Author Topic: Tektronix 2465B oscilloscope teardown  (Read 705677 times)

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Offline Uunoctium

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1800 on: March 11, 2024, 02:18:09 pm »
tl;dr ;-)
 

Offline AMR Labs

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1801 on: March 11, 2024, 02:20:41 pm »
tl;dr ;-)

Those two 290uF 200V high quality SPRAGE brand caps are usually almost always still in perfect condition, but you could also replace them if desired with 330uF 250V. But it will be hard to find those in axial type, so usually a bit of conversion needs to be done to more conventional radial types by extending and insulating one of the leads and bending it upwards over the body of the cap towards the other end to create a quasi-axial cap.
« Last Edit: March 11, 2024, 02:34:30 pm by AMR Labs »
 
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Offline MarkL

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1802 on: March 11, 2024, 02:20:51 pm »
What an informative thread. Thank you Bravo and all the others who contributed here. Im the happy owner a 2465A CT and I wanted to follow the advice of many here and recap the PS. Especially get those RIFAs out before they pop. Not sure if I should replace any other caps besides those. All my J119 DC voltages are within spec. I also have no error messages and scope appears to be working pretty good. My calibration waveform seems a bit noisy at certain timebases since the trace is not a thin line but a thick fuzzy line. Maybe that’s normal.
There are plenty of varying opinions on this, but mine is "if it ain't broke, don't fix it".  If your voltages and ripple are in spec, then leave well enough alone.  You can find plenty of posts from people looking for help after "recapping" because they've destroyed their equipment.  The only exception in these scopes is the RIFA caps, as they are a well-known and frequent point of failure.

The trace on this series scopes can look a little fuzzy because of their internal construction.  You can post a photo of yours, or take a look at the many photos in this thread and compare.

Quote
Also wanted to replace the Keeper II battery. Its reading 3.3v but dont want to risk losing my data.  What’s the best method for attaching a backup battery while doing the replacement?  I found these two online:
https://jestineyong.com/tektronix-2465a-dv-oscilloscope-memory-backup-battery-replacement/
https://cdn.hackaday.io/files/1638907011869760/Piggyback%20batt.JPG
Of those two, I like the Jestine approach since he is replacing the dead battery and not stacking a new one on a dead one.  Leaving a dead battery in there is asking for leaks, and there's no guarantee it wouldn't reduce the life of the new battery.

Quote
Also I would be using my grounded soldering iron.  Could that be a problem if the A5 board is out of the scope?  Would it be possible that the iron would ground the battery and the EAROM would lose its data? 
The EAROM is used on 2445 and 2465.  On later A and B scopes, it was replaced with battery backed SRAM , either combined in a single package or as two separate devices.  As long as the board is isolated, soldering should be ok.  Just don't short any pins by accident.

Quote
Lastly as a backup plan I was thinking of backing up my data with the a GBIP adapter which was mentioned in this thread. Maybe using the NI USB model. Has it been confirmed that it can be used to backup and fully restore the EAROM data in case I accidentally delete it during the battery replacement?
Yes.  I can attest the data can be saved and successfully restored with this method.  I have done it about a half dozen times.

Before trying anything with either GPIB or the battery, I would suggest you take a video of flipping through the NVRAM using EXER 02 and record all the values.  While the methods to get that data back in the NVRAM in case of failure will vary depending on what equipment you have at your disposal, at least you have the data.
 
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Offline tonedeak99

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1803 on: March 11, 2024, 04:36:08 pm »

There are plenty of varying opinions on this, but mine is "if it ain't broke, don't fix it".  If your voltages and ripple are in spec, then leave well enough alone.  You can find plenty of posts from people looking for help after "recapping" because they've destroyed their equipment.  The only exception in these scopes is the RIFA caps, as they are a well-known and frequent point of failure.
I come from the same camp. I haven't tested for ripple yet.  but my DC voltages are fine.

Quote
Also wanted to replace the Keeper II battery. Its reading 3.3v but dont want to risk losing my data.  What’s the best method for attaching a backup battery while doing the replacement?  I found these two online:
https://jestineyong.com/tektronix-2465a-dv-oscilloscope-memory-backup-battery-replacement/
https://cdn.hackaday.io/files/1638907011869760/Piggyback%20batt.JPG
Quote
Of those two, I like the Jestine approach since he is replacing the dead battery and not stacking a new one on a dead one.  Leaving a dead battery in there is asking for leaks, and there's no guarantee it wouldn't reduce the life of the new battery.


The EAROM is used on 2445 and 2465.  On later A and B scopes, it was replaced with battery backed SRAM , either combined in a single package or as two separate devices.  As long as the board is isolated, soldering should be ok.  Just don't short any pins by accident.
I agree I don't want to leave an old dead battery in there.  I was more asking for suggestions on which points to use to attach the temporary battery.  Also @factory added a third option for connection points: https://www.eevblog.com/forum/testgear/tektronix-2455b-ram-battery-replacement-advice-needed/msg5277409/#msg5277409
Any preferences on which is the safest or best points to use for the temporary battery?  Also thanks for the clarification on the EAROM vs SRAM.

Quote
Yes.  I can attest the data can be saved and successfully restored with this method.  I have done it about a half dozen times.

Before trying anything with either GPIB or the battery, I would suggest you take a video of flipping through the NVRAM using EXER 02 and record all the values.  While the methods to get that data back in the NVRAM in case of failure will vary depending on what equipment you have at your disposal, at least you have the data.
Excellent thanks.  I will follow your advice.  What software do I use to send commands to the scope?

Quote
Been there done that on my 2465B. If I remember correctly the usual leaking caps where the two (blue) 180uF 40V, and the (also blue) 250uF 20V ones, all to be replaced with 330uF 50V. Thing is sometimes you won't see the leakage pooled up under the cap until the cap itself has been pulled, but if the case make sure to clean well before installing the replacement. The green caps are usually still good, but while you are in there...

