Test Equipment Anonymous (TEA) group therapy thread

[Vince]

Hello Dave,

I was finding your absence suspicious, now we know what happened !

Thanks for the link for the power cord. One of my 4 Rochar TE came with one but it's too much of a pain having special cords for this and that, so I am trying to standardize on modern 3 prong sockets.
Have already retrofitted on my Rochar little DVM. It was so easy to do that I will now do it on all my Rochar gear. There is zero mechanical modification to do, it's drop in. One just need to solder a piece of earth wore and that's it.

Like you I don't have time to play with it right now sadly. The 4 wire plugin, Electropuce has one IIRC, but at 130 Euros (for the meter + plugin), nope , I am not that rich sadly.
I will contact him anyway but only to see if he has a manual to sell me.

[Vince]

You don't need to have 4 wire capability, all you need is a decent 2 wire meter with a Null function, short the leads together, press the null button and it will reset the display to read zero, then measure your .3ohm resistor and your meter will display .3ohms. A 4 wire meter is just spending more money, unnecessarily.

Ok, the URL seems to suffer from malignous redirection and some flunkie is posing as our friend Specmaster here!

Else it would be crystal clear that everyone should have at least one desk multimeter with 4 wire capability AND that the requirement to measure resistances below 1 Ohm is a perfectly good reason to aquire a milli/micro-Ohmmeter!

Nope it is I alright  , but I was under the distinct impression that Vince was looking to raise some Euro's not spend some, and for measuring resistances of the value that he was looking at, there is no need for a 4 wire meter. I have 3 such meters myself and I can't recall ever having to use them in such fashion, 2 wire has always been good enough, especially once the lead resistance has been nulled out of the readings. I like to only really buy what I need, but then again, I'm not in the same position of a lot of friends here who are single, I have to keep SWMBO happy as well 

Spec is right, I am trying to make money shifting these QUAD amps... and this µohm-meter at 1,500 Euros costs quite a bit more than my car. The car I get a lot of use and benefit from, every day, but a micro-ohmmeter not really.

However I am not quite at the other extreme like Spec is, having tp make do with basic DMM, because I have no wife and kids to feed and negotiate with.
If I only bought what I strictly needed, I would not have 45 scopes, literally, I guess....

So in my case the aim is in between those 2 extremes : a decent '90s half width VFD bench meter with 4W ohms and decent accuracy, up to 500 Euros.
So the target is the usual HPAK thingy, it fits my desires and budget just fine.
However it will take a lot of time before I can afford that, so maybe it could be fun to build my own milli-ohmmeter. A constant current source, my Metrix MX56C to read the voltage, and bob's your uncle.


Spec yes you are right I could have used my MX56C handheld meter, because very accurate AND, now you make me think of it.... has TWO decimal places in the low ohms range ! I am pretty sure it does.... can't be bothered to double check, I am still sick. No electroniking for me.

I tried to go to work this morning, didn't go well, boss and colleagues united to force me to go back home. I ordered at 16H30 a doctor to come visit me at my house.... he arrived 30 minute sago at 10PM!!!   
Good news is, he doesn't think it's COVID, and my problem with the left ear that makes a strange noise and can't hear squat at all... is most likely very benign, phew !

So that means I should be back in business electroniking away, soon 

For now it's still not great, can't stand staring at a computer screen for more than a few minutes, it's tiring... so no ordering components and spending hours on forums for me...

[tautech]

GWS Vince.

[factory]

I remember you mentioning looking for a manual before, let me know if you have any luck with Electropuce  , the other place at €77 seemed a tad overpriced. 

Here is what I ended up doing in the evenings without the web to distract me, I've plagiarised the design for the A14 board that is missing from my HP 5327B (the second one, part of HP 9500D-221 computer setup), luckily I had a board to measure & copy, just need to figure out what to replace the Motorola MDTL ICs with, the MC1806P, MC1808P & MC846P are available, but not at sensible prices, some MC1806P, MC1808P outputs are joined together too.
The custom 1820-0227 aka 1820-0413 divider IC will need replacing with a 7490 or similar, on an adaptor board Note: the ones of the A5 timebase board would need extra logic gates, as they use the gated output function.

P.S. the JCBPCB quick quote gives around $25 for this board with ENIG plating, anything other than green or purple solder mask is $$$ extra.

David

[Vince]

GWS Vince.

What's that, The Great White South ?!

[tautech]

GWS Vince.

What's that, The Great White South ?!

C'mon bud, use some imagination......and get well soon.

[Vince]

I told you I am sick, as well as super tired right now, going to bed... so I can't really think.

But since you insist, I bet it must refer to some Siglent product... 

[Specmaster]

You don't need to have 4 wire capability, all you need is a decent 2 wire meter with a Null function, short the leads together, press the null button and it will reset the display to read zero, then measure your .3ohm resistor and your meter will display .3ohms. A 4 wire meter is just spending more money, unnecessarily.

