Tek 7313

[mike11]

I am having a prob getting this scope to work after repairing it...... Here is the history of it .... I got it non working blowing fuses...... I found a bad cap and bridge in the ps........I replaced them and power sup works fine now........it has the following plug ins ....(2) 7A18Ns and a 7B50 time base unit......when powered up i only get 2 dots high and low in the right side of the screen ..... I am guessing this is what would be the display for voltage and time on top and bottom of the screen ......if so I am not getting any horiz deflection ..... I did go back in and check all the transistors on the back and all check out OK... also checked the voltage refernce points on the time base unit through the side of the machine with the cover off the plug in and the 50,15 and 5s are all there as they should be + and - as and where they should be .... Now I am at a brick ..... anyone have any ideas ??

Thanks

[tautech]

I am having a prob getting this scope to work after repairing it...... Here is the history of it .... I got it non working blowing fuses...... I found a bad cap and bridge in the ps........I replaced them and power sup works fine now........it has the following plug ins ....(2) 7A18Ns and a 7B50 time base unit......when powered up i only get 2 dots high and low in the right side of the screen ..... I am guessing this is what would be the display for voltage and time on top and bottom of the screen ......if so I am not getting any horiz deflection ..... I did go back in and check all the transistors on the back and all check out OK... also checked the voltage refernce points on the time base unit through the side of the machine with the cover off the plug in and the 50,15 and 5s are all there as they should be + and - as and where they should be .... Now I am at a brick ..... anyone have any ideas ??

Thanks

Welcome to the forum.

Sounds like the sweep is not functioning. 

This might be handy:
http://www.sphere.bc.ca/test/tek-parts/troubleshooting-scopes.pdf

[mike11]

yep .. lemme dig in with that troubleshooting tree and see where I end up ... thank you

[mike11]

kinda lost without know where the H amp section is in the machine ....is that part of the plug in or in the main frame itself ??

[jmsc_02]

Dear

The H deflection board is in the mainframe

I'm trying to find the  7313 service manual but I couldn't. Here is the 7623A service manual I suppose you can use it to troubleshoot a while and, at least, help to identify the parts of the frame hoping 7k series has similar construction design.

http://exodus.poly.edu/~kurt/manuals/manuals/Tektronix/TEK%207623A%20Operation%20&%20Service.pdf

Regards

[miguelvp]

Dear

The H deflection board is in the mainframe

I'm trying to find the  7313 service manual but I couldn't. Here is the 7623A service manual I suppose you can use it to troubleshooting a while

http://exodus.poly.edu/~kurt/manuals/manuals/Tektronix/TEK%207623A%20Operation%20&%20Service.pdf

Regards

Tek 7313 service manual is in here:
http://w140.com/tekwiki/wiki/7313

direct link:
http://w140.com/mmm/tek-7313.pdf

Note, it did take a while to upload so be patient.

[mike11]

thank you ... I did find pins 7 and 8 on plug p890 in the power sup are not right pin 7 shows +40 and +24.5.on the schem.. which is correct ?? pin 8 shows coming off of the transformer tap 15 at +13 which I have at the transformer but at p890 its 0v ... all resistors between there were tested lifted and right on the money .... CR820 and 821 arent testing like a normal diode should they or are they a special type of diode... out of circuit these charge up and open like a cap ...

http://w140.com/tekwiki/images/5/5f/Tek-7313-lvps.png

PS schem

Thank you

[jmsc_02]

Dear,

The 7th pin of my P890 connector of an 7623A scope has around 16V, but i believe that is more important if you have 130Vdc on pin 6 and maintain it indepently of the load because 7th pin "is the returning point" for the 130V supply. (It's not connected directly to ground as the others)

CR820 & CR821 are diodes and you can test it as an usual diode (The service manual type them as 1N5000 diodes).

[mike11]

As per the serv manual test chart all my voltages are as they should be ..... The trouble shooting tree is a bit misleading or confusing to say the least .... Explains set up and if trace appears focus if not press beam finder and explains for either a dot or no trace ..... Here's what I have ..... I have 2 smears which are the 2 traces and will move up and down ...... Left and right control I do not have ...... Not do I have the ms and v display on top and bottom of the screen ..... Everything on the horiz amp board seems fine from a Dvom check of the transistors anyway .... I'm confused as to if this is a horiz amp prob, time base prob or prob with deflection plates .... If so physically where is that circuitry located ?? I will upload a pic in a few mins
Thanks

[mike11]

heres a pic this is as good as i can get it and with intensity almost all the way up

[tautech]

That's a start.
There will be other members that are more familiar with Tek 73** than I so let's work through it.
Service manual is quite large and slow (here) to download so as yet I don't have it to refer to yet.

