Author Topic: Tektronix 2465B oscilloscope teardown  (Read 474395 times)

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Offline DC1MC

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1350 on: December 09, 2018, 12:02:13 pm »
So I've got this sad 2465 S/N B020171, in a relatively advanced state of decomposition  >:D, with the following issues:
  • No horizontal deflection (most likely U800).
     The front panel has all the LEDs turned on and doesn't reacts to any switches/buttons, the intensity of the LEDs is very faint.
     The logic board has been unscrewed but no sign of any work on it.
     The capacitors are the BEST capacitors ever I could measure, I removed all 3 from the A5 board and one from the power supply board, they are so good (low ESR and losses) that I practically don't have any similar quality caps, I have to eventually order them, the are also from '83  :scared: as well, how should I proceed with them ?!?!?
     All the front panel little buttons have their plastic retainers pulverize when I've pulled them out, so I'll have to superglue them back eventually, any other solution ?

What does look a bit OK:
 - Inside is very clean, I was surprised.
 - The tube si bright with no burn marks, the HV part (focus and stuff) seem to ork perfectly.
 - The channel 1 and 4 react to inputs.
 - The A1 board with U800 was definitely never unscrewed, just someone tried to put extra solder on U800 pins or it even be originally so. It does have a strange bodge wire (pictures at request ) but this seem to be an original intervention.
 - Having a brain fart I didn't measure the PS values before producing a bunch of parts and boards  |O, but the caps looks very good.
 - The ventilator is OK and not very noisy

Now after I look on the official Tektronix list of differences:
There were a multitude of changes between the original 2465 and the 2465B.
Changes between the 2465 to 2465A:
Auto Setup.
Save and Recall Setups.
Write Protection for Saved and Sequenced Setups.
Cursor Measurements on Delayed-sweep displays.
Elapsed-time record embedded in firmware.
Increase in bandwidth from 300 MHz to 400 MHz (350 MHz in 2465A).
2 mV/div Vertical sensitivity to probe tip at full bandwidth.
Rise time improvement from 1.17 ns to 1 ns.
Two independent B triggers for single- or Dual-channel dual-delay measurements (with CTT Option).
Changes between the 2465A to 2465B:
Standard probes changed from P6136 to P6137.
Rise time improvement from 1 ns to .875 ns.
Parametric Measurements: An additional button labeled "MEASUREMENT" was added to the front panel. By pushing "MEASUREMENT" and one additional button mapped with numbers around the vertical mode buttons, you can automatically measure several commonly used parameters:
1. Frequency
2. Pulse Width
3. Rise Time
4. Fall Time
5. Time Interval A to B
6. Voltage


 My big question is:

Is it worth trying to repair or should I split it for parts, anyone considers something of it worthy ?

And if I'm going on the repair paths, where should I start, the logic board seem to not be OK, besides the PS voltages what could go wrong to paralyze it completely, I've heard about different blinking codes, but this one stays with all leds on, in some kind of faint brightness ?

 Any words of wisdom and advice are welcome, also encouragements, or the poor old mummified 2465 will have a horrible fate  ;) !!!

 Cheers,
 DC1MC
 

Online med6753

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1351 on: December 09, 2018, 12:19:10 pm »
Start with the basics. Go back and measure the supply voltages at J119 on the main board. You may get lucky and find one or two not in spec.

You can't compare the basics of a 2465 vs a 2465A. They are almost like 2 different animals especially with respect to the A5 board. So it's imperative that you have service manuals for the 2465. I have a copy if you need it. My e-mail is in my profile.

If it appears that U800 as been monkey'ed around with chances are it's probably bad. Finding one can be a challenge and expensive unless you buy a parts unit.

I have 2 - 2465's. I've never seen the need to replace the caps on the A5 board. But I DID recap both the Inverter and Regulator boards. If you get past your boot and horizontal issues I recommend performing the recap.

Check the supply voltages at J119 then report back.
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Offline Satbeginner

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1352 on: December 09, 2018, 01:31:05 pm »
I own several, a 2465, 2465A ,2* 2465B and a 2465ADM , in my book they are always worthwhile repairing!

