Test Equipment Anonymous (TEA) group therapy thread

[med6753]

Company: AllTest located in New Jersey. When I bought a Tek 2430 from them as labeled “not working” I had intended on using it as a parts mule for the one I had. Well it turned out it worked fine other than a few minor issues so MY 2430 become the parts mule. I had the same thing happen when I purchased a 465B from them which is now why I have 2 of them. Well, it has happened again. Here's the 485 I just got delivered. Other than both volts/div knobs being broken, some dirty switches, and channel 1/1 MEG input needing a little compensation it works and seems to work well. So now what?

Here's what I'm going to do short term. I'm going to run with this 485. Take the volts/div knobs off mine and clean this one up. But I'm NOT going to scrap mine and just use it for parts. I am absolutely determined to find out why it won't trigger. Now that I have a working unit I can put them side-by-side and figure out what's wrong. But to do that I have to completely clean off one of the benches so I can fit them together. So long term that's what I'll do after some other pending projects are done.

If it sounds like I'm complaining...I'm not. I'm actually tickled that this 485 works.  I'm going to order the caps for the PSU plus other known troublesome tants. 

[bd139]

Hahaha that's a winner that is 

[med6753]

I finished cleaning up, calibrating, and testing the Heathkit voltage reference. It is ready to head to ebay.  Then I started thinking...

I have a Fluke 8800, Keithley 199, Keithley 197, B+K something or other, and at least one more HP DMM on the shelf. I plan on testing them, doing whatever simple calibration I can, makin' them pretty and selling them (Which will leave me with three 5.5 digit DMMs and three lesser one) to free up space and generate cash. So I look at the EU80-A and think, why don't I keep the that and use it as my voltage reference for calibrating these meters?

Great idea, right? So now the Heathkit is on my test bench, as is the 8800. I will keep the voltage reference long enough to check these meters and then sell it.

And we have another example why nothing ever seems to make it from my "sell" shelf to ebay.    

Are you sure that reference is accurate and stable enough to check 5.5 digit DMM's? Based upon what I saw plus a quick check of it's specs I would think not but that's just me. 

[med6753]

Hahaha that's a winner that is 

If I get the other one going I may actually consider selling it. Holy shit...that's right. I may ACTUALLY sell something. 

[Addicted2AnalogTek]

Congrats! 

I almost bought that same scope along with the other late SN (non starting) 485 that they still have, but I messaged them an offer for both and they never responded. I'm glad you got it and have a working 485 now, though!

I'm about to hijack parts from a 485 to repair the vertical output amp on my 7854, so if you find yourself in need of some unobtanium parts, let me know.  I never got the to-be parts mule to fully power up and I don't have another late SN unit to swap boards in, but I can test individual parts in my earlier SN unit.  Thus far, I'll be keeping the CRT, 155-0064-00, and some of the tunnel diodes. Aside from that, the rest is available.

[tggzzz]

Here's what I'm going to do short term. I'm going to run with this 485.

Don't forget to enjoy using it

As a start, connect the cal out to a channel,  on both high impedance and 50ohm modes. Then  use. T-connector and the other channel. The 1MHz cal out, of course, not a piffling 1kHz signal.

If you can't get your other one working, PM me.

[med6753]

Congrats! 

I almost bought that same scope along with the other late SN (non starting) 485 that they still have, but I messaged them an offer for both and they never responded. I'm glad you got it and have a working 485 now, though!

I'm about to hijack parts from a 485 to repair the vertical output amp on my 7854, so if you find yourself in need of some unobtanium parts, let me know.  I never got the to-be parts mule to fully power up and I don't have another late SN unit to swap boards in, but I can test individual parts in my earlier SN unit.  Thus far, I'll be keeping the CRT, 155-0064-00, and some of the tunnel diodes. Aside from that, the rest is available.

Thanks for the offer!  Even though I paid $150 USD plus shipping for this one the other one I got real cheap off of CL so I'm into this less than $250 USD total. Which is a smoking deal considering what functional 485's are going for on Ebay.

[med6753]

Here's what I'm going to do short term. I'm going to run with this 485.

Don't forget to enjoy using it

As a start, connect the cal out to a channel,  on both high impedance and 50ohm modes. Then  use. T-connector and the other channel. The 1MHz cal out, of course, not a piffling 1kHz signal.

If you can't get your other one working, PM me.

I've already checked both 50 ohm inputs with the 1MHz cal and they are both dead nuts. But channel 1 needs some tweaks on the 1MEG input.

[AVGresponding]

I was a little disappointed that no EE based solutions were offered.