Also keep in mind the orientation error for one of the caps on the PCB silkscreen, which is reversed. Best to replace only one cap at a time without using the silkscreen as a guide, and making sure to take notes of each cap's orientation before pulling it so as to install it exactly the same way the original was. Also when taking notes don't confuse the 10uF 100V with 100uF 10V (I think it was) as both will look almost identical in size. I did that mistake when I followed my own bad notes and ended up getting a loud POP which was the only thing that finally revealed the mistake, as I was still checking everything against my notes and could not figure out what was wrong. Not sure the silk screen error applies in your case with an earlier 2465ACT, but certainly it does in the 2465B. You can find plenty more information on this error here on this thread, plus recommended capacitor shopping lists, etc.
tl;dr ;-)

Those two 290uF 200V high quality SPRAGE brand caps are usually almost always still in perfect condition, but you could also replace them if desired with 330uF 250V. But it will be hard to find those in axial type, so usually a bit of conversion needs to be done to more conventional radial types by extending and insulating one of the leads and bending it upwards over the body of the cap towards the other end to create a quasi-axial cap.
I will probably leave these alone if they are unlikely to fail.  But great advice.  Also great advice on how to proceed with changing the caps one by one and which ones to change.  Thanks.  Any preferred shopping list?
« Last Edit: March 11, 2024, 04:50:28 pm by tonedeak99 »
 

Offline med6753

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1804 on: March 11, 2024, 04:54:23 pm »
Here is a complete guide for re-capping the PSU:

https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg1658102/#msg1658102

But it does not address changing the memory battery (the 2465 no suffix uses EAROM) nor does it address changing the SMT capacitors on the 2465B A5 board.
« Last Edit: March 11, 2024, 05:01:54 pm by med6753 »
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Offline hpw

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1805 on: March 11, 2024, 04:59:27 pm »
Btw: my 2465B is on sell as not any longer used ...
 

Offline factory

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1806 on: March 11, 2024, 06:40:45 pm »
The worst offenders were the larger radial Sprague caps with the resin bung, these were often found cracked and/or peeing electrolyte. I would give a list of what I used, but most of the caps I used are now discontinued.



Also if you don't have much experience replacing parts on double sided boards, I would suggest practising on something of no value first.

And as your scope has options, take note or pictures of where all the extra connectors are fitted, before removal.

David
« Last Edit: March 11, 2024, 06:44:09 pm by factory »
 

Offline tonedeak99

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1807 on: March 12, 2024, 12:08:53 am »
The worst offenders were the larger radial Sprague caps with the resin bung, these were often found cracked and/or peeing electrolyte. I would give a list of what I used, but most of the caps I used are now discontinued.



Also if you don't have much experience replacing parts on double sided boards, I would suggest practising on something of no value first.

And as your scope has options, take note or pictures of where all the extra connectors are fitted, before removal.

David
Thanks David.  Found a list by CondorAudio in the Tek group.  Unfortunately some caps are not available.  Any recommendations for substitutes?
Part#   Value   Watts         Mouser Part#
C1021   290 µF   200   ELCTLT      647-UPW2E331MRD
C1022   290 µF   200   ELCTLT      647-UPW2E331MRD
C1066   4.7 µF   35   ELCTLT      647-UPW1H4R7MDD
C1112   4.7 µF   35   ELCTLT      647-UPW1H4R7MDD
C1120   10 µF   100   ELCTLT      647-UPW2A100MED
C1130   10 µF   100   ELCTLT      647-UPW2A100MED
C1220   10 µF   100   ELCTLT      647-UPW2A100MED
C1240   10 µF   100   ELCTLT      647-UPW2A100MED
C1400   47 µF   25   ELCTLT      647-UHE1E470MDD
C1402   47 µF   25   ELCTLT      647-UHE1E470MDD
RT1010   7.0 ohm   NTC Thermistor         995-SG210
 

Offline AMR Labs

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1808 on: March 12, 2024, 12:41:13 am »
Almost all caps on that list have completely standard values and the ones that are not you can choose the closest available one above the original. For example use 330uF 250V for the 290uF 200V ones. It does not have to be exactly that brand and model specified as a Mouser PN either, you could also easily look for similar caps in another (good) brand, or even equivalents at Digikey as well, although personally I always prefer to stay with Mouser. For one the search at Mouser is very useful and usually provides you with a number of options to choose from for each capacitor.

Its been a while since I recapped my scope, but can't remember that thermistor you have on the list, where is it used? Is it really damaged? It rather sounds like something that just deals with cold startups to limit inrush current. (NTC/VDR).
« Last Edit: March 12, 2024, 12:44:07 am by AMR Labs »
 

Offline factory

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1809 on: March 12, 2024, 11:58:25 am »
The worst offenders were the larger radial Sprague caps with the resin bung, these were often found cracked and/or peeing electrolyte. I would give a list of what I used, but most of the caps I used are now discontinued.



Also if you don't have much experience replacing parts on double sided boards, I would suggest practising on something of no value first.

And as your scope has options, take note or pictures of where all the extra connectors are fitted, before removal.

David
Thanks David.  Found a list by CondorAudio in the Tek group.  Unfortunately some caps are not available.  Any recommendations for substitutes?
Part#   Value   Watts         Mouser Part#
C1021   290 µF   200   ELCTLT      647-UPW2E331MRD
C1022   290 µF   200   ELCTLT      647-UPW2E331MRD
C1066   4.7 µF   35   ELCTLT      647-UPW1H4R7MDD
C1112   4.7 µF   35   ELCTLT      647-UPW1H4R7MDD

C1120   10 µF   100   ELCTLT      647-UPW2A100MED
C1130   10 µF   100   ELCTLT      647-UPW2A100MED
C1220   10 µF   100   ELCTLT      647-UPW2A100MED
C1240   10 µF   100   ELCTLT      647-UPW2A100MED

C1400   47 µF   25   ELCTLT      647-UHE1E470MDD
C1402   47 µF   25   ELCTLT      647-UHE1E470MDD

RT1010   7.0 ohm   NTC Thermistor         995-SG210

For the 647-UPW2A100MED, I used 647-UCA2C100MPD for all of them, it's obsolete, but there are still a few thousand in stock.

For the 647-UHE1E470MDD, my choice of UPW1V470MED is no longer available, alternates I would choose from are; 667-EEU-FC1V470, 661-ELE-350ELL470MF1, or 232-35YXM47MEFR63X11, these are all 35V, but you could go with 25V as per the originals, I stocked up on the 35V version for various projects.

For the 647-UPW1H4R7MDD, there are some still available under numbers 647-UPW1H4R7MDD1TD (straight leads) and 647-UPW1H4R7MDD1TA (formed leads to 5mm pitch), all are obsolete.

The other parts I didn't replace.

David
 

Offline MarkL

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1810 on: March 12, 2024, 02:10:03 pm »
Yes.  I can attest the data can be saved and successfully restored with this method.  I have done it about a half dozen times.

Before trying anything with either GPIB or the battery, I would suggest you take a video of flipping through the NVRAM using EXER 02 and record all the values.  While the methods to get that data back in the NVRAM in case of failure will vary depending on what equipment you have at your disposal, at least you have the data.
Excellent thanks.  I will follow your advice.  What software do I use to send commands to the scope?
On Linux, you can use the ibtest utility that comes with the linux-gpib package.  It's somewhat low-level and not the most convenient, but it gets the job done without having to load or make anything extra.