I agree, start at the PS voltages.
You need a scope to repair a scope, and you need many multimeters to repair another multimeter!
*Tek 2467B, Tek 2465B, Tek 2465B, Tek 485, Tek 475A,  Keithley 175A, Keithley 2000, HP 3468B, HP 3457A, HP 34401A, PM 6671, PM 5716, Fluke 45, Fluke 75, Fluke 77, Fluke 79, AFX 9660BL, KPS 605D, etc. *
 

Offline DC1MC

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1353 on: December 09, 2018, 02:41:24 pm »
OK then, I'll do the following:
- Finish recapping the A5/PS and put it to spec (the PS, I have no idea how to debug the A5 if it's not a power problem).
- Remove the A1 mainboard (looks a bit like a pain), recap it and remove U800 and replace it with a nice Augat socket.

Hopefully put all back together and come back here for ideas on how to revitalize the U800, I'll go medieval on it :)) and press it nicely in between 2 plates of metal and cook it at 240C for half an hour or something.
Probably the rebonding technique used but that famous Japanese company was using some specific wavelength IR where the package it's transparent but it's absorbed by the chip and bounding wires, who knows.
If the logic board is gone, then I'm out of ideas, but please confirm it for me: if the U800 it's dead this should not deactivate the panel controls ?

 Cheers,
 DC1MC

P.S: If someone could share a recap BOM with suitable capacitor IDs for Mouser or DIgikey I'll be grateful.

@med6753 PM sent with my e-mail address for the Service Manual
 

Online med6753

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1354 on: December 09, 2018, 02:54:56 pm »
I would not do anything with U800 until you get a complete boot. I have a suspicion (unconfirmed) that you won't get any horizontal until it finishes booting, regardless if any trouble codes show up or not.

I got your PM and I'll send you the 2465 Service Manual. In Section 9 are the schematics and it also has a special section outlining the power distribution. I would check and make sure you have correct voltages on the A5 board and the display board. Since there is apparent evidence of someone being in there it's possible that a ribbon cable might be misplugged.

I have attached a file outlining the replacement PSU capacitor part numbers for Mouser and Newark.

Edit...also, if you go back in this thread I have a full pictorial and procedure for recapping the PSU.
 
« Last Edit: December 09, 2018, 03:04:25 pm by med6753 »
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Offline DC1MC

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1355 on: December 09, 2018, 04:10:33 pm »
They raped the Display Reading board  |O :scared:, look at the pictures, they tried to change the EEPROM and the other chip (SRAM ?!?!)  or just, I really don't know WTF they did there, maybe replaced some socket or such, I'm looking at the EEPROM and on one of the legs it's the metalization of the hole, the little copper cylinder was peeled off and raised on the pin :rant: and they put the device back and flood it with solder.
This I really don't understand, the people working with this scopes should have been educated or at least trained, not blabering cretins and flipping morons :'(
Look at the pictures, this board, I really have no idea on what to do with it, it is available for ca. 50EUR from the Greek ebay seller, but this how the whole device costed and there's no guarantee that will help.
I guess there's no content of those memories somewhere, the rest of the surrounding chips seem to be obtainable at a first look ?

 Depressed,
 DC1MC
 

Offline MarkL

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1356 on: December 09, 2018, 04:11:26 pm »
OK then, I'll do the following:
- Finish recapping the A5/PS and put it to spec (the PS, I have no idea how to debug the A5 if it's not a power problem).
- Remove the A1 mainboard (looks a bit like a pain), recap it and remove U800 and replace it with a nice Augat socket.
I would recommend not doing anything with the A1 board until you have the PS in spec.

And I know there are differing opinions on this, but if the PS is in spec I wouldn't do a re-cap or finish the re-capping on it either.  Because the scope doesn't work in the first place, re-capping only adds another variable to the troubleshooting mix.  Get it working first and then if you want to re-cap, go for it.

med6753 is right that you have to get it booting first.  By the look of the front panel, it doesn't look like it makes it through the boot.  Do any of the knobs, besides focus, do anything?  Those functions are controlled by the processor.

