Amazing Tektronix 2465 Repair Information
Today I was helping a friend by checking his electronic car key with my Tektronix 2440 and 2465 oscilloscopes. The car key was fed by two 3V lithium cells but no signals could be measured. The device was completely dead.
And after that I checked all smd components on that pcb with my new and very handy Mastech MS8911 smd LCR tester. All passive components were fine but the chip or the special quarts oscillator probably were defect. The chip likely had special firmware and obtaining a new key could cost my friend up to 400 euros. And repair would be just as expensive as he told me. Which was just too much for an old car and an old electronic key. And also the IR led was already missing and placing a normal led on those 2 layer pins of course showed no activity either. And the two buttons on his pcb worked very well and were the only thing that worked.
Suddenly I heard a small short bang and my electronics room was filled with a lot of smoke. My scopes still were working fine so I began to examine the other equipment by opening them. Checking them on blown components. I couldn’t find any defects so I began to suspect one of my oscilloscopes. And indeed the smell of smoked components came out of my secondhand in Texas USA on eBay bought Tektronix 2465 oscilloscope. I was very worried because the device did cost me at least 600 Euros a couple of years ago.
I already had replaced the Lithium Battery by a new one to prevent the oscilloscope from loosing his calibration firmware. And I had also replaced the old Fan by a new one that I luckily was able to find.
I knew how to open my oscilloscope by first removing the back plate. But removing the Power Board was something I never had done before on my 2465. But removing the Top plate was next of course.
Replacing the Lithium Battery, and later on also the Fan was quite easy. But removing the Power Board apparently was not! And I couldn’t find anything useful about how to disassemble the Power Board in the Service Manual either. So this repair will be a small guide on how to repair your Power board. Next photo shows the new replacement Fan that works fine in case you might look for a replacement Fan too. The Fan must be mounted with the text visible, facing the outside.
And following photos explain how to disassemble the Power board after the top plate, as shown on the first photo, is removed. And what exactly had happened to my sturdy old 2465.
The top plate was easily removed by loosening a couple of screws on the back and side and 4 on the top. The Power board is the board in the middle which is connected to the AC Voltage selector on the back and to 2 connectors in the middle and one flat cable going to the front left. And also connected with 3 long 5 pin legged copper (gold plated?) and one 3 legged plugs connected to the, also vertical placed, board on the left. And be careful with the scope crt tube that is visible on the right.
I was trying to remove the Power board but couldn’t at first as it was not only attached to screws on the transistor cooler plate and to screws on the back of the case, but also to the case by screws on the bottom board side. I stopped counting them but I made photos of all sides, no need to mention the obvious. Most of the screws are identical anyway and only 2 smaller screws on the top plate differ.
Following photo shows the 5 bottom panel screws that we also need to remove before the Powerboard with the second panel still attached to its left side can be removed. Notice the 5 red arrows. And the second photo shows the inside of the 2465 case after both boards are removed.
After removing the Voltage selector cap and all screws that hold both boards and the wires attached to it, both together can be removed by lifting the board end on the front side first. Notice the black circle in the last photo above on the right that shows why it is not possible to fully lift that entire panel straight up vertical. That is because of the Power board with the second board attached to it that still sticks into a small hole in the back plate of the case (on the left of the BNC connector).
Therefore we also have to loosen the back plate a bit by removing any tight screw which makes lifting up both boards much easier.
Only then it will be possible to extract the Power board for repair. But keep in mind that both boards are still connected to a coax cable to a connector on the back of the case. So don’t break that when removing the Power board from the left side board. See photo:
Following photo shows the left board after the power board is removed.
Following photos show the Power board and the pin connectors used to connect to the board on its left side:
Previous photo showed the 2 nuts and bolts plus the plastic black caps that hold together both boards plus screws and which also electrical separated them from touching each other unintendidly.
Next photo shows clearly how both boards are electrically connected by long legged plugs. And the earlier mentioned flat cable that is connected to the outside board.
( looking into the scope from the back like all photo shots are taken).
After I checked the component side of the Power board I immediately noticed the smelling blown open special 2X 250VAC 0.068uF capacitor. The second one (vertical blue circle position below in next photo on the next page was still okay).
And it seems that someone already replaced all now blue e-caps on the Power board component side as visible on the following photos after next photo of both 0.068 uF 2X capacitors with the now bad blown specimen on the right.
Previous photos show that the new replacement X2 0.068 uF 250 VAC now is soldered in place of the removed bad one.
My scope is repaired again with the last X2 0.068 uF 250VAC capacitor I had left. Of course I immediately ordered 20 of them marked up to 275VAC on eBay to make sure they last longer after our Power lines already changed to the higher 230VAC of today.