You will need to write the command "key 0" to your scope, followed by "earom? f".  The scope will respond with one or more chunks of data.  Just keep entering the "r" (read) command to ibtest until there is no more data.  The data will end with a ";".  You will end up with 255 16-bit words.

I'm sure there are additional utilities to run a single query more conveniently than ibtest.

If you have windows, I don't know because I don't run it.  Maybe someone else can jump in with a suggestion.

Here's what it looks like with ibtest (includes checking the ID of the scope first):
Code: [Select]
$ ibtest
Do you wish to open a (d)evice or an interface (b)oard?
   (you probably want to open a device): d
enter primary gpib address for device you wish to open [0-30]: 8
trying to open pad = 8 on /dev/gpib0 ...
You can:
    w(a)it for an event
    write (c)ommand bytes to bus (system controller only)
    send (d)evice clear (device only)
    change remote (e)nable line (system controller only)
    (g)o to standby (release ATN line, system controller only)
    send (i)nterface clear (system controller only)
    ta(k)e control (assert ATN line, system controller only)
    get bus (l)ine status (board only)
    go to local (m)ode
    change end (o)f transmission configuration
    (q)uit
    (r)ead string
    perform (s)erial poll (device only)
    change (t)imeout on io operations
    request ser(v)ice (board only)
    (w)rite data string
    send group e(x)ecute trigger (device only)

: w
enter a string to send to your device: id?
sending string: id?

gpib status is:
ibsta = 0x2100  < END CMPL >
iberr= 0

ibcntl = 4
You can:
    w(a)it for an event
    write (c)ommand bytes to bus (system controller only)
    send (d)evice clear (device only)
    change remote (e)nable line (system controller only)
    (g)o to standby (release ATN line, system controller only)
    send (i)nterface clear (system controller only)
    ta(k)e control (assert ATN line, system controller only)
    get bus (l)ine status (board only)
    go to local (m)ode
    change end (o)f transmission configuration
    (q)uit
    (r)ead string
    perform (s)erial poll (device only)
    change (t)imeout on io operations
    request ser(v)ice (board only)
    (w)rite data string
    send group e(x)ecute trigger (device only)

: r
enter maximum number of bytes to read [1024]:
trying to read 1024 bytes from device...
received string: 'ID TEK/2445A,V81.1,SYS:FV08,BB:FV02,CTT:FV05,DMM:FV01,GPIB:FV02;'
Number of bytes read: 64
gpib status is:
ibsta = 0x2100  < END CMPL >
iberr= 0

ibcntl = 64
You can:
    w(a)it for an event
    write (c)ommand bytes to bus (system controller only)
    send (d)evice clear (device only)
    change remote (e)nable line (system controller only)
    (g)o to standby (release ATN line, system controller only)
    send (i)nterface clear (system controller only)
    ta(k)e control (assert ATN line, system controller only)
    get bus (l)ine status (board only)
    go to local (m)ode
    change end (o)f transmission configuration
    (q)uit
    (r)ead string
    perform (s)erial poll (device only)
    change (t)imeout on io operations
    request ser(v)ice (board only)
    (w)rite data string
    send group e(x)ecute trigger (device only)

: w
enter a string to send to your device: key 0
sending string: key 0

gpib status is:
ibsta = 0x2100  < END CMPL >
iberr= 0

ibcntl = 6
You can:
    w(a)it for an event
    write (c)ommand bytes to bus (system controller only)
    send (d)evice clear (device only)
    change remote (e)nable line (system controller only)
    (g)o to standby (release ATN line, system controller only)
    send (i)nterface clear (system controller only)
    ta(k)e control (assert ATN line, system controller only)
    get bus (l)ine status (board only)
    go to local (m)ode
    change end (o)f transmission configuration
    (q)uit
    (r)ead string
    perform (s)erial poll (device only)
    change (t)imeout on io operations
    request ser(v)ice (board only)
    (w)rite data string
    send group e(x)ecute trigger (device only)

: w
enter a string to send to your device: earom? f
sending string: earom? f

gpib status is:
ibsta = 0x2100  < END CMPL >
iberr= 0

ibcntl = 9
You can:
    w(a)it for an event
    write (c)ommand bytes to bus (system controller only)
    send (d)evice clear (device only)
    change remote (e)nable line (system controller only)
    (g)o to standby (release ATN line, system controller only)
    send (i)nterface clear (system controller only)
    ta(k)e control (assert ATN line, system controller only)
    get bus (l)ine status (board only)
    go to local (m)ode
    change end (o)f transmission configuration
    (q)uit
    (r)ead string
    perform (s)erial poll (device only)
    change (t)imeout on io operations
    request ser(v)ice (board only)
    (w)rite data string
    send group e(x)ecute trigger (device only)

: r
enter maximum number of bytes to read [1024]: 2048
trying to read 2048 bytes from device...
received string: 'EAR 0:215,1908,1921,1921,1927,10204,10088,1917,10118,1970,10304,506,522,8715,8712,548,8647,8671,481,8668,508,8318,32,32,8221,28,15534,16052,7414,15560,16299,8099,16299,16292,16309,566,566,8756,8756,7450,7934,7699,4096,16304,16295,8105,16280,8105,743,744,740,740,10078,10334,2140,2133,10304,10340,2120,104,2133,10319,10322,2108,10321,2102,8297,835,820,817,1646,9814,9842,1630,722,752,14501,3762,3781,1840,1878,560,569,8545,314,1377,10238,1015,8970,1'
Number of bytes read: 448
gpib status is:
ibsta = 0xc100  < ERR TIMO CMPL >
iberr= 6
EABO 6: Operation aborted

ibcntl = 448
You can:
    w(a)it for an event
    write (c)ommand bytes to bus (system controller only)
    send (d)evice clear (device only)
    change remote (e)nable line (system controller only)
    (g)o to standby (release ATN line, system controller only)
    send (i)nterface clear (system controller only)
    ta(k)e control (assert ATN line, system controller only)
    get bus (l)ine status (board only)
    go to local (m)ode
    change end (o)f transmission configuration
    (q)uit
    (r)ead string
    perform (s)erial poll (device only)
    change (t)imeout on io operations
    request ser(v)ice (board only)
    (w)rite data string
    send group e(x)ecute trigger (device only)