For the knob internal clip breakage, I've heard some people use a small dab of silicone adhesive to glue them back on.  The adhesion is weak and you can pull them back off again.  I like to use a small square of 3M #4926 VHB (very high bond) foam tape pushed into the knob.  It's very thin so it doesn't make the knob stick out, and you can pull it off again.  It's usually good for a few cycles of on/off and it's not as messy as the silicone

One trick to get the knobs off without breaking them is to heat them gently before pulling on them.

And I would put in another vote of encouragement to fix it!  There's always something to be learned in the process.

 

Offline MarkL

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1357 on: December 09, 2018, 04:20:24 pm »
That's a terrible repair job on the readout board, but at this point there's no information that says it's not working.  I wouldn't jump to buying a replacement.

Hold your nose and put it back in, and finish the power supply checks.
 

Online Miti

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1358 on: December 09, 2018, 05:01:35 pm »
MC,

As everyone said, take a deep breath, put everything back together as it was, power it on, and check the supply voltages in J119 using multimeter and scope.
That big spark at power up was by design!
 

Online Miti

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1359 on: December 09, 2018, 11:18:44 pm »
I've tested the -3dB bandwidth of my Tek 2445B... and all the others that I have... using a Marconi 2025 signal generator that goes from 9KHz to 2.51GHz and is pretty leveled and here are the results.

Scope                                      -3dB BW        Max reasonably visible freq.
Tek 2445B                               215 MHz         400 MHz
Tek TDS210                             85 MHz           250 MHz (1 or 2 channels)
Rigol DS1054 (not hacked)        98 MHz          400 MHz 1 channel, 200 MHz 2 channels
Hitachi V-1585                         100 MHz         150 MHz

I used a 50 Ohm cable that I thought is pretty good quality, the best I have anyway, with T adapter and 50 Ohm terminator at the scope side, except for the 2445B that has 50 Ohm input. I should have tested the cable's gain before the experiment. Anyway, I tested it after the fact and it dips about 1dB towards 400MHz so the real bandwidth is even better than what I've got.
I started with 1MHz/1Vpp and I increased the frequency until the Vpp dropped to about 0.708Vpp.
The big surprise is Hitachi, I expected a bit more overhead.
That big spark at power up was by design!
 

Offline DC1MC

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1360 on: December 11, 2018, 09:31:13 pm »
Just an update on my sad little 2465, I have clenched my teeth and, as recommended, I've installed the PS back (provisorisch, there are some RIFA 2,2nF and 0,1uF HV caps with this transparent case that'll HAVE to go, they show fine cracks already) and I've measured the voltages on J119, of course, no luck, the voltages are perfect, both in value and in noise ;D.
Than I've changed focus to the A5 board, and the CPU seem to be dead as piece of wood, it is EXACTLY the same type and with the same symptoms like this thread, that I've strongly recommend for anyone interested in repairing an A5 board to read:

https://www.eevblog.com/forum/repair/tektronix-2445-bad-microprocessor-s68a08/


The same crappy S68A08P CPU with creeping corrosion on the pins, this time fully dead (the clock it's perfect, reset, halt and int signals are in 1), without any significant bus activity.
I've ordered some 68B02 originals form evilbay seller tv-sat, from Poland, it really pissed me off that nobody offers them in Germany, with this whole Christmas kerfuffle it will take AGES to reach me  >:(.
If somebody has one to sell or lend in Germany and can put it quickly in an envelope I'll be very grateful, also if someone wants one quick, I've got 3, to have a reserve, but I can offer 2 of them at cost to recover my shipping costs from Poland, I know what it means to need a part and not have it, now I have to stay with the table occupied for another 10 days or something.

So I'll let you know what will happen when I'll change the CPU, maybe Santa will give me a nice present if the U800 it's not gone  ;D.

Also thanks for encouragement and the BOM for PS rejuvenation.

 Cheers,
 DC1MC


 

Offline woodchips

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1361 on: December 14, 2018, 12:49:51 pm »
Just read through this whole thread, taken over a week. My thanks to all that have spent hours of time working on their scopes, posting, swearing and celebrating.