As a first thought ... how about an induction heating system to cook the cambium layer?  A sort of electromagnetic ring barking.

That would keep the subject on topic 

Quite, given the origins of this forum I'm frankly astonished that no-one has yet suggested attaching a lightning conductor to the top of the tree and waiting for nature and science to take its course. 1.21GW will kill most things, I expect...

[mnementh]

A quick heads-up passed on to me by eevBlog member Johnboy :

SMC has the part # 200-0633-01/214-0531-01/348-0013-00/252-0571-00  front cover used on Tek 453/454 and other series scopes for $20. It's about 3/4 of the way down the page; Stock #: TEKMECH67 . He bought one and they still have it up, so odds are they have more than one. I know a lot of you hate supporting the strip-miners out there, but I feel this is important enough to pass on in here; we're talking about protecting the scope you've already spent so much time on.

PS: Yes, I've already explained to him how a lot of us feel about the strip-merchants out there; no need to beleaguer the guy. 

mnem
 

[worsthorse]

I finished cleaning up, calibrating, and testing the Heathkit voltage reference. It is ready to head to ebay.  Then I started thinking...

I have a Fluke 8800, Keithley 199, Keithley 197, B+K something or other, and at least one more HP DMM on the shelf. I plan on testing them, doing whatever simple calibration I can, makin' them pretty and selling them (Which will leave me with three 5.5 digit DMMs and three lesser one) to free up space and generate cash. So I look at the EU80-A and think, why don't I keep the that and use it as my voltage reference for calibrating these meters?

Great idea, right? So now the Heathkit is on my test bench, as is the 8800. I will keep the voltage reference long enough to check these meters and then sell it.

And we have another example why nothing ever seems to make it from my "sell" shelf to ebay.    

Are you sure that reference is accurate and stable enough to check 5.5 digit DMM's? Based upon what I saw plus a quick check of it's specs I would think not but that's just me. 

No it is not, though it is reasonably stable if I let it warm up for a couple of hours and set the voltage by measuring it with my known good DMM. I just want to be able to represent that they work on all ranges reasonably well. I won't suggest that I have calibrated them.  I will take them to the next hamfest or offer them on a couple of the test equipment lists. About ebay I am not so sure. Certainly not at auction. I am tempted to sell them as-is just so I limit my interactions with PITA buyers.

[med6753]

Here's the 485 connected to my 5kHz/0.5V p-p test fixture. As you can see channel 1 needs some compensation tweaking. Channel 2 is OK. Going to let it burn-in for a while. Replaced both volt/div knobs. Installed my cabinet which was recently spray painted. After I got it back together discovered that the trigger slope switch is jammed on plus and won't move. That will need some attention. Other than those minor issues looking good. 

[Specmaster]

@med, that is a real winner you have there and I'd do exactly what you have said if they were mine you can check both units side by side and record the measurements in a spreadsheet to help pin point the problem area. To repeat the same trick twice with the same seller ought to give you the "Jammy Git" award in my view.

Edit:
Is it me or does the trigger slope control look like its been munted and been damaged when its been stood on the front panel for instance??

[GregDunn]

Spreading my current project pollution here rather than in the what did I buy .... thread.

MK II Fume extractor, smaller, stronger, simpler design, less parts and laser cut a filter sample which works great. Also split the rear fan cover to get better material use/sheet (jigsaw feature  ).

Any thoughts on what would a flatpack kit with everything (including hardware) bar the 120mm fan be worth delivered to your door? Postage with 4-6 filters is just on $7 USD anywhere on the planet.

I think I'd be interested in one as well...  I even have a couple of spare fans in the parts drawer.

[mnementh]

Freaking Philips Engineers; Too Clever for Their Own Good...

I'm in the process right now of tearing down my Philips/Respironics CPAP machine to stick the humidifier/air pathway parts in the dishwasher for sterilization; I've been feeling pretty sickly the last week or so and I wanted to eliminate it as a cause, as it has been allowed to get pretty fugly with my attention elsewhere. Plus, this is about as much strenuous activity as I can muster right now...

            

Anyways... one of the things people don't think about is the much tighter constraints medical equipment has to follow. One of them is that anything electrical has to be safe against ANY POSSIBLE electrical malfunction to the greatest extent possible; up to and including liquid contamination energizing control circuits with the maximum voltage the device can theoretically produce. This means hermetically sealed controls like this pot used for adjusting the temp threshold of the humidifier assembly.

