Buying a broken Tektronix 2465b - Page 1
Forum section: electronics / repair

author: LuisRene5
author_rank: Newbie
timestamp: April 22, 2017, 04:14:56 am
content: Hi guys, I want to buy a Tektronix 2465b, however the refurbished ones are out of my budget. So, there is a 2465b which is required to be Fixed. I dont mind to go for this adventure but I would like to know if someone has some experiencie or sugestions about the issue that the Scope presents. I attached a picture of the Scope. The seller says that it powers on but no trace and all LEDS remain ON. Thanks in advance for your help.

author: flynwill
author_rank: Regular Contributor
timestamp: April 22, 2017, 04:18:51 am
content: It's microprocessor is not booting up. Probably a major adventure to figure out why. I would give it a pass.

author: george.b
author_rank: Frequent Contributor
timestamp: April 22, 2017, 05:49:43 am
content: I, too, would pass, unless it was for almost free or something. The 2465B is full of ASICs which are known to go bad occasionally - who knows what else isn't working in there. Might end up as either an expensive and difficult repair, or as a fancy doorstop.

author: Wimberleytech
author_rank: Super Contributor
timestamp: April 22, 2017, 11:11:44 pm
content: A friend gave me a 2440 that he refurbished recently. He had refurbished several of them. Evidently, the firmware is loaded on a battery-backed-up RAM (a Dallas Semi part). When the battery dies, the firmware goes with it. He installed a zero-power SRAM (ST product I think), found the firmware somewhere and programmed it. It worked. Who knows re 2465...

author: tautech
author_rank: Super Contributor
timestamp: April 22, 2017, 11:18:19 pm
content: Check out this monster thread forallyou need to know on these scopes:https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/

author: LuisRene5
author_rank: Newbie
timestamp: April 23, 2017, 03:54:14 am
content: Thanks everyone, I Will check the links. I have been reading articles about common issues of the tektronix 2465b such as DallasRAM failure, the U800 chip, PSU. However, I've never seen something related to this problem of the Scope. The cost is around $200 dollars + shipping. Solo, do you think the problem is the microprocessor?Enviado desde mi Moto G (4) mediante Tapatalk

author: tggzzz
author_rank: Super Contributor
timestamp: April 23, 2017, 08:14:49 am
content: Quote from: LuisRene5 on April 23, 2017, 03:54:14 amInsufficient information; you have no clue what's wrong. That's far too expensive.And your using Wackawrite is irrelevant.

author: BravoV
author_rank: Super Contributor
timestamp: April 23, 2017, 01:06:23 pm
content: Quote from: tggzzz on April 23, 2017, 08:14:49 am+1, way too risky, they could have pulled out some hybrid chips, or worst board, as 2465B's parts are treated as commodity nowdays.A good example here, the whole logic A5 board was gone ->2465B Repair

author: LuisRene5
author_rank: Newbie
timestamp: April 23, 2017, 01:13:52 pm
content: Quote from: BravoV on April 23, 2017, 01:06:23 pmThanks BravoV, I have decided to wait for another 2465b. I agree that the 2465b parts are like pieces of art ir gold, too expensives. Thanks ti everyone. Only, one more cuestión, does someone can recommend a good seller on Ebay of 2465b?

author: LazyJack
author_rank: Frequent Contributor
timestamp: April 23, 2017, 01:25:27 pm
content: Quote from: Wimberleytech on April 22, 2017, 11:11:44 pmThat is complete nonsense. I have repaired 2440 and 2430 scopes, including replacing the Dallas RAMs. The firmware is in EPROMs and it stays there. The battery backed up RAM only stores the calibration data, user settings and saved waveforms. Of these only the calibration data has some importance, but since the 24xx digital scopes are mostly self-calibrating it is not a big deal even if calibration data is completely lost. In this case calibration is mostly about running self-cal and giving a couple of DC levels and 100kHz square wave to the scope and it will calibrate itself fine. For the 2430 is is even simpler, it just needs some DC levels.This is not quite the case for the 2465 and such analog scopes, where calibration is quite a chore so you don't want to loose cal data there.

author: LuisRene5
author_rank: Newbie
timestamp: April 23, 2017, 01:36:37 pm
content: Quote from: LazyJack on April 23, 2017, 01:25:27 pmLazyJack, the data stored in the Dallas memory is the same in two different but already %100 calibrated 2465b scopes? I mean, if I copy the data from another Scope, will it work?Enviado desde mi Moto G (4) mediante Tapatalk

author: BravoV
author_rank: Super Contributor
timestamp: April 23, 2017, 01:43:14 pm
content: Quote from: LuisRene5 on April 23, 2017, 01:36:37 pmThe Dallas DS1225 static ram, holds the calibration that is unique to that scope only.Copying calibration values from other scope, will it work ? YesWill it be accurate ? Well, I would say you better start to pray ...

author: LuisRene5
author_rank: Newbie
timestamp: April 23, 2017, 01:45:00 pm
content: Quote from: BravoV on April 23, 2017, 01:43:14 pmHahahaha okay, thanks!Enviado desde mi Moto G (4) mediante Tapatalk

author: LazyJack
author_rank: Frequent Contributor
timestamp: April 24, 2017, 12:50:14 pm
content: I'm not sure about the 2465, but the 2440 may fail and throw all kinds of errors if the calibration data is not matching the scope. Cal data is unique to the scope, as it needs to account for variances in the circuits or even for temperature. It does not blindly takes the calibration data, but during the self test it actually makes some self tests (of course...) based on these and if it gets results that are way off it may say that it is out of cal or actually fail the tests. Worse, as for self-calibration it takes this data as initial starting point, it may fail self-calibration. This is why a cold-start (clearing of cal data) is required if replacing the nvram or if it is suspect that the nvram data is corrupt. I believe the same stands for the 2465, so you may or may not be lucky with data from an other scope.

author: guido
author_rank: Regular Contributor
timestamp: April 24, 2017, 05:38:35 pm
content: The 2465 does not have nvram. It uses an "eeprom" (earom). In theory it is possbile to program such a thing (e.g adaptor with icprog program), but i don't think that has been done a lot. So if it fails you can only replace with a blank, unless you can indeed program it.

author: Tektron
author_rank: Contributor
timestamp: May 07, 2017, 12:05:43 pm
content: I repaired several such devices. It may be just PSU or, say, A5 troubles butsuccess isn't garanteed.Main question: is the CRT live or dead? With black screen nobody can say exactly. In this case all prices above simbolical $30 is overshot. Just my opinion.

author: oldway
author_rank: Super Contributor
timestamp: May 08, 2017, 07:09:50 am
content: Why choose a 2465?According to my opinion, it was one of the best portable analog oscilloscopes in its time, but it is no longer a good choice at present days because it is difficult to keep in good working order.It is much too complicated, uses many hybrid circuits hard to find, it has the problem of using digital technologies outdated and prone to breakdowns.The analog oscilloscope still has its place in the activities where it is necessary to check the shape of the signal, without having to make accurate measurements and without having to store it.This is the case for exemple of learning analog electronics and repairing analog, audio and power electronics.If it is necessary to make measurements or to store the signal, then the option that is required is the digital oscilloscope.Its measurement and calculation capabilities have no match in analog technology, and the price of these digital oscilloscopes has become very affordable.In place to buy a broken 2465b, I would prefer to buy a good working simpler model.This is why I would be moving towards analog oscilloscope technologies that are simpler and easier to repair such as:Tektronix:465B2235HP1740AHamegHM605HM1005