Usually on the schematics there are DC voltages that are ONLY relevant when the scope is set in a prescribed way, nevertheless they can be very useful in identifying the problem area/s.
In your case I'd start with the CRT plate output stages instead of going on a wild goose chase.


What plugins are installed and are they the only ones you have?

The Sweep circuitry will be in the Timebase plugin.

Do you have another scope?

[mike11]

I have a good 2213 I use ..... heres something its doing thats not in the flow charts... with beam finder held in I do get my test signal .... SWEEPING VERTICALLY ...    let it go and it goes off screen... What is the hell would cause it to sweep vertically off screen ........ Plug ins are (2) 7A18N and a 7B50 time base .. they are the only ones I have

[dom0]

Do yourself a favor and verify all the cabling before going any further.

[mike11]

Do yourself a favor and verify all the cabling before going any further.

how and where do I start ? i cant find anything showing what goes where.. the serv manual basically breifs over assuming your familiar with the unit

[dom0]

The schematics of each board marks every connector with it's ref designator and what's the ref designator of the other end. Usually Pxnn or Pxxnn or Jxnn or Jxxnn means x, xx = assembly number, nn = connector number. I.e. J2193 goes to J1193, and there is only one assembly 21 and one assembly 11 and one connector 93. Almost all of them are marked on the PC boards, too. Pin headers have an arrow indicating pin 1.

[Addicted2AnalogTek]

Do yourself a favor and verify all the cabling before going any further.

Solid advice.  I once spent a day or so totally baffled why my B sweep would not work at all... turns out I had the cables for X axis and Horizontal alt sync swapped.    I've gotten in the habit of making tiny flags for each cable end with the jumper number written on it when I have to take some out of their sockets.

[Vgkid]

For one of the issues, is there a trace rotation pot. Try adjusting it, and see what happens.

[mike11]

Only thing I saw off kilter in there is the external z input was on the wrong plug .... I saw a rotation pot on the schematic on the Z board ..... But now I just have a faint blotch no trace like the plug ins are out ... This things driving me nuts

[Addicted2AnalogTek]

don't feel bad, I have a 468 that's driving me nuts as well. Every time I think I found the problem I end up being wrong.  This one scope has been a never ending source of grief.

[tautech]

I have a good 2213 I use ..... heres something its doing thats not in the flow charts... with beam finder held in I do get my test signal .... SWEEPING VERTICALLY ...    



let it go and it goes off screen... What is the hell would cause it to sweep vertically off screen ........ Plug ins are (2) 7A18N and a 7B50 time base .. they are the only ones I have

First thing that comes to mind is stuck buttons. 

Give us some more history of this unit please.
Has it operated correctly in the time you've had it?

I have a good 2213

Great, you might need it to check waveforms match those in the service manual.

I do get my test signal

What's wrong with using the Probe Cal signal? 
Is it not working?

[mike11]

First thing that comes to mind is stuck buttons. 

Give us some more history of this unit please.
Has it operated correctly in the time you've had it?

I have a good 2213

Great, you might need it to check waveforms match those in the service manual.

saw tooth at a few test points was checked with the 2000 and ok

I do get my test signal

What's wrong with using the Probe Cal signal? 
Is it not working?
[/quote]

since I have it no ? my father was head of engineering at a company and ordered this new in the 90s for them, it was used and calibrated till one day his techs came to him and said its blowing fuses. being as old as it was they bought new and scrapped it. I repaired the power sup and this is how far I gotten ... PS had a shorted can cap and shorted bridge..

Probe cal signal on front of the display ?? if thats what youre referring to thats what the probe was in

[tautech]

OK. thanks.
When you had it open did you see any evidence of previous rework/repairs? Components that look different to the others? Different looking solder joints? Screws missing?


Could you have possibly made the wrong connections on reassembly after the PSU repair?

[jmsc_02]

What happens if you exchange the plugins? (Timebase where amplifier's place and viceversa?) In the operation manual says something like you can use amplifier plugin on the timebise slot to get different functions like X-Y mode and putting the timebase on the amplifier slot has the "raster-display" function.

Install a vertical amplifier on the time base slot to see what happens, if all is right you will get a lissajous figure on the screen. (i'm trying to discard a failure on the timebase unit)

[mike11]

no other than calibration labels its shows no evidence of tampering ........ Heres a few pics of what I just did
pic 1740 is with 2 vert units in
pic 1741 is with vert and TB ... looks like its tracing but wont move over into screen
pic 1742 is with vert and tb with beam find pressed

[mike11]

are the little buttons on the time base suppose to light when depressed these dont only trigger light comes on ... also this only displays those traces i showed in those pics with amp chosen on tb unit when time base is chosen you get nothing