Author Topic: A new fan for a Tektronix 2465  (Read 14093 times)

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Offline siggiTopic starter

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A new fan for a Tektronix 2465
« on: November 13, 2013, 07:35:04 pm »
Hi guys,

I recently aquired a beautiful old Tektronix 2465. She's my first scope, and a bit of a fixer-upper. The first thing I had to fix was the main power switch, no biggie, and she works like a charm now.
I didn't know about the A/B sweep feature until after I'd bought it, but - WOW!

The problem I have is that the fan is unbearably loud. I did manage to reduce the squeeling by lubricating it, but now it just vibrates instead.
So, while there's a guy who's restoring these [http://www.antiqueradios.com/forums/viewtopic.php?uid=30281&f=8&t=235478&start=0], the process is pretty painstaking, expensive (he's offering to sell the bearings he had made at what's a very reasonable price for the effort - I'm not complaining) and somewhat risky, given that I'm pretty much all left-hand thumbs. I'm also not sure that I'd get another 3 decades out of a restored motor unless the fan axle is also refinished...

I had a hard look, and it turns out there just enough room for an 80x80x25 fan on the back of the scope's case behind the back cover. A fan that size will however pretty much block the case exhaust hole (~53mm diameter) with the fan hub, and also ends up blocking the right-hand (outside) exhaust vents.

So, I figure I can replace the original fan by a "standard" 12V 60x60x20mm case fan, which'll leave plenty of room for the exhaust path. To ballpark the fan sizing, I looked at the airflow figures for the 2465A scope's fan, which turns out to be on the order of 24cfm, and which is reasonably easily matched with a 60x60x20 fan - although it'll have to run faster and probably a bit louder.

So, I was thinking to give this a try using this fan: http://www.digikey.ca/product-detail/en/PMD1206PKB1-A.(2).GN/259-1403-ND/1249276.
I'm also going to copy the 2465A's fan control circuit. This is basically an LM317 with an NTC to drop the unregulated 15V to ~6-12V depending on ambient temperature.

Has anyone here done a mod like this? Is there anything I'm missing that would make this a stupid thing to attempt?

Now for a noob question (I'm a software engineer dabbling in electronics, bear with me  ;)).
I have some LM317s in a TO-220 and I figure I'd better heatsink it a little. I think the dissipation will peak at ~220mA*8V (~19 on the unregulated rail, and ~12 out) or ~1.8W. The TO-200 is 80C/W  to ambient, and I figure that'd put me in trouble without heatsinking, especially as the fan will be running full at when it's 65C ambient or thereabouts. Do you guys think something like this [http://www.digikey.ca/product-search/en?WT.z_header=search_go&lang=en&site=ca&keywords=HS365-ND&x=14&y=17&formaction=on] do the job?
On the face of it at 28C/W*2W+65 ~= 121C it's not outlandish, and I figure I'd be able to put it somewhere where there's a bit of airflow.

Apparently if you lose the fan on those old'uns, you'll shortly after lose U800 which is allegedly made of unobtanium, so I'd hate to build my fan controller in constant thermal shutdown :).

Siggi
 

Offline mtdoc

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Re: A new fan for a Tektronix 2465
« Reply #1 on: November 13, 2013, 08:02:23 pm »
Congrats on your 2465. I have a 2467 (same scope but with MCP CRT).   Great scopes :-+

I would do a search of the excellent Yahoo TekScopes group. I know there has been past discussions there about fan replacement on 2465s.  You could also ask your question there and will surely get some well informed advice.
« Last Edit: November 13, 2013, 08:04:21 pm by mtdoc »
 

Offline siggiTopic starter

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Re: A new fan for a Tektronix 2465
« Reply #2 on: November 13, 2013, 10:01:17 pm »
Thanks, I'll take a look at the !@#$ Yahoo! group. Why do they have to make it so ... weird and difficult?
 