I had to find my tiniest neodymium magnets, but I was able to confirm that the magnets are configured as opposing poles upward; this forces the gold-plated balls to pull against the printed resistor and together, making the completed circuit. As the ribbon is laminated both sides with very heavy Mylar, I would guess dielectric strength in the 600-1000V range. 

Very clever.

mnem
 

[tggzzz]

I finished cleaning up, calibrating, and testing the Heathkit voltage reference. It is ready to head to ebay.  Then I started thinking...

I have a Fluke 8800, Keithley 199, Keithley 197, B+K something or other, and at least one more HP DMM on the shelf. I plan on testing them, doing whatever simple calibration I can, makin' them pretty and selling them (Which will leave me with three 5.5 digit DMMs and three lesser one) to free up space and generate cash. So I look at the EU80-A and think, why don't I keep the that and use it as my voltage reference for calibrating these meters?

Great idea, right? So now the Heathkit is on my test bench, as is the 8800. I will keep the voltage reference long enough to check these meters and then sell it.

And we have another example why nothing ever seems to make it from my "sell" shelf to ebay.    

Are you sure that reference is accurate and stable enough to check 5.5 digit DMM's? Based upon what I saw plus a quick check of it's specs I would think not but that's just me. 

No it is not, though it is reasonably stable if I let it warm up for a couple of hours and set the voltage by measuring it with my known good DMM. I just want to be able to represent that they work on all ranges reasonably well. I won't suggest that I have calibrated them.  I will take them to the next hamfest or offer them on a couple of the test equipment lists. About ebay I am not so sure. Certainly not at auction. I am tempted to sell them as-is just so I limit my interactions with PITA buyers.

Stability is more subtle than that.

If you then it off and on again after 1/10/1000seconds, does the value return to the same?
How about popcorn noise? One of my old professional sources has 1.5ppm popcorn noise
And then there's simple drift.

Welcome to the rabbit hole.

[tggzzz]

Here's the 485 connected to my 5kHz/0.5V p-p test fixture. As you can see channel 1 needs some compensation tweaking. Channel 2 is OK. Going to let it burn-in for a while. Replaced both volt/div knobs. Installed my cabinet which was recently spray painted. After I got it back together discovered that the trigger slope switch is jammed on plus and won't move. That will need some attention. Other than those minor issues looking good. 

Before twiddling trimpots and trimcaps, reseat the attenuators and use the usual IPA plus smooth paper technique to clean switch contacts.

[BU508A]

I was a little disappointed that no EE based solutions were offered.

As a first thought ... how about an induction heating system to cook the cambium layer?  A sort of electromagnetic ring barking.

That would keep the subject on topic 

Cooking the tree?
Why not using a microwave gun at 2.4GHz?
Magnetrons are cheap and teaching videos available on youtube (mostly in russian).
And it is dangerous like hell for some extra points.

 

Magnetron:
https://www.ebay.com/itm/352005764577

Teaching video:

[bd139]

Kreosan FTW!

[worsthorse]

I finished cleaning up, calibrating, and testing the Heathkit voltage reference. It is ready to head to ebay.  Then I started thinking...

I have a Fluke 8800, Keithley 199, Keithley 197, B+K something or other, and at least one more HP DMM on the shelf. I plan on testing them, doing whatever simple calibration I can, makin' them pretty and selling them (Which will leave me with three 5.5 digit DMMs and three lesser one) to free up space and generate cash. So I look at the EU80-A and think, why don't I keep the that and use it as my voltage reference for calibrating these meters?

Great idea, right? So now the Heathkit is on my test bench, as is the 8800. I will keep the voltage reference long enough to check these meters and then sell it.

And we have another example why nothing ever seems to make it from my "sell" shelf to ebay.    

Are you sure that reference is accurate and stable enough to check 5.5 digit DMM's? Based upon what I saw plus a quick check of it's specs I would think not but that's just me. 

No it is not, though it is reasonably stable if I let it warm up for a couple of hours and set the voltage by measuring it with my known good DMM. I just want to be able to represent that they work on all ranges reasonably well. I won't suggest that I have calibrated them.  I will take them to the next hamfest or offer them on a couple of the test equipment lists. About ebay I am not so sure. Certainly not at auction. I am tempted to sell them as-is just so I limit my interactions with PITA buyers.

Stability is more subtle than that.

If you then it off and on again after 1/10/1000seconds, does the value return to the same?
How about popcorn noise? One of my old professional sources has 1.5ppm popcorn noise
And then there's simple drift.

Welcome to the rabbit hole.

   but, my friend, subtlety is not my strong suit...

