Author Topic: Test Equipment Anonymous (TEA) group therapy thread  (Read 2600591 times)

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Offline beanflying

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #26100 on: February 25, 2019, 10:41:14 am »
Oh Great another set of paws for next years 2,3,5 am Clomp Fest  |O Within easy broom reach but I am a softy  :palm:

Sort of Cute.....

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Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #26101 on: February 25, 2019, 10:47:18 am »
And the 475A, what can I say but probably the highest performing 4xx scope they made.

<Cough>485</cough>. Including a real 50ohm input and attenuator, plus a pretty blue screen (usually) :)  None of that 50ohms stuffed across 20pF crap.

Quote
Still need to fix mine. Haven't had the motivation recently.

I have a 465B like that :( No sweep, hopefully just the trigger needs adjusting.

Completely forgot about the 485 there  :palm:
 

Offline med6753

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #26102 on: February 25, 2019, 10:47:59 am »
Oh Great another set of paws for next years 2,3,5 am Clomp Fest  |O Within easy broom reach but I am a softy  :palm:

Sort of Cute.....

Luckily the only marsupial we have here is the opossum and it has no voice but they sure are stupid and like to jump in front of moving cars.  :palm:
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Online tggzzz

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #26103 on: February 25, 2019, 11:12:12 am »
And the 475A, what can I say but probably the highest performing 4xx scope they made.

<Cough>485</cough>. Including a real 50ohm input and attenuator, plus a pretty blue screen (usually) :)  None of that 50ohms stuffed across 20pF crap.

Completely forgot about the 485 there  :palm:

The root cause is is easily fixable; you wouldn't forget it if you had one  >:D No, I don't have a working one that I'm prepared to part with.
There are lies, damned lies, statistics - and ADC/DAC specs.
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Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #26104 on: February 25, 2019, 11:31:32 am »
I will buy one if I see one go past for sure. Currently betting on a 2465B turning up at some point. I'm addicted to creature comforts like cursors and readouts.
 

Offline med6753

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #26105 on: February 25, 2019, 11:42:07 am »
I will buy one if I see one go past for sure. Currently betting on a 2465B turning up at some point. I'm addicted to creature comforts like cursors and readouts.

Given a choice you'd be better off with a 2465 (no suffix). True, "only" 300MHz vs 400MHz but fewer things to worry about. The 2465B has the SMT A5 board with the leaky tants that destroy the board. It also has the Dallas NVRAM chip with built in battery that goes flat and goodbye cal data. The 2465 has neither. Pin-thru-hole A5 board with NO tants and non-volatile EAROM for cal data. Yes, it does have the variable speed Seimens fan motor which is a trouble spot but can be fixed.     
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Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #26106 on: February 25, 2019, 12:00:46 pm »
Some good points there which I shall definitely bear in mind. The fan motor can be chucked out and replaced with a standard fan module AFAIK with some minor rework.
 

Offline med6753

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #26107 on: February 25, 2019, 12:06:32 pm »
Some good points there which I shall definitely bear in mind. The fan motor can be chucked out and replaced with a standard fan module AFAIK with some minor rework.

Stay tuned. Just by coincidence I had a Seimens fan motor failure over the weekend in one of my 2465's. I haven't finished the repair/modification yet. As soon as it's done I'll post it. It's not exactly "minor" rework.
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Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #26108 on: February 25, 2019, 12:16:44 pm »
Look forward to seeing it.

The other option I am considering at the moment is just buying a Rigol MSO5072, cracking it and selling everything else other than a power supply or two. That will give me 4 channels, 350MHz, 2 25MHz AWGs, FFT that isn't pants and a logic analyser / protocol decoder for £882.
 

Online tautech

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #26109 on: February 25, 2019, 12:38:25 pm »
Oh Great another set of paws for next years 2,3,5 am Clomp Fest  |O Within easy broom reach but I am a softy  :palm:

Sort of Cute.....
BANG !

They are truly a pest here in NZ dunno how many 1000's I've shot in nearly 50 years of toting a .22.
Which reminds me, before it gets too cold and wet we need to invite some local EEVBlog members and their kids for a 'shoot em up' session.
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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #26110 on: February 25, 2019, 12:40:07 pm »
I will buy [a 485] if I see one go past for sure. Currently betting on a 2465B turning up at some point. I'm addicted to creature comforts like cursors and readouts.
...
The other option I am considering at the moment is just buying a Rigol MSO5072, cracking it and selling everything else other than a power supply or two. That will give me 4 channels, 350MHz, 2 25MHz AWGs, FFT that isn't pants and a logic analyser / protocol decoder for £882.

