Author Topic: Test Equipment Anonymous (TEA) group therapy thread (Read 14780541 times)

beanflying · « **Reply #27625 on:** March 20, 2019, 01:15:59 pm »

Quote from: mnementh on March 20, 2019, 12:57:48 pm

That's what I get for thinking.

I like to let my Bling hang out that and I brought a heap of those Rose cases for very few $. As it is only 10 $\$\Omega\$$ maximum it will never have more than 17V across it so I wasn't worried about exposed joints etc either, was more about keeping it cool if I wanted to load up right up.

beanflying · « **Reply #27626 on:** March 20, 2019, 01:27:35 pm »

Space Herpes is actually a thing it seems not just part of a suspect Movie

https://youtu.be/Q03naoZwxBM

bd139 · « **Reply #27627 on:** March 20, 2019, 01:33:25 pm »

Well Tek 2225 arrived. Well packaged. Excellent condition. I am surprised. Focus is as expected, knackered but I can get a line with some careful tweaking and the rest of the scope seems fine. Woohoo.

Time to crack it open!

Edit: cracking it open appears to be more difficult than expected as there’s a dink in the side which means the cover won’t slide off.

mnementh · « **Reply #27628 on:** March 20, 2019, 01:52:17 pm »

Quote from: beanflying on March 20, 2019, 01:15:59 pm

Quote from: mnementh on March 20, 2019, 12:57:48 pm
That's what I get for thinking.

I like to let my Bling hang out that and I brought a heap of those Rose cases for very few $. As it is only 10 $\$\Omega\$$ maximum it will never have more than 17V across it so I wasn't worried about exposed joints etc either, was more about keeping it cool if I wanted to load up right up.

Yeah Rose-Bopla makes some nice boxes; I love their epoxy painted cast junction boxes with brushed AL face. The look is SO enigmatic.

They also make some delicious SS boxes and IP67/69 cabinets. Delicious pricetags too.

mnem
*Industrial Supply Junkie*

bd139 · « **Reply #27629 on:** March 20, 2019, 02:29:30 pm »

Ok so help request. How the hell do I get a stuck scope case off. It appears that the outer shell is deformed on one side and won't slide more than about 4 inches back from the front. I'd usually just lump it with a hammer until it's off but that's a stupid idea when the thing has a CRT in it.

mnementh · « **Reply #27630 on:** March 20, 2019, 02:32:45 pm »

No, if it's like the 2230, it's hanging up on the serial port on the side. Look inside, you may have to pry out on the edge of the opening a LITTLE to get it past the flange. If it's really deformed, I think you can take the entire expansion card off from the outside.

[EDIT] Big "Gotcha" on these: If you aren't extra careful taking it apart, you can VERY easily damage the 0.100" cable for the encoder pot at the top-center of the panel. The case likes to hang up on it. BIG TIME. [/EDIT]

mnem

bd139 · « **Reply #27631 on:** March 20, 2019, 02:56:40 pm »

Got it off. Total bastard that was. Side of case wouldn’t slide off. Carefully tapped a metal ruler down the side and worked it off slowly

Edit: it's had a knock to the side on the handle which has pushed it inwards. Also looks like focus resistors are fine. Fuuuu. Another money sink here I come!

med6753 · « **Reply #27632 on:** March 20, 2019, 03:02:55 pm »

Quote from: bd139 on March 20, 2019, 02:56:40 pm

Got it off. Total bastard that was. Side of case wouldn’t slide off. Carefully tapped a metal ruler down the side and worked it off slowly

Edit: it's had a knock to the side on the handle which has pushed it inwards. Also looks like focus resistors are fine. Fuuuu. Another money sink here I come!

And so it starts. Murphy got you again.

Edit, the resistors can look just fine but still be open. Check them anyway.

mnementh · « **Reply #27633 on:** March 20, 2019, 03:11:14 pm »

Quote from: beanflying on March 20, 2019, 12:00:49 pm

Need more power for Beans And yes it will glow under high load, LED high flow fans coming to compete with the Disco Green Fans on my Electronic Load

No Fans, No Heatsink paste, time to break out 60A supply 51C on the body of the 4 $\$\Omega\$$ in series/parallel so I think it will cope will plenty more than spec with fans under it if needed. On the numbers should be 2.5 $\$\Omega\$$ measured 2.498 $\$\Omega\$$ I can live with that

Hmmm?