Ok, the URL seems to suffer from malignous redirection and some flunkie is posing as our friend Specmaster here!

Else it would be crystal clear that everyone should have at least one desk multimeter with 4 wire capability AND that the requirement to measure resistances below 1 Ohm is a perfectly good reason to aquire a milli/micro-Ohmmeter!

Nope it is I alright  , but I was under the distinct impression that Vince was looking to raise some Euro's not spend some, and for measuring resistances of the value that he was looking at, there is no need for a 4 wire meter. I have 3 such meters myself and I can't recall ever having to use them in such fashion, 2 wire has always been good enough, especially once the lead resistance has been nulled out of the readings. I like to only really buy what I need, but then again, I'm not in the same position of a lot of friends here who are single, I have to keep SWMBO happy as well 

I was almost going so write a taunting reply akin to 'which spouse would not be perfectly happy about an improvement of the in-house measurement capabilities' when suddenly the view of my ex-SWMBO snarling at me 'I do not want to live in a f****** laboratory' appeared in my mind. So, duh.

Sleeping in the dog kennel is no fun is it 

[tautech]

I told you I am sick, as well as super tired right now, going to bed... so I can't really think.

But since you insist, I bet it must refer to some Siglent product... 

It don't !
We have SDS, SDG, SHS, SPD, SSA, SVA, SPS, SNA, SDL and SDM and soon after release next year, a SHA product range too.

But no GWS, you must be thinking about some other brand. 
You lost that bet. 

[Specmaster]

@Vince, I know you're feeling really rough because you didn't pick up on the massive hint tautech gave you, GWS = Get Well Soon 

[Vince]

After  a good night of sleep, I can think clearly now... GWS obviously must be some GW Instek piece of TE ! 
... though Tautech sells Siglent not GWInstek stuff so I am still a bit confused....

@Vince, I know you're feeling really rough because you didn't pick up on the massive hint tautech gave you, GWS = Get Well Soon 

Oh !     

Well thanks then, I will GWS hopefully ! 
Feeling better today already, and it's only noon. I should be fine Thursday morning when going back to work... ready to catch up on all the work that's piling up as we speak and will be waiting for me 
My current job is a one man affair...every day off I take for whatever reason good or bad, is just shooting myself in the foot because nobody there can do my job there on the spot. I will be the one having to deal with the backlog 

[Robert763]

Vince,
Don't buy TE while you are ill.
If looking at a 4W DMM consider the Fluke 8845 and various Keitleys (not just the 2000, I like my 199, 5-3/4 digit 299999 count 4W, LED and I only paid £125).
Get well soon and good work by the boss sending you home.

Robert G8RPI.

[Specmaster]

Vince, I'll join Robert in giving some suggestions for 4W DMM (bench meters), 5.5 digits with very good specs, TTi 1906 (200,000 count), Fluke 8840A or a Fluke 8842A, The 8842A will give you voltage readings as low as 0.1uv.  I can personally vouch for these meters, and even Dave likes them too. I was also going to say that they are not too expensive, but I've looked on eBay and the prices there quite frankly amaze me, they are far more expensive now than when I got mine, so it might seem that they are appreciating in value these days.

[duckduck]

New acquisition:

Rigol DP832 Programmable DC Power Supply

I bought this on Craigslist for USD100. It is in good nick, just a few little chips in the paint on top. It came with no accessories, but has the latest firmware, 1.16. I promptly installed all of the options using the popular hack:

• 1mV/1mA Resolution Option
• RS-232 and LAN interface option
• Detect and Analyzer option
• Four channels for trigger in & out option

Haven't tried out any of the options yet, other than high-resolution. I am especially excited to play with the LAN interface. I think that I'll keep my Riden RD6006P as my daily driver power supply since it has a nice interface and runs silently when not under much load. The new-to-me Rigol is going to take the place of the Tektronix PS280.

I am also sick since before our American Thanksgiving holiday last Thursday. Miserable stuff.

More info:

https://www.rigolna.com/products/dc-power-loads/dp800/

EDIT:

I hooked each of the channels up to my electronic load and DMM, and everything works as one would hope. In case I don't post until next year, enjoy your holidays and loved ones.

EDIT EDIT:

oh, yeah! It's supported by sigrok! https://sigrok.org/wiki/Rigol_DP800_series

[TERRA Operative]

Anyone got an Advantest R6142 Volt/Current Generator?

