Author Topic: Tektronix 2465B oscilloscope teardown  (Read 440383 times)

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Offline vik

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1075 on: June 20, 2018, 03:11:09 pm »
The 256 values should match what you see in EXER 02, in which case, yes, it has all of your calibration data.
A spot check of a few memory locations (including the start and end) indicates that the data does match up.

Putting the calibration data back via GPIB works on a 2465(plain), but I haven't heard of anyone trying it yet on an A or B.

I would try this if I could only find someone near me (around London, UK) who can re-calibrate the scope (for a sensible price) in the event of the experiment going wrong.

Also I'd like to replace the Keeper battery at some point but I cannot find a source for it on this side of the pond. There is an LTC-7PN sold on Ebay UK (https://www.ebay.co.uk/itm/EVE-EF651625-LTC-7PN-Size-750mAh-Lithium-Battery-Cell-3-6V-PCB-Pin-232542/142821167102) under a (rather convincingly named) brand called EVE or "Energy Very Endure". Has anyone used one of them? Looks like the difference is that the casing is metal rather than plastic. The US sellers I've looked at either won't ship overseas or charge an arm and leg.
 

Offline z01z

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1076 on: June 21, 2018, 07:53:09 pm »
Also I'd like to replace the Keeper battery at some point but I cannot find a source for it on this side of the pond. There is an LTC-7PN sold on Ebay UK (https://www.ebay.co.uk/itm/EVE-EF651625-LTC-7PN-Size-750mAh-Lithium-Battery-Cell-3-6V-PCB-Pin-232542/142821167102) under a (rather convincingly named) brand called EVE or "Energy Very Endure". Has anyone used one of them? Looks like the difference is that the casing is metal rather than plastic. The US sellers I've looked at either won't ship overseas or charge an arm and leg.
Yes, the availability of the original battery in Europe is limited. Mouser sells it, sadly only in the US.
I did manage to get one from ebay a few years back, as you've mentioned it's not urgent for you, so you could wait and see if one appears.
Btw, these other brands can be had from retailers, for example Conrad sells the one you've found. These might be just as good as the original, but you never know. Unless you buy one and use it for 30 years :).
 

Offline james_s

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1077 on: June 22, 2018, 04:34:11 pm »
Is there space to install a holder for something else? How about a CR2032? They're dirt cheap and readily available. I don't know how much the capacity of the originals is.
 

Offline Miti

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1078 on: June 25, 2018, 03:02:13 am »
I've got my 2445B few years ago and it was waiving like crazy. I knew there must be something wrong with the PS and I found this http://www.condoraudio.com/wp-content/uploads/Projects/Tektronix-2465B-Oscilloscope-Restoration-Repair.pdf. I recapped the power supply with the exception of the two big Sprague 290uF and the Rifa caps. Last week I ordered two 330uF Nichicon PW and the Rifa caps (well most of them, I missed two) and I opened it up to replace them. To my surprise, the Sprague ESR was better than the new Nichicon, 25mOhm Sprague and 100mOhm Nichicon so I didn't replace them. Sure enough, the Rifa caps were all micro cracked.
One relatively annoying issue that I have is that I can see a small flicker, a tiny fluctuation of the intensity. Do you know where it can come from? It has over 40K hours so I may need to recap the main board?
Also, the intensity knob is cracked. Do you know where I can get one without having to sell the scope to buy it?
« Last Edit: June 25, 2018, 03:07:03 am by Miti »
That big spark at power up was by design!
 

Offline z01z

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1079 on: June 25, 2018, 05:34:16 am »
Also, the intensity knob is cracked. Do you know where I can get one without having to sell the scope to buy it?
You could check Qservice, they sell various Tek parts. No affiliation, just a happy customer.
 

