hybridfree/eevblog-posts huggingface dataset:
Tektronix 11401 dsy kernel failure  - Page 1
Forum section: electronics / repair

author: Johnny10
author_rank: Frequent Contributor
timestamp: June 20, 2018, 06:09:20 pm
content: I just purchased a Tektronix 11401 Oscilloscope with 2- 11A52 Plug-ins.On start-up Self Test Error "dsy kernel failure" Second Line "Exec Communication" is displayed on screen.Since Kernel Diagnostics failed the Self-Tests will not run.I have a copy of the 11401/11402 Service ReferenceBut I haven't found the meaning of this error other than the problem is on the A7 Display Controller Board since red LED is lit.Anyone familiar with this issue?Voltage on board is within limits.Lithium batteries are 3.1 volts

author: Xtremexp
author_rank: Regular Contributor
timestamp: August 15, 2024, 06:24:38 pm
content: Hi,Did you manage to fix this issue? I am also having same error in my unit.
Tektronix 177 not working in nA ranges - Page 1
Forum section: electronics / repair

author: rodd
author_rank: Regular Contributor
timestamp: March 10, 2022, 08:40:41 pm
content: dear all,I am trying to fix a TEK 577/177 Curve tracer I was able to put my hands on.The step generator was finally fixed, so I made my first attempt to calibrate the instrument.In order to adjust the Vertical Gain, the 177 has to operate in the 50nA range.When trying to follow the procedure, the dot on the display goes all the way down instead of staying around the 8th division.There are two suspects capable of producing this behavior:1- The Vertical amplifier or2- The Vertical Preamp Section that is located on the 177.I am able to produce a "normal " display in all other ranges of the Vertical Current/Div switch (in the 177), except in the nA range.So I disassembled the 177 and checked for open or weird value resistors connected to S630, but I could not find any.However when I measure the resistance between TP617 (point "A") and the lower end of R640 (point "B", I get the expected values up to the nA range.In the nA range, the resistance is about 600k-800k (instead of 1M and 10M) and increases slowly with time (as charging a capacitor).The same happens when measuring the resistance between points "A" and "C" .Please refer to the attached schematics.I tried to remove Q604, butthe behavior is the same.Any ideas?Thanks

author: lazza96
author_rank: Newbie
timestamp: October 12, 2024, 09:30:26 pm
content: Hi, I have the same issue and in addition the yellow overrange light turns on, have you managed to solve the problem? I hope so…Thanks
Tektronix 2024C Schematic - Page 1
Forum section: electronics / repair

author: Flyingdancingfool
author_rank: Newbie
timestamp: August 10, 2022, 03:14:16 am
content: Greetings!I purchased a Tek 2024C on Facebook market place, and of course it doesnt work. Removing the back cover it is obvious it got a little wet, or was consistently damp, over some period of time.None the less, I would like to see if I can repair the scope by replacing the power board, or some other easily replaceable element.Can anyone point me to a schematic for the power supply module? I will start there and move forward. The downloadable service manual on Tek website does not have relevant information.Else, there could be some good parts (I dont know)Kenn
Tektronix 2205 recap? - Page 1
Forum section: electronics / repair

author: Mr Lurpak
author_rank: Contributor
timestamp: September 30, 2024, 08:51:17 pm
content: Hi there. I got a few Tektronix 2205 Oscilloscopes in very good condition - the questions are:1. should I recap if the scope works?2. would you do ALL caps or just the RIFA and high voltage ones? what about the electrolytes not on mainboard and Power supply?3. Is the 2205 prone to caps failure in general?

author: Bryn
author_rank: Regular Contributor
timestamp: October 01, 2024, 08:31:10 am
content: If you think a recap is necessary, go for it.But as for your other question, yes, the oscilloscope in question is prone to this kind of failure, given that it's an ancient piece of technology (over 30 years old actually).

author: Jeff eelcr
author_rank: Frequent Contributor
timestamp: October 01, 2024, 11:08:05 am
content: Experianced judgment is best, I do not own a 2205, however I have a 2225 and a 2815.The 2225 had a supply cap go bad the first year, then a few years ago I replaced all the other caps.The 2815 still has the same ones it started with.Jeff

author: MarkL
author_rank: Unknown
timestamp: October 01, 2024, 01:25:40 pm
content: You'll find a lot of opinions on this, but mine is if the scope is working, don't mess with it. This and other forums are littered with posts from people who attempted prophylactic recaps on working equipment and instead created a repair project.I would say the only exception is if the RIFA cap is showing signs of aging, such as severe yellowing or fine cracking, then replace it. Or if there is a known history of RIFA failure on this specific model, replace it.Optionally, you could verify your power supply voltages and ripple limits as described in the 2205 service manual. If any power rail is out of spec, then replace the filter cap(s) on that power rail and re-check.

author: Mr Lurpak
author_rank: Contributor
timestamp: October 01, 2024, 04:13:11 pm
content: Thanks, yeah RIFA caps is the no-brainer. Thanks for valueable inputs.
Tektronix 2211 Oscilloscope repair help - Page 1
Forum section: electronics / repair

author: visty
author_rank: Newbie
timestamp: August 25, 2020, 03:36:23 am
content: I recently bought a broken Tektronix 2211 scope from a gentleman on here to fix up for myself and was hoping anyone had any insight that could help me. the scope has a block of trace that can be moved with the vertical and horizontal controls. the block of trace can been seen below. any help is greatly appreciated and any common or helpful tips for when working with older scopes would also be helpful.ps. I also have the service manual coming in the post but it wont get here for a while.

