tek 2215 - Page 1
Forum section: electronics / repair

author: m3vuv
author_rank: Super Contributor
timestamp: October 20, 2021, 03:33:07 pm
content: Hi all,i have a tek 2215 just delivered from ebay in a crusty condition,i want to get inside of it to clean it,trouble is the service manual says remove the 2 screws holding the rear cover,then slide the cover off,i have done this but it seems solid!,am i missing something here,i dont want to break anything,tia paul m3vuv.

author: m3vuv
author_rank: Super Contributor
timestamp: October 20, 2021, 03:53:06 pm
content: dont worry about this,i have the covers off,there was a srew in one side i haddnt spotted,while im in there are there any caps that i should change,ie riffa etc?.

author: bob91343
author_rank: Super Contributor
timestamp: October 20, 2021, 05:23:56 pm
content: If it's not brokem, I wouldn't fix it.

author: David Hess
author_rank: Super Contributor
timestamp: October 21, 2021, 12:36:09 am
content: Before you continue, double check whether it is a 2215 or 2215A; they are very different instruments, and the service manuals are not interchangeable.

author: m3vuv
author_rank: Super Contributor
timestamp: October 21, 2021, 02:40:13 am
content: it isnt the a version,im more concerned with doing some preventitive maintenance while i have it apart realy.

author: m3vuv
author_rank: Super Contributor
timestamp: October 21, 2021, 03:10:14 am
content: just noticed both channel 1 and 2 are way to low down the screen,as in when fed a sine wave etc the lower portion of the trace is off screen,the position knobs dont seen to do a lot,any ideas where to look,it does it on both channels.

author: David Hess
author_rank: Super Contributor
timestamp: October 21, 2021, 03:48:42 am
content: Quote from: m3vuv on October 21, 2021, 03:10:14 amIs the amplitude correct?The output load resistors on the vertical CRT amplifier are known to overheat and go open on the 2213/2215 which might cause that.

author: m3vuv
author_rank: Super Contributor
timestamp: October 21, 2021, 04:05:02 am
content: its hard to tell on the amplitude as i cant see the bottom of the trace,any idea where the resistors are located ?.

author: m3vuv
author_rank: Super Contributor
timestamp: October 21, 2021, 04:23:20 am
content: if the load resistors are r378,r379,r389 and r 388 they measure as follows r378=314 ohm,r379=309 ohm,r389=321 ohm and r388=316 ohm.

author: m3vuv
author_rank: Super Contributor
timestamp: October 21, 2021, 04:23:52 am
content: none show signs of getting hot.

author: andy3055
author_rank: Super Contributor
timestamp: October 21, 2021, 05:35:34 am
content: I have a 2215 and will follow this thread.

author: m3vuv
author_rank: Super Contributor
timestamp: October 21, 2021, 05:48:44 am
content: hi andy,im pretty sure its q386 and q 387 in the vert amp that are shot,im trying to find out if i can sub bfy 50 or bc108 transistors in there place as i have these to hand

author: m3vuv
author_rank: Super Contributor
timestamp: October 21, 2021, 06:07:40 am
content: testing q 376 in circuit,as in diode voltage drop,+ve probe on the base i get base to emitter 0.1v and base to collector 0.7v drops,the base to emitter junction looks iffy to me.

author: m3vuv
author_rank: Super Contributor
timestamp: October 21, 2021, 03:32:31 pm
content: does the transistor readings make it leaky or low gain,ie,should i replace it?,tia m3vuv.

author: andy3055
author_rank: Super Contributor
timestamp: October 21, 2021, 04:22:15 pm
content: Q386 and 387 are listed as BFR96 and S006075 respectively. I could not find any data so far on these. I would check the voltages as per the service manual first. Also, if anything is amiss, check them out of the circuit.Noticed your last post says Q376. Is that a mistake?

author: m3vuv
author_rank: Super Contributor
timestamp: October 21, 2021, 04:28:51 pm
content: sorry meant to say q386,anyway i changed it for a bfy50,made no difference,also the two resistors feeding the deflection plates should be 51 ohm,mine both read 57,would that make much difference?