Offline VintageTekFan

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Re: A new fan for a Tektronix 2465
« Reply #3 on: November 13, 2013, 11:22:41 pm »
I did that mod, but I only used a simple 12V regulator and current limiting resistor.  I sized the resistor for peak startup current to stay below ~400mA.  I'd rather keep the scope cooler than meet the accuracy specs over the spec'd operating temperature, esp. since I have a 'flaky' U800.

One thing I did do, however, was mount the TO220 package (and everything else) on the backside of the aluminum case, to use it as a heatsink.  It ended up being near the exhaust flow, so it got the forced air cooling anyway.  I'll see if I can post a pic when I get home.

The three laws of thermodynamics:
1. You can't win.
2. You can't even break even.
3. You can't get out of the game.
 

Offline VintageTekFan

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Re: A new fan for a Tektronix 2465
« Reply #4 on: November 14, 2013, 12:10:58 am »
Picture as promised.

After looking at it again, I think I'm going to add in some insulating material under the leads, since the chassis connects to common.
« Last Edit: November 14, 2013, 01:06:24 am by VintageTekFan »
The three laws of thermodynamics:
1. You can't win.
2. You can't even break even.
3. You can't get out of the game.
 
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Offline GreyWoolfe

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Re: A new fan for a Tektronix 2465
« Reply #5 on: November 14, 2013, 01:34:30 am »
You can get a fan from the eBay user 2465b for $19 USD.
"Heaven has been described as the place that once you get there all the dogs you ever loved run up to greet you."
 

Offline Orpheus

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Re: A new fan for a Tektronix 2465
« Reply #6 on: November 14, 2013, 01:50:01 am »
But how could you not listen to advice from a VintageTekFan?

Talk about the horse's mouth!
 

Offline edavid

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Re: A new fan for a Tektronix 2465
« Reply #7 on: November 14, 2013, 02:59:43 am »
Apparently if you lose the fan on those old'uns, you'll shortly after lose U800 which is allegedly made of unobtanium, so I'd hate to build my fan controller in constant thermal shutdown :).

This is folklore.  There's no reason to think U800 failures are related to lack of cooling.
 

Offline edavid

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Re: A new fan for a Tektronix 2465
« Reply #8 on: November 14, 2013, 03:01:17 am »
You can get a fan from the eBay user 2465b for $19 USD.

No, you can't.  OP wants to replace the custom fan in the 2465, but the eBay item you mention is a replacement for the standard fan used in the later models of the series.  It won't fit in a 2465.  (Also, it's just a standard computer fan that 2465b has marked up a fair amount.)
 

Offline BravoV

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Re: A new fan for a Tektronix 2465
« Reply #9 on: November 14, 2013, 05:38:31 am »
Did I miss anything here ? Why the need for a custom/weird or hard to find fan ?

Although I'm not sure if its the same for 2465, but at my 2465B, it uses just standard ordinary 12 Volt fan, any good industrial fan as long with similar or higher current like later generation fan such as old Panaflo (Panasonic)/NMB or SanyoDenki or Nidec should be good enough.

Here the original fan came with my 2465B, and its now replaced with a good quality Sanyo Denki fan, and it works flawlessly. Also the replacement fan is a lot quieter than that decaces old design Nidec fan.

Photo from my 2465B teardown thread.

« Last Edit: November 14, 2013, 05:54:21 am by BravoV »
 

Offline edavid

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Re: A new fan for a Tektronix 2465
« Reply #10 on: November 14, 2013, 05:52:14 am »
Did I miss anything here ? Why the need a custom / weird or hard to find fan ?

Although I'm not sure if its the same for 2465, but at my 2465B, it uses just standard ordinary 12 Volt fan, any good industrial fan as long with similar or higher current like later generation fan such as old Panaflo (Panasonic)/NMB or SanyoDenki or Nidec should be good enough.

Nope, it's not the same.  The 2465 uses a custom fan.

ETA: It uses a Siemens 1AD3001-OA 1AD3001-0A motor, which occasionally turn up on eBay or other sources.

« Last Edit: December 08, 2020, 03:33:20 pm by edavid »
 

Offline BravoV

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Re: A new fan for a Tektronix 2465
« Reply #11 on: November 14, 2013, 05:57:24 am »
Nope, it's not the same.  The 2465 uses a custom fan.

