DR #27 - Tektronix 2213A Oscilloscope CRT Replacement & Tune-Up

hey everyone welcome to duality repair I have another Tektronix 22:13 a 60 megahertz oscilloscope to repair this one's got a pretty interesting problem and rather than show you I'll let you listen to it so you can hear that rattling around that's the CRT glass it imploded so this is going to be an interesting one for me this is my first CRT replacement and this was sent by a viewer who purchased this knowing that it had a problem he also purchased a spare CRT and I verified the models are the exact same so that will work which is good obviously I'm gonna replace the CRT I'm also going to tune this up as best I can you know I looked around the boards a little bit and everything looks to be in really good condition so I think once we get the CRT replaced we replace the electrolytic and maybe clean the potentiometers all the dials are here and everything I think this thing is gonna run really well I'll go through any of the adjustment procedures that I can that are highlighted in the service manual and we'll get this thing ready for ready for action so CRT replacement first things first I'll remove the anode so the anodes up here just on plugs there and I've already done this so ordinarily be a little more safe but I've already done this you just pull it out here's the anode tip right there when this is live it's at it looks like seven eight thousand volts and even when it's been off for a while it can still keep a charge so what you want to do is you want to discharge this to chassis so you want to make sure that your hands aren't on the chassis and the chassis is not sitting on anything conductive before you discharge it to the chassis and then now you know that the anode the CRT is safe this thing has been off for several weeks maybe months and it's also broken and I've also already grounded this to the chassis so I know it's safe so that's step one step two is removing the front of the CRT or disconnecting it and that's just these two bottom screws here Torx head t 15 maybe 250 220 and then we have to remove the vertical and horizontal deflection wires so here are the vertical wires right here you just remove them and then the horizontal are down here I'm definitely going to want to label these so that I know which way where they go when I put them back maybe T for top and B for bottom or something like that same with the bottom the horizontal deflection wire so make sure to do that the only thing I'm unsure of and I haven't consulted the service manual with that is is how to get the back out I think once I remove the front two screws and I get these disconnected and I get the anode disconnected it might just slide out to the right if I have a little trouble consult the service manual since it does have the CRT removal procedure in there but I'm gonna get working on that all right I got the CRT out it wasn't too much of a hassle there were a few things that I missed when I explained earlier number one these set of pins here you can see the two pins coming out of this board this is for the trace rotation so you do have to disconnect that trace rotation connector before you can remove the CRT and then two other things I mentioned that the front faceplate is connected with the two screws on the bottom and the front I missed the two screws on the top in the back so there's screw here and there's another screw in this corner here those also have to be removed once you get all of that removed and the other things I mentioned it does just slide out to the right which is perfect and so after I cleaned up all of the glass I'm ready to go now since it's well never the case we get to look at a CRT or that I get to anyway I thought we'd take a look at this huh pretty awesome so obviously it so got a few glass fragments on there those are just still adhered to some of the pins I'm not going to worry about trying to remove them obviously normally this entire enclosure is encased in encased in glass all the way to the front screen here also obviously broken it sits like this it's encased in glass and under vacuum but let's take a look around since we really never get to analyze something like this so the back is the connector you can see all the pins there one good thing that I noticed I was worried about how it was going to reconnect the new one you do not want to connect this incorrectly so if you can see there's a key right there this little slot it's keyed so that you can only insert this into the mating connection one-way so you can't really install it incorrectly which is great foolproof and so a little bit on the CRT functionality if we start on the left this little cylinder there that's going to be the cathode where the electrodes are generated all of this here is going to be various focusing so beam focusing and beam acceleration to focus and accelerate the electron beam down the electron gun we get here you can see this gold metal right here and there's another one on the opposite end that's one of the deflection plates so I think that's the vertical deflection plate although I'm not sure and then we have another set of plates right here you can see these a lot easier these are the opposite set of plates so either the vertical or horizontal and so these are the voltage difference between the two plates is going to determine the amount of deflection of the electron beam before it hits the screen and that's it for the electron gun portion let's take a look at the screen portion there's not too much to look at so you can see we've got this coil here and that's connected to this trace rotation connector that I mentioned and then of course the anode that we removed and the screen itself now if we look at the screen I thought this is kind of interesting you can see all these little defects those are on the inside so what happened was when this thing imploded a bunch of the shards of glass scraped off some of the phosphor the internal phosphor coating on the screen and so even if the screen was usable which obviously it never will be again you'd have all these really ugly defects that would make it unappealing to to visualize so so that's the CRT I'm gonna get this out of here I'm going to clean up the rest of the glass fragments that I have and I'm