Personally I prefer a useful variant of soduku to a digital readout of a guaranteed bad measurement. Neither 50ohms//20pF with the associated VSWR, nor a 10Mohm low impedance probe is a good starting point.

Me biassed? Shure shome mishtake.
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 

Online Specmaster

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #26111 on: February 25, 2019, 12:43:54 pm »
Some good points there which I shall definitely bear in mind. The fan motor can be chucked out and replaced with a standard fan module AFAIK with some minor rework.
Why can't a standard fan(12v or whatever) be fitted and just simply connected direct to a suitable supply rail, yes the fan would on all the time, but is that necessarily a bad thing? :-//
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Offline med6753

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #26112 on: February 25, 2019, 12:45:46 pm »
Some good points there which I shall definitely bear in mind. The fan motor can be chucked out and replaced with a standard fan module AFAIK with some minor rework.
Why can't a standard fan(12v or whatever) be fitted and just simply connected direct to a suitable supply rail, yes the fan would on all the time, but is that necessarily a bad thing? :-//

In simple terms, yes. The fitment is a little more complex. I'll post later when I'm done and it will answer all the questions.
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Online mnementh

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #26113 on: February 25, 2019, 01:20:49 pm »
Some good points there which I shall definitely bear in mind. The fan motor can be chucked out and replaced with a standard fan module AFAIK with some minor rework.
Stay tuned. Just by coincidence I had a Seimens fan motor failure over the weekend in one of my 2465's. I haven't finished the repair/modification yet. As soon as it's done I'll post it. It's not exactly "minor" rework.

See how you are! You said you'd try my "quick & dirty" 2465 fan motor service procedure if your "motor takes a dump again". Maybe.   *Crosses arms and goes "Harrumph!" loudly*

Or is that poor bastard child that came to you with the "A" hole already blown out and no thrust bearing/set screw at all? I suppose I could overlook that... just this once. ;)

mnem
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Online bd139

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #26114 on: February 25, 2019, 01:33:42 pm »
I will buy [a 485] if I see one go past for sure. Currently betting on a 2465B turning up at some point. I'm addicted to creature comforts like cursors and readouts.
...
The other option I am considering at the moment is just buying a Rigol MSO5072, cracking it and selling everything else other than a power supply or two. That will give me 4 channels, 350MHz, 2 25MHz AWGs, FFT that isn't pants and a logic analyser / protocol decoder for £882.

Personally I prefer a useful variant of soduku to a digital readout of a guaranteed bad measurement. Neither 50ohms//20pF with the associated VSWR, nor a 10Mohm low impedance probe is a good starting point.

Me biassed? Shure shome mishtake.

I don't tend to use the scope as such for that anything that tetchy. The power meter does that job and that's pretty flat to at least 200MHz.

The point is the cost effectiveness and space requirements of that scope versus separate instruments is a big win. If I sell the TF930, 33120A, TDS210 plus my spare laptop I don't need any more the entire cost is covered. It has better utility than the individual instruments.
« Last Edit: February 25, 2019, 01:35:17 pm by bd139 »
 

Offline med6753

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #26115 on: February 25, 2019, 01:36:51 pm »
Some good points there which I shall definitely bear in mind. The fan motor can be chucked out and replaced with a standard fan module AFAIK with some minor rework.
Stay tuned. Just by coincidence I had a Seimens fan motor failure over the weekend in one of my 2465's. I haven't finished the repair/modification yet. As soon as it's done I'll post it. It's not exactly "minor" rework.

See how you are! You said you'd try my "quick & dirty" 2465 fan motor service procedure if your "motor takes a dump again". Maybe.   *Crosses arms and goes "Harrumph!" loudly*

Or is that poor bastard child that came to you with the "A" hole already blown out and no thrust bearing/set screw at all? I suppose I could overlook that... just this once. ;)

mnem
*locating thumb-detecting nutfckuer for attitude adjustment*

I decided not to go that route which I'll explain later. And no, the poor bastard child fan motor is still working perfectly. It's the other 2465 that had the crap out.
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Online mnementh

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #26116 on: February 25, 2019, 01:46:13 pm »
Some good points there which I shall definitely bear in mind. The fan motor can be chucked out and replaced with a standard fan module AFAIK with some minor rework.
Why can't a standard fan(12v or whatever) be fitted and just simply connected direct to a suitable supply rail, yes the fan would on all the time, but is that necessarily a bad thing? :-//

That's a good question, and the answer is complex; but mostly it boils down to the nature of MOST axial fans: they are NOT meant to serve as a positive displacement air mover; they are meant as an air circulation device against zero head pressure/static load.