author: andy3055
author_rank: Super Contributor
timestamp: October 21, 2021, 06:51:56 pm
content: I am not sure. although I don't think it matters, you can eliminate by putting in new parts there. I have not gone into details very much on this scope as mine is working with no issue. If I get some time to read the manual, I will make some comments here.

author: andy3055
author_rank: Super Contributor
timestamp: October 21, 2021, 07:09:59 pm
content: CH1/CH2 position controls are associated with Q177/187 and 277/287, respectively. Since both traces are off to one side, I would start tracing backwards from those. I think it could be a voltage related to those and/or the transistors before them.I am looking at "CH1 &CH2 Vertical Preamps" - foldout 2.

author: David Hess
author_rank: Super Contributor
timestamp: October 22, 2021, 01:07:15 am
content: Quote from: m3vuv on October 21, 2021, 04:23:52 amThat is odd. They should show signs of running hot and the printed circuit board should be discolored under them.

author: m3vuv
author_rank: Super Contributor
timestamp: October 22, 2021, 03:17:53 am
content: well,i removed q387,it tests ok bith a beta of 84.

author: m3vuv
author_rank: Super Contributor
timestamp: October 22, 2021, 03:19:56 am
content: what page of the manual are q 177 ect on?,i cant find it.

author: andy3055
author_rank: Super Contributor
timestamp: October 22, 2021, 04:13:37 am
content: Foldout 2. Check and Check vertical preamps. You also got some good feedback on Tek groups.

author: m3vuv
author_rank: Super Contributor
timestamp: October 22, 2021, 05:38:39 am
content: i only have the service manual on pdf,ive just replaced the 4 riffa caps in the psu,used blue x types,only 2.1 nf not 2.2 like the originals but rated at 8kv.

author: andy3055
author_rank: Super Contributor
timestamp: October 22, 2021, 06:14:34 am
content: Open the pdf. Do a ctrl+f and that will open a little field for search. Type in Q177 and see if it will find it. I can check the pdf and get back to you in a bit.

author: m3vuv
author_rank: Super Contributor
timestamp: October 22, 2021, 06:22:14 am
content: the search cant find it.

author: andy3055
author_rank: Super Contributor
timestamp: October 22, 2021, 06:26:28 am
content: Yeah, those are protected files. Check pdf page 157.

author: m3vuv
author_rank: Super Contributor
timestamp: October 22, 2021, 06:41:16 am
content: it gives the location as beeing 2 c,is that on the board with all the controls on,gives a pic of the front pannel board on this manual.

author: andy3055
author_rank: Super Contributor
timestamp: October 22, 2021, 06:54:34 am
content: Get this manual:https://w140.com/tekwiki/images/9/9a/070-3826-00.pdfPage 157 has the Vertical preamps.

author: m3vuv
author_rank: Super Contributor
timestamp: October 22, 2021, 07:35:59 am
content: it gives the location as 2c,is that on the board with all the controls on it,ie the front panel board?

author: andy3055
author_rank: Super Contributor
timestamp: October 22, 2021, 08:08:16 am
content: Check page 156. It is on the A10 main board towards the bottom left. Location 2C area.I saw your posts on Tek Groups.io. Did you try the responses from those people?It is just past 1 AM for me in the bay area. I am going to sleep. Will catch up in the morning. Brain does not function at this hour!

author: m3vuv
author_rank: Super Contributor
timestamp: October 22, 2021, 08:53:50 am
content: well i have found them,again a total ass to get to with the crt in situ,looks an ass of a job to remove the crt,it may get put back together and go on ebay as spares or repair,cheers for the help,the tek group io have been no use whatsoever! .

