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On 3/22/2019 10:46 AM, peterp@... wrote:

Hello all, I just got a 2230 scope from the (in)famous website to help me with some vacuum
tube ham radio equipment and it came with a fault. Here are some pictures and a short movie
that show the fault:



Both channels display correctly when the signal is in the lower half-plane of the display. As
the displayed signals are moved to the upper half plane their part that falls in the first quadrant
(upper right hand fourth of the display) distorts practically identically when each channel's signal is
in the same position vertically.

I searched the group and found a thread about an issue that may be related to mine. Unfortunately,
the details are greek to me :-) Here's the old posts:

/g/TekScopes/topic/7647928#70205

/g/TekScopes/message/71388?p=,,,20,0,0,0::relevance,,2230+Displayed+signal,20,2,0,7648113

Also, if anyone has any leads to repair services in New Jersey please let me know. I also have a 2215A with ch2 inoperative and
a 475 that's screwed up so there's plenty of business for such a service.

Any help would be greatly appreciated,
Peter

On Saturday, March 23, 2019 1:59 PM, David Berlind <david@...> wrote:


Hey all.. spotted these 3 beauts for sale near me. Don't know the seller. But it's very close to me. Asking price for all 3 is $125. There's an extra 3A74 plug in that goes with the bunch. I have facilitated purchases and shipping for people in this group before (as some will attest to). However, I've yet to ship a Cadillac.

On Fri, Mar 15, 2019 at 9:37 AM <tekscopegroup@...> wrote:

On Thu, Mar 14, 2019 at 03:57 PM, tom jobe wrote:

There are about 17 one amp ultra fast diodes that are used to rectify
the low voltages on the secondary side of the transformer. About a dozen
of them are in a row next to the transformer in the middle of the A18
board and they are known to fail especially if they are marked "ZS" or
one other marking which I can't remember.

If they are marked ZM or ZS they are well known to get leaky. Replace
these diodes with MUR160 600V 1Amp from Mouser/DK.

On 3/22/2019 4:45 PM, chipbee40 via Groups.Io wrote:

Looking at your Youtube, something is obviously failing with heat so freeze spray would be helpful (upturned canned air is fine). My initial thought was U760 as the timebase is collapsing but I've not seen one fail such that the power led would flicker. Unplug the timebase, see if it still fails. (You are looking for the power LED to flicker, nice symptom, unusual!). Surprised the scope isn't tripping completely. I'd suggest monitoring the power rails to see if its just one rail failing or all rails. Complicated with switching supplies because all will drop on overload as the switcher detects a fault but not impossible to ascertain which rail is overloading. I would start by disconnecting the feed to the multiplier (so nothing on screen) and just observing the power led (or monitor the supplies) for any failings. You can also remove power to the attenuator board, an unlikely culprit but I have had the opamps go short. You could just pull all the power supply links and monitor the rails but without a load the fault might not show. What is the Y amp doing when it fails? Amplitude still good? Your replacement parts look ok. Hopefully you have checked the obvious, I've received these with loose screws jammed in unlikely places, solder bridges due to careless repairs. JC

-------- Original message --------From: guy232 <gry.russel@...> Date: 3/22/19 11:55 AM (GMT-08:00) To: [email protected] Subject: [TekScopes] 2213A Novice, unsolved anomaly encountered, documented & video Hello fellas! I have been reading/researching a ton over the past couple months while trying to get my new to me 2213A in proper working order. I bought one from the auction site and powered it on for less than a minute, seemed alright. Powered it down because I seen that its highly recommended to replace the power supply area electrolytics & safety caps before doing the initial LVPS tests.I have been documenting this on eevblog forum and have had some great help there from David Hess, thought I may post here too just to document my issue for others and maybe get some insight to give poor Mr. Hess a break from me, hah!In hopes of making this more concise and readable, I will section things up as such:- briefly explaining the anomaly & including a video link- listing the components I replaced- listing the 2 instances of my novice induced damage/mistakes I encountered. (I dont believe these are related to the anomaly though)----------------Anomaly: After replacing parts I powered up with scope settings set to "Baseline Trace", traces displays and everything looks good. After 2-3 minutes the trace starts shrinking, blinking and slowly fades out. The power led/trigger led also fade in and out during this time. After 10 or so seconds the power led finally goes dark and the machine displays nothing. Toggling power on/off doesnt help. After unplugging and waiting an hour or so and then trying to power on the unit works but will repeat the same process again in 2-3min.Video of the anomaly, feel free to skip to 2:19 which is when it starts to occur:? the suggestion of Mr. Hess; I checked temperatures of a few components in the power supply area right after the anomaly occured. All areas seem normal (24-27C). The "highest" temp was 29-30C on T944. Mr. Hess advised that these temperatures seemed alright and if a transformer was the cause I would expect to see very high readings.After much more reading around I haven't found any good leads in the right direction yet. Will keep this updated!-----------------------Parts replaced:C900: KEMET?R46 Series?FILM 0.15UF 10% 560VDC RADC902, C903, C904: KEMET Y2 Rating Film 2200pf 1kvdcC906: United Chemicon KXJ series?100?F?450VC925: Chemicon KY?100?F 25V?C940: Chemicon KYB?1200?F 63V?C942, C943: Nichicon UCS?10uf 160vC944: Kemet R82 Series?1?F Film Capacitor 40V 63V Polyester, Polyethylene Terephthalate (PET), MetallizedC954: Chemicon kxj?39?F 160V?C960-C970:? Chemicon KYB?1000UF 20% 25V?R892, 894, 888, 889, 890, 891: Vishay HVR37 510K 1/2W 1%Schaffner AC inlet/IEC: Qualtek?858-03/007------------------------------------Accidents/Errors/Damage:C944, Positive lead;? Lifted pad on bottom of board. The top side of the board still has pad intact. Used multimeter on bottom side of the board and the C944 positive lead shares continuity with other components connected to the ground, I believe this means that the lifted bottom pad isn't a big deal that requires repair.C956: I made a mistake due to the capacitor list I was using being incorrect. Initially installed a Nichicon UPW?47?F 63V cap. I caught this mistake and replaced it with the stock 270uf +100-10% 40V cap which still tested good for ESR & Capacitance. Ordered & waiting on new cap (nichicon upw 330uf 50v). Not sure if powering on with this cap caused any damage but after removing the 47uf cap it still tested good, replacing the stock 270uf cap did not solve the scope anomaly.----------------------------Thanks for any insight, I will still be researching meanwhile and will update if I find anything out.Cheers,Gary R.Treasure Coast, Florida