gonna pull the new CRT clean it up a little bit and get it installed alright the CRT went in without an issue and the traces show up as you can see which is great but there's still a lot of issues to deal with so let me show you few of them so channel one when I insert the probe into the calibration port I get nothing channel two I do get a signal which is great you get the nice square wave there so problem number one is channel ones input is not working problem number two is this channel selection switch here is really light what I mean by that is there's no resistance when I use these other two switches of the same type there's a lot of resistance and there's really discrete and definite steps when you change positions and this one just kind of almost free-floating so there's some sort of mechanical issue going on there that I'll have to address and I looked around the board a little bit more closely and I've discovered that somebody has definitely done some work on the power supply section so we'll go to the power supply section I'll show you what I found there and the work that will need to be done okay obviously we're looking at the back of the board but this section here outlined by this square is the power supply section and you can see there's a lot of redone so during saan here so you can see there's this two rows of four up here these are four resistors that were for some reason replace they're definitely not original all of these solder joints need to be redone we have a bank of four here that were redone we have this one here the one that's really concerning is this jumper added right here no idea what that's for that's gonna have to be looked at we have a whole bunch of other joints right here that have been touched up we have some over here that have been done and it looks like even that main filter capacitor the seventy-five micro farad at 450 volts was redone a little bit added some solder to it or whatever it's definitely still the original but they added some solder to that for some reason somebody touched up a whole bunch of joints down here as well so a lot of area for concern in just the power supply section alone so all of these joints are gonna have to be probably completely redone let me show you the top of the board with all of the components not as many problems to see from the top if we look at the top so right here see these four bigger resistors these are the ones that were replaced those are the ones that are not original the there's three electrolytic that were also replaced there's one right here one right here and one over here not sure why they only replaced three and why those three otherwise the rest look to be original there's some additional solder on this jumper right here this is the 100 volt test point and it's just a jumper but for some reason there's a whole bunch of extra solder on there and you're not gonna be able to see it but so there's a something mounted right here so you can see this package right here there's a transistor in there sorry for the focusing the transistor that drives the transformer here is mounted here and then there's this block down here and under there I believe there's another transistor or two and I can see a lifted trace sorry about the focus again you're not gonna be able to see if there's a lifted trace under here and that is likely what that jumper was for there's a whole bunch of issues to address just in the power supply section that's gonna fix some issues it's gonna make this thing more reliable but it's not gonna fix it's definitely not gonna fix the two issues and I spoke about earlier channel ones input signal failure is gonna probably come from this board here it's got the attenuation for channel 1 and channel 2 it's got the sweep selection switch right here and all of the necessary circuitry to deal with those signals and then that switch that I mentioned to with the likely mechanical failure is also it's on this front board here I've dealt with this type of board once or twice in the past it's a pain it's gonna be a pain to get this off to get this front board off but it's gonna need to be done so my first step is going to be to remove and replace all of these electrolytic sivan though three that have been replaced I should be able to find a fair replacement for this one it's not going to be an exact match but it'll be something very very close it'll be a lot smaller than this older version shouldn't mount to the board okay and then I'm going to as I said redo all of those weak solder joints on the back and I'll keep updated in front of the scope I have all of the replacement capacitors lined up for the a1 board the a1 board is the main board on the bottom of the unit on the right you can see I already removed the bulk smoothing capacitor and the reason I did this was to take a look at the lead layout as I'm unfamiliar with this type of capacitor so this is just an old style and this bottom pin here which is the smaller pin and a smaller lead is the positive and the other three on the outside are ground and so you can find replacements for this online say on eBay but I didn't want to buy used one so I bought this new one it's a standard two lead which would work just fine I will fill in the unpopulated two unpopulated ground through holes with solder should work this one is slightly higher in capacitance at 82 micro farad's versus 75 it's got the same voltage rating at 450 and obviously with a much smaller size that's a benefit as well so I have a lot of work to do I'm gonna get started on this capacitor replacement all the electrolytic have been replaced on the main board the scope turns on just fine and we still get nice clean sweeps across the screen for both channel 1 and channel 2 however we have a new problem before the work at least channel twos vertical deflection was present I could see the calibration signal with channel 2 but now I can't so both channel 1 and channel 2 no longer have the vertical deflection their signals are not getting through to the CRT so before I start looking at the schematics to try and identify where this problem might be I thought I'd look at the power supply voltages first as I replace all the electrolytes in the power supply section so we'll start with that I don't expect there to be any