author: andy3055
author_rank: Super Contributor
timestamp: October 22, 2021, 10:12:28 pm
content: I still think you should check the voltages per the service manual on that section. I get the feeling that something has failed there. Since it does this on both channels, it has to be a common thing like power for both channels.There are some good tips on this thread:https://www.eevblog.com/forum/repair/tek-2215-repair/msg2508945/#msg2508945

author: m3vuv
author_rank: Super Contributor
timestamp: October 24, 2021, 01:17:28 am
content: does anyone know where the voltage test poins are located on this,all i can see is a ground tag/tp.

author: m3vuv
author_rank: Super Contributor
timestamp: October 24, 2021, 02:06:19 am
content: i located the test points under the psu cover,they all read within 100mv of what the service manual states.

author: andy3055
author_rank: Super Contributor
timestamp: October 24, 2021, 02:24:18 am
content: Even though the test points have the specified voltages, check the transistors and make sure they have the correct voltages.

author: m3vuv
author_rank: Super Contributor
timestamp: October 24, 2021, 02:42:34 am
content: thats the next step,trouble is they are total bastards to get to with the crt in the scope,may have to remove it but that looks a major task in itself.

author: m3vuv
author_rank: Super Contributor
timestamp: October 24, 2021, 03:14:28 am
content: Wel i have the crt removed,wasnt a big job infact,thing is is it safe to turn the scope on without the crt in it,or is the eht gonna spark all over the place and kill things,or should i just reconnect the eht to the tube and fire it up?.

author: m3vuv
author_rank: Super Contributor
timestamp: October 24, 2021, 03:47:40 am
content: well while i was in there i thought i would check some caps for esr,there are what look like tantalum caps,see pic by the tip of red probe,is that a tant cap?if so it reads infinity.

author: David Hess
author_rank: Super Contributor
timestamp: October 24, 2021, 04:05:52 am
content: That is a polystyrene or possibly polycarbonate plastic film capacitor. Ignore it. It reads infinity because it has a low value of capacitance.

author: andy3055
author_rank: Super Contributor
timestamp: October 24, 2021, 04:18:03 am
content: I would follow the diagram instead of just checking random components because it tends to make you deviate from what you are after.

author: m3vuv
author_rank: Super Contributor
timestamp: October 24, 2021, 04:42:15 am
content: i took it out and measured it,its fine,i have just ordered a solder heat gun to remove the transistors and test them,with it being a double sided board i feel i will lift tracks etc,also need to know if i can power this up with the crt removed,or possibly with just the eht connected?

author: jonpaul
author_rank: Super Contributor
timestamp: October 24, 2021, 05:42:49 am
content: BonjourA bit puzzling to read all of these notes from m3vuv and similar posts on 2215 on the excellent TekScopes Groups .io,I can only wonder why the complete and correct version of the manual and schematics is not easily available?I suggest to follow a logical troubleshooting procedure.Finally as an active contrib on both EEVblog and groups.io TekScopes, i can highly recommend the TekScopes and very surprized that it seems unresponsive to this thread.Bon Chance,Jon

author: m3vuv
author_rank: Super Contributor
timestamp: October 24, 2021, 06:26:00 am
content: Hi jon,im supprised by the lack of responce from the tek io groupe,my main issue is running the scope to check transistor base voltages in the vert amp section with the crt removed as its nearly imposible to probe them with the crt in the scope,but im wondering if i power it up without the tube in,will the eht rise to crazy levels and kill something,thats where i am at at this moment in time,sort of chicken and egg,i have the correct manual,but on a pdf its hard going,i much prefer paper! 73 m3vuv.

author: m3vuv
author_rank: Super Contributor
timestamp: October 24, 2021, 03:07:12 pm
content: is it safe to power the scope up with the crt removed to take measurments?,as stuck until i get advice on doing this.tia.

author: Ground_Loop
author_rank: Frequent Contributor
timestamp: October 24, 2021, 03:41:34 pm
content: With no input signal and the input switch set to GND can the trace be positioned in the center of the CRT?

author: m3vuv
author_rank: Super Contributor
timestamp: October 24, 2021, 06:09:50 pm
content: FFS cant you guys read my last post!!!!