After this unexpected repair I luckily got the space on my ‘work floor’ back again. These devices do take up a lot of living space. So I was happy that I could put him back completely fixed on my worktable. I ask you… What other firm can claim such long operating times like Tektronix can?
By-the-way: You will need Torx T10 and T15 for this repair.
Latest Update:
Concerning my Tektronix 2465 repair I yesterday replaced both 0.068uF 250VAC caps after I had received the ordered new 275VAC caps.
Both caps are C1016 and C1018 in the Tektronix service manual schematic on Board A2A1. And only the C1016 0.068uF capacitor had blown which also damaged the serie resistor R1016 of 68 ohm 5%.
Which also was replaced.
They protect the Diode Bridge CR1011 (600V 3A Fast Recovery type RKBPC606-12) against damage by high AC power voltages. The Diode Bridge was not damaged. My oscilloscope is happily working as new again. (48019 HRS of service in 32 years or so).
Albert van Bemmelen, Weert, The Netherlands.
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Note: You can read his previous repair article in the below link:
https://jestineyong.com/65-watt-autovoltage-laptop-power-adapter-repair/
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Parasuraman
April 22, 2018 at 12:03 am
A dare devil operation! Congratulations! Very thorough and informative article.
Albert
April 22, 2018 at 4:02 pm
Thank you Parasuraman. It indeed is always a bit tricky to disassemble such expensive and old devices. But the other option to leave it as it was is of course out of the question. A decision as they say that was a complete no-brainer.
Menahem Yachad
April 22, 2018 at 1:51 am
Albert
You are welcome to download my 2465 Repair PDF at CONDORAUDIO.
I also offer a comprehensive parts kit to do ALL the correct restoration work of your scope, ONCE and for all.
https://www.ebay.com/itm/252865418970
Albert
April 22, 2018 at 4:02 pm
Thank you for your very interesting reply Menahem. If my scope needs other parts in the near future I certainly will have a look at your eBay link! I believe I already read your interesting restoration page recently. And I wonder if you replace C1016 and C1018 to prevent the thing that happened to my scope or that your scope suffered from the same illness already? It probably is a well known fact that will occure in time. Very well written and detailed document Menahem. I'm sure it is a great help to other Tektronix scope owners too! How to disassemble both boards was still missing though. The Vishay components you proposed I could not find on Aliexpress or eBay. So I bought similar C1016 and C1018 capacitors in Germany on eBay.
Robert Calk
April 22, 2018 at 4:36 am
Excellent work Albert! I'm glad that your scope is fixed. Did you check to see which end of the cap was the foil end, and install it correctly? You can't always assume the banded end is correct. If the scope seems to be picking up some RFI from somewhere then that may be the cause.
I talked about it on my article, "Playing with IC's Part 3": https://jestineyong.com/playing-with-ics-part-3/.
Nice photos! Thanks for sharing the repair with us!
Albert
April 22, 2018 at 4:01 pm
Good question Robert! I didn't bother to check that thinking they probably are bipolar? But I know what you are referring to.
And in this case the AC input voltage changes periodically every 20ms (50Hz) anyway.
By-the-way Robert: I found an old article today in one of the first (pre)Elektuurs that had an article about your Accutron watch.
See this link: https://archive.org/details/ElectronicaWereldApril1961
Robert Calk
April 23, 2018 at 7:01 pm
Hi Albert,
Yes of course they are bi-polar. The Band/foil/shielded end of the cap needs to go to ground or the lower impedance of the circuit.
I'll probably get back into those Accutron's in a couple months.
Anthony
April 22, 2018 at 5:14 pm
Great repair work and also nice photos accompanying your article Mr Albert. Very delicate electronics surgery
and lots of patience required to remove those boards but glad you have successfully resuscitated your
Tektronic CRT scope ! And it's a very fine scope as you have pointed out ! Well done and thanks for
sharing this information here.
Kind Regards
Albert
April 23, 2018 at 9:23 pm
Thanks Anthony, although repair was needed my scope still worked splendidly but the smell of the damaged protective capacitor made immediate action urgent. I hope these sudden incidents are rare. But if I would buy a new scope I think this Rigol is a very nice one that also has a build in Logic Analyzer. https://www.banggood.com/RIGOL-DS1054Z-Digital-4-Channels-50MHz-Bandwidth-1GSs-7inch-WVGA-12Mpts-30000wfm-Oscilloscope-p-1112065.html?rmmds=buy&admitad_uid=6b32bbc341b45d21bcad2f6b506420d7&cur_warehouse=CN
But it sadly only has a bandwidth of 50MHz were my Tek's still go up to 350MHz!