: r
enter maximum number of bytes to read [1024]:
trying to read 1024 bytes from device...
received string: '261,1948,9614,1975,1586,1349,1832,9242,9710,9014,710,9000,1362,9158,1187,1029,9109,1015,8928,8387,203,8361,20735,57054,57054,57054,57054,199,252,254,4,58,57054,57054,5543,5290,5366,5323,532,5500,5460,5517,5470,5386,8279,8286,8323,8292,8205,8,6359,6382,6484,7034,7110,6649,6612,6741,7291,7354,5525,5537,5509,5181,5535,5570,5575,5549,5221,5608,8292,65246,280,57054,57054,15764,37288,56338,24767,57054,57054,9480,57054,38308,9781,35954,25263,57054,5705'
Number of bytes read: 449
gpib status is:
ibsta = 0xc100  < ERR TIMO CMPL >
iberr= 6
EABO 6: Operation aborted

ibcntl = 449
You can:
    w(a)it for an event
    write (c)ommand bytes to bus (system controller only)
    send (d)evice clear (device only)
    change remote (e)nable line (system controller only)
    (g)o to standby (release ATN line, system controller only)
    send (i)nterface clear (system controller only)
    ta(k)e control (assert ATN line, system controller only)
    get bus (l)ine status (board only)
    go to local (m)ode
    change end (o)f transmission configuration
    (q)uit
    (r)ead string
    perform (s)erial poll (device only)
    change (t)imeout on io operations
    request ser(v)ice (board only)
    (w)rite data string
    send group e(x)ecute trigger (device only)

: r
enter maximum number of bytes to read [1024]:
trying to read 1024 bytes from device...
received string: '4,57054,57054,12168,13935,20320,30175,57054,57054,57054,57054,30465,23778,44986,9647,57054,57054,57054,57054,48387,47423,41792,57871,57054,57054,57054,57054,64452,24830,31824,27670,57054,57054,57054,57054,41740,12751,16266,5113,57054,57054,57054,57054,50098,2404,34593,63623,57054,57054,57054,57054,63304,2170,65206,18463,57054,57054,57054,57054,54824,8886,63400,47442,57054,57054,57054,57054,38880,2266,60688,13813,57054,57054,57054,57054,48872,16499,14;'
Number of bytes read: 455
gpib status is:
ibsta = 0x2100  < END CMPL >
iberr= 0

ibcntl = 455
You can:
    w(a)it for an event
    write (c)ommand bytes to bus (system controller only)
    send (d)evice clear (device only)
    change remote (e)nable line (system controller only)
    (g)o to standby (release ATN line, system controller only)
    send (i)nterface clear (system controller only)
    ta(k)e control (assert ATN line, system controller only)
    get bus (l)ine status (board only)
    go to local (m)ode
    change end (o)f transmission configuration
    (q)uit
    (r)ead string
    perform (s)erial poll (device only)
    change (t)imeout on io operations
    request ser(v)ice (board only)
    (w)rite data string
    send group e(x)ecute trigger (device only)

: r
enter maximum number of bytes to read [1024]:
trying to read 1024 bytes from device...
received binary data (hex): ffffffff
Number of bytes read: 1
gpib status is:
ibsta = 0x2100  < END CMPL >
iberr= 0

ibcntl = 1
You can:
    w(a)it for an event
    write (c)ommand bytes to bus (system controller only)
    send (d)evice clear (device only)
    change remote (e)nable line (system controller only)
    (g)o to standby (release ATN line, system controller only)
    send (i)nterface clear (system controller only)
    ta(k)e control (assert ATN line, system controller only)
    get bus (l)ine status (board only)
    go to local (m)ode
    change end (o)f transmission configuration
    (q)uit
    (r)ead string
    perform (s)erial poll (device only)
    change (t)imeout on io operations
    request ser(v)ice (board only)
    (w)rite data string
    send group e(x)ecute trigger (device only)
:

EDIT: The above example produces the right result, but shouldn't need multiple reads.  See next post for update on using ibtest.
« Last Edit: March 12, 2024, 05:02:05 pm by MarkL »
 

Offline MarkL

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1811 on: March 12, 2024, 05:00:23 pm »
Here's a better example of using ibtest to capture the NVRAM data.  Previously I didn't notice that the reason multiple reads were needed was because ibtest does not use the default timeout from the GPIB configuration file (gpib.conf).  Each read got some of the data but then timed out because the scope is so slow.

Here it is again, explicitly setting the timeout to 10 seconds in ibtest so the response is read in one shot.  Also note the larger buffer of 2048 bytes specified for the "r" (read command).

Sorry for the re-do.  I don't usually use ibtest.

Code: [Select]
$ ibtest
Do you wish to open a (d)evice or an interface (b)oard?
   (you probably want to open a device): d
enter primary gpib address for device you wish to open [0-30]: 8
trying to open pad = 8 on /dev/gpib0 ...
You can:
    w(a)it for an event
    write (c)ommand bytes to bus (system controller only)
    send (d)evice clear (device only)
    change remote (e)nable line (system controller only)
    (g)o to standby (release ATN line, system controller only)
    send (i)nterface clear (system controller only)
    ta(k)e control (assert ATN line, system controller only)
    get bus (l)ine status (board only)
    go to local (m)ode
    change end (o)f transmission configuration
    (q)uit
    (r)ead string
    perform (s)erial poll (device only)
    change (t)imeout on io operations
    request ser(v)ice (board only)
    (w)rite data string
    send group e(x)ecute trigger (device only)

: t
enter the desired timeout:
      (0) none
      (1) 10 microsec
      (2) 30 microsec
      (3) 100 microsec
      (4) 300 microsec
      (5) 1 millisec
      (6) 3 millisec
      (7) 10 millisec
      (8) 30 millisec
      (9) 100 millisec
      (10) 300 millisec
      (11) 1 sec
      (12) 3 sec
      (13) 10 sec
      (14) 30 sec
      (15) 100 sec
      (16) 300 sec
      (17) 1000 sec
13
gpib status is:
ibsta = 0x100  < CMPL >
iberr= 0

ibcntl = 0
You can:
    w(a)it for an event
    write (c)ommand bytes to bus (system controller only)
    send (d)evice clear (device only)
    change remote (e)nable line (system controller only)
    (g)o to standby (release ATN line, system controller only)
    send (i)nterface clear (system controller only)
    ta(k)e control (assert ATN line, system controller only)
    get bus (l)ine status (board only)
    go to local (m)ode
    change end (o)f transmission configuration
    (q)uit
    (r)ead string
    perform (s)erial poll (device only)
    change (t)imeout on io operations
    request ser(v)ice (board only)
    (w)rite data string
    send group e(x)ecute trigger (device only)

: w
enter a string to send to your device: id?
sending string: id?

