Tek 7313  - Page 1
Forum section: electronics / repair

author: mike11
author_rank: Contributor
timestamp: January 26, 2016, 05:30:35 am
content: 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

author: tautech
author_rank: Super Contributor
timestamp: January 26, 2016, 05:36:03 am
content: Quote from: mike11 on January 26, 2016, 05:30:35 amWelcome 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

author: mike11
author_rank: Contributor
timestamp: January 26, 2016, 06:29:03 am
content: yep .. lemme dig in with that troubleshooting tree and see where I end up ... thank you

author: mike11
author_rank: Contributor
timestamp: January 26, 2016, 06:53:57 am
content: 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 ??

author: jmsc_02
author_rank: Regular Contributor
timestamp: January 26, 2016, 08:18:05 am
content: DearThe H deflection board is in the mainframeI'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.pdfRegards

author: miguelvp
author_rank: Super Contributor
timestamp: January 26, 2016, 08:51:10 am
content: Quote from: jmsc_02 on January 26, 2016, 08:18:05 amTek 7313 service manual is in here:http://w140.com/tekwiki/wiki/7313direct link:http://w140.com/mmm/tek-7313.pdfNote, it did take a while to upload so be patient.

author: mike11
author_rank: Contributor
timestamp: January 26, 2016, 09:01:24 am
content: 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.pngPS schemThank you

author: jmsc_02
author_rank: Regular Contributor
timestamp: January 26, 2016, 10:21:24 am
content: 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).

author: mike11
author_rank: Contributor
timestamp: January 26, 2016, 01:15:56 pm
content: 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 minsThanks

author: mike11
author_rank: Contributor
timestamp: January 26, 2016, 01:19:58 pm
content: heres a pic this is as good as i can get it and with intensity almost all the way up

author: tautech
author_rank: Super Contributor
timestamp: January 26, 2016, 06:14:41 pm
content: 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?

author: mike11
author_rank: Contributor
timestamp: January 26, 2016, 07:19:38 pm
content: 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

author: dom0
author_rank: Super Contributor
timestamp: January 26, 2016, 09:25:32 pm
content: Do yourself a favor and verifyallthe cabling before going any further.

author: mike11
author_rank: Contributor
timestamp: January 26, 2016, 09:35:37 pm
content: Quote from: dom0 on January 26, 2016, 09:25:32 pmhow 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

author: dom0
author_rank: Super Contributor
timestamp: January 26, 2016, 09:38:32 pm
content: 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.

author: Addicted2AnalogTek
author_rank: Frequent Contributor
timestamp: January 26, 2016, 11:19:55 pm
content: Quote from: dom0 on January 26, 2016, 09:25:32 pmSolid 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.

author: Vgkid
author_rank: Super Contributor
timestamp: January 27, 2016, 12:21:24 am
content: For one of the issues, is there a trace rotation pot. Try adjusting it, and see what happens.

author: mike11
author_rank: Contributor
timestamp: January 27, 2016, 05:12:25 am
content: 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

author: Addicted2AnalogTek
author_rank: Frequent Contributor
timestamp: January 27, 2016, 05:32:49 am
content: 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.

author: tautech
author_rank: Super Contributor
timestamp: January 27, 2016, 08:00:51 am
content: Quote from: mike11 on January 26, 2016, 07:19:38 pmFirst 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?QuoteGreat, you might need it to check waveforms match those in the service manual.QuoteWhat's wrong with using the Probe Cal signal?Is it not working?

author: mike11
author_rank: Contributor
timestamp: January 27, 2016, 08:37:34 am
content: 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?QuoteGreat, 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 okQuoteWhat's wrong with using the Probe Cal signal?Is it not working?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

author: tautech
author_rank: Super Contributor
timestamp: January 27, 2016, 08:50:22 am
content: 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?

