Nice video! I wish I had seen this before replacing my caps because it took me a minute to figure out how that black plastic shield on the underside comes off. No need to remove the vertical board though, only the plastic clip, which was already missing on yours.
I just bought two 2213A which share almost all of the same parts as the 2235. I've spent quite a few hours/days researching them over the last couple weeks. Those 2-3 wima/rifa plastic safety caps that you removed and 1-2 similar styled y caps seem to always be the first required replacement recommended by all of the guys who are familiar to them. The only other required replacement in addition to that is the AC Inlet (the original one is schaffner branded). It has a similar type of safety cap inside of it that commonly explodes in the same manner but much worse. Not always a fire but can cause alot of clean up and can exhaust a big mess out of the back. The proper replacement IEC I'm buying is a Qualtek 858-03/007, probably the same for your 2235 but would double check. I'll soon be doing a few more checks on it for the common issues. Hope to see more, cheers
Thanks for your comments and all the information! Yes, I forgot to mention the AC inlet X2 capacitor. I, too, believe all of these X2 capacitors should be replaced. Good luck with your future projects!
@@OldSchoolElectronics No problem buddy, do you know about the Tekscopes group? If not, search web for "Tekscopes Groups.io" so much good info and super active.
Thanks for your kind words! It would not be a bad idea to replace those X2 capacitors and check the power supply electrolytic capacitor. My electrolytic capacitors all tested good, but I will replace them with high-temperature electrolytics in the future. My power supply was getting quite hot; I have now installed a low-wattage 12-volt fan.
Great repair! That thing was pregnant! :) I need to work on both of my scopes, but I'm just not that excited in ripping off the head to access the boards...however, I am currently trolling for another older scope. ~Jack, VEG
Thanks for your comments! Yeah, that thing was pregnant; baby daddy skipped out won't be paying child support. Anyway, glad I caught that capacitor as it self-destructed. I very rarely leave my equipment on when I am not in the same room. Now imagine if I would have taken my non-existing dog for a walk...
I too try to keep things powered off, unless I know I am going to use them and they need to warm up and stabilize, such as freq counter,sig-gen, etc...but that's only if I'm in the house, never leave with them on! Yes, to visit your imaginary girlfriend...your real wife woulda had a cow! :) ~Jack, VEG
X is a cross so think across the mains. Y is line to earth as you said. I would love to know the leakage current the eye valve closes at if you ever get the chance to measure it. Thanks regards Chris
Old School Thanks on the leakage current. I have recently bought a cheap insulation resistance meter from Amazon. It has a 250, 500, and a 1000 volt settings and thought this could be quickly employed for testing capacitor. I will be mentioning X Y rated capacitor in my next video as I have some to deal with a 1950s Cossor TV pattern generator. Keep making the video great content thanks for sharing. Regards Chris
All right, cool. That insulation tester could most certainly be used to test capacitors, I think. Anyway, I will watch the video on that and the X-Y video. I remember those generators; we used to call them crosshatch generators.
I've replaced so many of these cracked case RIFA capacitors in the Tek 2400 series scope power supplies and also the Tek 462 & Tek 465 spectrum analyzer power supplies. You have to get them out. They do a lot of damage to the PCB when they fail spectacularly.
Hi . I'm diego from Italy, thanks for the videos they are interesting, I also have a tex 2235 and I would like to change the parts that you have explained, I would like to ask if you have already made the video with the replacement of all the capacitors… .. the defect in the sine wave do you think that is the problem of some capacitor? thanks.how can i send you photos of the sinusoid defect? Thanks again.
Hi Diego. Sorry, not on UA-cam every day. You should join this group if you have not already did so: groups.io/g/TekScopes/search?p=relevance,,tek+2235,20,2,100,0 These people are in a better position to help you since I only repair scopes when my own scopes go bad. I do mostly audio work. I have not yet changed the capacitors since I have other projects to work on first. I will probably make a video then.