problems since the rest of the scope is functioning but it's worth a check the nice thing about this unit is that the power supply voltages are all printed nicely on the board and their test points are very easily accessible so let's start at the top I'll read them out there should be positive 30 positive 20 9.8 that's okay blow that 100 to positive 100 good way down here positive 8.6 that's good below that positive 5 good and below that negative 8.6 and that's good so write all of the power supply voltages are present they're all very very close to what they should be so I don't think the problem is they're likely their problem is going to be something to do with this attenuator board here but I'll take a look at the schematics to try and identify where we want to start probing all right finally troubleshooting time so the first thing I want to look at is channel 1 I want to look at this first since this was a problem before I even started working on this unit and so I've done quite a bit of work I ready to identify what the problem is you can see that setup I have here so I have my B and K 1477 scope hooked up that's what I'm gonna probe with channel 1 or channel a I have the Tektronix channel 1 hooked up to my B and K calibration signal so when I hit the signal with the probe I should get a nice square wave I was able to identify that the attenuator board is the problem with channel a I checked the output of that board and I got no signal so I know the problem is somewhere on the board if we look at the schematic the signal enters on the left of the B and C it travels through a whole bunch of different components before exiting the right through that connector that I mentioned and so there's a few ways to do this you can probe from left to right until you stop seeing the signal you can probe from right to left until you start seeing the signal or you can start in the middle and then if you see the signal you move to the right if you don't see the signal you can move to the left I'm just gonna probe from left to right so I want to look for some identifiable and easily accessible components r2 is pretty much where the signal enters the board so let's look at our 2 here and we have the signal there let's look at our 3 next we have the signal there as well let's check the base of Q 13 and it's there let's check the base of Q 18 it's there as well now we have this resistor pack here it's gonna enter at pin six here it's gonna exit pin five here all right so a signal is making it almost to the end of the line we're at this custom Tektronix I see here it's the u 30 and it's gonna enter pin four so let's measure pin 4 and we have it there and it should exit through a differential signal out of pins 10 and 13 so let's look at pin 10 and you can see we have nothing there and 13 we have nothing there as well so it's likely that that custom Tektronix IC is a problem which is unfortunate because it's of course decades old they haven't made any new ones for decades you can find a few here and there online but they're fairly expensive for what they are that might be what we have to do the only other thing you want to do to rule out anything else other than the IC is to check the incoming voltage to that so if we look at the schematic again pin 6 has minus 8 point 6 volts coming across our 34 and I measure there and that's accurate and pin 14 should have positive 8 point 6 volts coming across the three resistors there two resistors excuse me and you should have something like two and a half volts at that pin and that was accurate as well so it's very very likely that I see you thirty is the problem with channel 1 now I'm not going to order and replace that yet I want to identify what the problem is with channel 2 if the problem is also on the attenuator board and the part is either expensive or difficult to obtain it may be easier and cheaper just to replace an entire attenuator board so let's get started with channel twos troubleshooting I was unable to replicate the problem I was seeing earlier with channel 2 so I'm going to ignore that for the moment I was able to find a replacement for you 30 this is the old one I was able to remove it after quite a bit of effort and the new one came in this genuine Tektronix box and it was advertised as brand new so we'll see if that works before I test it I want to clean this front faceplate here you can see all of the exposed areas are much dirtier than the unexposed where it was covered by the knob so I'm going to clean all this up really well I'm also gonna clean up all of the previously reworked solder on the back of the board mostly in that power supply area and then we'll be ready to test all right I clean the front faceplate up pretty well it's about as close to original as I'm gonna get it I also cleaned up the back of the board with all of the rework solder joints and I put the cover back on and clean that up as well so we're ready to test it out and so I have a 1 megahertz 4 volt peak-to-peak sine wave at both inputs and as you can see they both look great so I already checked most of the frequency range on this scope at least as high as my signal generator will go that's 15 megahertz and everything looks good I also went through a good section of the voltage range as well my signal generator goes up to I believe 20 volts peak-to-peak and it looks good there as well the last thing that I mentioned previously of potentially wanted to repair or replace was this channel selection switch I mentioned that it was loose there was no tension or no resistance but I've tested it and as you can see if I switch from channel 1 to both the channel 2 back to both there's absolutely no issue electrically with this switch so I've already investigated it a little bit this is attached to this front PCB here and it's very very difficult to access that really you have to remove the front PCB it's mounted to this bottom PCB and there's about I don't know 30 or 40 solder joints to remove and those are very difficult joints to remove so I don't think it's worth trying to remove that board to investigate it any further since we've already checked the voltages and everything is looking really really great I'm gonna call this one repaired and I will see you in the next video thanks for watching