If you are trying to blow against a static load like a radiator or heavy grill, or in the case of a 2465, you are trying to pull a partial vacuum inside a sealed case so that air is drawn across specific components via strategically located air vents, then it matters VERY MUCH what kind of fan you use.  :scared:

There ARE axial fans which are designed to move positive pressure against a static load; they have more powerful motors and a different airfoil shape and more aggressive pitch to the blades, and tend to be a lot noisier than their non-static-load-rated cousins. This is why Tek chose a centrifugal fan/squirrelcage fan instead of an axial/muffin fan.

However, it appears their solution was met with both reliability issues and customer complaint, so in later versions they did in fact revise to use a noisier static-load rated axial blower.

Myself, if I were replacing the fan due to complete failure, I'd look for a centrifugal blower of approximately the same size wheel and current draw and remove the outer shell so I could install it in the back cover. Or possibly a Noctua axial blower rated for static load, though it might be hard to find one small enough AND reasonably quiet.

Cheers,

mnem
Yes, I have spent entirely too much time thinking about this. Thank you for noticing.  :-DD

« Last Edit: February 25, 2019, 02:10:10 pm by mnementh »
 
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Online mnementh

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #26117 on: February 25, 2019, 02:03:18 pm »
I decided not to go that route which I'll explain later. And no, the poor bastard child fan motor is still working perfectly. It's the other 2465 that had the crap out.

Take note of my post above, and choose your substitute fan carefully. Remember that those who've done this mod are really operating in uncharted territory, and we only have a few years of "reliability data" on this mod. If it's the 3DP/axial fan mod I've seen elsewhere, that is.

Cheers,

mnem
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Online mnementh

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #26118 on: February 25, 2019, 02:20:47 pm »
The Sleevening: The Final Chapter

So, my 12" SATA cables have arrived; and with them, (hopefully) the last chapter in the 1055T/FX580 case migration saga can be written. I hope to have it finished with pics sometime this evening.

Cheers,

mnem
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Offline med6753

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #26119 on: February 25, 2019, 02:32:20 pm »
Some good points there which I shall definitely bear in mind. The fan motor can be chucked out and replaced with a standard fan module AFAIK with some minor rework.
Why can't a standard fan(12v or whatever) be fitted and just simply connected direct to a suitable supply rail, yes the fan would on all the time, but is that necessarily a bad thing? :-//

That's a good question, and the answer is complex; but mostly it boils down to the nature of MOST axial fans: they are NOT meant to serve as a positive displacement air mover; they are meant as an air circulation device against zero head pressure/static load.

If you are trying to blow against a static load like a radiator or heavy grill, or in the case of a 2465, you are trying to pull a partial vacuum inside a sealed case so that air is drawn across specific components via strategically located air vents, then it matters VERY MUCH what kind of fan you use.  :scared:

There ARE axial fans which are designed to move positive pressure against a static load; they have more powerful motors and a different airfoil shape and more aggressive pitch to the blades, and tend to be a lot noisier than their non-static-load-rated cousins. This is why Tek chose a centrifugal fan/squirrelcage fan instead of an axial/muffin fan.

However, it appears their solution was met with both reliability issues and customer complaint, so in later versions they did in fact revise to use a noisier static-load rated axial blower.

Myself, if I were replacing the fan due to complete failure, I'd look for a centrifugal blower of approximately the same size wheel and current draw and remove the outer shell so I could install it in the back cover. Or possibly a Noctua axial blower rated for static load, though it might be hard to find one small enough AND reasonably quiet.

Cheers,

mnem
Yes, I have spent entirely too much time thinking about this. Thank you for noticing.  :-DD

Trust me, you are over thinking it and I'll prove it later.
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Online Specmaster

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #26120 on: February 25, 2019, 03:07:44 pm »
Some good points there which I shall definitely bear in mind. The fan motor can be chucked out and replaced with a standard fan module AFAIK with some minor rework.
Why can't a standard fan(12v or whatever) be fitted and just simply connected direct to a suitable supply rail, yes the fan would on all the time, but is that necessarily a bad thing? :-//

That's a good question, and the answer is complex; but mostly it boils down to the nature of MOST axial fans: they are NOT meant to serve as a positive displacement air mover; they are meant as an air circulation device against zero head pressure/static load.

If you are trying to blow against a static load like a radiator or heavy grill, or in the case of a 2465, you are trying to pull a partial vacuum inside a sealed case so that air is drawn across specific components via strategically located air vents, then it matters VERY MUCH what kind of fan you use.  :scared:

There ARE axial fans which are designed to move positive pressure against a static load; they have more powerful motors and a different airfoil shape and more aggressive pitch to the blades, and tend to be a lot noisier than their non-static-load-rated cousins. This is why Tek chose a centrifugal fan/squirrelcage fan instead of an axial/muffin fan.