Ahh .. no wonder, ok, just knew this.

This will be noted and could be useful if my local seller trying to offer me a 2465, an advantage for further "deep" bargaining point, thanks.  >:D

Offline amyk

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Re: A new fan for a Tektronix 2465
« Reply #12 on: November 14, 2013, 09:31:04 am »
That is certainly an unusual choice (and construction) of fan motor... could it be replaced with a small brushless motor of the type used for RC planes?
 

Offline siggiTopic starter

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Re: A new fan for a Tektronix 2465
« Reply #13 on: November 14, 2013, 02:06:52 pm »
Picture as promised.

After looking at it again, I think I'm going to add in some insulating material under the leads, since the chassis connects to common.

Thanks, this helps a lot, good to see others have done this successfully. Do you use the scope with the back cover on, or "nude" like this?

That is certainly an unusual choice (and construction) of fan motor... could it be replaced with a small brushless motor of the type used for RC planes?

I've looked around but haven't found anything suitable. The original design is wonderfully quiet until the bearings go, and I'm not sure a random RC motor would be able to match. The R/C motors are typically designed for maximal power/weight ratio, but this motor is all about just being quiet.
According to Matthew who did this restoration [http://www.antiqueradios.com/forums/viewtopic.php?uid=30281&t=235478] even the 2465A/Bs with slow running 80mm case fans don't match the original 2465 in the low, low fan sound.

NB: Matthew will/is offering this fan motor restoration as a service. It's pricey as there's a lot of manual labor involved - you have to dismantle and unwind the motor before you can get to the bearings.
 

Offline VintageTekFan

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Re: A new fan for a Tektronix 2465
« Reply #14 on: November 14, 2013, 11:11:35 pm »
Thanks, this helps a lot, good to see others have done this successfully. Do you use the scope with the back cover on, or "nude" like this?

I use it with the back cover on - it originally came rack-mounted, so there are only 4 screws keeping it on.
The three laws of thermodynamics:
1. You can't win.
2. You can't even break even.
3. You can't get out of the game.
 

Offline amyk

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Re: A new fan for a Tektronix 2465
« Reply #15 on: November 15, 2013, 12:00:35 pm »
But how could you not listen to advice from a VintageTekFan?

Talk about the horse's mouth!
:-DD

Quote
The R/C motors are typically designed for maximal power/weight ratio, but this motor is all about just being quiet.
They can be quite loud at maximum speed but if you run them far below rated power they're usually rather quiet.
 

Offline siggiTopic starter

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Re: A new fan for a Tektronix 2465
« Reply #16 on: November 17, 2013, 10:11:33 pm »
So I installed that 60x60x20mm fan - it's a Sunon 5000RPM, 27.5cfm model, using the 2465B's fan control circuit. The circuit runs the fan at ~8V at 25C ambient, ramping to ~13V for 65C ambient. The good news is that there's ample space for the fan back there, there's no issue with ventilation or exhaust. The bad news is that even at the lowest speed, the fan is pretty loud.
One day when I've accrued sufficient hobby budget, I think I may have Matthew perform his restoration magic on my fan motor, or I may try and buy a replacement. There really is a world of difference between the noise level from the original fan (when not squeeking or rattling) to the fan I installed. At least now it's just a consistently annoying fan noise, and not an ever-changing rattling that'd sometimes find resonance in my workbench :/.
 

Offline VintageTekFan

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Re: A new fan for a Tektronix 2465
« Reply #17 on: November 18, 2013, 04:59:19 pm »
When I originally got my 2465, the fan was melted into a solid blob - no idea how loud it was.
The three laws of thermodynamics:
1. You can't win.
2. You can't even break even.
3. You can't get out of the game.
 

Offline siggiTopic starter

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Re: A new fan for a Tektronix 2465
« Reply #18 on: January 21, 2014, 03:29:36 pm »
I was lucky enough to score a brand-new fan motor on eBay for a very reasonable price. I was surprised to find it, but now my old scope is restored to it's former whisper-quiet fan performance.
Well worth the time and money, IMHO, there really is a world of difference in the noise level.
 