author: Tom45
author_rank: Frequent Contributor
timestamp: August 25, 2020, 05:04:06 am
content: In your photo the screen intensity is way too high. Until you get it working properly it is best to set the intensity way down to where whatever is displayed is weakly visible. You don't want to risk burning the screen.Are you familiar enough with analog scopes to properly set the various controls? Ideally the only real problem is not knowing how to set it up. The early mixed analog/digital scopes can be especially tricky to figure out without guidance.In any case you can download a scan of the operator's manual from TekWiki:https://w140.com/tekwiki/wiki/2211That can help you learn about the scope and how to use it until your paper copy arrives. The display that you show isn't right, but it isn't anything that I recognize.

author: visty
author_rank: Newbie
timestamp: August 25, 2020, 06:30:23 pm
content: I am still very new this whole project is to help me learn about analog scopes and scopes in general by a learn by doing kind of thing, thanks for the tip about the intensity and I will start reading through the operation manual like you recommend before my paper copy gets here.
Tektronix 2213 Intensity control - Page 1
Forum section: electronics / repair

author: beanhauler
author_rank: Contributor
timestamp: January 24, 2021, 09:37:42 pm
content: Would be very grateful if anyone has a visual of a waveform on test point 19 of the circuit of the intensity control of a Tektronix 2213 scope.Originally the intensity control did not work and it was maxxed out and looked around the z driver stage to see if anything was wrong there.Noticed that there was no incoming intensity control square wave that was supposed to modulate the z drive.I have definitely the 20khz from the power transformer that is around 100V pk to pk but no incoming square wave from the x driver or timebase as was missing.Checking further i found CR868 was short so replaced it with a fast diode that will handle an amp and suitable reverse voltage.Now when i powered it up it had a beam that just gets fainter and fainter and disappears.My guess is that the grid is now charging via the changed diode and pinches off the beam current. It would seem that the missing waveform could be the key.The duty waveform arrives on pin 11 of U825B and is also the control switch which switches between pin 12 @gnd and the intensity control setting.This exits on pin 14 and after being integrated by the RC combination should according to the waveform be seen on pin 3 going back into the switch which i do not see. Neither do i see it on pin 4 which is hard switched by the logic around the 14503.Is it likely the 14503 is dead? Anyone had any experience of the intensity controls on the 2213?Funny thing is that text in the manual makes mention of the "average" voltage but no direct referrals to the waveforms itself. does the switch waveformwith its fall to ground get replicated in the following Op Amp.Any info or suggestions on this appreciated.
Tektronix 2213 no horizontal trace - Page 1
Forum section: electronics / repair

author: philo
author_rank: Newbie
timestamp: April 06, 2023, 07:25:38 pm
content: Hi! How are you? I've got this tektronix 2213 which doesn't show anything on screen unless I press the "BEAM FIND" button (and the SEC/DIV rotary switch on XY, on the rest of SEC/DIV option you can bearly see the trace) and a short horizontal trace shows at the right of the screen. I do have apparently some trouble at the horizontal amp. With the BEAM FIND button unpressed I get at the H+: 85v and at H-: 15v, when BEAM FIND button is pressed I get at H+: 40v and H-: stays at 15v aprox.I recently got this scope being sourced as non functional, the only two faulty components I could found where: Q386 (vertical output transistor) was leaky because it measured a reversed diode from emitter to collector, and R379 vertical output resistor 340ohms was open. I've individually measured out of circuit almost every transistor related to horizontal and vertical circuit: Q763 Q753 Q747 Q780 Q785 Q789 Q736 Q730 Q731 Q720 Q770 Q779 Q775.I'm really lost, all resistors and caps measured related seemed fine. Removed SEC/DIV rotary switch from A12 sweep board and completely cleaned it with no changes.All PSU output voltages are OK. If you need any measures taken please let me know. Thanks!PS: attaching photos of both channels getting body noise with tweezers on XY setting in SEC/ DIV

author: MathWizard
author_rank: Super Contributor
timestamp: April 10, 2023, 01:46:36 am
content: Looking at page 173 of the manualhttps://w140.com/tekwiki/images/1/1c/070-3827-00.pdfSo are you saying -15V is at point 24, I only see the negative 8.6 rail close by, and they say it should be +47V between the (-) Hor drive BJTs. And there's a resistor divider path to -8.6 right there too. Is that -8.6 rail really working ? nevermind, +15V. I'm trying to make some of the circuit ion the sim, but IDK what BJT's or FETs to use, to try and see the DC biasing.When it was all in 1 piece, did you measure any of the voltages around there, there's a bunch listed in the schematic ?What was the history of it, did it work before, did u just buy it ?