o--1Ω--o--2Ω--o = 3Ω R¹
| |
o--3Ω--o--4Ω--o = 7Ω R²
| |
o o
+ Measure -

R¹ x R² 21
--------- = ----- = 2.10Ω
R¹ + R² 10

Should yield 2.10Ω

Of course I'm just guessing at your layout; a legend on your panel would be nice for those of us playing along at home.

mnem
Still ~~crazy~~ math-defective after all these years...

mnementh · « **Reply #27634 on:** March 20, 2019, 03:14:20 pm »

Quote from: med6753 on March 20, 2019, 03:02:55 pm

Quote from: bd139 on March 20, 2019, 02:56:40 pm
Got it off. Total bastard that was. Side of case wouldn’t slide off. Carefully tapped a metal ruler down the side and worked it off slowly

Edit: it's had a knock to the side on the handle which has pushed it inwards. Also looks like focus resistors are fine. Fuuuu. Another money sink here I come!
And so it starts. Murphy got you again.

Edit, the resistors can look just fine but still be open. Check them anyway.

*Says a prayer for bd's sanity over the next few days*

mnem

Coming from me... will that help or hinder...?

bd139 · « **Reply #27635 on:** March 20, 2019, 03:16:47 pm »

Quote from: med6753 on March 20, 2019, 03:02:55 pm

Quote from: bd139 on March 20, 2019, 02:56:40 pm
Got it off. Total bastard that was. Side of case wouldn’t slide off. Carefully tapped a metal ruler down the side and worked it off slowly

Edit: it's had a knock to the side on the handle which has pushed it inwards. Also looks like focus resistors are fine. Fuuuu. Another money sink here I come!

And so it starts. Murphy got you again.

Edit, the resistors can look just fine but still be open. Check them anyway.

Have checked them all. R182 is reading 1M but it's got the focus pot across it of 2.2M so should read about 700k. Focus pot be open!

Ergo at least I know what the problem is!

Going to check the voltage across R182 when it's powered up and find a suitable replacement pot for it. Bourns do some cermet ones that are good to 500V or so. Hopefully it's less than that!

mnementh · « **Reply #27636 on:** March 20, 2019, 03:19:02 pm »

Quote from: bd139 on March 20, 2019, 03:16:47 pm

Going to check the voltage across R182 when it's powered up and find a suitable replacement pot for it. Bourns do some cermet ones that are good to 500V or so. Hopefully it's less than that!

*tzzzzzzt*

mnem
*agitating-ily*

med6753 · « **Reply #27637 on:** March 20, 2019, 03:19:57 pm »

Quote from: bd139 on March 20, 2019, 03:16:47 pm

Quote from: med6753 on March 20, 2019, 03:02:55 pm
Quote from: bd139 on March 20, 2019, 02:56:40 pm
Got it off. Total bastard that was. Side of case wouldn’t slide off. Carefully tapped a metal ruler down the side and worked it off slowly

Edit: it's had a knock to the side on the handle which has pushed it inwards. Also looks like focus resistors are fine. Fuuuu. Another money sink here I come!

And so it starts. Murphy got you again.

Edit, the resistors can look just fine but still be open. Check them anyway.

Have checked them all. R182 is reading 1M but it's got the focus pot across it of 2.2M so should read about 700k. Focus pot be open!

Ergo at least I know what the problem is!

Going to check the voltage across R182 when it's powered up and find a suitable replacement pot for it. Bourns do some cermet ones that are good to 500V or so. Hopefully it's less than that!

Good deal. You may be able to fix it. Is it open across the resistive element or the wiper? if wiper there's a chance it could be fixed.

bd139 · « **Reply #27638 on:** March 20, 2019, 03:49:00 pm »

Diagnostics complete. Pot is nuked from end to end.

Turns out 2.2M pots are virtually impossible to find in the UK ... usual places dont have anything suitable. May have to bodge something.

med6753 · « **Reply #27639 on:** March 20, 2019, 03:51:43 pm »

Quote from: bd139 on March 20, 2019, 03:49:00 pm

Diagnostics complete. Pot is nuked from end to end.

Turns out 2.2M pots are virtually impossible to find in the UK ... usual places dont have anything suitable. May have to bodge something.