Go-on, upgrade it to an R6144! It's easy! (shameless youtube link )


https://youtu.be/s-sH-r22xMc

[McBryce]

New acquisition:

Rigol DP832 Programmable DC Power Supply

I bought this on Craigslist for USD100. It is in good nick, just a few little chips in the paint on top. It came with no accessories, but has the latest firmware, 1.16. I promptly installed all of the options using the popular hack:

• 1mV/1mA Resolution Option
• RS-232 and LAN interface option
• Detect and Analyzer option
• Four channels for trigger in & out option

Haven't tried out any of the options yet, other than high-resolution. I am especially excited to play with the LAN interface. I think that I'll keep my Riden RD6006P as my daily driver power supply since it has a nice interface and runs silently when not under much load. The new-to-me Rigol is going to take the place of the Tektronix PS280.

I am also sick since before our American Thanksgiving holiday last Thursday. Miserable stuff.

More info:

https://www.rigolna.com/products/dc-power-loads/dp800/

EDIT:

I hooked each of the channels up to my electronic load and DMM, and everything works as one would hope. In case I don't post until next year, enjoy your holidays and loved ones.

I don't think they come with any accessories worth mentioning when you buy them new either. At least I can't remember any extras when I bought mine new.

McBryce.

[factory]

Took a break from the 198kHz convertor problem and had a look at the Rochar A1466 A1481 DVAM & HP 132A oscilloscope this afternoon.

First was the Rochar, had to take it apart & clean all the spider circuits & debris out. 
 




The circuitry looks quite similar to the other Rochar DVMs Vince has, just a little more crammed in.



Quite a lot of can capacitors, the two smaller grey ones look to be a part of the voltage doubler for the display and note the grease on the connector, two of the board connectors have this. 



Two of the plug-in boards, one with the crystal reference and one of the display counter boards (only two are the same).





The voltage/current plug-in, with very heavy duty looking rotary switch and I suspect the voltage reference is under the small cover.





David

[factory]

Testing was done with a 60W lamp limiter in series with the mains, to allow any caps to reform and not burn up the transformer if they decide to short.



All seemed to be functioning OK, last two digits are a bit unstable.





With the lamp limiter switch in bypass mode, we have a problem, it goes into max count in the 20000 check position and reads incorrectly, guessing the PSU is not regulating properly. 



The 1/10 resolution switch just turns off the last digit and finally this sticker fell out when I opened the case.



David

[Neomys Sapiens]

@Vince - regarding 4Wire-capable DMMs: from time to time there are Prema 6001 to be had which do not cost you a major organ to get. I could notify you if I see one. And there are the Schlumbergers from the 7151 upwards.
And Robert is right: when looking at Keithley, one should not focus singularely on the 2000 - they make a 2001 too!
 
But seriously - I would not have recommended to buy a milli/microohm-meter at that price - recently there was a declared as working HP4338b for 550.- and I got my TTI for a bit less than 300.- !

[Robert763]

Got my items from the latest Peaker Pattenson Auction yesterday.
TTI TS3021S PSU was outputing 42V regardless of control settings. I did do some fault finding but as expected one of the output devices was showing as a diode junction Collector - Emitter. Three 2N3055H's in a parralel pair with Darlinton connected driver. The manual said output pair must be "H" suffix. I didn't have a pair of Hs so I fitted 3 MJ15015s, output pair having been matched for HFE at current some time in the past. The MJ15015 is an "enhanced" 2N3055 with twice the voltage rating and 50% higher dissipation but the same dynamic performance so no stability issues.
The failled 243055H had very poor heatsink compound application. Ther was also "black plastic fuzz" on the black Phier presets but not the red ones. I think this is plasticiser leaching out.
The PSU now works.
The Phillips (designed and made by Labgear in Cambridge UK) PM 5503 colour bar generator just works, even the RF output. Sits nice with my PM 5110 RC oscillator
 

[TERRA Operative]

A couple more bits arrived today for the Tek TDS Scope calibration PC. 

Got a 17" 1280x1024 LCD monitor in practically mint condition for 2000yen-ish, no yellowing on it at all.
Then a 2m National Instruments GPIB cable arrived and the HP 10834A GPIB extender arrived too, to give me clearance from the rear of the PC case. The cable cost somewhat less than 3000yen shipped, and the extender cost about 2500yen, not bad when they are around 8000yen new. 

So all I need now is a replacement slimline floppy drive (just won an auction now) and this PC is complete on the hardware side.
It's running MS-DOS 6.22 at the moment, but I want to dual-boot to something to let me take advantage of the 1Gb RAM, dual 600MHz Pentium III CPU's and the Quadro FX3000 GPU. Maybe XP for some good retro gaming action........ 

[Ice-Tea]

Turns ou these hings have a weight limit for  a reason.

Who knew. 

[TERRA Operative]

Wellll, tell us what you bought!

[Ice-Tea]

Heheh... Nothing to get you guys worked up about. 3 5kW UPS's ;-)

[tautech]

Turns ou these hings have a weight limit for  a reason.

Who knew. 

No problem at all to get 1 dozen modern instruments on these trolleys without challenging their weight limit.