Why? Just bought a couple of 2465 scopes from an auction.

A 2465B s/n 134xxx for about £140.
A 2465 s/n 104xxx for about £220.

These join a 2445 (s/n 107xxx) and 2445A (s/n 112xxx) I already have.

Both the 2445's have problems, one has smoking mains caps, the other a failed Y amplifier, only get deflection downwards.

Both the 2465's worked, one still does, the other started smoking, mains caps again.

From previous battles with a 2440 when I replaced the CRT, I am not overly keen on taking these to pieces. I did take the cover off the smoking 2465 and unscrewed the top screen, then it got caught up in the option 5 PCB and lots of leads from the character generator PCB. Put it all back together.

I have a number of parts mule mainboards etc, missing some chips, got others, but no useful label saying why it was turned into a parts mule. Is the only sensible way of checking the Y amplifier by substitution?

After the two 2445's died I went back to my 7000 series scopes, but they don't really fit on the shelf over the workbench so neatly. Got a 2245 there at the moment, works fine, fast enough, perhaps the 24x5's will go back on the one day pile.

 

Online med6753

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1362 on: December 17, 2018, 04:58:23 pm »
Adding this link here for reference in case some one else has same/similar issues...

https://www.eevblog.com/forum/repair/tektronix-2465a-troubleshooting/
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Offline DC1MC

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1363 on: December 22, 2018, 08:35:19 pm »
^-^ ^-^ ^-^ IT'S ALIVE !!! 8) 8) 8)
Hello everybody, finally my replacement MC6802 arrived from Poland (3 more available at cost in DE if anybody interested !!!) along with two 100ohm Isabellenhütte Manganin resistors, for no others reason that they were looking cool and will become  part of my calibration set of resistors (also dirt cheap).

The seller is: https://www.ebay.de/usr/tvsat_electronic and I can only highly recommend him, as a customer I was always satisfied.

The replacement CPUs are original, but that means the pins were having this strange whitish oxidation/patina, nothing even remotely like the abject corrosion of the previous dead CPU, and the package was looks nicely closed and tight. A bit of ultra-fine sandpaper took care of it, just in case.
I plugged it in the A5 board socket and somehow victory, the board booted, the relays clacked, but there was no horizontal sweep   :palm:, oh well, I thought, here goes U800 and starts the hassle to remove it...
But then an old man dressed in red with a white beard stopped to my window and said "Ho, ho, ho, check again the voltages !!!", considering that he always brought me some nice gifts I've mumbled "But I did this already..." but did checked the voltages on J119, and then phuck, the high voltages were gone !!!  :scared:, what in the hell had happened now, check the PS, OK, check the J119, nothing, what the frak  :-BROKE, all other voltages were OK  :-// ?!?!?

So I got a look at the two cables that transport the power to the mainboard, and one of the plugs that goes to the mainboard was a bit crooked, pulled them out and cleaned the connectors with this occasion (planned to do it anyway at the final assembly) put them back and power on !!!
And amazing, everything worked OK from the start, I've put the buttons back for level and time base and even did run the auto-testing (I think I did managed to press and hold the right buttons ?!?), it showed the results like in the first picture, and there also some other pictures for you to observe if I have something else to do on it that must be done.
Now I have to put the A5 capacitors back (all the tests in the picture were run without the 3 elcos of the A5 board), eventually change the RIFA almost cracked caps on the PS, and then what, should I fully recap the PS and mainboard, should I just be happy that it works like a charm so far (there seem to not be too much noise on the highest sensitivity setting and the triggering seem to be stable), also should I attempt a calibration, barely I should have what is necessary for it ?
Also the U800 DO gets hot, should I put for peace of mind some radiator on it ? Please advise, or the lucky X-mas scope will be closed and it will take a place on the bench together with the AGILENT and Rigol.

Many thanks one more time for your encouragement and advice  :-+ :-+ :-+  :clap: :clap: :clap:

 Cheers,
 DC1MC

P.S> I faintly hear in dark "Ho, ho, ho, told you so..."