gpib status is:
ibsta = 0x2100  < END CMPL >
iberr= 0

ibcntl = 4
You can:
    w(a)it for an event
    write (c)ommand bytes to bus (system controller only)
    send (d)evice clear (device only)
    change remote (e)nable line (system controller only)
    (g)o to standby (release ATN line, system controller only)
    send (i)nterface clear (system controller only)
    ta(k)e control (assert ATN line, system controller only)
    get bus (l)ine status (board only)
    go to local (m)ode
    change end (o)f transmission configuration
    (q)uit
    (r)ead string
    perform (s)erial poll (device only)
    change (t)imeout on io operations
    request ser(v)ice (board only)
    (w)rite data string
    send group e(x)ecute trigger (device only)

: r
enter maximum number of bytes to read [1024]:
trying to read 1024 bytes from device...
received string: 'ID TEK/2445A,V81.1,SYS:FV08,BB:FV02,CTT:FV05,DMM:FV01,GPIB:FV02;'
Number of bytes read: 64
gpib status is:
ibsta = 0x2100  < END CMPL >
iberr= 0

ibcntl = 64
You can:
    w(a)it for an event
    write (c)ommand bytes to bus (system controller only)
    send (d)evice clear (device only)
    change remote (e)nable line (system controller only)
    (g)o to standby (release ATN line, system controller only)
    send (i)nterface clear (system controller only)
    ta(k)e control (assert ATN line, system controller only)
    get bus (l)ine status (board only)
    go to local (m)ode
    change end (o)f transmission configuration
    (q)uit
    (r)ead string
    perform (s)erial poll (device only)
    change (t)imeout on io operations
    request ser(v)ice (board only)
    (w)rite data string
    send group e(x)ecute trigger (device only)

: w
enter a string to send to your device: key 0
sending string: key 0

gpib status is:
ibsta = 0x2100  < END CMPL >
iberr= 0

ibcntl = 6
You can:
    w(a)it for an event
    write (c)ommand bytes to bus (system controller only)
    send (d)evice clear (device only)
    change remote (e)nable line (system controller only)
    (g)o to standby (release ATN line, system controller only)
    send (i)nterface clear (system controller only)
    ta(k)e control (assert ATN line, system controller only)
    get bus (l)ine status (board only)
    go to local (m)ode
    change end (o)f transmission configuration
    (q)uit
    (r)ead string
    perform (s)erial poll (device only)
    change (t)imeout on io operations
    request ser(v)ice (board only)
    (w)rite data string
    send group e(x)ecute trigger (device only)

: w
enter a string to send to your device: earom? f
sending string: earom? f

gpib status is:
ibsta = 0x2100  < END CMPL >
iberr= 0

ibcntl = 9
You can:
    w(a)it for an event
    write (c)ommand bytes to bus (system controller only)
    send (d)evice clear (device only)
    change remote (e)nable line (system controller only)
    (g)o to standby (release ATN line, system controller only)
    send (i)nterface clear (system controller only)
    ta(k)e control (assert ATN line, system controller only)
    get bus (l)ine status (board only)
    go to local (m)ode
    change end (o)f transmission configuration
    (q)uit
    (r)ead string
    perform (s)erial poll (device only)
    change (t)imeout on io operations
    request ser(v)ice (board only)
    (w)rite data string
    send group e(x)ecute trigger (device only)

: r
enter maximum number of bytes to read [1024]: 2048
trying to read 2048 bytes from device...
received string: 'EAR 0:215,1908,1921,1921,1927,10204,10088,1917,10118,1970,10304,506,522,8715,8712,548,8647,8671,481,8668,508,8318,32,32,8221,28,15534,16052,7414,15560,16299,8099,16299,16292,16309,566,566,8756,8756,7450,7934,7699,4096,16304,16295,8105,16280,8105,743,744,740,740,10078,10334,2140,2133,10304,10340,2120,104,2133,10319,10322,2108,10321,2102,8297,835,820,817,1646,9814,9842,1630,722,752,14501,3762,3781,1840,1878,560,569,8545,314,1377,10238,1015,8970,1261,1948,9614,1975,1586,1349,1832,9242,9710,9014,710,9000,1362,9158,1187,1029,9109,1015,8928,8387,203,8361,20735,57054,57054,57054,57054,199,252,254,4,58,57054,57054,5543,5290,5366,5323,532,5500,5460,5517,5470,5386,8279,8286,8323,8292,8205,8,6359,6382,6484,7034,7110,6649,6612,6741,7291,7354,5525,5537,5509,5181,5535,5570,5575,5549,5221,5608,8292,65246,280,57054,57054,15764,37288,56338,24767,57054,57054,9480,57054,38308,9781,35954,25263,57054,57054,57054,57054,12168,13935,20320,30175,57054,57054,57054,57054,30465,23778,44986,9647,57054,57054,57054,57054,48387,47423,41792,57871,57054,57054,57054,57054,64452,24830,31824,27670,57054,57054,57054,57054,41740,12751,16266,5113,57054,57054,57054,57054,50098,2404,34593,63623,57054,57054,57054,57054,63304,2170,65206,18463,57054,57054,57054,57054,54824,8886,63400,47442,57054,57054,57054,57054,38880,2266,60688,13813,57054,57054,57054,57054,48872,16499,14;'
Number of bytes read: 1352
gpib status is:
ibsta = 0x2100  < END CMPL >
iberr= 0

ibcntl = 1352
You can:
    w(a)it for an event
    write (c)ommand bytes to bus (system controller only)
    send (d)evice clear (device only)
    change remote (e)nable line (system controller only)
    (g)o to standby (release ATN line, system controller only)
    send (i)nterface clear (system controller only)
    ta(k)e control (assert ATN line, system controller only)
    get bus (l)ine status (board only)
    go to local (m)ode
    change end (o)f transmission configuration
    (q)uit
    (r)ead string
    perform (s)erial poll (device only)
    change (t)imeout on io operations
    request ser(v)ice (board only)
    (w)rite data string
    send group e(x)ecute trigger (device only)
:
« Last Edit: March 12, 2024, 07:05:27 pm by MarkL »
 

Offline tonedeak99

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  • Posts: 42
  • Country: us
Re: Tektronix 2465B oscilloscope teardown
« Reply #1812 on: March 13, 2024, 07:01:53 pm »
The worst offenders were the larger radial Sprague caps with the resin bung, these were often found cracked and/or peeing electrolyte. I would give a list of what I used, but most of the caps I used are now discontinued.



Also if you don't have much experience replacing parts on double sided boards, I would suggest practising on something of no value first.

And as your scope has options, take note or pictures of where all the extra connectors are fitted, before removal.