author: jonpaul
author_rank: Super Contributor
timestamp: April 10, 2023, 01:58:57 am
content: go to tekwiki, w140, DL complet service manual for the serial numberDO NOT fiddle with transistors yet! Very unlikely!Usually just control and contact clean g, then PSU, perhaps recapping...Use troubleshooting flow chart,first check every power supply DCV and rippleNext following proceedure for check HV supply.Notice that many scopes shipping is poorly packaged, one drop by the freight carrier and the CRT can be damaged.jon

author: philo
author_rank: Newbie
timestamp: April 10, 2023, 02:12:32 am
content: I've downloded the 200 and something service manual, in which I couldn't find the vertical circuit. It's just briefly explained, i cleaned twice with contact cleaner the rotary switches. PSU caps where almost all replaced, all voltages are on spot. HV I'm not able to measure it, it is produced cause I can discharge the anode but don't know if 8kv are getting there. Thanks!
Tektronix 2213A 'ADD' - Page 1
Forum section: electronics / repair

author: Coll
author_rank: Contributor
timestamp: December 16, 2020, 04:44:29 pm
content: I have noticed an odd quirk that when I am using the add function on the vertical selection when both channels should be at zero I am getting a positive deflection. I would expect it to be 0 and this deflection also affects measurements. Is there a way to adjust this so it adds properly. I am not finding anything specific in the manual for making this adjustment or how I may be able to remedy this issue.

author: torquil
author_rank: Regular Contributor
timestamp: December 16, 2020, 05:36:30 pm
content: Check the answer by David Hess in this thread :https://www.eevblog.com/forum/repair/tektronix-2213a-and-bothadd-vertical-mode/msg2902610/#msg2902610

author: David Hess
author_rank: Super Contributor
timestamp: December 16, 2020, 08:36:52 pm
content: I remember that discussion.Unlike many other Tektronix oscilloscopes, the CRT amplifier on the 2235 series, which includes your 2213A, has no vertical zero adjustment so when each channel is individually adjusted to to show zero on the CRT, there is a small offset and in ADD mode, those get added together causing a vertical shift. So what looks like zero on the CRT is actually off by a small amount.In that discussion thread, I describe how the CRT amplifier can be modified to zero the CRT removing the shift in ADD mode.

author: Coll
author_rank: Contributor
timestamp: December 16, 2020, 09:12:49 pm
content: Thank you to you both for this information I will take a look at it and try to go from there.Quote from: David Hess on December 16, 2020, 08:36:52 pmFor this modification does this affect anything else or just the ADD mode? I haven't taken a look at the schematic yet for this change I will soon but if I consider doing this what else might it affect?

author: David Hess
author_rank: Super Contributor
timestamp: December 17, 2020, 01:22:41 am
content: Quote from: Coll on December 16, 2020, 09:12:49 pmThe change would shift the zero position of the vertical position controls by the same amount but probably closer to true zero. That would be the only other effect.Like I said, other Tektronix oscilloscopes did have an adjustment for the CRT amplifier zero which depends on the tolerance of the CRT. Usually having the vertical position shift slightly in ADD mode is not a problem unless the oscilloscope has a readout, and in that case like with the 2232, the readout board has a vertical zero adjustment, but still not the CRT amplifier.
Tektronix 2215(Non-A) w/ Opt48 - Need list of all maintenance replacement parts - Page 1
Forum section: electronics / repair

author: t1d
author_rank: Super Contributor
timestamp: February 08, 2021, 07:06:33 am
content: I am preparing to open my scope and change out all of the known problem components... Electrolytic caps, carbon comp resistors, Rifa caps, paper caps, etc. I am concerned that I might miss something, either on the board, or in making my parts order. So, I am hopeful that you can point me to a known, good, comprehensive list of the parts that should be changed out, as a matter of course in maintenance.I have searched the web, but I only find incomplete lists, or lists that include "ghost"parts... a term I am using for parts incorrectly labled in the manufacturer parts list, such as tantalum caps listed as electrolytics...I really love my 2215. Even though I have a digital scope, an analog scope is the right tool for particular jobs... such as looking at curve traces. I would hate to lose it over a simple component failing and cooking it, or leaking and eating up the board, etc.After swapping out the parts, I will need a good thread on calibrating it... But, only one bite of the elephant at a time.Thank you for your help.

author: wizard69
author_rank: Super Contributor
timestamp: February 09, 2021, 03:22:46 am
content: I don't know of any such lists. Your best bet is to tear the unit apart and inventory the board looking for obvious issues to address quick. You might try searching Google for a BOM (bill Of Materials), it is surprising what can show up with a Google search if you get your Google fu working right.I can't say I'm a big fan of replace everything for maintenance, however capacitors are a real issue so starting there makes sense. Also looking for repair logs or threads should give you insight into other failure points beyond capacitors.
Tektronix 2215 High Pitched Whine - Page 1
Forum section: electronics / repair

author: warpigs330
author_rank: Contributor
timestamp: July 28, 2024, 01:52:40 pm
content: I just recently received a Tektronix 2215. It was rescued from going into a dumpster when a manufacturing operation was cleaning out their stuff. So now I have it, and from my initial testing everything seems to work fine on it. But it does emit a very high pitched whine, that increases and decreases in volume as the scope is powered. There are times when the scope is completely silent. Then other times when the whining will be enough to make me not really want to use the scope. I was looking through other topics similar to this one, and found this:https://www.eevblog.com/forum/repair/tektronix-2215-pulsingchirping-noise-no-trace/The poster on that topic said "The sound is heard when the high pitch HV should be heard" which leads me to think that maybe this high pitched noise is just normal? I would love to fix it if I can, because I do audio work, and having a scope with no fans and completely silent would be a big help. I also wouldn't mind just generally doing maintenance on this scope, if there is anything y'all recommend, I'm not super experienced with repairing vintage gear.

