Test Equipment Anonymous (TEA) group therapy thread

[Robert763]

Snagged this Telemeter LCR Databridge 6401 beast as consolation price, I was hoping for the HP from zhoffler, but it went for crazy money  .
The UK fellas, do you know anything about it, any service manual ?

Cheers,
DC1Mc

There were two versions of these Racal/Telemeter/Aim/Tinsley/Prism LCR bridges one was 0.1% basic accuracy with 3 test frequencies, the other 0.25% with two. Both are nice units. They do take up a lot of bench, or possibly wall, space though. The 6401 is 0.25% http://amtest.com.pl/Tinsley/catalog/LCR%20leaflet.pdf
Look for the Racal Dana 9341 manuals.

[factory]

My recently acquired TEA items. By the readings I wonder if these were made in the same factory at all? 

Any chance you bought the Y7651 on ebay-kleinanzeigen? Because it's got modified jacks on front, very unusual. In any case you might want to get nice binding posts like shown below to upgrade from ikea cable to proper shorting bar, like on original unit. VERY nice stack otherwise
Edit: Any chance to have a non destructive peek inside the data card? I would also immensly appreciate a detail shot of it's connector.
I posted a proposed pinout over on the Metrology section, it might help the investigation along.
https://www.eevblog.com/forum/metrology/yokogawa-7651-programmable-dc-source/

Is the memory card similar at all to those SRAM cards for ancient laptops & CNC machines?

David

[bd139]

Hang in there Vince, we don't want to lose you! 

I try to xrunner, I try but it's a challenge ! 

I will try to go one step farther into TEA.... that discord thing. Only recently heard about it. Don't know how it works. Last saturday I tried to connect to it but it was not seamless... I failed.   IIRC I had to first FIND the chatroom for TEA... so I entered the keyword " TEA " but of course I was flooded with irrelevant entries ! So I did not even locate our TEA room... also, ISTR I was then asked for some password, some "invitation" or something, like I could not simply spy on the chatroom but had to show my ID card and passport and driving license before I am allowed to enter the scene.

So if someone could give a link direct to the TEA chatroom, with relevant directions as to how to get in there, password, "invitation" or whatever it is that I need to do in order to participate, or at least watch silently... thanks in advance !

Last time I was in a chat room was in 1998 IIRC, at the library at uni, was this thing called " IRC " or something, if I am not mistaken....

https://discord.gg/CdbGV8V4

Channel #teatime

I too started IRC at university, in the library, in the 90s

[factory]

Snagged this Telemeter LCR Databridge 6401 beast as consolation price, I was hoping for the HP from zhoffler, but it went for crazy money  .
The UK fellas, do you know anything about it, any service manual ?

Cheers,
DC1Mc

Used the AIM version of that one at work a lot, we never had any problems with it.
Now have two of the Racal 9343M versions from a member on the UK vintage radio forum, I believe he acquired them from the Ramco auctions a few years ago, they seem to have sold a fair amount recently too.


David

[bd139]

They're good - will take a lot of DC bias externally as well. Good for testing varicaps etc.

[mansaxel]

I too started IRC at university, in the library, in the 90s

I'm still on IRC. That's how the Internet is run.

[Vince]

Thanks BD, looks like I am in business now ! 

At first I thought there were already a million messages, then realized the thing was displaying the entire history of messages from previous days...  as for this evening, I am only 6 messages behind it seems, not bad !

[DC1MC]

They're good - will take a lot of DC bias externally as well. Good for testing varicaps etc.

Varicaps, that's something that didn't cross my mind, of course if the external bias is available, that makes it possible, cool  .
Mine seems to have 100Hz and 1KHz, I was wondering if possible to enable/add the 10KHz as well, in the manual it says that if the both LED are on, then is 10KHz, but it may be a factory option or something. It seems it has a Z80 as CPU, that makes me happy as well.

Thanks for the info.
DC1MC

[bd139]

Have no idea to be honest. Might be a software config option. should be fairly easy to reverse engineer it to some degree. Racal manuals are pretty good in that space.

[tautech]

Last week i had a sleep over.. a Siglent SSA3021X PLUS,
andy advice, how to tell the wife... its maybe going to stay a bit longer? 

i thin k i fell in love 

It will grow on you more I can guarantee that and when you become brave enough to convert it to a SVA1032X the full RF rabbit hole opens. Great instrument and full of capability. 
No advice on how to break it to the wife however they are small enough not to have too much trouble to hide.

[factory]

Makes sense to me, Shango066 on youtube has had this happen with old TVs/radios that haven't been used for decades, they can get better with extended use. But not always, sometimes they are knackered and that was the reason they got retired from use in the first place.

Re: trying to rejuvenate Trintron CRT's from a few pages back, Shango066 has tried & failed with a knackered one at some point in the last year, I'm sure he said it rarely works with Trintron CRT's and can sometimes make them worse. If a brightner was fitted then it's probably a waste of time trying to rejuvenate them.

