Author Topic: Test Equipment Anonymous (TEA) group therapy thread  (Read 224980 times)

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Offline khs

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #3075 on: October 23, 2017, 07:53:04 AM »
The 7A13 is a differential comparator with +-10V internal offset. So you can display a 10V DC signal with  1 mV/div resolution.

The 7A22 is a plugin with down to 10 µV / div resolution for very small signals. I use it to display the 77.5 KHz DCF77 signal in Germany to 'calibrate' my signal generator. ( I hope there is no time-nut around)

You may take a look at the storage mainframe like the 7613 / 7623 or 7623 too. It's like a x-y or x-t plotter. I use it to display variations of a pwm signal.
 
But the real advantage is the amplifier output you find at the rear side of you 7804, so your mainframe/plugin setup is a preamplifier / signal conditioner too with 10 MOhm input impedance if you use a 10:1 probe.

The 7B53 is not only a timebase, it's a delay generator too. Just put you signal into a plugin, trigger the 7B53 with this channel and then you get from your 7B53 timebase a delayed signal to trigger a pulse generator or others..

So look around in the manuals of your mainframe / plugins and have a lot of fun with your new 7804.. :-+
 
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Offline bitseeker

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #3076 on: October 23, 2017, 04:32:42 PM »
@W8LV: Wow, Bill, that was quite the adventure! :-DD
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Online neo

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #3077 on: October 23, 2017, 05:14:06 PM »
The 7A13 is a differential comparator with +-10V internal offset. So you can display a 10V DC signal with  1 mV/div resolution.

The 7A22 is a plugin with down to 10 µV / div resolution for very small signals. I use it to display the 77.5 KHz DCF77 signal in Germany to 'calibrate' my signal generator. ( I hope there is no time-nut around)

You may take a look at the storage mainframe like the 7613 / 7623 or 7623 too. It's like a x-y or x-t plotter. I use it to display variations of a pwm signal.
 
But the real advantage is the amplifier output you find at the rear side of you 7804, so your mainframe/plugin setup is a preamplifier / signal conditioner too with 10 MOhm input impedance if you use a 10:1 probe.

The 7B53 is not only a timebase, it's a delay generator too. Just put you signal into a plugin, trigger the 7B53 with this channel and then you get from your 7B53 timebase a delayed signal to trigger a pulse generator or others..

So look around in the manuals of your mainframe / plugins and have a lot of fun with your new 7804.. :-+

Those now too are on my list.  :-DD
Small correction however, you said 7804 while mine is 7704A
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Offline mnementh

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #3078 on: October 23, 2017, 11:58:30 PM »
He knows you're going to get the 7804 mainframe so you can make proper use of that plugin, sure as I'm sittin' 'ere.

'ow? Because you're sittin' 'dere, readin 'dis gorp group.  :-DD


mnem
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Offline zucca

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #3079 on: October 24, 2017, 01:34:44 AM »
I got a package delivered to me. What did I ordered? Don't remember anymore...
Yes, another TEA symptom.
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Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #3080 on: October 24, 2017, 01:44:19 AM »
I'm like that with all the shit I order from China. I get a jiffy bag every few days with some crap I ordered over a month ago. Can't remember what it is or why I ordered it.

Got a bag of MC34063 switching regulators this morning. Had to spent 20 minutes working out why I'd bought them. The answer? To see if the no brand ones were as good as the branded ones. A project I will never complete because I spend so much time buying things and playing with them.

Talking of which, landed another scope today for silly money. Picking it up this evening.
 
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Offline Mr. Scram

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #3081 on: October 24, 2017, 04:27:05 AM »
I was bidding on a decade resistance box today, but got saved by the ridiculous prices. Some of those boxes go for outright stupid prices.
 

Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #3082 on: October 24, 2017, 04:32:11 AM »
Yeah they go for insane amounts. No idea why. They’re just some resistors and switches in a damn box.

I have taken to just soldering a pot in and then pulling it and measuring it or just using fixed values. I was going to make one but for the sake of using it once every week or two it’s not worth the time and cost.
 

Offline Mr. Scram

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #3083 on: October 24, 2017, 04:34:14 AM »
Yeah they go for insane amounts. No idea why. They’re just some resistors and switches in a damn box.