However, it appears their solution was met with both reliability issues and customer complaint, so in later versions they did in fact revise to use a noisier static-load rated axial blower.

Myself, if I were replacing the fan due to complete failure, I'd look for a centrifugal blower of approximately the same size wheel and current draw and remove the outer shell so I could install it in the back cover. Or possibly a Noctua axial blower rated for static load, though it might be hard to find one small enough AND reasonably quiet.

Cheers,

mnem
Yes, I have spent entirely too much time thinking about this. Thank you for noticing.  :-DD


If it were mine, then I'd be inclined to take a bloody tin opener to it and cut a hole on the opposite of the case somewhere and install a fan there as well so I could operate as a push n pull air flow as some PC CPU coolers do and I'd try and make sure that airway was as free of obstacles as is possible to maximise the airflow rate.  In fact that is how my PC case is designed, 2 huge pusher fans in the front and 3 more (2 at top and 1 at rear) pulling the air through and it remains nice and cool.
« Last Edit: February 25, 2019, 03:10:03 pm by Specmaster »
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Offline med6753

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #26121 on: February 25, 2019, 04:54:54 pm »
Here's the 2465 fan modification. I had noticed that the Siemens fan motor in the no option 2465 had started to rattle a bit so I had intended on pulling it out soon and servicing it. But over the weekend it became strangely quiet. This got me suspicious so I checked it. The fan wasn't operating at all! I gave it a spin and it wasn't seized and it didn't make any noise. So an emergency teardown.

Luckily I'm a self professed expert in pulling the 2465 PSU. I've done it at least a half dozen times. In 15 minutes it was on the bench. I pulled the fan motor assembly off the PSU and powered it with the required 15VDC and started troubleshooting. A good hour and half later I came to the conclusion that the motor was open internally. That's really odd because it's a brushless motor. So I had to make a decision. Pull it apart in the hopes I can find the problem or go with the ready made solution I've had sitting on the shelf for the past 2 years. I went with the later. Install a standard 80 x 80 fan and get rid of this Siemens motor.



Here's the new fan installed. The fan itself is enclosed in a shroud of plastic sheet and it sits approx 0.5 inches away from the rear plate and centered directly over the hole where the Siemens motor shaft used to protrude. The idea in my mind to space it away from the rear plate so it would draw air better. The fan assembly is attached to the rear plate with 3M automotive grade double sided foam tape. It ain't going nowhere and the tape provides noise isolation. It is powered by the 15VDC supply (actually measured almost 18VDC) that powered the old fan. Now that is much too high for a 12VDC fan so in line is an LM317T regulator with a trim pot to adjust the speed. I can make the fan roar or whisper. And obviously I had to trim the rear plastic cover as shown. That's the unfortunate part. It won't fit unless you do this extensive trimming. The Dremel tool was put to good use.



Completed. I chose to install the piece removed from the rear cover spaced out approx .5 inches. It does  put some back pressure on the fan but not a lot. And the scope can longer be stacked up on it's rear feet but that's not an issue for me.  I have checked airflow with smoke and it is drawing air into the vents underneath where U800 and the hybrids are. In past experiments the airflow appears to be equal or better than before. I also determined in past experiments that in 72 F ambient the rear plate never exceeds 100 F. I will perform that check again. I think this mod is going to work without any issues.




Let the Monday morning quarterbacking begin.            :-DD
« Last Edit: February 25, 2019, 04:57:08 pm by med6753 »
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Online Specmaster

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #26122 on: February 25, 2019, 05:13:45 pm »
Looks good and that was what I was thinking when I mentioned a standard 12V fan, although I was not aware of the 18V supply so the regulator and trimpot is a good idea and judging by your past tests should suffice to keep the hybrids nice and cool as well  :-+
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Offline med6753

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #26123 on: February 25, 2019, 05:23:23 pm »
Looks good and that was what I was thinking when I mentioned a standard 12V fan, although I was not aware of the 18V supply so the regulator and trimpot is a good idea and judging by your past tests should suffice to keep the hybrids nice and cool as well  :-+

The schematic said the supply was 15VDC. I think it's unregulated (didn't check it's source) and when I measured it there was no load so that probably explains the 18VDC.
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Offline bitseeker

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Re: Test Equipment Anonymous (TEA) group therapy thread
« Reply #26124 on: February 25, 2019, 08:12:13 pm »
Re grey knob, picture below - I think I might take one of the original to a hobby store and get a better colour match.

Not bad at all. Nicely remedies the gaping void that'd be there otherwise.
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