Tektronix 2215 (Non A) Horizontal Flickering/Jitter - Page 1
Forum section: electronics / repair

author: TheBay
author_rank: Unknown
timestamp: December 10, 2018, 06:47:37 pm
content: This has me baffled, I was given a Tek 2215 a few months back, this was like new and had been sat in storage for 30 odd years.It was all working perfectly but today I noticed it flickering horizontally slightly which was annoying me as I assumed it was an issue with what I was working on!I've had it in pieces and gone through everything, all voltages are correct and within spec. This issue is present on both inputs I suspect its an issue with the Horizontal deflection circuitry.However I do not have access to another scope at the moment so it's a bit of a chicken and egg situation. I have a feeling the input section and controls are all okay, I did check it all over for dry joints and given it a good tap and wiggle everywhere, the V/H wires are fine on the CRT.Hoping this is a common or known issue with this, I know they are not the best scopes but it suits my needs and the CRT had zero hours on it, so hoping to keep this going.Excuse the poor video, but just uploaded this to YouTube to give a rough idea of what's going on:

author: t1d
author_rank: Super Contributor
timestamp: December 10, 2018, 08:35:27 pm
content: What a great gift! Wow! Mine was a gift, too...I do not have a suggestion on the flickering, other than the broad idea that 30 year old caps, used, or not, are suspect. I replaced the big cap, in mine, when I first got it and it fixed whatever was wrong. Seems I remember that it was leaking.I found a seller that had Nichicon "UPF2A471MRH." I think it belongs to this series:https://www.mouser.com/datasheet/2/293/UPF-1187210.pdf470uF/100V. I think it had all the proper dimensions and just dropped right in. I'm not certain of that, but I do know that it was easy to install it.I like mine a lot.

author: TheBay
author_rank: Unknown
timestamp: December 10, 2018, 09:09:19 pm
content: Quote from: t1d on December 10, 2018, 08:35:27 pmHere's the original post when I got it a few months ago:https://www.eevblog.com/forum/testgear/tek-2215-never-been-used!/I might just replace any electrolytics in it as they are original and this thing had not been used or had any repair work done to it, so yes 30+ years old components.I don't think there are many in it looking inside, glad you fixed your problem with yours.It could well be ripple from aged capacitors causing an issue.One annoyance was I went through the service manual and thought this doesn't seem right, reading it again now there were a lot of updates on it and only the later part of the service manual applies to my revision so have to go through it all again, such a strange PSU setup on this scope.*EDIT*Just a little update, decided to power the scope up from one of my Bench PSU's, which is a TTI TSX3510, this only goes up to 35V but was enough to get the scope running to do some testing, the issue still remains so it's not related to the Sub PSU board.

author: bd139
author_rank: Super Contributor
timestamp: December 10, 2018, 11:21:20 pm
content: I’ve got a 2235 (same chassis) with similar problem. I replaced pretty much everything in the power supply, which promptly exploded. This was repaired. Still does it.Turned out to be the voltage multiplier (waiting on replacement now)Repair thread here:https://www.eevblog.com/forum/testgear/tektronix-2235-repair-thread/I have a ton of 510k HV resistors left if you end up having to replace them. This is a common problem on these scopes. If you need any PM me your address and I’ll send enough FOC.

author: TheBay
author_rank: Unknown
timestamp: December 11, 2018, 08:35:23 am
content: Hope a multiplier turns up soon for you, just read your repair thread it made for an interesting read.I'm not suspecting the multiplier just yet as my luminosity and focus are rock solid.So far ruled out the Sub PSU PCB, going to check the "Mallory" branded electrolytic capacitors and the 510K Resistors today,thank you for your kind offer I'll let you know if mine are within spec today.Shopping list so far:5x 1000uf (Above 12v) - Tested the existing 840uf 12v (All around 950-1000uf, ESR is fine, but changing anyway)2.2uF (160v or more) Tested OK470uf (50v or more) Tested OK270uf (40v or more) - Reading 330uf, good ESR but replacing.33uf (160v or more) Tested OK100uf (10v or more) Tested OK*EDIT* The string of resistors on mine are 1Mohm not 510K, they all read correctly and look in good shape, so a slight difference between models here.

author: David Hess
author_rank: Super Contributor
timestamp: December 11, 2018, 05:27:24 pm
content: That looks like just horizontal movement to me.1. Make sure the trigger is set correctly. Marginal triggering can cause that.2. Why is the trace only half of the screen width? Was the horizontal position control set to the left?3. Work the horizontal position control. Maybe the potentiometer is dirty.4. Does it do the same thing on other horizontal time/div settings? Dirty switch contacts can cause some odd things.

author: TheBay
author_rank: Unknown
timestamp: December 11, 2018, 05:30:27 pm
content: Quote from: David Hess on December 11, 2018, 05:27:24 pmThanks for your reply.1, It does it even on external sync or looking at a flat line.2, My phone kept correcting the jitter when I tried to record it, must be something to do with image stabilisation, so shifted it across to make it easier to seeits still worse in real life than the video shows.3, That's all perfect.4, Does it on any setting, which is making me think its an issue with the H deflection circuitry or ripple.

author: David Hess
author_rank: Super Contributor
timestamp: December 11, 2018, 08:34:47 pm
content: Quote from: TheBay on December 11, 2018, 05:30:27 pmIf it is a mechanical problem like a dirty switch or cracked trace or connection, then tapping each control and inside with an insulating stick may reveal approximately where it is.See what it does in XY mode. Turn the brightness down to avoid burning the screen. Since the horizontal voltages are fixed in XY mode, a multimeter can be used for diagnostics. See where the noise starts if possible.It might be popcorn (flicker or 1/f) noise in a bad transistor in the horizontal signal path but a mechanical problem is more likely.

author: TheBay
author_rank: Unknown
timestamp: December 12, 2018, 12:09:46 am
content: Quote from: David Hess on December 11, 2018, 08:34:47 pmIt does the same in all modes, including XY, I've thoroughly done the tap/wiggle test, reseated connectors, cleaned everything.As mentioned this scope is "brand new", it was sat for over 30 years unused, this only recently happened after I was using it for a while so I think a component is breaking down, I've pulled all the PSU caps and they all check out fine, I will replace them all while they are out. Good call on the multimeter in XY mode I'll give that a go. I guess electronics don't like being sat unused for years.I'm determined to get to the bottom of this as although these were one of if not the worst Tek offering, I don't think there are many out there in this condition.Also the TV Field mode is very useful to me and use that a lot.

author: David Hess
author_rank: Super Contributor
timestamp: December 12, 2018, 02:33:05 am
content: One of my 2230s had popcorn noise in the vertical channel switch before the digitizer. This was more common in the past and it is not the most likely cause but in XY mode it should be relatively easy to track down with a multimeter by probing the horizontal signal path.

author: TheBay
author_rank: Unknown
timestamp: March 06, 2019, 05:44:35 pm
content: Replaced all the caps in this but still have this issue, surprised that ALL my caps still were in spec and had low ESR after all these years of being sat there.Just bought a unused Hameg 1004-3 so hopefully can use this to find out whats wrong with this Tek! Hopefully its not the trippler.

author: David Hess
author_rank: Super Contributor
timestamp: March 07, 2019, 01:47:48 am
content: Quote from: TheBay on March 06, 2019, 05:44:35 pmAn ESR test is not always sufficient. Sometimes aluminum electrolytic capacitors fail such that the ESR is high at high frequencies which a common ESR or even dissipation test will not detect.