Offline pquadrat

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1080 on: June 25, 2018, 09:03:36 am »
I've got my 2445B few years ago and it was waiving like crazy. I knew there must be something wrong with the PS and I found this http://www.condoraudio.com/wp-content/uploads/Projects/Tektronix-2465B-Oscilloscope-Restoration-Repair.pdf. I recapped the power supply with the exception of the two big Sprague 290uF and the Rifa caps. Last week I ordered two 330uF Nichicon PW and the Rifa caps (well most of them, I missed two) and I opened it up to replace them. To my surprise, the Sprague ESR was better than the new Nichicon, 25mOhm Sprague and 100mOhm Nichicon so I didn't replace them. Sure enough, the Rifa caps were all micro cracked.
One relatively annoying issue that I have is that I can see a small flicker, a tiny fluctuation of the intensity. Do you know where it can come from? It has over 40K hours so I may need to recap the main board?
Also, the intensity knob is cracked. Do you know where I can get one without having to sell the scope to buy it?

I think the light flicker is normal and part of the design. All of my three scopes have it, one has only 800 hours of operation. Also the flickering of the LEDs on the front panel when You press buttons seems to be normal. Did not change with replacing all caps in the power supply at all.
 

Offline BravoV

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1081 on: June 25, 2018, 09:18:57 am »
I've got my 2445B few years ago and it was waiving like crazy. I knew there must be something wrong with the PS and I found this http://www.condoraudio.com/wp-content/uploads/Projects/Tektronix-2465B-Oscilloscope-Restoration-Repair.pdf. I recapped the power supply with the exception of the two big Sprague 290uF and the Rifa caps. Last week I ordered two 330uF Nichicon PW and the Rifa caps (well most of them, I missed two) and I opened it up to replace them. To my surprise, the Sprague ESR was better than the new Nichicon, 25mOhm Sprague and 100mOhm Nichicon so I didn't replace them. Sure enough, the Rifa caps were all micro cracked.
One relatively annoying issue that I have is that I can see a small flicker, a tiny fluctuation of the intensity. Do you know where it can come from? It has over 40K hours so I may need to recap the main board?
Also, the intensity knob is cracked. Do you know where I can get one without having to sell the scope to buy it?

I think the light flicker is normal and part of the design. All of my three scopes have it, one has only 800 hours of operation. Also the flickering of the LEDs on the front panel when You press buttons seems to be normal. Did not change with replacing all caps in the power supply at all.

Mine does that too.

Read this somehere that its common for B model (2445B & 2465B), to have that annoying whole panel's faint LEDs flickering everytimes when any button was pressed.

Online tautech

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1082 on: June 25, 2018, 09:24:55 am »
I've got my 2445B few years ago and it was waiving like crazy. I knew there must be something wrong with the PS and I found this http://www.condoraudio.com/wp-content/uploads/Projects/Tektronix-2465B-Oscilloscope-Restoration-Repair.pdf. I recapped the power supply with the exception of the two big Sprague 290uF and the Rifa caps. Last week I ordered two 330uF Nichicon PW and the Rifa caps (well most of them, I missed two) and I opened it up to replace them. To my surprise, the Sprague ESR was better than the new Nichicon, 25mOhm Sprague and 100mOhm Nichicon so I didn't replace them. Sure enough, the Rifa caps were all micro cracked.
One relatively annoying issue that I have is that I can see a small flicker, a tiny fluctuation of the intensity. Do you know where it can come from? It has over 40K hours so I may need to recap the main board?
Also, the intensity knob is cracked. Do you know where I can get one without having to sell the scope to buy it?

I think the light flicker is normal and part of the design. All of my three scopes have it, one has only 800 hours of operation. Also the flickering of the LEDs on the front panel when You press buttons seems to be normal. Did not change with replacing all caps in the power supply at all.

Mine does that too.

Read this somehere that its common for B model (2445B & 2465B), to have that annoying whole panel's faint LEDs flickering everytimes when any button was pressed.
Now there's a nice little challenge for you !
Is more front panel bulk capacitance needed for the LED supply rails or is it a digital glitch affecting the the switching for the LEDs ?
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Online med6753

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1083 on: June 25, 2018, 09:25:19 am »
I've got my 2445B few years ago and it was waiving like crazy. I knew there must be something wrong with the PS and I found this http://www.condoraudio.com/wp-content/uploads/Projects/Tektronix-2465B-Oscilloscope-Restoration-Repair.pdf. I recapped the power supply with the exception of the two big Sprague 290uF and the Rifa caps. Last week I ordered two 330uF Nichicon PW and the Rifa caps (well most of them, I missed two) and I opened it up to replace them. To my surprise, the Sprague ESR was better than the new Nichicon, 25mOhm Sprague and 100mOhm Nichicon so I didn't replace them. Sure enough, the Rifa caps were all micro cracked.
One relatively annoying issue that I have is that I can see a small flicker, a tiny fluctuation of the intensity. Do you know where it can come from? It has over 40K hours so I may need to recap the main board?
Also, the intensity knob is cracked. Do you know where I can get one without having to sell the scope to buy it?