Anthony
April 24, 2018 at 8:27 am
You are right Mr Albert, new Oscilloscopes and digital multimeters have more tricks up their sleeves
and can beat the old style equipment from yesteryear hands down....but there's something about
seeing the needle swing on an analogue meter and a signal in "real time" on a CRT scope that
warms the heart. Lol,
Cheers
Mark
April 23, 2018 at 6:24 am
Hey Albert,
Good repair and well explained. I have a BWD 880 Powerscope given to me as a faulty unit. It is on the ever-growing 'to do' pile. I am looking forward to getting to repair it in the future as it looks like an interesting project. Thanks for such a detailed explanation of your repair. It is one thing to do a repair for a customer, but your heart really sinks when an important piece of your equipment that you use regularly decides to give up the 'magic smoke'!
Albert
April 23, 2018 at 9:23 pm
Thanks Mark. I guess the 'so many to do things' is part of life. I like to keep my electronic equipment in great working order but those e-caps keep deteriorating in time. Recently I added a new to do thing job to my hobby to make an end of all piles of old now rare books and magazines on electronics I have kept (Mostly RadioElektronica and RadioBulletin magazines). Throwing them away without saving them first seems a bad thing to do. So I bought a fast Bookscanner (the EZ16 pro) recently to save some time digitizing them to PDF.
Waleed Rishmawi
April 23, 2018 at 1:31 pm
very informative article, thanks for sharing your experience. God bless and have a good day
Albert van Bemmelen
April 23, 2018 at 9:36 pm
Have a great day too Waleed! I do hope that god sees to it that nothing bad happens to my now fixed equipment.
Yogesh Panchal
April 23, 2018 at 2:24 pm
Albert,
No words!
Thanks for sharing
Albert van Bemmelen
April 23, 2018 at 9:48 pm
Two words!: Thanks Yogesh! (LOL)
Justice
April 24, 2018 at 5:20 pm
Thanks for the lecturetive article. These are very interesting articles to all electronic fraternity, thank Albert.
Roy Trevor
August 1, 2023 at 8:35 pm
Hi Albert,
Thank you for posting your well written write up. The clear pictures and explanations are very informative and are sure to assist many Tektronix owner’s around the world.
I am even more grateful for not having to translate anything!
I have just recently acquired my Tektronix 2465 cro after confirming the existence of such a helpful bunch of people like yourself, who are willing to share information and assist on-line with their experience and knowledge.
My scope also has the notorious Rifa caps, one of which clearly indicates failure and leakage as well as signs of a resistor’s catastrophic failure.
After opening the item, I was daunted by the prospect and potential for damaging other components. Discovering your write up has provided some encouragement for me to undertake the project challenge.
Are there any other parts that you would suggest replacing while the machine is dismantled?
Albert Hoekman NL
April 24, 2018 at 7:09 pm
Hey Albert, a good and intensive job you did there on your scope. A few years ago I had the same problem with my 12 years old Tectronics scope, it took me nearly one week to find and repair the problem.
Congratulations with solving the problem and I hope you might use your scope still for many, many years!
Thanks for sharing.
Albert
April 26, 2018 at 10:04 pm
Thanks Justice and Albert. Sorry about the late reply but my shared internet connection at home often simply refuses to upload any of my comments. None of my 5 browsers do. So Jestine places them after I emailed them to him. And thank you Albert, I also do hope your Tek will servive for many more years to come!
Jon PAUL
August 15, 2019 at 6:25 pm
Hello
Many thanks for this fine post. Renewing a late model 2465B with bad power supply.
1/ Any tips on removal of the PSU for a novice? I have seen the teardown posts but it seems rather difficult.
2/ Some posts mention a 100 uF cap that must be exactly 100 uF, yet lytics are normally wide tolerance, your comment? Any list the exact caps you used?
3/ Besides recapping, are there any transistors or rectifiers prone to failure? Best part numbers to use?
