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    tektronix 2710 spectrum analyzer

    Hi, my name is Manuel,
    I bought a used tek 2710 few months ago, it was in very good conditions and perfectly working:D.
    Two days ago I turned it on and a I saw this message on the display "CANNOT COUNT PHASE LOCK VCO".
    Now many nomalyzations fail and the frequency values displayed are not true.
    Somebody may help me
    Thanks
    Manuel[/i]

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    ektronix 2710 service manuals

    Search this forum for other posts on it.
    Please do not PM me questions that are better asked in the PCB forum :)


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    tektronix 2710 spectrum analyzer

    My tek 27 shows this new problem.
    May you help me?

    Added after 4 minutes:




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    Re: tektronix 2710 spectrum analyzer

    My problem is no dispaly of characters or reference lines or markers.
    Does anyone know of a common circuit(s) failure point that would cause this?

    I might be able to help with 2710 documentation in the near future.



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    Re: tektronix 2710 spectrum analyzer

    I have de same problem of Manuel and de intensity command not work. I do not see the letters. Please, have you the solution?
    My name is Virgílio and email: a.virgilio.teixeira@gmail.com



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    Re: tektronix 2710 spectrum analyzer

    Quote Originally Posted by Gary N View Post
    My problem is no dispaly of characters or reference lines or markers.
    Does anyone know of a common circuit(s) failure point that would cause this?

    I might be able to help with 2710 documentation in the near future.
    hoal , tengo el mismo problema , pudiste resolverlo ? gracias por la respuesta
    norberto



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    Re: tektronix 2710 spectrum analyzer

    Does that translate to "And have you fixed it 3 years later?" :)
    Please do not PM me questions that are better asked in the PCB forum :)



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    Re: tektronix 2710 spectrum analyzer

    Quote Originally Posted by cyberrat View Post
    Does that translate to "And have you fixed it 3 years later?" :)
    already is that 3 years have passed, but as your answered, also contact me with Virgil, that this trip and I specializing when .mi problem again is the same of mabi, characters appear in a rectangle clear, can be read, and points across the screen, would appreciate if anyone able to resolve it and tells it me
    Thank you



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    Re: tektronix 2710 spectrum analyzer

    Caro Norberto
    As primeiras notícias são boas. Acabei agora mesmo de substituir o Q308. Por acaso pedi o tipo de caixa TO223 e não é. A caixa TO223 é um pouco maior, quase o dobro do transistor original. Com alguma dificuldade consegui colocá-lo. Passei a poder regular a luminosidade e de imediato passei a fazer leituras. Para já é só o que posso dizer para além de que há um ligeiro movimento na imagem que me parece relacionar-se com filtragem na alimentação do CRT. Vou prosseguir para tentar detectar esta anomalia. Saudações



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    Re: tektronix 2710 spectrum analyzer

    Hello Virgilio,

    I have a spectrum analyser TEKTRONIX 2710, and have a video problem.
    While searching on the net, i found your post in answer of the same problem.

    Could you repair your analyser ? If yes, what have you changed ?

    Thanks for your help,
    Patrick

    Quote Originally Posted by A_Virgilio View Post
    Caro Norberto
    As primeiras notícias são boas. Acabei agora mesmo de substituir o Q308. Por acaso pedi o tipo de caixa TO223 e não é. A caixa TO223 é um pouco maior, quase o dobro do transistor original. Com alguma dificuldade consegui colocá-lo. Passei a poder regular a luminosidade e de imediato passei a fazer leituras. Para já é só o que posso dizer para além de que há um ligeiro movimento na imagem que me parece relacionar-se com filtragem na alimentação do CRT. Vou prosseguir para tentar detectar esta anomalia. Saudações


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    Re: tektronix 2710 spectrum analyzer

    Sorry for digging up this old topic, I just joint this forum so I do not know if it is allowed.
    I have a 2710 that has the same problem as the photo in this topic. I can not read spanish but I think he talks about replacing Q308 and maybe other solutions. Google translate makes it not really clear.

    At this moment I think I have found a bad 74LS27 but must order a replacement to be sure. If not the PLS is dead.
    If I probe there and tought by accident an other pin I get parts of charakters on the screen that stay there until I do that again. The input of the 74LS27 1 and 2 inputs is 1.75V. this should be under the low threshold. input 13 has pulses so either way the output should react.but does not. It stayes in the wrong state. So that is a problem .

    And a found there must be a problem between a PLS on the digital staorage board and the Z axis transistors. I miss parts of the blacking/unblancking traces that go to the CRT. . My ramps go from +5 to 115V and I miss the 30-115V part.
    I have no response to input signals.

    I have the servicemanual. But it is veryhard , sometimes impossible to read the partbnummers in the schematic, I have no extenders so it is a hell of a job. (I have test gear enough)

    All menu functions seem to work (but unreadable) and beeps on startup like my 2712 but the menu stays until I press a button. Traces stored in RAM from early days come up if I press a-d so memory seems to work. Logamp etc seems to work to.
    I got it in a non working state with the boards and coax not connected. It has allnmost every possible option installed.

    The TG gives out a signal if I check it with my 2712
    All caps are replaced. Many were bad. PSU is now clean and synced. But it wobbles a 50 mV following the sweep. If I turn off the read out it is stable. If I have read out on but stop the ramp generator (single sweep) it gets stable too. So something is pulling the psu down in the rithm of the sweep.