David
Thanks David.  Found a list by CondorAudio in the Tek group.  Unfortunately some caps are not available.  Any recommendations for substitutes?
Part#   Value   Watts         Mouser Part#
C1021   290 µF   200   ELCTLT      647-UPW2E331MRD
C1022   290 µF   200   ELCTLT      647-UPW2E331MRD
C1066   4.7 µF   35   ELCTLT      647-UPW1H4R7MDD
C1112   4.7 µF   35   ELCTLT      647-UPW1H4R7MDD

C1120   10 µF   100   ELCTLT      647-UPW2A100MED
C1130   10 µF   100   ELCTLT      647-UPW2A100MED
C1220   10 µF   100   ELCTLT      647-UPW2A100MED
C1240   10 µF   100   ELCTLT      647-UPW2A100MED

C1400   47 µF   25   ELCTLT      647-UHE1E470MDD
C1402   47 µF   25   ELCTLT      647-UHE1E470MDD

RT1010   7.0 ohm   NTC Thermistor         995-SG210

For the 647-UPW2A100MED, I used 647-UCA2C100MPD for all of them, it's obsolete, but there are still a few thousand in stock.

For the 647-UHE1E470MDD, my choice of UPW1V470MED is no longer available, alternates I would choose from are; 667-EEU-FC1V470, 661-ELE-350ELL470MF1, or 232-35YXM47MEFR63X11, these are all 35V, but you could go with 25V as per the originals, I stocked up on the 35V version for various projects.

For the 647-UPW1H4R7MDD, there are some still available under numbers 647-UPW1H4R7MDD1TD (straight leads) and 647-UPW1H4R7MDD1TA (formed leads to 5mm pitch), all are obsolete.

The other parts I didn't replace.

David
Thanks for helping with substitutes.  I'm confused on the importance of brand (i.e Nichicon) and ripple. (Nichicon UPW vs UCA).  Do these factors matter?  I'm reading some mixed information.

Here's a better example of using ibtest to capture the NVRAM data.  Previously I didn't notice that the reason multiple reads were needed was because ibtest does not use the default timeout from the GPIB configuration file (gpib.conf).  Each read got some of the data but then timed out because the scope is so slow.

Here it is again, explicitly setting the timeout to 10 seconds in ibtest so the response is read in one shot.  Also note the larger buffer of 2048 bytes specified for the "r" (read command).

Sorry for the re-do.  I don't usually use ibtest.

Code: [Select]
$ ibtest
Do you wish to open a (d)evice or an interface (b)oard?
   (you probably want to open a device): d
enter primary gpib address for device you wish to open [0-30]: 8
trying to open pad = 8 on /dev/gpib0 ...
You can:
    w(a)it for an event
    write (c)ommand bytes to bus (system controller only)
    send (d)evice clear (device only)
    change remote (e)nable line (system controller only)
    (g)o to standby (release ATN line, system controller only)
    send (i)nterface clear (system controller only)
    ta(k)e control (assert ATN line, system controller only)
    get bus (l)ine status (board only)
    go to local (m)ode
    change end (o)f transmission configuration
    (q)uit
    (r)ead string
    perform (s)erial poll (device only)
    change (t)imeout on io operations
    request ser(v)ice (board only)
    (w)rite data string
    send group e(x)ecute trigger (device only)

: t
enter the desired timeout:
      (0) none
      (1) 10 microsec
      (2) 30 microsec
      (3) 100 microsec
      (4) 300 microsec
      (5) 1 millisec
      (6) 3 millisec
      (7) 10 millisec
      (8) 30 millisec
      (9) 100 millisec
      (10) 300 millisec
      (11) 1 sec
      (12) 3 sec
      (13) 10 sec
      (14) 30 sec
      (15) 100 sec
      (16) 300 sec
      (17) 1000 sec
13
gpib status is:
ibsta = 0x100  < CMPL >
iberr= 0

ibcntl = 0
You can:
    w(a)it for an event
    write (c)ommand bytes to bus (system controller only)
    send (d)evice clear (device only)
    change remote (e)nable line (system controller only)
    (g)o to standby (release ATN line, system controller only)
    send (i)nterface clear (system controller only)
    ta(k)e control (assert ATN line, system controller only)
    get bus (l)ine status (board only)
    go to local (m)ode
    change end (o)f transmission configuration
    (q)uit
    (r)ead string
    perform (s)erial poll (device only)
    change (t)imeout on io operations
    request ser(v)ice (board only)
    (w)rite data string
    send group e(x)ecute trigger (device only)

: w
enter a string to send to your device: id?
sending string: id?

gpib status is:
ibsta = 0x2100  < END CMPL >
iberr= 0

ibcntl = 4
You can:
    w(a)it for an event
    write (c)ommand bytes to bus (system controller only)
    send (d)evice clear (device only)
    change remote (e)nable line (system controller only)
    (g)o to standby (release ATN line, system controller only)
    send (i)nterface clear (system controller only)
    ta(k)e control (assert ATN line, system controller only)
    get bus (l)ine status (board only)
    go to local (m)ode
    change end (o)f transmission configuration
    (q)uit
    (r)ead string
    perform (s)erial poll (device only)
    change (t)imeout on io operations
    request ser(v)ice (board only)
    (w)rite data string
    send group e(x)ecute trigger (device only)

: r
enter maximum number of bytes to read [1024]:
trying to read 1024 bytes from device...
received string: 'ID TEK/2445A,V81.1,SYS:FV08,BB:FV02,CTT:FV05,DMM:FV01,GPIB:FV02;'
Number of bytes read: 64
gpib status is:
ibsta = 0x2100  < END CMPL >
iberr= 0

ibcntl = 64
You can:
    w(a)it for an event
    write (c)ommand bytes to bus (system controller only)
    send (d)evice clear (device only)
    change remote (e)nable line (system controller only)
    (g)o to standby (release ATN line, system controller only)
    send (i)nterface clear (system controller only)
    ta(k)e control (assert ATN line, system controller only)
    get bus (l)ine status (board only)
    go to local (m)ode
    change end (o)f transmission configuration
    (q)uit
    (r)ead string
    perform (s)erial poll (device only)
    change (t)imeout on io operations
    request ser(v)ice (board only)
    (w)rite data string
    send group e(x)ecute trigger (device only)

: w
enter a string to send to your device: key 0
sending string: key 0

gpib status is:
ibsta = 0x2100  < END CMPL >
iberr= 0

ibcntl = 6
You can:
    w(a)it for an event
    write (c)ommand bytes to bus (system controller only)
    send (d)evice clear (device only)
    change remote (e)nable line (system controller only)
    (g)o to standby (release ATN line, system controller only)
    send (i)nterface clear (system controller only)
    ta(k)e control (assert ATN line, system controller only)
    get bus (l)ine status (board only)
    go to local (m)ode
    change end (o)f transmission configuration
    (q)uit
    (r)ead string
    perform (s)erial poll (device only)
    change (t)imeout on io operations
    request ser(v)ice (board only)
    (w)rite data string
    send group e(x)ecute trigger (device only)