author: jmsc_02
author_rank: Regular Contributor
timestamp: January 27, 2016, 10:54:48 am
content: 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)

author: mike11
author_rank: Contributor
timestamp: January 27, 2016, 02:16:06 pm
content: no other than calibration labels its shows no evidence of tampering ........ Heres a few pics of what I just didpic 1740 is with 2 vert units inpic 1741 is with vert and TB ... looks like its tracing but wont move over into screenpic 1742 is with vert and tb with beam find pressed

author: mike11
author_rank: Contributor
timestamp: January 27, 2016, 02:18:49 pm
content: are the little buttons on the time base suppose to light when depressedthese 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

author: dom0
author_rank: Super Contributor
timestamp: January 27, 2016, 02:51:32 pm
content: The small mainframes (73xx, 74xx, 75xx, 76xx) usually don't have the lamp power fitted.If you have checked all connections, power supplies and knobs, then I'd say it's time to get out another scope and check whether the vertical and horizontal signals are correct, working backwards from the deflection plates or bisecting from the main board.

author: mike11
author_rank: Contributor
timestamp: January 27, 2016, 03:18:27 pm
content: Quote from: dom0 on January 27, 2016, 02:51:32 pmi would appreciate some guidance as to what to check and where ... I have another here to check what ever is needed.....I just checked all my voltages on the Z board again to be sure a few are low but not sure if this is my prob or nothere is what they are at the following plug locationsPLUG 1172Volts Measured volts250 232130 13050 5015 15-15 -12.2-75 -69PLUG P1171-50 -49.9pin 7 -12.2130 130+50 +49.9+15 +15+5 +4.9-15 -12.2PLUG P1170-15 -12.25 4.915 15130 129.9250 231

author: tautech
author_rank: Super Contributor
timestamp: January 27, 2016, 08:42:07 pm
content: Table 3-1 on P3-4 of the service manual specifies the correct voltages, ripple and tolerances of PSU voltages.Get all these to spec first, namely -15 and -75 that by your measurements are out of tolerance.But, this may not be a PSU issue, more likely a cap between those rails and GND dragging the rails down.There is much info regarding finding the problem area, have a good study and work your way through things.No need to make things hard for yourself, just find what is dragging the PSU down, fit this and then trace the scopes analogue signal path with the schematics and the waveform test points.Any digital stuff can be left unit later if there is a need to look at it.Again, break this repair into blocks, fix (get to spec) and move to the next step.

author: jmsc_02
author_rank: Regular Contributor
timestamp: January 27, 2016, 09:24:29 pm
content: How the post above my, verify caps of the power supply. Recently i've changed C811 (cap of the -15v rail) and all the troubles disappear. If I put my scope on the supply rail, I could see a lot of ripple instead of a plane and constant signal.

author: mike11
author_rank: Contributor
timestamp: January 28, 2016, 04:23:29 am
content: My -15 on a scope looks like a saw tooth .... Lots of rip .....

author: tautech
author_rank: Super Contributor
timestamp: January 28, 2016, 07:47:59 am
content: Quote from: mike11 on January 28, 2016, 04:23:29 amThat's common also WHEN the supply rail is overloaded.(PSU operating beyond design)Time to start isolating parts of the scope to see where the culprit is....more reading for you to do.

author: mike11
author_rank: Contributor
timestamp: January 28, 2016, 11:53:04 am
content: As much as a pain it was to pop that cap out I did... My capacitance meter won't go that high but a check with a Dvom and it's wide open, won't charge up at all .... I'm gonna get a good one in there and rule that out before going any further and see where I end up

author: jmsc_02
author_rank: Regular Contributor
timestamp: January 29, 2016, 10:47:28 am
content: that's fine. It's a little tricky change the PSU caps but nothing impossible.Good luck!

author: mike11
author_rank: Contributor
timestamp: February 02, 2016, 12:55:19 pm
content: ok ... making headway.... changed that cap and now voltages are right on the spotnow with beam find on I can see the traces..... they are compressed horizontally.... they do stretch a hair and are fully moveable up and down...seems now I have a prob in the H ampany suggestions ?

author: mike11
author_rank: Contributor
timestamp: February 04, 2016, 07:09:36 pm
content: bueler ?