Offline vikbez

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Re: A new fan for a Tektronix 2465
« Reply #19 on: August 04, 2018, 02:58:31 pm »
Hi

I just bought a 2465A with option 01 & 09 and to my surprise it has the old Siemens fan.
I'm here because the fan is noisy, but hours count on scope is only 453. Is this normal lifetime for this fan ? (and is this many for the scope ?)
Because of this I'm hesitating between buying a NOS fan or replacing it with a DC 12v standard one.

Siggi what value did you use for the NTC ? And did you use the 15v unregulated voltage for the old motor assembly ?

Thanks

Edit: I found the fan control schema for the 12vdc fan in the 2465B service manual so I will just copy it if needed.
But still I would like to know the expected lifetime of the original fan. Thanks
« Last Edit: August 04, 2018, 03:32:38 pm by vikbez »
 

Offline siggiTopic starter

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Re: A new fan for a Tektronix 2465
« Reply #20 on: August 04, 2018, 05:45:54 pm »
I just bought a 2465A with option 01 & 09 and to my surprise it has the old Siemens fan.
I'm here because the fan is noisy, but hours count on scope is only 453. Is this normal lifetime for this fan ? (and is this many for the scope ?)
Because of this I'm hesitating between buying a NOS fan or replacing it with a DC 12v standard one.
The hours count on the scope is intended to be reset on calibration, so it's not (necessarily) a lifetime counter.

Before you switch to a case fan, try flushing and re-lubricating the old motor. It's a bit of a PITA, as (IIRC) you need to de-solder the motor from the driver board to gain access to the thrust bearing screw in the back. Once you have the screw out, you can flush the old gunked-up dirt-in-lubrication out with IPA, then put in a couple of drops of oil. I used synthetic 5W-30 IIRC, which made my 485's run nice and quiet again.

See Matt D'Asaro's fan rebuild for good pictures of a dissected fan motor: http://antiqueradios.com/forums/viewtopic.php?f=8&t=235478.
 

Offline vikbez

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Re: A new fan for a Tektronix 2465
« Reply #21 on: August 04, 2018, 11:55:36 pm »
Many thanks !
I relubricated the motor and it's now perfectly quiet  :)

Hope it will stay that way now, I don't feel like rewinding the motor !
 

Offline Kartika

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Re: A new fan for a Tektronix 2465
« Reply #22 on: December 06, 2020, 08:55:08 pm »
Hiflow Fan replacement for tektronics 2465b 2467b
Sunon
ME80201V1 60m3/h First replacement Replacement is almost equal...
Second one is stronger 90m3/h
PMD1208PKB1-A 90m3/h
fan dimesion 80x80x20mm
https://www.tme.com/ca/en/katalog/dc12v-fans_112524/...
 

Offline Non-Abelian

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Re: A new fan for a Tektronix 2465
« Reply #23 on: December 07, 2020, 04:44:56 pm »
You can find parts for Tek scopes (and almost anything) from qservice electronics.

https://www.qservice.tv/
That's not right - It's not even wrong - W. Pauli
 

Offline Per Hansson

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Re: A new fan for a Tektronix 2465
« Reply #24 on: December 07, 2020, 05:33:20 pm »
Nope, it's not the same.  The 2465 uses a custom fan.

ETA: It uses a Siemens 1AD3001-OA motor, which occasionally turn up on eBay or other sources.
Just thought it worth mentioning that there is a typo in the partno above, it has the letter O instead of the number 0.
So the correct partno is: 1AD3001-0A
Right now there is a seller of these on eBay, please note I have no affiliation and also no idea if it is actually the correct item.
Just thought it worth mentioning since I work with these Siemens article numbers daily and have seen the same mistake countless times :)
https://www.ebay.com/itm/siemens-Motor-1AD3001-0A-From-HP-Spectrum-Analayzer/264274419076
 
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