author: andrewtaylor
author_rank: Contributor
timestamp: July 28, 2024, 02:09:10 pm
content: Check for dried Out capacitors , all electrolytics one primary and secondary
Tektronix 2215 sec/div switch - Page 1
Forum section: electronics / repair

author: Floopy
author_rank: Regular Contributor
timestamp: June 18, 2019, 05:15:59 pm
content: Hello, I've recently acquired a Tektronix 2215. Everything worked except the B timebase. The switch was spinning freely. I thought that it was just a screw or something, but apparently it isn't. I took it apart and taking a quick look around I can see that there is one RIFA cap on the current limiting board.So my first question is what type of replacement capacitors should I get? I know that something like an electrolytic won't work.Going on, the attenuator board on which the switch is located can be easily removed. I can't say the same for the switch. It's soldered on the board. So about an hour later and what felt like desoldering a thousand pins I pulled it out. Then I took another half hour figuring out how to take the switch apart. Although once I had it apart, it was easy to access what I wanted. Looking at the shaft it seems like the shaft and the plastic piece have just separated. Fortunately the plastic has not broken into pieces. I think I should just be able to glue it back together?If so, what type of glue would work best? I don't want to have to take this thing apart again in the future.Thank you!

author: Floopy
author_rank: Regular Contributor
timestamp: June 18, 2019, 05:18:46 pm
content: Some pictures for those of you who only care about that.

author: tautech
author_rank: Super Contributor
timestamp: June 19, 2019, 09:05:59 am
content: Have a look here:https://www.sphere.bc.ca/test/tek-parts/tek-knobs.htmlIf you had to glue it then Epoxy plus maybe a tiny worm drive hose clip for additional strength.Or maybe a short length of small metal tube fashioned like those permanent hose clips you sometimes see on oxy acetylene leads {} where the tits are squeezed with pliers.

author: Floopy
author_rank: Regular Contributor
timestamp: June 19, 2019, 04:21:09 pm
content: Where has this webpage been all my life! They have knobs! Lots of them.I ended up doing getting some JB weld epoxy. I wanted to ask here first to see if anyone else had anything to say. Hopefully it'll hold. I don't want to take this thing apart ever again.
Tektronix 222 AUTO LVL PUSH control and display glitching ... - Page 1
Forum section: electronics / repair

author: mossygreen
author_rank: Contributor
timestamp: May 07, 2022, 08:17:54 pm
content: I just got a Tek 222 from an online auction and ran it through its paces. Everything I've worked looks good but the inner knob of the trigger control (AUTO LVL PUSH) doesn't hold the shaft it's on (something is off w/r to its set screw, but I can fix that) and the shaft itself just freely rotates. Reading the manual I can't see that rotating it would have any utility. However, it's really odd to have a round control where turning it has no effect. Pushing on the control or shaft has the documented behavior and you can feel a distinct "button pushed" sensation. Given that the label on the control has an orientation I would expect it to not turn at all.I can imagine that something is loose inside but before I got looking I thought I'd ask to see if other people's 222's have the same property.W/r to the display glitching ... it looks a little like infrequent noise showing up in the signal at the rate of 0.2-2Hz. My analog 2465 doesn't do that, nor does my modern R&S scope. Is this to be expected, or a sign of something wrong?

author: m k
author_rank: Super Contributor
timestamp: May 18, 2022, 03:16:20 pm
content: It seems that all Tek folks have been elsewhere.Manual says it's different from its buddies, button of some kind I guess.Have you advanced?
Tektronix 222 Repair - Page 1
Forum section: electronics / repair

author: Simonv92
author_rank: Newbie
timestamp: April 09, 2020, 04:57:49 pm
content: Hi All!I have a Tektronix 222 scope that doesn't work. It won't startup.Battery is dead so I'm powering it with the external jack with a bench supply set to 14V.When I apply power the Trigger led blink for a second and I can hear a "beep", after that nothing happens. Doing some test on the Power Supply Board (A4) I've found that the power FETs that drives the main transformer becomes very hot (the unit in this state draws about 12W of power so there's something wrong).After some tests I've isolated the 120V line after the transformer, now the scope draws less power and the FETs stays cool but I can't make it work.I'm using the 222A service manual which include boards schematics, they are not exactly the same but pretty similar:https://www.eserviceinfo.com/download.php?downloadstart=1&fileid=70093In the troubleshooting procedure guide I've read that the pin 13 and 14 on the TL594 on the Power supply board should stay near 0V in normal operation, on mine they always stays at about +5V.I think taht something isn't working properly on the power supply board but I can't find what.Do you have any idea? Any help will be appreciated!Thank all!Simone

author: jxjbsd
author_rank: Regular Contributor
timestamp: April 10, 2020, 08:14:05 am
content: Go tohttps://groups.io/g/TekScopessearch, maybe there's an answer
Tektronix 2220 -  something not working? - Page 1
Forum section: electronics / repair

author: AppleJuce
author_rank: Newbie
timestamp: October 05, 2019, 03:01:18 pm
content: Hey!I have a problem with the oscilloscope, when I turn it on the screen displays X, none of the buttons work, I did not find anything in the manual that could help me. Also it happens to be random.Thanks for help!

author: shakalnokturn
author_rank: Super Contributor
timestamp: October 06, 2019, 03:39:07 pm
content: I seem to remember a topic on this exact problem on either tektronix Yahoo or Groups.ioI'll have a quick search, but suggest you search yourself just in case...