author: Ground_Loop
author_rank: Frequent Contributor
timestamp: October 25, 2021, 12:28:45 am
content: Quote from: m3vuv on October 24, 2021, 06:09:50 pmI was just asking to see if you had tried it before taking the CRT out. Anyway, I doubt anyone is going to tell you it's safe to run the scope with the CRT disconnected and I hope the reason is obvious. Try it, see what happens.

author: bdunham7
author_rank: Super Contributor
timestamp: October 25, 2021, 03:52:26 am
content: Quote from: m3vuv on October 24, 2021, 03:07:12 pmI've never run one without a CRT in it so I can't be completely sure that nothing will burn up due to no load, but I don't know what it would be. As for personal safety, there's about -2000V on some of the CRT socket terminals, about +10kV on the red wire that you disconnected from the front of the CRT and a few hundred volts or so on the 4 wires you disconnected from the middle of the CRT. I'd be super careful not to let any of those short out on anything, especially the horizontal and vertical deflection wires.. Usually I can do everything I need as far as testing from underneath, but if that isn't practical and you want to do it with the CRT out, I wouldn't go probing around a live board. Connect up with test clips, then power on and be sure to power off and wait a bit before moving on.

author: m3vuv
author_rank: Super Contributor
timestamp: October 25, 2021, 05:59:09 am
content: Well i hooked up the eht to the crt and moved the whole lot to one side,heres a few readings i took,on q387 base i get 8.8v,it should be 2.6!,r290 wiper measures as follows,fully cw=3.44,fully ccw 3.4v,r190 is fully cw3.4,fully ccw 3.4v,dont know if this helps?

author: m3vuv
author_rank: Super Contributor
timestamp: October 25, 2021, 06:01:26 am
content: groundloop,with both inputs set to ground and no input the furthest up the screen i can get both traces is about 2 divisions from the bottom of the screen.

author: andy3055
author_rank: Super Contributor
timestamp: October 25, 2021, 07:21:52 pm
content: Quote from: m3vuv on October 25, 2021, 05:59:09 amThat poor change should give you the clue to the problem. this is the area you should concentrate on.The 2 wipers are connected to 2 resistors R191 and 291. The other ends of those resistors are connected to -8.6 volts. Check if that supply is there. If not, trace back from that point to find where the -8.6 volts is disappearing.Also check the +8.6 volts on one side of R178 and 278. If that is missing, trace back for the +8.6 volts.

author: m3vuv
author_rank: Super Contributor
timestamp: October 26, 2021, 12:20:59 am
content: I get -8.6v on one end of r191 and r291 and +8.6v on one end of r178 and r278,tia.

author: andy3055
author_rank: Super Contributor
timestamp: October 26, 2021, 12:51:47 am
content: Those wipers should vary between 3.5 to 4.8 volts, 4.3 volts being the mid range, from what I see on the manual. I am not home to check my scope. I wonder if there is some sort of a poor connection where the leads from the pot is mating that board since it happens on both channels. May be you can re-seat any plugs in that vicinity, just in case!

author: m3vuv
author_rank: Super Contributor
timestamp: October 26, 2021, 03:30:24 am
content: the voltages on the vert position pot wipers is as follows fully ccw=3.6v,halfway point =1.2v,fully cw =3.6v,there are no bad conections.

author: bdunham7
author_rank: Super Contributor
timestamp: October 26, 2021, 03:58:28 am
content: Quote from: m3vuv on October 26, 2021, 03:30:24 amWhen the scope was all together, was the behavior such that if you rotated the knob all the way CCW the trace would be at on extreme (low, I guess) and as you rotated it CW, it would come up to a maxima somewhere in the center and then go back down again as you reached the CW limit?

author: m3vuv
author_rank: Super Contributor
timestamp: October 26, 2021, 07:09:13 am
content: im pretty sure when it was together the controls operated normaly but just wouldnt move the traces more than about 3 divisions from the bottom,i understand what your getting at but no it didnt go up and down with knobs turned in one direction,although the wiper voltages say it should do,if it had i would of noticed that as it would of been odd.