I have taken to just soldering a pot in and then pulling it and measuring it or just using fixed values. I was going to make one but for the sake of using it once every week or two it’s not worth the time and cost.
It seems the ones with single ohm or even tenth ohm scales go for even more money. I'm not that's absolutely necessary, although single ohm would be nice.

I do already own a capacitance box, so having a resistance box should make for some filtering fun. That's pretty much my main concern, plus maybe easily stepping through values to test the multimeters.
« Last Edit: October 24, 2017, 04:36:07 AM by Mr. Scram »
 

Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #3084 on: October 24, 2017, 04:42:25 AM »
I’ve got some 0.1% Dale RN55 resistors for DMM checks. They were a whopping £1 (about $1.25) delivered.
 

Offline Mr. Scram

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #3085 on: October 24, 2017, 04:49:57 AM »
I’ve got some 0.1% Dale RN55 resistors for DMM checks. They were a whopping £1 (about $1.25) delivered.
Sure, there are other options. However, a lot of the additions to the lab are based on increasing comfort and speed, rather than just capabilities, and a decade resistance box fits that idea nicely.

The only regret I'm really having is not investing in proper kit sooner. I want tools that help me get the job done, rather than tools that need to be fought to get anywhere.
 

Online Specmaster

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #3086 on: October 24, 2017, 05:04:36 AM »
Yeah they go for insane amounts. No idea why. They’re just some resistors and switches in a damn box.

I have taken to just soldering a pot in and then pulling it and measuring it or just using fixed values. I was going to make one but for the sake of using it once every week or two it’s not worth the time and cost.
Yes, I've been looking for a while now but they do seem stupid amounts of money, so I'm guessing that they must be equal to or better than .05% resistors in them?
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Offline Mr. Scram

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #3087 on: October 24, 2017, 05:07:44 AM »
Yes, I've been looking for a while now but they do seem stupid amounts of money, so I'm guessing that they must be equal to or better than .05% resistors in them?
A lot are 0.1% or even 1%. Granted, you need a handful, it's small scale production and proper switches aren't cheap, but still. Even the Chinese ones are often close to $100.
 

Offline Cerebus

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #3088 on: October 24, 2017, 06:06:29 AM »
I picked up this little beauty a while back (off the bay, natch), a bit of a cut above your average decade resistance box.



Those are hermetically sealed foil resistors inside, Vishay HPs, which are the precursor to Vishay VHPs which trip in at the £20-30 level for a single resistor. VHPs are 0.005% tolerance and alter less than 60ppm between -55C and +125C. I won't say the annoying low price I won it for for, but it didn't break 2 figures.

Anybody got a syringe I can use to squeeze the magic smoke back into this?
 

Offline Mr. Scram

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #3089 on: October 24, 2017, 06:16:47 AM »
I picked up this little beauty a while back (off the bay, natch), a bit of a cut above your average decade resistance box.



Those are hermetically sealed foil resistors inside, Vishay HPs, which are the precursor to Vishay VHPs which trip in at the £20-30 level for a single resistor. VHPs are 0.005% tolerance and alter less than 60ppm between -55C and +125C. I won't say the annoying low price I won it for for, but it didn't break 2 figures.


Nice score! It seems that some listings get a lot of attention, and therefore go for insane prices. Unfortunately, most listings I watch lately seem to be of that type.
 

Online tggzzz

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #3090 on: October 24, 2017, 06:23:14 AM »
I picked up this little beauty a while back (off the bay, natch), a bit of a cut above your average decade resistance box.

Yes, how annoying (for us :) ).

The nearest I have is a 121.1ohm Dekapot (DP1311), but it has the advantage that the dials go all the way up to 11. It cost all of £10, at a local hamfest.
There are lies, damned lies, statistics - and ADC/DAC specs.
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Offline Cerebus

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #3091 on: October 24, 2017, 06:44:19 AM »
I just missed out on a three decade Dekapot a few weeks back.
Anybody got a syringe I can use to squeeze the magic smoke back into this?
 

Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #3092 on: October 24, 2017, 06:51:01 AM »
Back from my local crap merchant and have scored another Tektronix scope, this time a 465B. This one is sick like the 475 was. Apparently people have seen it and run a mile. However it's not all that bad: the CRT is defocused and to the right and intensity doesn't work. The HT is definitely working though so that's less of a worry. Probably power supply or intensity control shot. Time will tell.  And for less than £30 again.