: w
enter a string to send to your device: earom? f
sending string: earom? f

gpib status is:
ibsta = 0x2100  < END CMPL >
iberr= 0

ibcntl = 9
You can:
    w(a)it for an event
    write (c)ommand bytes to bus (system controller only)
    send (d)evice clear (device only)
    change remote (e)nable line (system controller only)
    (g)o to standby (release ATN line, system controller only)
    send (i)nterface clear (system controller only)
    ta(k)e control (assert ATN line, system controller only)
    get bus (l)ine status (board only)
    go to local (m)ode
    change end (o)f transmission configuration
    (q)uit
    (r)ead string
    perform (s)erial poll (device only)
    change (t)imeout on io operations
    request ser(v)ice (board only)
    (w)rite data string
    send group e(x)ecute trigger (device only)

: r
enter maximum number of bytes to read [1024]: 2048
trying to read 2048 bytes from device...
received string: 'EAR 0:215,1908,1921,1921,1927,10204,10088,1917,10118,1970,10304,506,522,8715,8712,548,8647,8671,481,8668,508,8318,32,32,8221,28,15534,16052,7414,15560,16299,8099,16299,16292,16309,566,566,8756,8756,7450,7934,7699,4096,16304,16295,8105,16280,8105,743,744,740,740,10078,10334,2140,2133,10304,10340,2120,104,2133,10319,10322,2108,10321,2102,8297,835,820,817,1646,9814,9842,1630,722,752,14501,3762,3781,1840,1878,560,569,8545,314,1377,10238,1015,8970,1261,1948,9614,1975,1586,1349,1832,9242,9710,9014,710,9000,1362,9158,1187,1029,9109,1015,8928,8387,203,8361,20735,57054,57054,57054,57054,199,252,254,4,58,57054,57054,5543,5290,5366,5323,532,5500,5460,5517,5470,5386,8279,8286,8323,8292,8205,8,6359,6382,6484,7034,7110,6649,6612,6741,7291,7354,5525,5537,5509,5181,5535,5570,5575,5549,5221,5608,8292,65246,280,57054,57054,15764,37288,56338,24767,57054,57054,9480,57054,38308,9781,35954,25263,57054,57054,57054,57054,12168,13935,20320,30175,57054,57054,57054,57054,30465,23778,44986,9647,57054,57054,57054,57054,48387,47423,41792,57871,57054,57054,57054,57054,64452,24830,31824,27670,57054,57054,57054,57054,41740,12751,16266,5113,57054,57054,57054,57054,50098,2404,34593,63623,57054,57054,57054,57054,63304,2170,65206,18463,57054,57054,57054,57054,54824,8886,63400,47442,57054,57054,57054,57054,38880,2266,60688,13813,57054,57054,57054,57054,48872,16499,14;'
Number of bytes read: 1352
gpib status is:
ibsta = 0x2100  < END CMPL >
iberr= 0

ibcntl = 1352
You can:
    w(a)it for an event
    write (c)ommand bytes to bus (system controller only)
    send (d)evice clear (device only)
    change remote (e)nable line (system controller only)
    (g)o to standby (release ATN line, system controller only)
    send (i)nterface clear (system controller only)
    ta(k)e control (assert ATN line, system controller only)
    get bus (l)ine status (board only)
    go to local (m)ode
    change end (o)f transmission configuration
    (q)uit
    (r)ead string
    perform (s)erial poll (device only)
    change (t)imeout on io operations
    request ser(v)ice (board only)
    (w)rite data string
    send group e(x)ecute trigger (device only)
:

Thanks Mark.  I will see how to run this in windows and report back.
 

Offline tggzzz

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1813 on: March 13, 2024, 08:35:59 pm »
Thanks for helping with substitutes.  I'm confused on the importance of brand (i.e Nichicon) and ripple. (Nichicon UPW vs UCA).  Do these factors matter?  I'm reading some mixed information.

The capacitance of an electrolytic decoupling capacitor is not critical. Look at the tolerances of the original capacitors: often they were -20% +100%.

Obviously the voltage has to be suitable; don't run anything at the rated voltage!

The more subtle points are all inter-related: ripple current, operating frequency (mains or SMPS), temperature, and lifetime. Higher is better :) Lower will work, but not necessarily as well nor for as long.
There are lies, damned lies, statistics - and ADC/DAC specs.
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Offline factory

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1814 on: March 13, 2024, 09:09:12 pm »
Thanks for helping with substitutes.  I'm confused on the importance of brand (i.e Nichicon) and ripple. (Nichicon UPW vs UCA).  Do these factors matter?  I'm reading some mixed information.

The brand was just my preferred option at the time and some of the parts were changed to what the local suppliers had available in stock at the time. I've used a mix of Rubycon & Panasonic for a couple of these PSUs too.

For the one that is no longer available, I gave similar parts from three other brands. Just make sure you choose reputable brands from reputable suppliers and not some unknown brand or fake crap from ebay/amazon/aliexpress etc. Unrelated to this thread, I did notice Nichicon have EOL'ed lots of their higher voltage capacitors.

David
« Last Edit: March 14, 2024, 12:56:47 pm by factory »
 

Offline jonpaul

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1815 on: March 14, 2024, 12:33:51 pm »
Menachem at Conrad Audio in Isreral has lots of tips, recapping lists and parts for every TEK 246X model

j
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Offline tonedeak99

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1816 on: March 14, 2024, 09:20:02 pm »
Thank you all so much.  I have my order ready.  It's definitely more than I was hoping to spend.  I checked the hours with EXER 05 and the scope has 5000.  Is there a particular point when a full recap is truly necessary?  Or can I get away with just changing the SRAM battery and the RIFA caps?  Is checking the ripple important to make this decision?  I also took a video of EXER 02 as recommended by many here.  Also any help on the proper/best points to attach a temp battery to the SRAM will be greatly appreciated.
« Last Edit: March 14, 2024, 09:53:58 pm by tonedeak99 »
 

Offline tonedeak99

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1817 on: March 15, 2024, 12:43:10 pm »
hi all.  I was trying to understand how to measure the ripple for chart 5-1 in the service manual.  Can someone please explain the difference between total p-p ripple and 2x the line frequency p-p ripple and how each is measured.  I have a 20MHz analog scope I was going to use with a 1x probe grounded to the chassis set to the settings in the manual below Table 5-1.  Also I'm a bit worried about the Tek scope overheating, especially U800.  I've read warnings against running the scope with the cover off for extended periods, but this check requires that you let the scope warm up for 20mins plus the time needed to perform the checks.
 