author: andy3055
author_rank: Super Contributor
timestamp: October 26, 2021, 04:32:01 pm
content: Quote from: m3vuv on October 26, 2021, 03:30:24 amYour cw and ccw positions have the same voltage?Take a look at what I wrote earlier which is based on the service manual. Your readings will not make the cut.

author: m3vuv
author_rank: Super Contributor
timestamp: October 27, 2021, 10:59:43 am
content: quick update q 350 base goes from -.273v fully ccw to +.456v fully cw,360 base fully ccw =+.392v to -.364v,only changes with pos 1 pot.

author: m3vuv
author_rank: Super Contributor
timestamp: October 28, 2021, 04:34:10 am
content: well i managed to get some more readings before a 10nf riffa cap that i had missed blew up!,on q360 emitter i get 1.129v on q350 emitter i get 0.574v,q386 base reads-4.8v should be -4.3v,q387 base reads-4.099,should be +2.6v,also is the size of the riffa caps critical as i am struggling with replacements,it should be 10 nf all i have is 2.1nf at 8kv.

author: m3vuv
author_rank: Super Contributor
timestamp: October 28, 2021, 04:45:27 am
content: sorry the caps i have are 2138nf not as i said before.

author: m3vuv
author_rank: Super Contributor
timestamp: October 28, 2021, 06:39:38 pm
content: some more readings, Heres what i measure in respect of groundq377 C=1.8v E=-2.1v B= -1.5vq387 C= 21v E= 9.4v B= 9.9vq376 C= -2.3v E= -5.6v B= -4.97vq386 C=9.5v E= -5.7v B= -3.1vthats with ch pos pot about halfway.

author: bdunham7
author_rank: Super Contributor
timestamp: October 28, 2021, 07:22:15 pm
content: Quick transistor troubleshooting tip--Vbeshould always be about 0.6V or so (or -0.6V as the case may be) and when it isn't, something is wrong. In this case Q386 has a Vbeof 2.6V, which means it should be saturated on, but Vceis 15.2 V. Unless I've made some obvious error--which I do regularly since I can't keep left/right, +/- or PNP/NPN straight in my head--it looks to me like Q386 is bad.

author: m3vuv
author_rank: Super Contributor
timestamp: October 28, 2021, 07:44:59 pm
content: well just an update,my hot air soldering gun arrived yesterday so used it to remove q386,tested it on my component tester off board and it read as a back to back diode!,hope thats the issue,just orderes 2 replacements for that and its twin,2 genuine phillips brf 96s transistors for £3.50,hope they fix the scope,if so it will stand me at about £25 and a few hours work.

author: m3vuv
author_rank: Super Contributor
timestamp: October 28, 2021, 08:01:16 pm
content: would a bc-107/8/9 be ok as a sub just for testing to see if the vert deflection position control works?,tia m3vuv

author: bdunham7
author_rank: Super Contributor
timestamp: October 28, 2021, 09:00:14 pm
content: I don't know of any reason that any small-signal NPN wouldn't nominally work, a 2N3904 might even work OK up to a fair portion of the BW. Is your board noticeably discolored in that area?

author: m3vuv
author_rank: Super Contributor
timestamp: October 28, 2021, 10:10:33 pm
content: no the board looks like new,no signs of heat.

author: m3vuv
author_rank: Super Contributor
timestamp: October 29, 2021, 03:54:13 am
content: this is how q386 tests on my component tester out of circuit.

author: bdunham7
author_rank: Super Contributor
timestamp: October 29, 2021, 04:02:02 am
content: If that is one of the versions of the ATMEGA328 based tester, that would be one typical result indicating a bad transistor. What goes wrong internally I don't know.