I think the light flicker is normal and part of the design. All of my three scopes have it, one has only 800 hours of operation. Also the flickering of the LEDs on the front panel when You press buttons seems to be normal. Did not change with replacing all caps in the power supply at all.

Mine does that too.

Read this somehere that its common for B model (2445B & 2465B), to have that annoying whole panel's faint LEDs flickering everytimes when any button was pressed.

My 2465 DMS does it but strangely my no option 2465 does not.  :-//
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Offline BravoV

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1084 on: June 25, 2018, 09:31:54 am »
I've got my 2445B few years ago and it was waiving like crazy. I knew there must be something wrong with the PS and I found this http://www.condoraudio.com/wp-content/uploads/Projects/Tektronix-2465B-Oscilloscope-Restoration-Repair.pdf. I recapped the power supply with the exception of the two big Sprague 290uF and the Rifa caps. Last week I ordered two 330uF Nichicon PW and the Rifa caps (well most of them, I missed two) and I opened it up to replace them. To my surprise, the Sprague ESR was better than the new Nichicon, 25mOhm Sprague and 100mOhm Nichicon so I didn't replace them. Sure enough, the Rifa caps were all micro cracked.
One relatively annoying issue that I have is that I can see a small flicker, a tiny fluctuation of the intensity. Do you know where it can come from? It has over 40K hours so I may need to recap the main board?
Also, the intensity knob is cracked. Do you know where I can get one without having to sell the scope to buy it?

I think the light flicker is normal and part of the design. All of my three scopes have it, one has only 800 hours of operation. Also the flickering of the LEDs on the front panel when You press buttons seems to be normal. Did not change with replacing all caps in the power supply at all.

Mine does that too.

Read this somehere that its common for B model (2445B & 2465B), to have that annoying whole panel's faint LEDs flickering everytimes when any button was pressed.
Now there's a nice little challenge for you !
Is more front panel bulk capacitance needed for the LED supply rails or is it a digital glitch affecting the the switching for the LEDs ?

Its the digital glitch, as pquadrat pointed above, and also again read it somewhere (damn, I forgot where ? maybe years ago at old Tek yahoo group ? :palm:) that modding or improving the bulk cap at the panel's rail doesn't fix it.

Challenge ? Don't have the gut yet and I guess this will involve heavy use on logic analyzer.  :P

Offline Miti

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1085 on: June 25, 2018, 12:18:13 pm »
It is not front panel LED flicker, it is CRT flicker. Tiny but noticeable and random, not following a pattern. I did recap all of the power supply with the exception of the two big blue Sprague caps which are OK.
That big spark at power up was by design!
 

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1086 on: June 25, 2018, 12:34:24 pm »
It is not front panel LED flicker, it is CRT flicker. Tiny but noticeable and random, not following a pattern.
How can they be one in the same ?  :-//
Sounds like a power rail issue to me......tantalums sputtering maybe ?

We well know Tek wasn't conservative with tant voltage ratings so I wonder now many are running close to their rated voltages in 24** scopes ?
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Online tggzzz

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1087 on: June 25, 2018, 02:12:36 pm »
One relatively annoying issue that I have is that I can see a small flicker, a tiny fluctuation of the intensity. Do you know where it can come from? It has over 40K hours so I may need to recap the main board?

Is the flicker still there when the readouts are turned off, i.e. the readout control in the central position? The readouts "steal" time from the main trace, and that can cause intensity variations depending on the sweep time.
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Offline David Hess

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1088 on: June 25, 2018, 06:48:14 pm »
I think the light flicker is normal and part of the design. All of my three scopes have it, one has only 800 hours of operation. Also the flickering of the LEDs on the front panel when You press buttons seems to be normal. Did not change with replacing all caps in the power supply at all.

