tektronix 2213 cant view both trace

[topology]

hi all
recently i  bougth a tektronix 2213 scope  when i test it .......it can trace CH1 then i switch to CH2 and it trace that to nice 
BUT ,
WHEN I SELECT BOTH IT ONLY SHOW ONLY ONE TRACE 
this problem  only on CHOP , ALT in VERTICAL MODE  & INTENSE MODE
>THIS SCOPE CANT VIEW 2 TRACE<

i have downloaded the service manual but i don't know where to start   

[Addicted2AnalogTek]

did you hit beam find while you were attempting to view 2 traces to see if it's actually there but just not visible? 

[topology]

yes i did nothing just one trace

[Addicted2AnalogTek]

I'm fairly new to all of this myself, but what I would do is try to isolate what area the problem is in.   

Possibilities:
-Able to view both channels separately but not together =
1 - Chop/Alt clock not properly functioning?
2 - 2nd trace sweep not being triggered when Chop/alt clock active?
etc.

it sounds like you've probably done this already, but mess with every last setting and try every possible combination of settings and list what ones are not working correctly, and then compare and find what section all of these issues have in common.   

My personal first guess is the chop/alt clock.  download the manual and start checking voltages and waveforms. 

[topology]

this is what i found

[Addicted2AnalogTek]

bingo.   I've noticed that even though my Tek 465 works properly, the chop clock seems to have some leakage issues. The 468 I'm repairing also had chop clock issues.    I will download the manual and take a look to see if I can aid further.   

  In the meantime, I suggest you start on the vertical mode switch board testing the voltages (or as close as you can get to that point - such as the pins of the connector that goes into the vertical switching logic).    I'm guessing that the manual is one which does have voltages specified in the schematics, and the settings in which you should have the scope in order to get proper readings. 

Are all 3 (CH1 enable, CH2 enable, and Chop Clock) stuck at the same voltage?  do they change at all when you cycle those vertical mode selector switches, or do they just stay constant?

I'll have a look at the manual soon and get back with some more ideas.

[topology]

yes they changed and i need to do more test 

[Psi]

I don't know this scope but have you checked you don't have math functions on A+B etc

Never mind, I see you have found bad signals on the board

[Addicted2AnalogTek]

Even though this isn't going to have anything to do with your problem, go ahead and check your power supply voltages, waveforms, and ripple on the regulated side and make sure that they are within spec.  If they aren't, they could easily affect any of the waveforms/voltages you measure throughout this troubleshooting and make you think that you may have issues where you really do not.

After that, check the waveforms from the picture below and see if you find anything off.   If you don't, then the culprit will likely be U310A (on diagram 3).   However I think you will find some bad waveforms in the sweep logic (diagram 5).   maybe a fried VR644 (check voltage across it), a cracked resistor, or bad cap, or it could be something else.

[topology]

u know what the manual i have downloaded schematic 3 is missing   
on other hand U317 PIN 3 which have the missing clock signal is connected only to U301 PIN 3  ONLY ?!!!! the datasheet just say CLK1 .......if i fined those IC's tommorro i am going to replace them

[Addicted2AnalogTek]

http://ko4bb.com/manuals/index.php

download the 2nd one.   

I noticed that diagram 3 was missing from the ElektroTanya manual also.

It can't hurt to replace those IC's, but it might not solve your problem.   The origin of your problem could be further back in the circuit. If swapping those out doesn't solve it, I think you might find your answer in the diagram that I posted.

[topology]

thank you for this manual
i swap those IC's ..... no effect on target 
i think i need to deeper

[Addicted2AnalogTek]

I had a feeling that swapping those wouldn't do anything.    I very recently began going thru my first real scope troubleshooting and repair, and have learned loads since.   I've probably spent a couple hundred dollars on various parts (in quantity) before I figured out how to trace and identify the actual problem parts.   

I wouldn't suggest replacing anything else unless you know that it's definitely bad.  Either that, or because you're left with no other choices other than process of elimination type tactics. 

[topology]

that's all u can do with no schematics
i agree with you but i do not have  time for my scope wright now
and those ic's i have them for around 3$ thank you for the schematic again