Test Equipment Anonymous (TEA) group therapy thread

[m k]

Not much of a quiz, but somebody said somewhere that they've never seen a socket of 10.
Well, that doesn't change here.

[shakalnokturn]

8 bit Genrad game console / computer 
So what is U44 ?

[shakalnokturn]

Bought myself one more multimeter last week, a MetraHit 28S selling as not powering on after a long storage time. I figured the batteries must need replacing   
45€ posted is more than I'll usually put into a defective DMM but couldn't resist the 300k counts, received it a couple of days ago, finished repairing today and thought I'd report here.

The no power issue was simple enough, I think it had seen previous mild battery leakage (The PCB was pretty clean on the whole) the battery holder had been replaced but keeping a couple of cm of wire of the original one running from the PCB to solder to. The initial leakage must have seeped down between the conductor and insulation and eventually disintegrated the wire by electrolysis where it met the solder on the PCB.

Another problem, actually the first to meet my eye, was a burnt FDS6930A dual MOS for the mA current shunt switching so someone had managed to abuse it quite severely.
On the hidden side one of the BYD77 Melf clamping diodes across the shunt was cracked, heated pads had started lifting from PCB.

Back shield that had been cracked near the screw when I received it was glued with PVC glue and covered with conductive paint for the sake of ensuring a good electrical link.

On the whole it was a quite easy repair and I think well worth the price. Now my two 28S meters don't agree enough to my liking on the Volts ranges which is going to stop me from sleeping... Anyone out here no the requirements for closed-box readjustment on Mertra's ?

Also my first 28S has never been my go-to DMM and every time I've needed it the batteries were discharged. They both draw about 110-120µA in standby. It looks reasonable to me but is it normal?

[Zoli]

...
So what is U44 ?

Something sitting in a chopped socket 

[Robert763]

That isn't a video game. Looks like a Genrad DigiBridge maybe a 1689.

Robert.

[factory]

Would need more RAM & other bits for that....

...
So what is U44 ?

Something sitting in a chopped socket 

Looks like another LH0002CN buffer, same as the one near the top right of the PCB.

David

[AVGresponding]

That isn't a video game. Looks like a Genrad DigiBridge maybe a 1689.

Robert.

Would need more RAM & other bits for that....

David

Yeah it's a more primitive one like a 1657 or something


EDIT: Here's the innards of my early 80s 1657

[TERRA Operative]

The angled free floating plug-in PCB bothers me......

[McBryce]

The angled free floating plug-in PCB bothers me......

Those two screws on the left and right would suggest that it's not free floating, but that the support isn't visible from this angle.

McBryce.

[AVGresponding]

The angled free floating plug-in PCB bothers me......

Those two screws on the left and right would suggest that it's not free floating, but that the support isn't visible from this angle.

McBryce.

Exactly so, it has two aluminium brackets, attached using stainless steel machine screws.

[m k]

My first picture has those support arms.
Under the left one is a regular pinheader power connector.

Somebody somewhere said also that capacitor markings have had some variations.
The big one beside the angled connector is 125uF/100V and capacity marked as MFD.

That isn't a video game. Looks like a Genrad DigiBridge maybe a 1689.

Robert.

Unfortunately my machine is only 1658.

Also unfortunately without GPIB board.
Bright side is that the board is quite simple with two 6820 PIAs.
And of course I have few, almost new from previous millennia.
Means also that all of its higher functionality can be readily available.

Power supply has couple bigger caps.
Based on those caps one could think that output connector should have thicker pins.

[CalibrationGuy]

And some field instruments to calibrate with the 3458a......

[Vince]

Not muchj to report in the lab... house work is now the priority now that the nice weather is back, or kind of. Weird weatherthe past 6 months...

Still, lab is not 100% dead. Although I am in clearing mode rather than buying mode, you gotta stay open minded and cease good opportunities when they pop up... so that's what I did.

I saw a couple ads here on leboncoin.fr for BNC coax 50R cables. With 40+ scopes and a good half a dozen Nikc counters, I need cables don't I...

Combined, these two ads amount to 75 Euros for 20 cables, that's 3/4 Euros per cable, and it's good stuff. 3/4 of them branded Radiall, length 50, 100 and 200cm.
Cable type R285, found a datashett for that, good for 3GHz perfect for my humble uses... I am not into RF.

1/4 of them are branded "ATEM" whoever they are.. cable type RG223, datasheet says 8GHt IIRC.... more than I will ever have the use for, that's for sure.

All in tip top shape, both the cables or the connectors.

I thought at that price they might be cheap Chinese counterfeit stuff that would bite me in the ass one day but... no. All these cables do look in excellent shape, but also clearly have patina to them, they are used... which is good. Makes it more believable that they are genuine. The Radiall cables do have "Radiall" molded into the plastic of the strain relief piece, which is another good sign.

So overall a really good buy I thought. It happens once in a while...
Seller still has plenty more such cables for sale, but I gotta stop somewhere, can't buy them all.
Looks like he got a palette full of the stuff... maybe at his work they decommissioned a huge test setup with tons of cables wiring up tons of scopes and sig gens and what have you...who knows.