author: m3vuv
author_rank: Super Contributor
timestamp: October 29, 2021, 05:59:24 am
content: Well theres good news and bad news on this one,after subbing the duff transistor,i was replacing the crt,i found the horiz deflection plates a pig to get to so decided to extend the wires so i could connect them before pussing the crt into its socket,i had the scope on its side to do this as it was better to solder the wires back into the pcb,i then put the scope normal way up and fitted the crt,ok time to test,on power on after a few seconds smoke came from under the crt,i quickly unplugged it from the mains and turned it over to look at the underside of the pcb where sat a small coil of soler wire that had shorted out the underside of the pcb,powered it up againe to see both traces now sitting about 3/4 up the screen,its the oposit of the original fault!,also it sees no input on either channel and the traces only do a horiz sweep of about 4 divisions,i will wait untill the replacement bfr -96s transistors arrive and fit them and test againe but i feel its not looking good, angry over making sutch a stupid mistake!!

author: m3vuv
author_rank: Super Contributor
timestamp: October 29, 2021, 06:01:31 am
content: yes it is,brought it as a kit,only issue is the zif socket isnt the best but as it was only about £8 i cant moan,its a very handy tool.

author: m3vuv
author_rank: Super Contributor
timestamp: October 29, 2021, 06:03:53 am
content: the case is made up of scrap pcb material,i have a piece of veroboard with 3 pins on it that fit into the ziff socket with 3 small leads with insulated croc clips on.

author: bdunham7
author_rank: Super Contributor
timestamp: October 30, 2021, 12:35:55 am
content: Quote from: m3vuv on October 29, 2021, 05:59:24 amI've misprobed and broken a few things, I like not to remember them too much. However, do be very, very careful working with those deflection plate pins on the CRT--never put any sideways force on them or pry against the glass, no matter how stuck they are. You can break things internally pretty easily, and in the worst case blow up the CRT and injure yourself. Worst case you cut the wire, then when the CRT is out you can get at them a bit better. Oh, and I haven't yet had the misfortune of shorting the board like that, but a lot of the times on scopes if I'm working on them with the case off, I'll turn them on their left side (CRT down). 2400 series are different, I jack those up with blocks and put a fan on the side. There's lots of volts at some points on the board, best to keep it away from anything.

author: m3vuv
author_rank: Super Contributor
timestamp: October 30, 2021, 04:52:12 am
content: i realise that now! hindsite is a wonderfull thing!! lol

author: m3vuv
author_rank: Super Contributor
timestamp: October 30, 2021, 04:56:09 am
content: Im not doing anything else to it untill i fit the replacement transistors after they arrive,at the moment q386 and q 376 are just random npn replacements from my junkbox,but at least the pos pots sort of work now.

author: m3vuv
author_rank: Super Contributor
timestamp: November 01, 2021, 08:47:05 pm
content: well the replacement transistors are fitted,i now hove the trace for want of a better word adjustable but now have no sweep,did i mention i put the scope down on a pice of coiled solder wire,it shorted sommat on the main board as sommat smoked,pulled the plug but to late i think!,cant see any signs of anything beeing fried tho,all i get now is 2 dots on the screen,as if in xy mode,any ideas where to start,seems i fixed one issue and created a bucket load more,teach me to keep my bench clean!!p.s the only way i get anything on screen is by using the beam finder. tia

author: m3vuv
author_rank: Super Contributor
timestamp: November 04, 2021, 08:32:57 am
content: can anyone spot q736 on the pcb pic attached,i cant see it!.

author: jdragoset
author_rank: Frequent Contributor
timestamp: November 04, 2021, 01:24:58 pm
content: Q 736 is on A-12 "attenuator/sweep board.

author: m3vuv
author_rank: Super Contributor
timestamp: November 04, 2021, 06:40:52 pm
content: found it,base measures moving the horiz pos ccw=-8.27v cw=-8.24v tb pos makes no difference.

author: m3vuv
author_rank: Super Contributor
timestamp: November 04, 2021, 08:16:58 pm
content: i may start pulling transistors and testing them,can someone give me a good starting point?ie q whatever or board ref a1 etc,im talking about the main board here ok .