On the audio repair forums they often call them the capacitors of death. Never seen one fail but always wondered about them. Should this be part of a rebuild? I'm sure they don't cost to much.
Thanks for your comments, Pat. It would not hurt to change them since they are exposed to AC mains voltage and they are not really expensive. I have seen a few go up in flames and smoke without any warning signs. Stinks, too. But overall this does not happen too often, but you never know....I would especially change them if they are made by a company called Rifa.
Thanks for the video. X2 and Y capacitors are explained in the following RS datasheet: rsfor.narod.ru/datasheets/pdf/232_6001.pdf (search for 232_6001.pdf if not found). These types of capacitors have to fail safe, they are subject to transient voltages from the mains so their life varies. No need to replace the plastic cased ones unless shorted, but the old Rifa types crack and fail prematurely and if more than 20 years old should be replaced on sight.
It should have both a y and an x. The X goes from line to neutral and the y goes from line to chassis(ground). At least my 2225 has both. In fact my 2225 has on x and 2 y types.
I think the value changed over time. I saw a parts list that someone used a 2200pF , but my 2235A has a .068uF 250v in the C904 safety cap position. Like the guy in this video.
This video explains what also should be done with 2235: ua-cam.com/video/lrXCVg6T-ek/v-deo.html Installing a fan is a must because those inductance coils in the PSU get very hot and when they are shot it is very hard to find them.
Nice video! I wish I had seen this before replacing my caps because it took me a minute to figure out how that black plastic shield on the underside comes off. No need to remove the vertical board though, only the plastic clip, which was already missing on yours.
Thanks! Hope you got yours fixed.
Good call on using the variac to turn on the "fixed" oscilloscope. Why? Because other damage could have occurred when the X2 cap blew!
You got that right. Thanks for explaining that to my watchers; something I forgot to do.
I just bought two 2213A which share almost all of the same parts as the 2235. I've spent quite a few hours/days researching them over the last couple weeks.
Those 2-3 wima/rifa plastic safety caps that you removed and 1-2 similar styled y caps seem to always be the first required replacement recommended by all of the guys who are familiar to them.
The only other required replacement in addition to that is the AC Inlet (the original one is schaffner branded). It has a similar type of safety cap inside of it that commonly explodes in the same manner but much worse. Not always a fire but can cause alot of clean up and can exhaust a big mess out of the back.
The proper replacement IEC I'm buying is a Qualtek 858-03/007, probably the same for your 2235 but would double check.
I'll soon be doing a few more checks on it for the common issues. Hope to see more, cheers
Thanks for your comments and all the information! Yes, I forgot to mention the AC inlet X2 capacitor. I, too, believe all of these X2 capacitors should be replaced. Good luck with your future projects!
@@OldSchoolElectronics No problem buddy, do you know about the Tekscopes group? If not, search web for "Tekscopes Groups.io" so much good info and super active.
Thanks! I don't know that group and will check it out.
Awesome video ! I have the same scope and now im thinking on opening it up to check things :) Thank you !
Thanks for your kind words! It would not be a bad idea to replace those X2 capacitors and check the power supply electrolytic capacitor. My electrolytic capacitors all tested good, but I will replace them with high-temperature electrolytics in the future. My power supply was getting quite hot; I have now installed a low-wattage 12-volt fan.
Great repair! That thing was pregnant! :) I need to work on both of my scopes, but I'm just not that excited in ripping off the head to access the boards...however, I am currently trolling for another older scope. ~Jack, VEG
Thanks for your comments! Yeah, that thing was pregnant; baby daddy skipped out won't be paying child support. Anyway, glad I caught that capacitor as it self-destructed. I very rarely leave my equipment on when I am not in the same room. Now imagine if I would have taken my non-existing dog for a walk...