author: shakalnokturn
author_rank: Super Contributor
timestamp: October 06, 2019, 06:09:47 pm
content: Fond the topic by Stewart Barker on Yahoo groups at the time, there was no positive outcome to the X on the display.It was supposed that it was either an alignment mode for the digital section on the CRT or a way of displaying a fault condition...Does your scope display this on every startup?

author: AppleJuce
author_rank: Newbie
timestamp: October 07, 2019, 06:43:13 pm
content: No, this happens randomly, around 7/10 turns on the oscilloscope

author: shakalnokturn
author_rank: Super Contributor
timestamp: October 07, 2019, 08:04:20 pm
content: The above mentioned case was the same, kind of random...If you can find a service manual, otherwise 2221 or 2230 should be close.Try checking loose jumpers, interconnect and socketed I.C. seating.Also check PSU voltages/ripple, including locally on the digital board. (Maybe near the more power hungry components, usually the hottest.)Other things I would look into are squashed logic levels on buses, flaky EPROMS (rewrite a pair on new IC's), finding some something to disconnect that will give you the X every time could also give some clues...I have a 2230 that I bought cheap and hardly ever use, bought cheap because it had a "display issue" since I have it it has always worked but I can't help think that maybe the 2230 is capable of displaying the X too.
tektronix 2220 - Page 1
Forum section: electronics / repair

author: Hellfish69
author_rank: Newbie
timestamp: December 14, 2021, 05:11:40 pm
content: Hello,if got a Tektronix with some different problems. I want to fix it but i can't find a service manual.Have somebody this manual?Mike

author: highpower
author_rank: Regular Contributor
timestamp: December 14, 2021, 05:34:45 pm
content: Available here:https://artekmanuals.com/manuals/tektronix-manuals/

author: Hellfish69
author_rank: Newbie
timestamp: December 14, 2021, 08:08:50 pm
content: There are no free available manuals?

author: george.b
author_rank: Frequent Contributor
timestamp: December 14, 2021, 08:54:01 pm
content: Quote from: Hellfish69 on December 14, 2021, 08:08:50 pmSeemingly not. Tektronix, TekWiki, BAMA and Elektrotanya don't have it. If you do end up buying a copy from Artek, I don't think there would be anything legally wrong with uploading it somewhere publicly available, as it's not their intellectual property (standard disclaimers about me not being a lawyer apply), and you'd possibly do someone somewhere a solid.

author: bdunham7
author_rank: Super Contributor
timestamp: December 14, 2021, 09:02:38 pm
content: The manual for the 2221 will be close enough to serve for most issues you are likely to run into. The basic scope is virtually the same, the 2221 has a few more digital features.What's going on with it?

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: December 14, 2021, 10:13:03 pm
content: The Artek manuals I have purchased are much better copies than anything I have found for free. Especially the schematics

author: Hellfish69
author_rank: Newbie
timestamp: December 15, 2021, 02:07:41 pm
content: I've got the manual from Artek .Quote from: bdunham7 on December 14, 2021, 09:02:38 pmFist problem was an exploding riva cap. That's not really the problem.The real problem ist that i have no traces on the screen after powering up. Only with the button "beam find" i have something like a small trace on the screen.I have no idea where i should start the troubleshooting.

author: bdunham7
author_rank: Super Contributor
timestamp: December 15, 2021, 02:12:10 pm
content: Post a clear photo of the entire front of the scope so that we can see how the controls are set. Then I can walk you through a few troubleshooting steps. If beam find shows a trace, then the situation is a bit more promising and you likely don't have a major problem.

author: Hellfish69
author_rank: Newbie
timestamp: December 17, 2021, 09:12:05 pm
content: Here are some pictures. The power supply voltages are all good.
Tektronix 2221 : Repair of Power-Supply-Issue   - Page 1
Forum section: electronics / repair

author: Pak03841
author_rank: Newbie
timestamp: June 05, 2021, 10:22:32 am
content: Hey Guys,Im new to the forum. Im an electrician but my elektronik skills r kinda low.I got a the Tektronix 2221 from a friend it wasnt working. After inspection, i plugged the powercord in. The Power-Unit makes a squeaking noise at a rate of 1 or 2 Hz. No function at all, even the status LED is dead. I would imagine that there is somekind of short that changes the cycle of the Switchmode? Maybe?I measured some Voltages. Confusing part is that the Voltage after the Full-Bridge-Rectifier in the plan is 145V. My DMM reads like 300V DC. The Volatage over C925 is not like stable 14,3 V it ranges from 12 to 20V DC.I attached the circuit diagramm of the powerunit and marked the Voltages.I would be very grateful if u guys could give me some help or advice.Thanks

author: jdragoset
author_rank: Frequent Contributor
timestamp: June 05, 2021, 09:15:31 pm
content: Looks like the preregulator in the 2235.Should produce 43 volts at 1 amp to the power supply inverter(Q 944, 946 & 947, T 944 & 948), which can be provided with an external DC power supply to TP 940.If current is too high (as continuously tested across the 0.2 ohm resistor) it will shut down and restart repeatedly, chirp, chirp, chirp.Over voltage will trip the SCR crowbar (Q 935), over current load with the same effect.Be careful with this circuit, as there are no valid earth potential points so a scope ground cannot be connected unless the AC supply is provided through an isolation transformer.Download the preregulator trouble shooting guide from the manualhttps://w140.com/tekwiki/wiki/2221

author: bdunham7
author_rank: Super Contributor
timestamp: June 05, 2021, 09:41:15 pm
content: The 145V is based on 120VAC line voltage. The back of your scope should read "90-250VAC", and the 145V point will be higher, of course.Do you have access to a DC PSU that could put out 40-45 volts at several amps? That might help in the troubleshooting process.