 
 

Online med6753

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1364 on: December 22, 2018, 09:17:42 pm »
Always good to see a successful repair. Congrats!  :-+ :-+

U800: Leave it alone. It WILL get warm when you have the scope outside the case and you have an active sweep. Once back in the case as long as the fan is in good shape the airflow will keep it within acceptable temperatures. 

The Regulator/Inverter boards: save the recap for another day as long as you are confident there are no leaking caps.
« Last Edit: December 22, 2018, 09:20:35 pm by med6753 »
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Offline DC1MC

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1365 on: December 22, 2018, 09:20:06 pm »
Always good to see a successful repair. Congrats!  :-+ :-+

U800: Leave it alone. It WILL get warm when you have the scope outside the case and you have an active sweep. Once back in the case as long as the fan is in good shape the airflow will keep it within acceptable temperatures.

What about the recapping and calibration ?!?!?

 

Online med6753

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1366 on: December 22, 2018, 09:23:51 pm »
Always good to see a successful repair. Congrats!  :-+ :-+

U800: Leave it alone. It WILL get warm when you have the scope outside the case and you have an active sweep. Once back in the case as long as the fan is in good shape the airflow will keep it within acceptable temperatures.

What about the recapping and calibration ?!?!?

I modified my answer for the recap. Calibration? Check some of the important parameters such as timebase accuracy, vertical height, etc. If they are in spec I wouldn't bother doing a recal.
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Online Miti

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1367 on: December 23, 2018, 01:46:53 am »
I recaped my 2445B ... power supply, A5, A1, HV, everything. But it's just me, I'm a perfectionist.  :blah:
That big spark at power up was by design!
 

Offline AMR Labs

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1368 on: December 30, 2018, 03:31:57 pm »

Also the U800 DO gets hot, should I put for peace of mind some radiator on it ? Please advise, or the lucky X-mas scope will be closed and it will take a place on the bench together with the AGILENT and Rigol.


I concur with med6753 on this: leave it alone. The consensus is Tektronix knew what they where doing, so no need for any meddling with U800. So far the U800 in your scope has been doing its thing for a very long time, and has survived fine.

Also, notice that while the scope is idle, U800 may only get mildly warm to the touch, which some people take as a relief but it really doesn't mean anything. Under normal operating condition the IC mostly only gets hot under heavy load while displaying high repetition, or high frequency waveforms, etc, but proper airflow as-is with the cover on the scope, and a properly functioning fan, should provide ample cooling to keep the IC temperature within spec.

On the ever popular issue of trying to make improvements on the U800 heat dissipation department, I wanted to share this TekIO group message bellow from a very experienced member I think is the best explanation that so far I have found:

===============================================
START https://groups.io/g/TekScopes/message/152372
===============================================

Everybody please listen!

U800 is not heat sensitive, and I have found that many of
the "tricks" folks have gotten from the internet on how
to "protect" their U800 chip actually harm the chip due
to over-tightening the nuts on the studs that support the
chip. I have also found that glued/taped on heat sinks
have raised the temperature of the chip by impeding the air
circulation around the chip.

I have also found glued/taped heat sinks floating freely
inside of scopes that have been sent to me for service!

Tektronix botched the mounting of U800. That, in my
experience, is why they fail.

U800 was designed to have its pins pass through a 2-3mm
thick aluminum heat sink mounted underneath the chip.
The belly of the chip is metal to engage this heat sink.

DIP style IC's have pins that are made with a wide part to
prevent the belly of the IC from bottoming onto the PCB.
This allows air circulation under the chip. U800 is no
exception.

The engineer that designed U800 was excessively cautious,
and overestimated the heat that would be generated by his
new IC. When it came back from fab, he found that it did
*NOT* need any heat sinking to meet the full +50C design
temperature rating of the brand new 2465 scopes. So, the
heat sink was left off of the board.

(Thought experiment: when was the last time you operated
your 2465 at 50C?)

The problem is the designer needed -5V to bias U800's
substrate, and he used the metal heat sink frame and tab
to make that connection.