Offline MarkL

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1818 on: March 15, 2024, 03:34:18 pm »
hi all.  I was trying to understand how to measure the ripple for chart 5-1 in the service manual.  Can someone please explain the difference between total p-p ripple and 2x the line frequency p-p ripple and how each is measured.  I have a 20MHz analog scope I was going to use with a 1x probe grounded to the chassis set to the settings in the manual below Table 5-1.  Also I'm a bit worried about the Tek scope overheating, especially U800.  I've read warnings against running the scope with the cover off for extended periods, but this check requires that you let the scope warm up for 20mins plus the time needed to perform the checks.
Total p-p ripple is letting the measuring scope trigger on whatever it finds and you can measure the p-p on the resulting waveform.  To measure twice the line frequency, you need to synchronize the scope triggering to the incoming AC line by selecting LINE trigger.  Basically you're looking for variation of two peaks spaced 120Hz apart to make sure there's no major imbalance between the positive and negative peak of the incoming AC after it's been rectified.

U800 will be fine with no fan running over it (but not true for some other model Tek scopes, which is where this concern comes from).  There's been much discussion about U800's thermal properties over on https://groups.io/g/TekScopes.  Also, it does not need a heatsink fitted, and don't be tempted to turn the mounting nuts.  Mechanical failure is its downfall.

For a temporary battery attachment point, any ground on the card will do for the battery negative, and the battery positive should go to any point connected to the SRAM Vcc.  The link you posted before from Jestine shows two possible points that would work.
 

Offline AMR Labs

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1819 on: March 15, 2024, 04:27:50 pm »
For a temporary battery attachment point, any ground on the card will do for the battery negative, and the battery positive should go to any point connected to the SRAM Vcc.  The link you posted before from Jestine shows two possible points that would work.

Don't forget to put a small 1N4148 diode in series with the temporary battery, just in case to avoid any current going into that battery while the main lithium battery is still connected, or the power of the instrument is still turned on.
 

Offline MarkL

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1820 on: March 15, 2024, 05:12:36 pm »
For a temporary battery attachment point, any ground on the card will do for the battery negative, and the battery positive should go to any point connected to the SRAM Vcc.  The link you posted before from Jestine shows two possible points that would work.

Don't forget to put a small 1N4148 diode in series with the temporary battery, just in case to avoid any current going into that battery while the main lithium battery is still connected, or the power of the instrument is still turned on.
I was thinking power would not be applied again until this operation was complete, since you don't want to be soldering these wires with the board un-isolated.  But if you did, and the scope was powered on, you're right that the +5V would flow into the temporary battery.  The lithium battery already has a diode which would keep its contribution below the 3V of the temporary battery, so that should be ok.

A series diode could be used for added safety if desired.  A Schottky diode would provide for a lower voltage drop.
 

Offline tonedeak99

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1821 on: March 15, 2024, 11:11:58 pm »
hi all.  I was trying to understand how to measure the ripple for chart 5-1 in the service manual.  Can someone please explain the difference between total p-p ripple and 2x the line frequency p-p ripple and how each is measured.  I have a 20MHz analog scope I was going to use with a 1x probe grounded to the chassis set to the settings in the manual below Table 5-1.  Also I'm a bit worried about the Tek scope overheating, especially U800.  I've read warnings against running the scope with the cover off for extended periods, but this check requires that you let the scope warm up for 20mins plus the time needed to perform the checks.
Total p-p ripple is letting the measuring scope trigger on whatever it finds and you can measure the p-p on the resulting waveform.  To measure twice the line frequency, you need to synchronize the scope triggering to the incoming AC line by selecting LINE trigger.  Basically you're looking for variation of two peaks spaced 120Hz apart to make sure there's no major imbalance between the positive and negative peak of the incoming AC after it's been rectified.
Thanks Mark.  I tried CH1 trigger and LINE trigger and the waveform is exactly the same.  Also there are tiny spikes in the waveform, do I measure those or just the center band of the waveform?

Attached are some example waveforms and my results below:
J119 Pin    Vdc   p-p ripple (with spikes, without spikes)
1        -14.95   8mw, 4mv
2        4.98   35mv, 20mv
4        9.96   8mv, 4mv
5       -4.96   10mv, 7mv
6       14.92   8mw, 5mv
8        86   10mv, 8mv
9       41.7   8mv, 6mv
11       -7.99   8mv, 4mv
12        4.96   15mv, 5mv
« Last Edit: March 16, 2024, 12:21:01 am by tonedeak99 »
 

Offline add_ocean

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1822 on: March 16, 2024, 09:19:59 pm »
About keeper battery replacement.

I was worrying about this 37 year old battery (dated 1987). So have bought new chinese one, manufactured 2023.
But when measured the voltage, both old and new battery measured 3,5V (within few of 1/1000 tolerance).
Who knows which battery will fail first or maybe last for the next 30 years?
This chemistry lasts 100 years in theory, but manufacture culture makes difference in practice.

So, the solution:
Attached new battery without detaching the old one. Each battery is connected via own diode and resistor, so these are isolated from each other.

No need to take the board off and de-solder, no risk of loosing calibration. Double reliability.
 

Offline tonedeak99

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1823 on: March 16, 2024, 09:54:07 pm »
About keeper battery replacement.

I was worrying about this 37 year old battery (dated 1987). So have bought new chinese one, manufactured 2023.
But when measured the voltage, both old and new battery measured 3,5V (within few of 1/1000 tolerance).
Who knows which battery will fail first or maybe last for the next 30 years?
This chemistry lasts 100 years in theory, but manufacture culture makes difference in practice.

So, the solution:
Attached new battery without detaching the old one. Each battery is connected via own diode and resistor, so these are isolated from each other.

No need to take the board off and de-solder, no risk of loosing calibration. Double reliability.
Thanks for your advice but if you look at the data sheet you will see that the Keeper II batteries die abruptly. Also lithium batteries can leak acid and destroy the board. Therefore I’d rather not take a chance and remove the old one and replace it with the same brand and model.
« Last Edit: March 16, 2024, 10:06:49 pm by tonedeak99 »
 

Offline calibrationfixture

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Re: Tektronix 2465B oscilloscope teardown
« Reply #1824 on: March 17, 2024, 06:38:35 am »
Hi,

I agree, replace them notwithstanding the voltage. Done that myself several times. No problems. Mouser doesn't deliver these Timekeeper Batteries to Europe, but Conrad has the same Battery (LTC-7PN). Same Pin-Out. This time without its casing.

https://www.conrad.com/en/p/eve-ef651625-non-standard-battery-ltc-7pn-u-solder-pins-lithium-3-6-v-750-mah-1-pc-s-650799.html

Calibrationfixture
« Last Edit: March 17, 2024, 06:51:06 am by calibrationfixture »
 


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