Kind Regards,
Jon
Albert van Bemmelen
April 5, 2021 at 7:33 pm
Sorry for my very late reply Jon Paul. I normally never see any new reply on my old articles. It is just now that I saw your post because I'm thinking of replacing my Tektronix 2465A D4464-200 SRAM memory chip (that stores the scope's very important calibration values!) by FM16w08 Ferromagnetic memory Ram. To prevent data loss in case the Lithium Backup battery no longer works. But before I can do that I first have to try to copy the 8K stored data to a useful .bin file for safety copying. It also stores all data with even and odd parity checks which is important not to lose the exact calibration resulting in a unwanted diagnostic bootup error! And reading out in-circuit that SRAM chip data is likely a problem when my programmer (TL866II used as 27c64 eprom reader) sees a conflicting data- and addressbus because of the other connections to microcontroller and the databuffers. And maybe it is possible to remove the microcontroller to be able to do just that without any conflict which is easier when that DIP40 controller already is placed in a socket. About your questions I only can tell you to be very careful by preventing electric static charges and first copy and print any information that is useful with any photos to guide you in the right direction while preventing any mistakes that others warned us for. About the replacing of the caps there is no special list because at best all caps should be replaced after the +30 years they are old now if you can. And never to leave your scope working for too long out in the open when the metal outside case is removed. Which effects the internal cooling airflow that is missing when the scope is opened! And take your time, print out any of the free Tektronix servicemanuals that may be of any help, and create enough workspace on a large table if you can. Like the old saying "Better safe than sorry!". Good luck!
Albert van Bemmelen
April 10, 2021 at 5:10 pm
Today 10 April '21 I was successfully able to copy the 4464 8192Bytes (8K) SRAM in my Tektronix 2465A oscilloscope that also contains all Calibration data.
I modified my 28 pin testclamp with 28 pins socket and used my TL866II as 27c64 eprom reader to extract the content of my RAM as bin copy. Simply by adding a 1N4148 diode to Vcc of the 28 pins socket this way accidentally avoiding losing the backup lithium voltage on pin 28 of the 4464 static RAM while starting to read it. And added two 100 ohm resistors to pin 27 (/PGM) and pin 26 (CE) to prevent accidentally writing instead reading the SRAM. (those wires from testclamp to the 28 pins socket can be left unconnected). But therefore you also disable the pin contact test in the TL866II program and do not need the chip ID check either. And after reading the Ram also verify it to make sure it was read correctly without errors! I already ordered 2 FM16w08 special Ferromagnetic RAMs that never lose their data even without any Lithium backup voltage present. One will be used to replace the 4464 in my 2465A scope the other will be used in my 2440 as soon I've also successfully backupped that SRAM. And because the square pins on the 16w08 to DIP adapter board are too thick for the standard IC sockets to be inserted into the scope SRAM position I also ordered 2 ZeroForce 28 pins 3M textool sockets that easily fit into the mainboard.
Update: The Tektronix 2440 SRAMS are HM62256 32KB type rams that require the special FM1808-70-PG ferro magnetic memory chips instead the FM16w08 (or the FM1608 DIP) that have 4 times more memory capacity compared to the original DS1230 32K chips often used in the 2440 memory oscilloscope. I was able to buy 2 FM1808s DIP on eBay for only US$5.89 (about 4,95 Euro). And they have a worry free retention time of 10 years without the need of any dangerous lithium backup battery. That also can leak in time! The above mentioned testclip with 28 pins socket cable can still be used after pin 26 is reattached to the testclip and its 100 ohm pull up is removed because it here is address line A13 instead of the CE pin it was on the 4464 SRAM.
Albert van Bemmelen
April 10, 2021 at 5:13 pm
PS: Both 100 ohm resistors to pin 27 (/PGM of a 27c64 eprom) and pin 26 (nc at 27c64 eproms but CE at the 4464!) are pullups to the Vcc voltage.
Albert van Bemmelen
April 10, 2021 at 11:15 pm
PS2: there is no need to remove any of the databuffer chips or the CPU to be able to read the data in the 4464 SRAM because if the scope is powered off there is no address or databus line conflict since at this moment the Sram will be the only functioning component in the 2465A (or the 2440 or other equally designed Tektronix) scope!
Albert van Bemmelen
April 18, 2021 at 1:04 am
Update: Programming the RAMTRON FerroMagnetic FM16w08 chips with the brandnew TL866II is simply impossible! Although they are supported in the device list the universal programmer sadly kept giving at least 24 verify errors. And also a second brandnew FM16w08 failed in the same way!
Luckily my RT809H was completely capable to program, read and verify both memory chips! But only after I upgraded the windows program to version 20210222. Because previous RT809H version only supported the FM1808 type.
John
June 6, 2021 at 1:00 pm
Hi Albert
My 2465 just blew its A2C1016 capacitor and the A2R1016 resistor.
Loud bang followed by awful smell !
Thanks to your article, I will be repairing my scope instead of recycling it.
John
Tektro-user
July 13, 2023 at 6:12 am
My 2465 blew up today while doing its work as usual...
Similarly : eBay find imported from USA to Europe.
I now have enough information to repair it !