author: bdunham7
author_rank: Super Contributor
timestamp: November 04, 2021, 08:21:32 pm
content: Quote from: m3vuv on November 04, 2021, 08:16:58 pmIf you just want to test transistors in a powered circuit, just measure all the voltages, or at least Vbeand you should be able to spot any that aren't 'in the zone'. This can be done pretty quickly by just putting one probe on the base, then the other on C and E in succession, noting the voltages. Then measure Vcedirectly and make sure the math works out.I'm not clear what the issue is right now and your posts are hard to read--are you using a phone? We can tell...I know you fried something, but exactly what doesn't work?

author: m3vuv
author_rank: Super Contributor
timestamp: November 04, 2021, 08:25:15 pm
content: the horiz position doesent work,neither the tb no sweep on any settings trigg xy normal mode etc,all i get is a dot with the beam finder pressed.i can move the dot up and down with the vert pos pot,thats the lot!

author: m3vuv
author_rank: Super Contributor
timestamp: November 04, 2021, 08:29:40 pm
content: i would rather remove the transistors and test with my component tester off board ,i find it less hassle to remove them with my hot air solder station than probe them,poor eyesight dont help !,just want to know where to start removing them,if that makes sense? tia.

author: bdunham7
author_rank: Super Contributor
timestamp: November 04, 2021, 08:31:28 pm
content: Quote from: m3vuv on November 04, 2021, 08:25:15 pmOK, so the dot is off the screen unless you press beam finder and even in XY mode you can't get it back on the screen with the horizontal position knob. Do you know the exact location or general area that you shorted it out? Have you tested voltages at Q763? And then working your way out from Q763? Your best bet right now is to slow down and print out a copy of the XY/Horizontal schematic and then test and write down all the voltages.

author: bdunham7
author_rank: Super Contributor
timestamp: November 04, 2021, 08:34:05 pm
content: Quote from: m3vuv on November 04, 2021, 08:29:40 pmWell, that takes away a lot of clues because then you don't have the in-circuit voltages and those can guide you in the direction of the problem. If you want to test components, start with Q763 and in the area of the shorting. As for eyesight, try much brighter room (not local) lighting.

author: m3vuv
author_rank: Super Contributor
timestamp: November 04, 2021, 08:51:05 pm
content: Q763 tests ok with a beta of 166.

author: m3vuv
author_rank: Super Contributor
timestamp: November 05, 2021, 04:01:47 am
content: well i have removed the following transistors and tested them: q763=ok,q780=ok,q789=ok,q785= tests as a back to back diode,see pic,just wondered what i can use as a replacement?,also is it likley to have led to more damage like in an audio amp when theone transistor fails and wipes out others?

author: m3vuv
author_rank: Super Contributor
timestamp: November 05, 2021, 06:24:25 am
content: any idea what q785 actualy is ie what does the tek part number = in the real world,i cant find the civy part number in the manual.

author: m3vuv
author_rank: Super Contributor
timestamp: November 05, 2021, 07:57:21 am
content: well ive been told by the folks at tech groups io that its a 2N5551,just need to find its pnp partner now,ive just ordered 20 from ebay for £1.50,just hope there not chineesium fakes!!

author: m3vuv
author_rank: Super Contributor
timestamp: November 08, 2021, 04:24:23 am
content: well replacements for q785 are ordered,well heres a list of whats been removed and tested so far q763,q780,q789,q785,q765,q770,q753,q779,q775,q747 all test good apart from q785,can anyone suggest any more i should test while i am at it?,cheers Paul.

author: Gyro
author_rank: Super Contributor
timestamp: November 08, 2021, 08:17:28 pm
content: Quote from: m3vuv on November 05, 2021, 04:01:47 amWhilst waiting for replacement transistors, I'd take a step back and give your work area a deep clean. Analogue test gear doesn't take well to that degree of contamination being transferred into their innards.

author: t1d
author_rank: Super Contributor
timestamp: November 09, 2021, 03:30:53 pm
content: I have not read your thread, but I thought you might like to have the files that I googled, when I first got my 2215. Maybe I found something that you did not. Hope they help. I uploaded them to DropBox =https://www.dropbox.com/s/s72iu3thvknaolb/Tektronix%202215%20Oscilloscope.zip?dl=0