author: Addicted2AnalogTek
author_rank: Frequent Contributor
timestamp: February 04, 2016, 09:21:55 pm
content: You really should go thru and read the Tek troubleshooting guide. It will have the answer to the majority of your questions regarding the repair of your scope.http://sphere.bc.ca/test/tek-parts/troubleshooting-scopes.pdf

author: mike11
author_rank: Contributor
timestamp: February 04, 2016, 10:31:48 pm
content: My machine slows down so bad with PDFs it literally takes a few mins for one page to load then when you realize your 20-30 pages away in the book where you need to be wait another 5 mins for the next of you scrolled to to open and see where you are ...... Frustrating like you can't imagine

author: miguelvp
author_rank: Super Contributor
timestamp: February 04, 2016, 10:38:20 pm
content: Add more memory it seems you are swapping to the disk all the time.What CPU/OS/Memory combination?I mean, if you can't open an 800 page pdf, how good is your system for doing any electronics? without reading details on the datasheets you are kind of flying blind.

author: mike11
author_rank: Contributor
timestamp: February 04, 2016, 10:43:11 pm
content: i ha a ttl bible here from ti i use for datas.........its vista not sure on mem but adobe slows it to a crawl

author: tautech
author_rank: Super Contributor
timestamp: February 05, 2016, 05:30:49 am
content: Quote from: mike11 on February 04, 2016, 10:43:11 pmBite the bullet and upgrade it or download that Tek PDF and get somebody to else to print it, it does comp!cement the Tek service manuals.

author: Addicted2AnalogTek
author_rank: Frequent Contributor
timestamp: February 05, 2016, 10:17:53 pm
content: Quote from: tautech on February 05, 2016, 05:30:49 amThat Tek troubleshooting PDF is the single most informative and important tek scope troubleshooting document for a hobbyist or even a fresh technician (besides the scope-specific manual)... you're pretty much going to be clueless without it.. If you have to pay $5 to get it printed out at a copyshop or UPS store, then do it.

author: miguelvp
author_rank: Super Contributor
timestamp: February 05, 2016, 11:07:44 pm
content: Or if you want to stick to Vista and not upgrade your memory, lookup ReadyBoost compatible USB thumb drives and google how to use ReadyBoost, this link is for windows 7 but I think it's similar for Vista:http://windows.microsoft.com/en-us/windows/turn-readyboost-on-off-storage-device#1TC=windows-7This one covers Vista, 7, 8 and 8.1https://www.winhelp.us/use-readyboost-in-windows-vista-and-7.htmlEdit: More info from Wiki of coursehttps://en.wikipedia.org/wiki/ReadyBoostDon't expect this to do miracles, but it might help with opening those pdf files.

author: poot36
author_rank: Frequent Contributor
timestamp: February 06, 2016, 06:45:28 am
content: If your computer is using the integrated graphics then upgrade to dedicated graphics because most ATI and Nivida cards accelerate Adobe Reader by using the GPU to render the PDF. There should be a list of compatible cards out there. You can also try disabling the Areo interface to speedup graphics display and reduce ram usage. Ready Boost is limited to the speed of the USB port which for 2.0 ports would be around 20Mbits to 30Mbits per second way slower then using the HDD as swap (around 60Mbits/s or more depending on the HDD). You can also try a third party pdf reader like Foxit or Cute PDF.

author: miguelvp
author_rank: Super Contributor
timestamp: February 06, 2016, 07:31:28 am
content: It's not about the rendering, it's slowing down because it has to swap applications to the swap file on the hard drive which is very slow because it doesn't have enough memory.

author: Addicted2AnalogTek
author_rank: Frequent Contributor
timestamp: February 06, 2016, 01:20:52 pm
content: Any of you guys think that enlarging the virtual memory allocation would help with his RAM issues even slightly?Also, I have a couple video cards that might suit your system well if you've got integrated video. One is a GeForce 4 MX440-T8X 64MB AGP W/TV OUT and the other is unlabeled, but if I remember correctly it is out of a Dell Dimension 8250. If the vid card option suits you, I would give you the MX-440 card free. The other I think is a 1GB DDR GeForce.