Mine does that too.

Read this somehere that its common for B model (2445B & 2465B), to have that annoying whole panel's faint LEDs flickering everytimes when any button was pressed.

Now there's a nice little challenge for you !
Is more front panel bulk capacitance needed for the LED supply rails or is it a digital glitch affecting the the switching for the LEDs ?

Like the 4 channel 22xx series oscilloscopes, the LEDs are controlled through 74164 style shift registers which lack a registered output so every time the shift register data is clocked, the LEDs flicker as their data is reloaded.  In a way this is advantageous albeit annoying because it shows that the shift registers are being accessed.

Technically since the shift registers driving the LEDs have their own independent clock, they only need to be accessed when the LED outputs are updated but for whatever reason, Tektronix updates them on certain events even when their data is not changed.

One relatively annoying issue that I have is that I can see a small flicker, a tiny fluctuation of the intensity. Do you know where it can come from? It has over 40K hours so I may need to recap the main board?

Is the flicker still there when the readouts are turned off, i.e. the readout control in the central position? The readouts "steal" time from the main trace, and that can cause intensity variations depending on the sweep time.

Exactly, the beam is multiplexed to produce the readout while traces are being drawn resulting in trace flicker.  Shut all of the readout off by centering the readout intensity control to see if the flicker stops before assuming that there is a problem.
 
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Offline Miti

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1089 on: June 26, 2018, 01:37:19 am »
Also, the intensity knob is cracked. Do you know where I can get one without having to sell the scope to buy it?
You could check Qservice, they sell various Tek parts. No affiliation, just a happy customer.

Thanks, I will think about it $7.99+$9=16.99. I may try to repair mine first.
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Offline Miti

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1090 on: June 26, 2018, 01:44:04 am »
One relatively annoying issue that I have is that I can see a small flicker, a tiny fluctuation of the intensity. Do you know where it can come from? It has over 40K hours so I may need to recap the main board?

Is the flicker still there when the readouts are turned off, i.e. the readout control in the central position? The readouts "steal" time from the main trace, and that can cause intensity variations depending on the sweep time.

Yes, it is still there with the readout off....but....I don't think it is the scope. Since I don't have much use for it these days I connected my Dutchtronix scope clock just for fun. It is that thing that flashes I think. Probably the internal processing makes it miss some scan cycles.
Looks like a square wave from the Feeltech FY6600 doesn't flicker. I will check more tomorrow, I'm too tired tonight. Thank you all for your suggestions!
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Online med6753

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1091 on: July 08, 2018, 11:38:20 pm »
The subject of this several part post will be a road map for re-capping the PSU Regulator/Inverter boards in the 2465, 2465A, and 2465B. It will not cover known issues with the A5 board which went under considerable change through out the 24XX series. I think most of what will be discussed here will also apply to the 2445 but I'm not totally sure. If someone knows that answer go ahead and chime in.

The candidate: The top 2465. The bottom 2465 DMS had it's PSU re-capped 2 years ago by me.



What I know about this 2465: I purchased it 2 months ago. Appears to have a build date of 1983. It was owned by IBM. I suspect it has low hours judging by it's condition which is very good. (The 2465 does not have EXER05 which logs the hours so I can't be absolutely sure). No errors on power up and all critical parameters appear to be in spec. I had it apart about a month ago and measured the supply voltages at J119 and they were all in spec. The supply caps are all original hence the re-cap. But no leakers were observed.

Tools required: All the fasteners in the 24XX are torx. So you will need a suitable driver. Also refer to post #1069 where I attached the cap replacement chart used. All the caps were purchased from Mouser.


Upon removal of the rear cover if you have a 2465 you will encounter this cage fan. The 2465A and B use a conventional computer type fan which requires no additional attention. This cage fan is notorious  for becoming very noisy and rattling. The one in this 2465 is whisper quiet, which gives me additional evidence that this scope has low hours. The cage fan in my 2465 DMS rattles like hell for about a half hour and then settles down to quiet. I do have a replacement computer fan built up and ready to be installed if required but will require modification to the rear cover. The cage fan is driven by a Siemens motor which is unobtanium as a replacement and ridiculously complex to rebuild as shown by this link:

http://antiqueradios.com/forums/viewtopic.php?f=8&t=235478



Remove the center nut on the fan. Spray some Deoxit into the center hub to act as a lubricant. Now the fun begins. VERY CAREFULLY start to pry the fan off the shaft. If you are lucky the fan and center collet will come off in one piece. The other alternative is that the fan will come off and the center collet will remain on the shaft. That's also OK. But what most likely will happen is the collet will snap in half with part on the shaft and part inside the fan. But don't worry, it can be epoxied back together. This happen to me when I pulled it apart a month ago but didn't happen this time. And you are not alone here, it happens to just about all of them.