He found that U800's stud could not clamp tightly to
the PCB (REMEMBER: shoulders on pins...) without putting
excessive pressure on U800's pins, so he put a pair of star
lock washers onto the mounting studs before mounting U800.

The washers served to make the electrical connection, and
to provide the needed spacing to protect the chip....

He hoped.

Everything is fine if nobody ever, ever, over-tightens the
nuts that hold the U800 to the board. If they do, the
extra pressure will collapse the star lock washers and
embed them into the PCB and the bottom of one end of the
epoxy body. When this happens, the lead frame of U800 will
crack at some of the pins

If you come along later, having listened to all the bloviation
about U800 fixes, and happen to tighten up the nuts a little
bit more: crack! You will have damaged the chip while trying
to protect the chip.
===============================================
END https://groups.io/g/TekScopes/message/152372
===============================================

So if at this point you still want to put some form of additional heat dissipation on U800, make sure to verify that heat is actually being conducted away from the IC body into the added heatsink and you have not inadvertently created a heat barrier instead. And in the case of clipped-on or epoxied-on heatsinks, make sure that it can definitively not at some point fall off, and land right into a live circuit and possibly destroy other "unobtainium" stuff. And above all, do not to over tighten the mounting nuts. Or even better, try to avoid having to mess with the U800 mounting nuts altogether.

Happy New Year to all!

EDIT: small typo corrections.

« Last Edit: December 30, 2018, 03:40:44 pm by AMR Labs »
 

Offline BravoV

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1369 on: December 30, 2018, 05:49:56 pm »
Yep, the design is clearly flawed, badly.

Took a close up photos on the board without the chip and the chip's bottom view -> Post #933 HERE

A quick sketch on the situation ... a picture speaks thousand words.



The ideal path for dissipating the IC's heat still thru a metal plate placed at the chip bottom though.
« Last Edit: December 30, 2018, 07:21:31 pm by BravoV »
 

Offline PaulAm

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1370 on: December 30, 2018, 07:43:11 pm »
Just a headsup for those thinking about a recap.

The 330uf/250V replacements for C1021 and C1022 are pretty scarce at the moment and I couldn't find anyone with current stock for Nichicon UPW caps.  Mouser has them on order with 2 delivery dates and, as of today, there were 10 uncommitted for the mid-January delivery.  Once those are gone the next scheduled delivery is in May.
 

Online med6753

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1371 on: December 30, 2018, 09:58:30 pm »
Just a headsup for those thinking about a recap.

The 330uf/250V replacements for C1021 and C1022 are pretty scarce at the moment and I couldn't find anyone with current stock for Nichicon UPW caps.  Mouser has them on order with 2 delivery dates and, as of today, there were 10 uncommitted for the mid-January delivery.  Once those are gone the next scheduled delivery is in May.

And I have also found that C1021 and C1022 to be in excellent condition on my 2nd 2465 and I did NOT replace them. So check them for ESR and value and you may find them to be OK.
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Offline AMR Labs

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1372 on: December 30, 2018, 10:36:37 pm »
Yep, the design is clearly flawed, badly.

Yes, undoubtedly not ideal design, could have been somewhat better -mechanically- speaking, but given limitation at the time and clearly according to Tek engineers that hands on designed the chip, still perfectly OK to leave it alone and it will (has for many years) done just fine. So with all due respect the idea of any thermal concerns are clearly a non-issue in real world terms. Something that keeps on going and going for 30+ years will probably be perfectly alright to be left exactly the way it is and will keep on going and going. Just my 2 cents.

 

Online Miti

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1373 on: December 31, 2018, 01:30:38 am »
And to support the "leave U800 alone" idea, in the adjustment section of the service manual, they mention that you have to remove the cabinet in order to do the adjustments, you have to warm it up for 20 min, but it doesn't say anywhere to do it quick or you will blow up the U800.
The way I read this is, you can operate it without cabinet for quite long periods of time.
That big spark at power up was by design!
 

Offline LapTop006

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1374 on: December 31, 2018, 02:03:18 pm »
(Thought experiment: when was the last time you operated
your 2465 at 50C?)

Other than us Australian's without aircon.  :P
 


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