You are, of course, correct. Using the EU80A results in, at best, slide rule accuracy. But if these DMMs read within a couple of percent of expected value on all scales, I can say, honestly, that they are in good working order and that's all I want to be able to do. For this project, I am matching the precision of the process to the desired goal.

And I shamefacedly admit that this approach is antithetical to everything we stand for in this thread. 

[tggzzz]

I finished cleaning up, calibrating, and testing the Heathkit voltage reference. It is ready to head to ebay.  Then I started thinking...

I have a Fluke 8800, Keithley 199, Keithley 197, B+K something or other, and at least one more HP DMM on the shelf. I plan on testing them, doing whatever simple calibration I can, makin' them pretty and selling them (Which will leave me with three 5.5 digit DMMs and three lesser one) to free up space and generate cash. So I look at the EU80-A and think, why don't I keep the that and use it as my voltage reference for calibrating these meters?

Great idea, right? So now the Heathkit is on my test bench, as is the 8800. I will keep the voltage reference long enough to check these meters and then sell it.

And we have another example why nothing ever seems to make it from my "sell" shelf to ebay.    

Are you sure that reference is accurate and stable enough to check 5.5 digit DMM's? Based upon what I saw plus a quick check of it's specs I would think not but that's just me. 

No it is not, though it is reasonably stable if I let it warm up for a couple of hours and set the voltage by measuring it with my known good DMM. I just want to be able to represent that they work on all ranges reasonably well. I won't suggest that I have calibrated them.  I will take them to the next hamfest or offer them on a couple of the test equipment lists. About ebay I am not so sure. Certainly not at auction. I am tempted to sell them as-is just so I limit my interactions with PITA buyers.

Stability is more subtle than that.

If you then it off and on again after 1/10/1000seconds, does the value return to the same?
How about popcorn noise? One of my old professional sources has 1.5ppm popcorn noise
And then there's simple drift.

Welcome to the rabbit hole.

   but, my friend, subtlety is not my strong suit...

You are, of course, correct. Using the EU80A results in, at best, slide rule accuracy. But if these DMMs read within a couple of percent of expected value on all scales, I can say, honestly, that they are in good working order and that's all I want to be able to do. For this project, I am matching the precision of the process to the desired goal.

And I shamefacedly admit that this approach is antithetical to everything we stand for in this thread. 

We have a tendency to be hillbilly bodgers here. The metrology mob are the purists

It is easy and cheap to ensure all your equipment agrees on a value. It is trickier to ensure they agree in a week's time. It is difficult and expensive to ensure they agree with other people's equipment.

[mnementh]

Meanwhile, for the rest of us...


FLUKE sez BAM!!!

mnem
*Huggles his 189 close; thankful he doesn't need any more digits than that*

[BU508A]

We have a tendency to be hillbilly bodgers here. The metrology mob are the purists

It is easy and cheap to ensure all your equipment agrees on a value. It is trickier to ensure they agree in a week's time. It is difficult and expensive to ensure they agree with other people's equipment.

But, I'm a part of this metrology mob. A very very tiny one ...   


 

[factory]

Nice knobs. No way that you could send me the "Sync. Selector" knob?    

It's so much more than knobs, it's a 7.6 GHz vacuum tube frequency generator. Brains and beauty, It's eyes are right there and all you choose to look at are it's knobs, shame on you.... shame!

The answers is maybe.... if I can find a look alike close enough to suit me then maybe. Wouldn't be cheap though.

Looks way too big anyway if it's for BU508A's 3460A.

David

[BU508A]

Nice knobs. No way that you could send me the "Sync. Selector" knob?    

It's so much more than knobs, it's a 7.6 GHz vacuum tube frequency generator. Brains and beauty, It's eyes are right there and all you choose to look at are it's knobs, shame on you.... shame!

The answers is maybe.... if I can find a look alike close enough to suit me then maybe. Wouldn't be cheap though.

 

Even though I'm a German you shouldn't take me too serious. Sometimes I'm trying to make a joke (and fail) 

Honestly, I've set a search in ebay on this kind of knob, hoping, that sometimes one will show up with
the right diameter (25mm from peak-to-peak, 20mm the outer ring, the diameter for the drive shaft is 6.25mm)

Or I'll do it the med-way, finding a parts-mule.
Btw, it is a nice generator, would be a crime to rip off a knob.   

Edit:
Maybe this one would fit:
https://www.ebay.com/itm/Hewlett-Packard-HP-Model-202H-FM-AM-Signal-Generator-8-KNOB-LOT/303155915017



What's the size of a quarter anyway?