I sold one of the two in front for $150. Makes one single cup at a time but more than a bit rare. Way better Coffee makers out there for way way less.

Looks like a crystal meth lab. 

mnem
Actually, in context, very similar role... at least in an existential sense. 

In that vein, this situation:      made this:   

a very welcome sight when the postie came earlier. Talk about an existential crisis....

I'm still teaching my son how to make a proper pot of coffee... this morning it was "COLD WATER, son... always COLD. The percolator requires the difference in temp between the water at the top and that at the bottom to actually brew the coffee. Starting with hot just makes pee water, not coffee."


   http://ars.userfriendly.org/cartoons/?id=20060927

This pretty much sums it up...

mnem
*toddles off to do something... outside...*

[URI]

Damn downtime!
Missed page 3499, ok here is my Agilent 3499A anyway.