The fan successfully removed from the motor shaft.



And now to the top cover. This 2465 has no options so just remove all the fasteners and pull it off. But if you have any options such as GPIB, Counter/Trigger, Probe Power, etc things are a little more complex. There will be a buffer board attached to the underside of the cover and additional wiring interconnects, including to the PSU. Note where everything goes and take additional pictures if necessary. If you have a 24XX with the DMM option you have to totally remove that board before you can even access the top cover. And wiring interconnects running all over. And it's a nightmare to put put back together. The 2465 DMS is that nightmare.



Once the cover is removed the supply is now accessible. Part 2 will remove it and get it ready for re-cap.

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Online med6753

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1092 on: July 09, 2018, 12:54:28 am »
Part 1 got the scope torn down to access the PSU. Part 2 here will get the supply out and the Regulator and Inverter boards separated to perform the re-cap.

Remove the ribbon cable from the A5 board.



Remove the plastic cover from the line filter. If your mains voltage is 240V you should consider changing the line filter. There have been reports of magic smoke release from 240V but not from 120V. My mains is 120V so I'm leaving it. Remove the jumpers from the line filter and fuse holder to the PSU. Same for voltage selector switch under it. Remove the 2 white wire connectors in the center of the board. The boards are secured by 2 fasteners on the back panel and 3 fasteners on the lower heatsink. Once they are removed the board can be pulled out.



The PSU on the bench, ready to be disassembled. Take lots of pictures from multiple angles on how it goes together.



There are 4 clips....2 on top, 2 on the bottom. Carefully pry them off.   



There are 4 of these interconnects. Release the tab and carefully pull them up completely. Do not bend them or you'll have a hard time in reassembly.



Disassemble and pull the Regulator board off the Inverter board. Set the Inverter board aside. The Regulator board will be done first.



The Regulator board is now ready for re-cap.



I strongly recommend you do one capacitor at a time. Do NOT do a mass remove then mass install. Folks that have done that have run into issues. There is a famous mistake in the service manual, specifically on the parts diagram that reverses C1132 and C1115 resulting in a low voltage cap in a high voltage circuit. You know the result.

Follow the value/rating you remove with what you install. One by one. Yes, it takes a lot longer. But it will be accurate. And note that the replacement chart DOES have some upgrades to higher value. That is OK and will work fine. Tomorrow we'll complete the re-cap of both boards and re-install.
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Offline BravoV

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1093 on: July 09, 2018, 09:09:23 am »
Wow .. thanks for sharing med6753 !  :-+  :clap:

PS : All your images are saved, just in case Imageshack acting up in the future, hope you don't mind.

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1094 on: July 09, 2018, 09:29:14 am »
Wow .. thanks for sharing med6753 !  :-+  :clap:

PS : All your images are saved, just in case Imageshack acting up in the future, hope you don't mind.

Don't mind at all!  :-+

(Busy re-capping  :-DD)
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Re: Tektronix 2465B oscilloscope teardown
« Reply #1095 on: July 10, 2018, 01:21:52 am »
This is Part 3 of the PSU re-cap. In this section we'll get both boards re-capped and reassembled.


Here is the Regulator board re-cap complete. No leakers or bulging caps were found. But the one RIFA cap did have it's typical internal cracking which indicated impending failure.



Next is the Inverter board. Remove the metal shield. If you have a 2465A or B chances are the right side of the board looks very different. (I've not seen one so I'm assuming). That assembly contains the fan motor, which only the 2465 has, and  C1021 and C1022.



Remove that cover to expose the capacitors and the fan motor.