David

I've watched many of his videos and he certainly has a unique, and sometimes unsafe, way of doing things. He would make Paul Carlson faint in panic. And he's also not beneath doing massive bodges to fix things. But most of the time he gets results. 

Yes he isn't bothered about high voltage wires everywhere, twisted together mains connections, things burning up, etc. But is bothered about hazardous chemicals, dust & rodent glaze, hence the use of gloves & working outside. Also amazing how he manages to get things going that look way too far gone.

He also has quite a lot of vintage test gear too which gets used occasionally in the videos, I blame him for me wanting to buy a few things including that nice eye-bulb based LCR bridge, still need to add a signal tracer to my TEA collection.
Seem to remember a video where he wants an eevblog meter to replace his Fluke 27FM with the faded display, but he wants one for free. 

David

[beanflying]

For those of us who wanted some OCXO playthings but don't feel the NEED for 10. This seller has a twofor sale reduced for 3 hours more eBay auction: #143779790317 now for the waiting...... 

You rat bastard.   I stayed away because of the prices for 10 - but now I am waiting on two pair ..... all thanks to you.

Harrumph! *crosses arms and glowers*

See how you ozzies are!!! I posted that same exact listing 2 weeks ago when I bought mine... at the same price!!! 

mnem
*toddles off to nuke a bicycle headlamp*

In TEA years that is lifetimes and likely 30 pages ago add to that the Server Dumpster fire hiatus and my 50+ year old brain .....

And most of all Evilbay recommended it as I looked at the 10 buy listing  a second time

[Kosmic]

I’m slowly working on a curve tracer. To the point I had a working low voltage prototype. It slowly mutated into an SMU 

Excellent DIY unit here: http://www.paulvdiyblogs.net/2017/12/building-curve-tracer.html

Found this project recently. http://www.djerickson.com/diy_smu/

pretty cool.

[DC1MC]

Snagged this Telemeter LCR Databridge 6401 beast as consolation price, I was hoping for the HP from zhoffler, but it went for crazy money  .
The UK fellas, do you know anything about it, any service manual ?

Cheers,
DC1Mc

Used the AIM version of that one at work a lot, we never had any problems with it.
Now have two of the Racal 9343M versions from a member on the UK vintage radio forum, I believe he acquired them from the Ramco auctions a few years ago, they seem to have sold a fair amount recently too.


David

I've seen that the HW is different, 5 digits instead of 4, most likely the insides are different as well, so no (easy) 10KHz for me  , but if you sometimes open one of them and make some nice detailed PCB pictures it will be great, also if you can read the EEPROMS it will be better, and perfect if you want to part of, or exchange one against his lower spec brother, you know, diversity is our strength .

 Cheers,
 DC1MC

[tautech]

Discord.............

[tggzzz]

They're good - will take a lot of DC bias externally as well. Good for testing varicaps etc.

Varicaps, that's something that didn't cross my mind, of course if the external bias is available, that makes it possible, cool  .

And currently the most important type of varicap are the MLCC decoupling capacitors that lose 80% of their datasheet value at the rated voltage!

[DC1MC]

Ok well today’s task went to shit. I was going to start measuring all these crystals. Managed to get nowhere. Went for an amble, did some shopping and generally got sod all done.

Reminder: Discord this UTC evening 

I also need to measure the motional parameters of 2-300 crystals, mostly form Golledge and Russia, but I've hit the following snag, the bloody Colpitts oscillator (the one with switchable series cap for determining ser/par resonance) it overloads the crystal (almost 9Vpp  ) and creates a huge short term frequency instability, and I want to get them into 10-20Hz tolerance pools for my filters, combined with the fact that they're freaking ultra sensitive to temperature (if you touch them with your hand while inserting in the socket, they drift, I needed to use a plastic SMD tweezers) makes life miserable  .

Does anyone have an idea of an oscillator that loads the crystal a bit less ?

 Thanks,
 DC1MC

[DC1MC]

They're good - will take a lot of DC bias externally as well. Good for testing varicaps etc.

Varicaps, that's something that didn't cross my mind, of course if the external bias is available, that makes it possible, cool  .

And currently the most important type of varicap are the MLCC decoupling capacitors that lose 80% of their datasheet value at the rated voltage!

I've actually see some "copium" video from Kemet, where the poor company drone was demonstrating the "proper" way to measure them to get near the manufacturer value/specifications and was ripped in the comments.
I have to Chinese blue ceramics in range 100pf - 100nF, I'm actually curious what is their variance.

[bd139]

Ok well today’s task went to shit. I was going to start measuring all these crystals. Managed to get nowhere. Went for an amble, did some shopping and generally got sod all done.

Reminder: Discord this UTC evening 

I also need to measure the motional parameters of 2-300 crystals, mostly form Golledge and Russia, but I've hit the following snag, the bloody Colpitts oscillator (the one with switchable series cap for determining ser/par resonance) it overloads the crystal (almost 9Vpp  ) and creates a huge short term frequency instability, and I want to get them into 10-20Hz tolerance pools for my filters, combined with the fact that they're freaking ultra sensitive to temperature (if you touch them with your hand while inserting in the socket, they drift, I needed to use a plastic SMD tweezers) makes life miserable  .