author: Pak03841
author_rank: Newbie
timestamp: June 06, 2021, 08:27:17 am
content: TY for the Help and the Information. The failure is in the secondary side. When i disconnect q9070 the power unit is working. I went for the troubleshootguide. Q9070 is dead. Sadly i released the magic smoke out of q908. So I need to order some parts.
Tektronix 222/224 Portable scope CRT pinout? Picture request. - Page 1
Forum section: electronics / repair

author: TERRA Operative
author_rank: Super Contributor
timestamp: March 19, 2019, 04:40:43 am
content: So I had a bit of a problem crop up while restoring a Tektronix 224 scope...While removing the CRT, the plug housing came apart and all the pins fell out and I don't know what order they go back in.Is there anyone who has a Tek 222 or 224 portable scope who can pop the cover off and take a few photos?I know what pin numbers each wire is supposed to be for, but I don't know what the actual pin numbering is on the tube itself to match to the wires.Any help would be awesome

author: jdragoset
author_rank: Frequent Contributor
timestamp: March 21, 2019, 01:21:14 pm
content: Here are some Pix taken this AM.There is a single white wire in the dielectric shield at about 1:30, unused pin/space on either side, probably anode or focus if anode has its own HV connector near the screen.Numbering starts just past 3:00 with a brown stripe in gray jacket and proceeds clockwise, red, orange ... to gray stripe before the unused pin/space back to white.I did not remove the socket from the CRT.I can send more if needed.Jim

author: TERRA Operative
author_rank: Super Contributor
timestamp: March 21, 2019, 02:35:24 pm
content: Awesome, thanks for the helpI found some pics, but this helps confirm I got it correct.Scope CRT is now back up and working again.Here's the pinout attached below if anyone else happens to be looking for it in the future.

author: xxx2fan
author_rank: Contributor
timestamp: June 07, 2019, 10:43:30 pm
content: Try this link it should help you.http://w140.com/tekwiki/wiki/Main_Pagexxx2fan
Tektronix 2225 oscilloscope showing only two Dots instead of two lines - Page 1
Forum section: electronics / repair

author: megadeth
author_rank: Newbie
timestamp: March 14, 2024, 11:16:53 am
content: Hi everyone,Just got a secondhand Tektronix 2225 oscilloscope as my first oscilloscope, when I switch it on only showing two dots on the screen which representing the two channels, they are responsive to vertical and horizontal position knobs, unfortunately, I got the oscilloscope without the probesso I will not be able to test if these dots are responding to the measured waves unless I buy the probes, could anyone advise how to start troubleshooting this problem.Thanks in advance.

author: Circlotron
author_rank: Super Contributor
timestamp: March 14, 2024, 11:44:44 am
content: Is the SEC/DIV knob set to XY? That will produce a stationary dot.

author: megadeth
author_rank: Newbie
timestamp: March 14, 2024, 11:52:08 am
content: Quote from: Circlotron on March 14, 2024, 11:44:44 amNo, it is not on XY, I will take a photo to it once I reach home and posted here.Thanks,

author: David Hess
author_rank: Super Contributor
timestamp: March 14, 2024, 01:24:09 pm
content: Having the beam unblanked but the sweep stuck often means that the sweep generator has failed. Sometimes it is as easy as the JFET buffer being bad.

author: CaptDon
author_rank: Super Contributor
timestamp: March 14, 2024, 01:54:56 pm
content: Try the AUTO TRIG mode. If no input then the thing probably isn't even triggered!!

author: megadeth
author_rank: Newbie
timestamp: March 14, 2024, 02:43:59 pm
content: Quote from: CaptDon on March 14, 2024, 01:54:56 pmOMG, Thanks a lot i got it work perfectly now.Appreciate your help, and thanks to everyone who tried to help.

author: TimFox
author_rank: Super Contributor
timestamp: March 14, 2024, 04:19:25 pm
content: "Auto trigger" means that the CRO horizontal sweep waits for a finite time without receiving a trigger, and then triggers itself regardless of the trigger level setting.

author: artag
author_rank: Super Contributor
timestamp: March 14, 2024, 07:20:34 pm
content: Just poke a bit of wire (or a resistor) into the centre of the input BNCs. Your fingers will pick up lots of 50/60Hz mains noise and give you a display.