And thus another thread is born: http://www.eevblog.com/forum/repair/tektronix-465b-repair-97327/

 

Offline guido

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #3093 on: October 24, 2017, 08:35:27 AM »
The 7A13 is a differential comparator with +-10V internal offset. So you can display a 10V DC signal with  1 mV/div resolution.

Those now too are on my list.  :-DD
Small correction however, you said 7804 while mine is 7704A

Keep in mind that the 7A13 is full of very Tek specific relays. With a footprint that prevents an easy replacement. Unfortunately they do fail on a regular basis, specially the double contact ones. In the old days they actually repaired them, using a Dremel to open them. I made two test jigs to test them. Seems to help if you connect them to a FG and let them switch a large number of times.



Tek 7k stuff is addictive. On the bench: 7603 with 7A22, 7A13 and 7B53A. 7623A with 7L5+TG. On cart: 7704A with 7A18, 7S11, 7T11 and 7B70. Then 5 more 7xxx mainframes as spare and a number of parts/fix-up plugins. Like another 7L5 (looking for the big knob assembly), 7A13 without relays (guess why), some more 7A..amps and a number of spare 7B53As. And one self made 7xxx extender cable. About half the mainframes have new PS caps, using adapter pcb's. I had to fix the 7704A a number of times. Bad resistors/arcing in the HV section. Primary bridge rectifier shortened and a shortened tant cap somewhere. Keeps you busy. But all easy fixes.

I have a similar list of TM5xx(x) stuff, next to the regular gear. Yep, I fit in here  :)



 

Offline BU508A

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #3094 on: October 24, 2017, 05:07:27 PM »
I was bidding on a decade resistance box today, but got saved by the ridiculous prices. Some of those boxes go for outright stupid prices.

I am in the middle of assembling my own resistor box (seven decades, starting from 0.1 Ohms). It is not super accuate, something between 0.1 and 1% but it fits for my needs. The switches are relays and the value is directly showed with some nice red Kingsight 7-segements LEDs. The value will be set by 7 BCD rotary switches.

Yeah, I know, it is a kind of overkill and not optimal, but I like the fun in assembling it.

If you (people from the forum here) are interested, I'll show (in a separate thread) the schematics and pictures of it.
“Chaos is found in greatest abundance wherever order is being sought. It always defeats order, because it is better organized.”            - Terry Pratchett -
 

Offline bitseeker

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #3095 on: October 24, 2017, 05:15:52 PM »
Yeah, I know, it is a kind of overkill and not optimal, but I like the fun in assembling it.

That's what counts!

Quote
If you (people from the forum here) are interested, I'll show (in a separate thread) the schematics and pictures of it.

Of course! Was that a trick question? ;D
It's TEA time! You know you want some.
 

Offline bitseeker

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #3096 on: October 24, 2017, 05:18:36 PM »
Take a look at what's painted on the top of this Fluke 8800A. Is it a sign? :-DD

https://www.ebay.com/itm/Fluke-8800A-Digital-Multimeter-Power-Tested-/232530603798

(Warning: There's a sizable chunk of the side of the case missing.)
It's TEA time! You know you want some.
 

Offline BU508A

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #3097 on: October 24, 2017, 05:23:36 PM »
Of course! Was that a trick question? ;D

You'll never know ...  ;D
“Chaos is found in greatest abundance wherever order is being sought. It always defeats order, because it is better organized.”            - Terry Pratchett -
 

Offline bitseeker

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #3098 on: October 24, 2017, 05:24:36 PM »
As long as you post the link here, all will be well. :-+
It's TEA time! You know you want some.
 

Offline BU508A

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #3099 on: October 24, 2017, 05:26:28 PM »
Take a look at what's painted on the top of this Fluke 8800A. Is it a sign? :-DD

If you have ever seen "Sleepless in Seattle" then you'll know: everything could be a "sign"  ;D
(love the scene when they discussing movie scenes  ^-^ )
“Chaos is found in greatest abundance wherever order is being sought. It always defeats order, because it is better organized.”            - Terry Pratchett -
 


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