I too try to keep things powered off, unless I know I am going to use them and they need to warm up and stabilize, such as freq counter,sig-gen, etc...but that's only if I'm in the house, never leave with them on! Yes, to visit your imaginary girlfriend...your real wife woulda had a cow! :) ~Jack, VEG
X is a cross so think across the mains. Y is line to earth as you said. I would love to know the leakage current the eye valve closes at if you ever get the chance to measure it. Thanks regards Chris
Thanks for the "X is a cross tip"! Good idea. I can probably get the leakage current soon; thanks for watching!
Old School Thanks on the leakage current. I have recently bought a cheap insulation resistance meter from Amazon. It has a 250, 500, and a 1000 volt settings and thought this could be quickly employed for testing capacitor. I will be mentioning X Y rated capacitor in my next video as I have some to deal with a 1950s Cossor TV pattern generator. Keep making the video great content thanks for sharing. Regards Chris
All right, cool. That insulation tester could most certainly be used to test capacitors, I think. Anyway, I will watch the video on that and the X-Y video. I remember those generators; we used to call them crosshatch generators.
I've replaced so many of these cracked case RIFA capacitors in the Tek 2400 series scope power supplies and also the Tek 462 & Tek 465 spectrum analyzer power supplies. You have to get them out. They do a lot of damage to the PCB when they fail spectacularly.
Thanks for the tip! Let's hope people read your comment.
Hi. Could u tell where did u buy the caps? Thanks
Hi. Where did u buy this cap? Pls give me link. Tks
Hi. Sorry, I had this at home and don't remember whether I got this through mail order or at a local store.
Hi . I'm diego from Italy, thanks for the videos they are interesting, I also have a tex 2235 and I would like to change the parts that you have explained, I would like to ask if you have already made the video with the replacement of all the capacitors… .. the defect in the sine wave do you think that is the problem of some capacitor? thanks.how can i send you photos of the sinusoid defect? Thanks again.
Hi Diego. Sorry, not on UA-cam every day. You should join this group if you have not already did so: groups.io/g/TekScopes/search?p=relevance,,tek+2235,20,2,100,0
These people are in a better position to help you since I only repair scopes when my own scopes go bad. I do mostly audio work. I have not yet changed the capacitors since I have other projects to work on first. I will probably make a video then.
On the audio repair forums they often call them the capacitors of death. Never seen one fail but always wondered about them. Should this be part of a rebuild? I'm sure they don't cost to much.
Thanks for your comments, Pat. It would not hurt to change them since they are exposed to AC mains voltage and they are not really expensive. I have seen a few go up in flames and smoke without any warning signs. Stinks, too. But overall this does not happen too often, but you never know....I would especially change them if they are made by a company called Rifa.
@@OldSchoolElectronics Once the epoxy mantel cracks they catch fire from what other people say, they are bad and must go.
Thanks for the video. X2 and Y capacitors are explained in the following RS datasheet: rsfor.narod.ru/datasheets/pdf/232_6001.pdf (search for 232_6001.pdf if not found). These types of capacitors have to fail safe, they are subject to transient voltages from the mains so their life varies. No need to replace the plastic cased ones unless shorted, but the old Rifa types crack and fail prematurely and if more than 20 years old should be replaced on sight.
Thanks for all of these infos! I also had to replace the Rifas in an old HP3325b. Also, for thanks watching!
The capacitor in my tek 2235 was a 2200PF 240v Y class capacitor. What is the serial number on yours?
It should have both a y and an x. The X goes from line to neutral and the y goes from line to chassis(ground). At least my 2225 has both. In fact my 2225 has on x and 2 y types.
I think the value changed over time. I saw a parts list that someone used a 2200pF , but my 2235A has a .068uF 250v in the C904 safety cap position. Like the guy in this video.
This video explains what also should be done with 2235: ua-cam.com/video/lrXCVg6T-ek/v-deo.html
Installing a fan is a must because those inductance coils in the PSU get very hot and when they are shot it is very hard to find them.
Thanks for that information and for watching. It does get quite hot.
@@OldSchoolElectronics I did all the mods in that video and I'm very satisfied with the results.
All right, thanks! I will take a look!