[Andrew_Debbie]

Quick hello.      I had a half day off work today.  Decided to spend it in the office fixing my Racal-Danna 1998 Counter.    A few of the push buttons failed, a common problem.  Several threads on here about repairs.


A few notes, in case anyone else is about to do this:


Take off the sensitivity knob and the lock ring from the A input.





Along with the obvious screws, remove the two screws holding the assy. at the bottom left of this photo.  They might look like they just attach the shield. They connect the thing to the front panel.   Yes mine has an ovened crystal.  Sometimes you get lucky.

I managed to find buttons that almost drop in.     I'll have to either modify the button tops or print new ones.     It is not easy getting the buttons to be in exactly the right spot. 

Back in service pending button top replacement.   I've never adjusted it.  I don't think anyone has touched it in many years.  It had been sitting in a shed for ages.  Cal sticker is from 2004.    I just ordered a Bodnar GPSDO.  I'm curious to see how far out it is.   Maybe it is still in spec???   


 

[m k]

I guess a device quiz is a bit too much, can't find a single online picture.
But maybe a type of the device.

[Robert763]

Well it clearly has a battery operated high voltage DC supply. Transformer and cockcroft-walton type multiplier. Dot sure that the rotary and toggle switches do.  Could be any of:
Insulation tester
Proving unit (for testing safety voltage detectors before use)
Geiger counter
HV power supply
Gas discharge lamp tester

Robert.

[shakalnokturn]

I guess a device quiz is a bit too much, can't find a single online picture.
But maybe a type of the device.

Spark gap tester?
Programmable fly zapper?
Air ioniser...

[shakalnokturn]

Looks like he got a palette full of the stuff... maybe at his work they decommissioned a huge test setup with tons of cables wiring up tons of scopes and sig gens and what have you...who knows.

I've been following that seller for a while now, he's had plenty of good TE selling for decent prices including a couple of SA's.
The first batches of BNC cables he sold were really interesting, since he's realised he could make a bit more money out of them. Prices are still very reasonable.

[Andrew_Debbie]

Leo Bodnar  LPE-1420  GPS Locked Clock arrived today.   Best if I test it to make sure it works.   

After 35 minutes,  my counter is reading 10mHz high.    It had been drifting toward 10.00000000MHz but is now short-term stable.   EDIT: Now bouncing between 9 and 10.     I will let everything run for several hours before considering making any adjustments.   

The cal sticker is stamped Jul 1991.   It has not been adjusted in a long time, possibly not since '91. 

[Andrew_Debbie]

I left the 1998 on standby overnight.  STBY keeps the OCXO powered on.    This morning it now reads 10.00000004 MHz.     I don't think I will adjust anything.  I might make it worse.

[m k]

I knew that cascade is too easy.

It's sort of a double action insulation tester.
And that 3x3 pin thingy is finally a simple push button.

Around 500W UPS transformer 7-0-7 to 0-230-240 had full primary as level 2 and secondary as level 11 of inductance metering.

(sunlight was even worse)

[factory]

Well I don't think I've seen an insulation tester without scale markings in MΩ before, is there a guide on the back cover of what the switch numbering means?

David

[m k]

No, but I'm quite sure Elma TR1000 is its sequel.
There new function is that rotary 12 is connected to a trimmer for even higher inductance.

Maybe ohms are missing because the old model has few different scales.
Manual would be nice of course, but most likely hided very thoroughly.

E,
I found a picture of the old model yesterday.
(and successfully edited this message, of course)
It's from Swedish machinist forum where "rag top" tractor owner wondered what other things he has.
So probably without a manual.

Motortester blue is used for some car tester stuff around here, some old SAAB testers have that same theme.
Maybe it's just a coincidence, the blue seems to be some sort of a fashion.

[McBryce]

Well I don't think I've seen an insulation tester without scale markings in MΩ before, is there a guide on the back cover of what the switch numbering means?

David

It looks like it was custom made for some sort of "go / no-go" test for a specific device. Most likely for motor windings and possibly in coordination with additional test equipment. That would at least explain the lack of a definitive scale.

McBryce. 

[factory]

There seems to nothing for this Dana Danameter DMM on the forum, from what I've read on the web, people seem to claim it was the first handheld portable DMM with an LCD & long battery life, predating the Fluke LCD DMM rubbish  , I found an advert from 1974 here (see pages 6&7);  http://www.bitsavers.org/magazines/Electronic_Design/Electronic_Design_V22_N05_19740301.pdf






Sadly my example (2000A/2002A) hasn't aged well, as the LCD is knackered, the segments have bleed together.
It's still with the original box & instructions and according to the paperwork, it was a retirement gift to an ex-Racal employee in 1987, inside the meter has datacodes of 1982/83. The instructions claim the case is virtually unbreakable (Cycolac T), so I can at least use it as a hammer to beat the yellow Fluke* crap to death. 

Some internal pictures.









Yes that is probably was a 100MΩ carbon composition resistor (top left).



This is what the display looks like when switched on.





*thankfully I own no Fluke handheld DMMs.

David