If you can't find something let me know and I'll order it from here and send it to you.

mnementh · « **Reply #27640 on:** March 20, 2019, 03:53:41 pm »

Metallux HV Pot Catalog

Also, while searching that, I stumbled across these interesting EMCO Proportional HV DC-DC converters...

mnem
*Off to get a collision repair estimate on my wife's car*

med6753 · « **Reply #27641 on:** March 20, 2019, 04:03:33 pm »

Here's some from Mouser. No 2.2M but 2.0M or 2.5M. Haven't tried Digi-Key.

https://www.mouser.com/Passive-Components/Potentiometers-Trimmers-Rheostats/Potentiometers/_/N-9q0yp?P=1z0vkooZ1z0x86rZ1z0yqrwZ1yhozxvZ1yzbppy

https://www.mouser.com/Passive-Components/Potentiometers-Trimmers-Rheostats/Potentiometers/_/N-9q0yp?P=1yhozxvZ1z0vkjl

bd139 · « **Reply #27642 on:** March 20, 2019, 04:23:51 pm »

Thanks everyone for offers and suggestions.

No luck finding anything yet. Piher do a close one but it will require some shaft adaptation and the hole is slightly too small. Original was a Citec unit.

So after much wiggling and swearing, a Citec 2.2M linear carbon 20%, 0.25W, 250V max rating. 8/10mm hole, 4mm shaft pot popped out.

There's a close-ish Piher one available on rapid but shaft is 6mm which will require some mechanical adaptation but should do the job. Will try TME and some other shops first and the junk box as I've got hundreds of the damn things in already.

tggzzz · « **Reply #27643 on:** March 20, 2019, 04:40:34 pm »

Quote from: mnementh on March 20, 2019, 01:08:33 pm

Quote from: tggzzz on March 20, 2019, 10:15:04 am
Quote from: mnementh on March 20, 2019, 04:01:38 am

*Passes the Stick of Enlightenment on to beanflying*

"Use it wisely, my son. Use it often and without hesitation; wherever it is most needed."
Hmmm. Apparently you don't need to explicitly copyright a media work in order to be able to extract royalties. I'm going to be rich at this rate

*Arrrou?!?* I know where I snurched this pic from... was that YOUR auction all those years ago?

As for it being the "Stick of Wisdom" or "Stick of Enlightenment"... to my knowledge, that was a term coined ~~years~~ decades ago inside HP; I think Rick Jones was one of the originators thereof...?

We referred to them as "pit props".

I don't know (or can't remember) an auction, but here's a picture of it in its current location (just NW of the centre of the picture).

bd139 · « **Reply #27644 on:** March 20, 2019, 04:50:37 pm »

Just found a 2.5M pot in the junk box that's reading 2.3M across it ... will try that

bd139 · « **Reply #27645 on:** March 20, 2019, 05:07:54 pm »

Well that was fun.

Bodged the pot in loose to start with just to check it worked.

Bingo!

nice and crisp as well. Need to modify the pot slightly to get it in the hole. Will do that this evening.

neo · « **Reply #27646 on:** March 20, 2019, 05:21:57 pm »

Quote from: bd139 on March 20, 2019, 05:07:54 pm

Well that was fun.

Bodged the pot in loose to start with just to check it worked.

-snip-

Bingo!

-snip-

nice and crisp as well. Need to modify the pot slightly to get it in the hole. Will do that this evening.

Well done.

Specmaster · « **Reply #27647 on:** March 20, 2019, 05:35:14 pm »

Quote from: mnementh on March 20, 2019, 12:57:48 pm

Quote from: beanflying on March 20, 2019, 09:02:41 am
I present the Quantum Flux Resistor Rated at 1.21 daW

Okaaaaaaayyyy... That is pretty much the EXACT OPPOSITE of what I thought you were going to do; I was expecting the heat sink stack to be on the INSIDE of that casting, which was to be used as a faceplate for a shelf-standing unit.

mnem

That's what I get for thinking.

Bean, my concern about this is that there would appear to be a total lack of airflow through the heatsink stack, raising the heatsinks of the face of the enclosure would greatly enhance the overall efficiency and capability of as a load..

Hmmm... sitting here munching on a couple of well buttered hot cross buns

Specmaster · « **Reply #27648 on:** March 20, 2019, 05:41:03 pm »

I'm so pissed off with not having a new toy to play with that I have just pressed the button on a TI Nspire calculator, now to source some of the alternative keyboards for it.

bd139 · « **Reply #27649 on:** March 20, 2019, 05:52:59 pm »

LOL. That bored?

More 2225 pictures.

Pot has been modified. I had to file a flat on either side of the thread so it'd kit in the keyed hole. Now it's a 6mm shaft. Dug in the junk box and found an old 6.35mm coupling. Fits snugly behind the input board. Winner winner chicken dinner:

Total cost for repair £0!

Celebrating with a curry. I'll beat the dents out of the case tomorrow and reassemble it. No RIFAs either!


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Author Topic: Test Equipment Anonymous (TEA) group therapy thread (Read 14780541 times)

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