Remove the fan motor and put it aside. Now this is where things get a little muddy and confusing. As you can see the original capacitors are axial lead. The replacement capacitors are radial lead. This presents a fitment issue. I ran into this issue when I re-capped the 2465 DMS 2 years ago and I had to modify the assembly to get the capacitors to fit properly. I've since learned that these particular capacitors almost never fail. I tested these two capacitors and they are OK. So I've made the decision to NOT replace them. You have to decide if you want to leave them or replace them.



Regardless of what you decide to do with C1021 and C1022 you have to lift one lead from the board and remove that assembly to gain access to 2 capacitors underneath mounted to the board.



Once those capacitors are replaced re-install the assembly and re-solder C1021 and C1022. Install the fan motor then replace the top piece. Then continue with the rest of the re-cap of the board.



The re-cap of the Inverter board is now complete. Again, no leaking or bulging caps were found but 3 RIFA caps had internal cracking.



Install the shield back onto the board.



Re-assemble the Inverter and Regulator boards back together. They are now ready to install. Part 4 will do the install and power up.


« Last Edit: July 10, 2018, 02:02:48 am by med6753 »
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Re: Tektronix 2465B oscilloscope teardown
« Reply #1096 on: July 10, 2018, 01:58:56 am »
OK, here is Part 4 of the PSU re-cap and the moment of truth. Will it power up?

Here is the PSU installed. The plastic shield back over the line filter and if you have a 2465 the cage fan is installed in the back. Then install the top cover. And if you have options make sure all interconnects are seated.



Here it is. Power up and boot with no errors! Whew!  :phew:



One final check. Allow the scope to stabilize for about 5 to 10 minutes then check J119, pin 4. That is the reference voltage. It should be between +9.99V and +10.01V. If it's out of spec adjust the pot on the Regulator board. Then verify all the voltages at J119 as per the service manual. But keep in mind that if you have options some of them derive their supply voltages from the Inverter board. The DMM option does this to insure isolation between common and ground. So if one of your options is not working properly you may need to check it's supply voltages.

Don't run the scope outside the case any longer than necessary. The case insures proper airflow to those expensive hybrids and the unobtanium U800.   

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1097 on: July 30, 2018, 04:21:33 pm »
Hi all
    I have just now (finally!) joined this forum, prompted by a need/desire to do a bit of work on my Tek 2465 scope (no B or anything).

I plugged it in after many months idle a week or so ago and got a dreaded bang and puff of smoke... Having read through some of the wonderful teardown info here, from a visual inspection it looks like one of my X2 mains caps has gone (the scope still worked, even as I was powering it off quickly). But I'm taking advantage to do a few other things whilst replacing those.

One thing I am nervous about though - this removal of the fan/mandrel. Are there any other tips anyone can give apart from 'go gently and glue back up if you have to'? I've read elsewhere that you can also push a bit on the mandrel, after loosening the nut a little. I also wondered about making some sort of jug to apply pressure in the right place. Can anyone give me advice or reassurance here?

Thanks a lot from the UK

Jon N


 

Online med6753

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1098 on: July 31, 2018, 12:18:37 am »
One thing I am nervous about though - this removal of the fan/mandrel. Are there any other tips anyone can give apart from 'go gently and glue back up if you have to'? I've read elsewhere that you can also push a bit on the mandrel, after loosening the nut a little. I also wondered about making some sort of jug to apply pressure in the right place. Can anyone give me advice or reassurance here?

Thanks a lot from the UK

Jon N

Your concern about the fan assembly is certainly understandable. If you apply pressure incorrectly you could break the fan itself. That would be a difficult repair.

I haven't heard about pushing the assembly forward slightly and I'm not sure if it would help because the mandrel is tapered. And all those years assembled has resulted in the fan and the mandrel "cold fusing" together. That's where the deoxit or some other penetrating oil would help. A long thin pair of needle nose pliers against the rear hub and carefully pry forward seems to be the best method that I found. The point is....don't be afraid of it....just work carefully and chances are it will come apart.     
An old gray beard with an attitude.
 

Offline james_s

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1099 on: July 31, 2018, 12:46:41 am »
I wonder why they used such a complex fan instead of just putting a muffin fan in the panel like practically every other instrument out there.
 


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