author: donlisms
author_rank: Frequent Contributor
timestamp: March 15, 2024, 04:50:54 pm
content: Or maybe not...BNC connectors actually have specs and precision tolerances and that sort of thing. It's generally a bad idea to risk loosening up the contacts with a random piece of wire, if you want to keep your connections in good shape forever.(Not that I would ever do that... :-) )

author: David Hess
author_rank: Super Contributor
timestamp: March 15, 2024, 05:34:00 pm
content: On vintage oscilloscopes the BNC for channel 1 is often worn out through normal use anyway.There is nothing special about the BNCs on a 50 MHz oscilloscope, so they can be easily replaced. Check out the wire dressing going to the BNCs on the 50 MHz 2225, or any of the 100 MHz 22xx oscilloscopes. It is usually a low value air wired 1/8 watt carbon composition resistor.
Tektronix 2230 psu rebuild question. - Page 1
Forum section: electronics / repair

author: pitpat
author_rank: Contributor
timestamp: February 26, 2021, 08:16:14 pm
content: Hi, recently I've got on my bench this really nice (yet big) scope.It probably has some problems on thepre-regulator section since the crowbar system got in action giving the tik-tik sound.Surfing a bit on the internet i found out that a viable solution might be to feed 43v on a testing point skipping all the pre regulation.Since from what I've read this technique it's meant more for a test rather than a solution, do you guys think it might be good for apermanent fix? Should I look for a particular switching psu?Also English is not my native language so be kind on meThanks a lot for checking in!Federico

author: pitpat
author_rank: Contributor
timestamp: February 26, 2021, 08:21:47 pm
content: Service manual in here:https://de.tek.com/manual/2230-service-manualSchematics should be at page 372

author: bob91343
author_rank: Super Contributor
timestamp: February 26, 2021, 08:34:14 pm
content: It's a common problem. I solved mine by replacing the IRF power transistor on the power supply board. Nicer fix than to have a separate power supply. But that works also. Not critical.

author: David Hess
author_rank: Super Contributor
timestamp: February 27, 2021, 02:42:15 pm
content: Quote from: pitpat on February 26, 2021, 08:16:14 pmI know of at least one person who did that successfully. As I recall, they found a small 48 volt off-line switching power supply which could be adjusted down to 43 volts to drive the inverter.

author: pitpat
author_rank: Contributor
timestamp: February 28, 2021, 09:50:21 am
content: Ok, thanks a lot! i think that i'll try to fix it before get into the plan b.Also i'm trying to check the capacitors ESR with a cheap LCR. What values should be considered to be replaced in this situation? I'd say below 1 ohm should be "fine" or at least not trigger the crowbar.Am i right?
Tektronix 2230 PSU repair - Page 1
Forum section: electronics / repair

author: THM60
author_rank: Contributor
timestamp: November 24, 2022, 09:59:50 am
content: As described herehttps://www.eevblog.com/forum/repair/tektronix-2230-scope-mechanical-parts/msg4529390/#msg4529390I became owner of a poor Tek 2230 that undergo a moron's attempt to "repair" it. Its PSU was blown, not the tiniest sign of life in there. The numbskull who massacred it had installed a 5A fuse, adding further damage to initial failure.It took a fair amount of hours and a lot of head scratching but it ended in a successfull repair. Some pictures here :https://photos.app.goo.gl/8B4YyACh2ZtfrG8d9I had to replace : CR90, CR907, Q9070, Q908, U930, CR908, R909, R908, C904. Given the dreadful access to those parts it has been the worst experiment I had since many years, but I'm very happy with the result.Something worries me with the way Tektronix designed the PSU: the value of the C906 (75µF) located after the full-wave rectification, is the image of the energy supplied by the power supply. The more the voltage supplied by the rectifier increases, the more the value of the capacitor decreases to supply the same energy and therefore the same power. Under 220V, it will provide four times more energy, which can cause Q9070 to explode in the event of a malfunction or a voltage spike, or a parasite on the mains network.Q = C x U in coulombs (Quantity of electricity)E = 1/2 C x U² in joules (Energy)which gives :- with mains voltage = 110 V : E = 1/2 x 75 10 -6 x 110 ² = 0,45 J- with mains voltage = 220 V : E = 1/2 x 75 10 -6 x 220 ² =1,8 Jthat's enormousI might be worrying for nothing though, but I'm tempted to power the scope through a 220/110V transformer.I now have to find an elegant solution to fix what the moron did with his Dremel :https://photos.app.goo.gl/8B4YyACh2ZtfrG8d9Thanks for your attention.

author: David Hess
author_rank: Super Contributor
timestamp: November 25, 2022, 04:36:50 pm
content: Tektronix uprated the power supply in the 2235 series by changing the value of various parts so you might take a look at the parts list for the late 2232.

author: THM60
author_rank: Contributor
timestamp: November 25, 2022, 05:54:44 pm
content: Without knowing I uprated or modified the following items :- CR901,CR902,CR903,CR904 : HER208G (1000V/2A) instead of the original and obsolete MR5061 (600V/1,5A). Among other issues, scope was DOA and CR901 was shorted.- CR907 : single 31DF4 (400V 3A 75ns) instead of the two paralleled BYD73G, one of which was shorted- Q908 : 2N2907A SI-P 60V 0.6A 0.4W 200MHZ in TO18 metallic package. Q908 (TO92 2N2907A) had exploded.- R908 : changed from 3KR to 2,2KR- cut off Q9070 Molex connector and directly soldered wires to TO220

author: Allen49
author_rank: Contributor
timestamp: March 23, 2024, 09:50:52 pm
content: Thanks for this post. It looks almost identical to the Tektronix 2221 I am trying to repair. I have a short to chassis ground on the 5 volt rail. Mine has started blowing the fuse.
Tektronix 2235 100K and 10K Input Attenuators - Page 1
Forum section: electronics / repair

author: jdragoset
author_rank: Frequent Contributor
timestamp: October 18, 2020, 09:56:51 pm
content: When you have a channel going goofy (high amplitude, 1,2,5 volt, 100k, .1, .2, .5 volt, 10 k) it may not be the cam operated switch but the attenuator (six internal solder joints) the problem.Swap the attenuator (they plug in) to verify.Easy fix compared to cam/switch leaf dis-assembly and cleaning.Re-flow the six pin-to-ceramic attenuator connections after removing the cover.