Does anyone have an idea of an oscillator that loads the crystal a bit less ?

 Thanks,
 DC1MC

Same application here. You can use a standard colpitts oscillator. Just turn the voltage down quite a bit. As for temperature stabilisation I'm adding this to my test rig. It will not record the crystal value until it has stopped drifting by more than 2Hz/min

Also you can bias the colpitts a lot lower so emitter is at 1V and current at 500uA it'll still work and not hammer the poor crystal too hard.

[exor]

My recently acquired TEA items. By the readings I wonder if these were made in the same factory at all? 

Any chance you bought the Y7651 on ebay-kleinanzeigen? Because it's got modified jacks on front, very unusual. In any case you might want to get nice binding posts like shown below to upgrade from ikea cable to proper shorting bar, like on original unit. VERY nice stack otherwise
Edit: Any chance to have a non destructive peek inside the data card? I would also immensly appreciate a detail shot of it's connector.
I posted a proposed pinout over on the Metrology section, it might help the investigation along.
https://www.eevblog.com/forum/metrology/yokogawa-7651-programmable-dc-source/

Yes, I bought it from eBay. Maybe it is some safety related modification, there is also yellow exclamation mark sticker added. I will get some jumper plugs, not worth to (un)modify it any further.

The card is 512kB version (378905) that came with 7552. I do have an 8kB card on order.

Card is very difficult to open without ruining it so not gonna even try

[Wolfgang]

Ok well today’s task went to shit. I was going to start measuring all these crystals. Managed to get nowhere. Went for an amble, did some shopping and generally got sod all done.

Reminder: Discord this UTC evening 

I also need to measure the motional parameters of 2-300 crystals, mostly form Golledge and Russia, but I've hit the following snag, the bloody Colpitts oscillator (the one with switchable series cap for determining ser/par resonance) it overloads the crystal (almost 9Vpp  ) and creates a huge short term frequency instability, and I want to get them into 10-20Hz tolerance pools for my filters, combined with the fact that they're freaking ultra sensitive to temperature (if you touch them with your hand while inserting in the socket, they drift, I needed to use a plastic SMD tweezers) makes life miserable  .

Does anyone have an idea of an oscillator that loads the crystal a bit less ?

 Thanks,
 DC1MC

Why dont you measure them in an IEC444 test fixture on a VNA ?

If it needs to be measured in an oscillator, the following caveats apply:

- never overrun maximum crystal power (thats a few ten microwatts, normally). Reasons: Nonlinear effects (pulling), heating,
  in worst case electrode damage, permanent frequency change or death.
- Your oscillator needs limiting. Simple way: Schottky diode from AC base to ground.
  Better: power regulator. Pick off Colpitts output, use AD8307 log detector and op amp regulator to drive base bias.
  Advantage: power level can be accurately chosen and stabilized.

Regards, 73
  Wolfgang DL1DWG

[ch_scr]

My recently acquired TEA items. By the readings I wonder if these were made in the same factory at all? 

Any chance you bought the Y7651 on ebay-kleinanzeigen? Because it's got modified jacks on front, very unusual. In any case you might want to get nice binding posts like shown below to upgrade from ikea cable to proper shorting bar, like on original unit. VERY nice stack otherwise
Edit: Any chance to have a non destructive peek inside the data card? I would also immensly appreciate a detail shot of it's connector.
I posted a proposed pinout over on the Metrology section, it might help the investigation along.
https://www.eevblog.com/forum/metrology/yokogawa-7651-programmable-dc-source/

Yes, I bought it from eBay. Maybe it is some safety related modification, there is also yellow exclamation mark sticker added. I will get some jumper plugs, not worth to (un)modify it any further.
(Attachment Link)
The card is 512kB version (378905) that came with 7552. I do have an 8kB card on order.

Card is very difficult to open without ruining it so not gonna even try

Thanks for the picture of the connection. Please do tell when you get the 8kb card, I might ask for some comperative resistance checks on them.

[Robert763]

Re crystal measurements. I'v got a Sanders imedance meter tucked way in the attic, probably a 150C. I could dig it out if anyone is interested. Them seem pretty rare in the UK.

[Kosmic]

Its 24degC outside, I'm drinking a Harp and doing BBQ. Life is good 

[mnementh]

yawwwwwwwnnnnnn...

I got this far before I had to pull the plug for my own safety; I found myself waking up to the tone of the iron going to sleep. While it was still in my hand.

Tomorrow's a chance for all new mistakes.

mnem
 

Been there before, scary. That said, often I have my best flashes of inspiration after everyone else has gone to bed

Last Checkout now... triple checking everything with a meter, then connecting the last two jumpers to make it live with the module. As you can see, some last minute changes to the design...

mnem