author: bob91343
author_rank: Super Contributor
timestamp: October 18, 2020, 10:57:14 pm
content: This is confusing. Only one message on this topic and it appears to be responding to some other one.

author: David Hess
author_rank: Super Contributor
timestamp: October 19, 2020, 03:41:51 pm
content: I have had the same problem once so far. The pins are riveted to the attenuator hybrid and the electrical connection may fail. I soldered them with silver solder.Beware that swapping the attenuators will compromise the input capacitance and compensation until calibration is done.

author: jdragoset
author_rank: Frequent Contributor
timestamp: October 19, 2020, 09:13:35 pm
content: Did not mean to confuse.Had high amplitude noise in the 1,2 & 5 volts/div on one channel only.I unplugged the attenuator to clean the cam switch contacts for that attenuator with a narrow manila strip and IPA.After the problem remained I temporarily swapped the attenuator into the good channel, where the problem followed the attenuator.David,Is there a low temp silver solder?The one used on the ceramic terminal strips?

author: David Hess
author_rank: Super Contributor
timestamp: October 19, 2020, 10:11:12 pm
content: Quote from: jdragoset on October 19, 2020, 09:13:35 pmCommon leaded 2% silver solder (Sn62Pb36Ag2) is suitable. The only risk is if you use normal solder, the silver used to make the trace on the hybrid may dissolve leaving no trace behind.
Tektronix 2235, A/N-USM 488 Horizontal Alternate Intensify Error - Page 1
Forum section: electronics / repair

author: jdragoset
author_rank: Frequent Contributor
timestamp: July 27, 2019, 08:51:50 pm
content: Any quick check for A intensify always running to end of A trace regardless of B setting?Start of intensify is correct and moves with delay time and B trace is correctly displayed.

author: jdragoset
author_rank: Frequent Contributor
timestamp: July 30, 2019, 12:30:50 am
content: Found Q643 (Tek 1510190-00) with OC emitter junction and temporarily replaced with a 2N5961 until Tek replacement arrives."A" intensified now works correctly.
Tektronix 2235 Dead CRT? - Page 1
Forum section: electronics / repair

author: kontour
author_rank: Newbie
timestamp: July 28, 2023, 02:10:47 pm
content: Picked up a nice Tek 2235 for cheap the other day. Get it home and find CRT works but trace is all messed up. Following tek troublshooting guide points to an issue with horizontal deflection. Get to the end of the chain just before the CRT with everything checking out ok.I’m probing the last testpoint when the probe ground lead slips off the test point. I hear a bzzt and the scope loses power. Check fuse and it’s blown. Scope will now blow the main fuse everytime it’s powered on. I can bring it up on the variac to about 60v and the indicator lights come on and I can hear transformer whine but then the fuse pops. Swear at myself a lot before packing it in for the evening.Return the next day to find the culprit for the mucked up horizontal was simply that the lead had come off the pin on the CRT aka I’m an idiot and should have checked the most simple solution first.So now I’ve spent the last two nights attempting to troubleshoot the power issues. Appears the SCR mosfet is dead but can’t find any other definitive issues. $80 worth of parts from digikey later and all it needed was a new SCR.Scope now powers up fine but I’ve got a lot of distortion in the CRT, both at the edges and in the middle as per the photos below.I have very limited experience with CRT’s so I’m wondering if the CRT is dead or I’m looking at another issue to diagnose….

author: kontour
author_rank: Newbie
timestamp: July 28, 2023, 02:34:31 pm
content: Having played with it a bit more, I’m leaning towards this CRT being damaged by impact before I purchased it, see picture below.

author: EggertEnjoyer123
author_rank: Frequent Contributor
timestamp: July 28, 2023, 05:47:14 pm
content: Does the horizontal output still look good?You could have killed other components when you shorted the supply out,

author: David Hess
author_rank: Super Contributor
timestamp: July 28, 2023, 06:31:58 pm
content: Quote from: kontour on July 28, 2023, 02:34:31 pmThat is what it looks like to me. What often happens is some glass supports inside the CRT fracture due to external impact, and the pieces dent the scan expansion mesh causing the CRT geometry to become weird and non-linear, like a crumpled mirror.You might gently shake the CRT or roll it and see if you hear any rattling inside. Visual inspection toward the back of the neck might show lose pieces.
Tektronix 2235 display issue - Page 1
Forum section: electronics / repair

author: abhi1981
author_rank: Regular Contributor
timestamp: July 09, 2025, 05:56:00 pm
content: Hi,All of a sudden the display went out on my Tektronix 2235. The beam find shows the trace and by looking at it it seems that the other controls are working.What could be the problem?I had recapped it some time back -https://www.eevblog.com/forum/testgear/tekhind-2235-(tektronix-india)/msg4944865/#msg4944865Even after recapping, sometimes it has a mind of its own and doesn't power up. And when it does, it works fine.

author: ondraN
author_rank: Regular Contributor
timestamp: July 10, 2025, 09:21:20 am
content: As a first step, I would check all the supply voltages from the power supply. If that is OK, I would proceed from the CRT deflection circuits towards the input circuits. Determine if the Y or X channel is deflecting the trace from the screen and proceed accordingly.