    So it could be I have more problems but that screenshot is just my main problem and I wonder if there was a solution.

    http://www.pa4tim.nl/?p=4522 pictures of my 2710


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    Re: tektronix 2710 spectrum analyzer

    Sorry but i d'ont speak englhish. The language that i used is "PORTUGUÊS) not Spanish. My first damage in 2710 as image that you see, haves simultaneous a no function of the command "intensity". folowed the circuit and i find the Q308. damaged. It worked until one mount ago. Now, the damage are different. Virgílio (a.virgilio.teixeira@gmail.com)



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    Re: tektronix 2710 spectrum analyzer

    Hi PA4TIM

    I didn't work on my own 2710 since my last post. I got a much better S.A since...
    But i'm still interested if you can find a solution !
    Mine worked perfectly and started to have this problem after several time of operation. Now it has the problem at cold startup...

    73, Patrick
    Last edited by tk5ep; 3rd August 2013 at 15:17.



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    Re: tektronix 2710 spectrum analyzer

    My Q308 is OK, but the 74LS27 (U402) that controls the Z axis (and Q308) is dead. I must order a new one but temporart mounted a through hole 74LS02 on the bottom and disconnected pin 1,2,13,12 from U402
    After this the dots and blocks are gone. I see a small line the width of a character going up over each character, The Z signal on the testpoint is now OK. Still no signal and no read out, Did some tests, I think the problem is befor U402. It looks like it gets no data.

    The PSU still wobbles a bit, the voltage over the 0,1 shunt does to so I think a problem in the YIG control, maybe a short in the coil or driver but I have not measured there.
    I just ordered a better scanned manual from Dave at Artekmanuals. And I'm thinking about making an externder because working this way (removing board, tagsolder some pins for probes, mounting back etc) goes to slow.

    I will keep you informed. I'm making some boardpictures with component numbers on them and testpoints, I will place those on my side when ready. Works faster as that oscure drawings Tek uses


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    Re: tektronix 2710 spectrum analyzer

    Placed a new 74LS27 display changed but still not good. Pins one and two still 1,7V. So the PLS before the character generator is probably dead. Then I connected a 100 Ohm resistor between pin 1 an 2 and gnd to pull it down.. The result is a perefect readout. Very strange, refresh looks a bit slower but for the rest it seems to work.
    Itbooted with a big errorlist, a lot of strange files. It asked to fix the FS that succeded. Then normalisation., the frequency failed.Now it starts without error messages.

    Still no signal visible. 100 MHz oscillator is OK, Step attenuator is OK., Next step will be following the signal.

    To be continued.



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    Re: tektronix 2710 spectrum analyzer

    The Yig seems to be doing something, attenuation, inputswitching, TG are good. There is signal but around the 400 MHz filter it is very weak and to low in frequency.
    The normalisation tells me the frequency main dac offset fails. And indeed, the LO is to low in frequency in zero span. It does however sweep more or less. But distorted and not constant in amplitude.
    I removed the RF board to get to the YIG 1e LO interface. On that board are two 820 uF/10V electrolytic caps parallel to the YIG coil. I tested those and one of them was a dead short. The other about half the capacitance value it should have and a very high DF. So replaced both of them. Now I have to rebuild it before testing. This is thing a repair nightmare. The maual is bad, it is nearly impossible to find out the number and location of all the coax and rigid connectors. Finding board locations is an adventure, there are no marks on most boards and if they are inside shielding you just have to guess or take it apart and look if you recognize it from the pictures in the manual.
    There are testpoints but many you can not reach. I thought about making an extender but 3 boards are coupled on the bottom too and some have coax connected, so that means a lot more as just an extender vable.

    A tip; I remove the board, solder little pins/wires to the testpoints, or IC pins, or resistors or whatever I must measure. Reinstall the board and then it is easy to clip a probe to it


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  17. #17
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    Re: tektronix 2710 spectrum analyzer

    replaced a dead 74LS00 in the LFVCO. Still nothing more as a noisefloor on the screen. Tracing the signal it disapears after the 2nd LO, so the 3rd IF is 0Hz insteda of 10 MHz.
    Only thing I can come up with is a dead 3rd mixer. If that was OK and the 110 MHz was missing I should measure 100 MHz from the reference oscillator that serves as a LO here.

    Problem is the shieding. It is on the RF motherboard and shielded. This shielding looks like it is soldered all around. So removing it can cause damage. Any one experience with this ? I have a pace MB250 (de)solderstation and a OKI hot air station. No preheater but I do not like the idea of heating the whole unit.



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  18. #18
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    Re: tektronix 2710 spectrum analyzer

    I removed the shielding with the use of a paintstripper and was able to measure the frequencies of the LO's and mixer outputs with a scope and after adjusting some things I had a 10 MHz IF and a trace on the screen. It still won't normalize the frequency but it is allready useable as SA. Now I have to follow all adjustment directions. Problem is the HFvco adjustment. I must follow the directions the sa gives on the crt and these make no sense. Adjust until you measure 8,5V at a feedtrough capacitor at the bottom of the HFvco. There are 3 points there, +8,5 , -8,5 and +15V, all from the PSU and not related to the adjustment. If I look in the schematic I can not find a link between a feedtrough or 8,5V or the adjustment. Very frustrating. The manual also has a lot of mistakes. Like you need to disable frequency corrections and do some things and two steps later you have to disable it again, but is still disabled. So one off the 2 must be enable.....
    My Util menu has more levels and functions as the manual states. You have to choose standard factory defaults for normalizing in a menu option that is not there in my SA. It is spread over several menus and submenus. Maybe because I have a TG my menu is different in many occasions. There is a manual for the later SA's (that I do not have). Mine is upgraded in 1991 and probably has the firmware of the later model.


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    Re: tektronix 2710 spectrum analyzer

    Update: All filters needed to be aligned, still no succes in normalisation. Maybe the dead PLS is the cause. But for the rest it seems to work fine. Now I first do all adjustments in the book.



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    Re: tektronix 2710 spectrum analyzer

    After doing the first paragraphs of the ajustments all normalisations now are without errors. Looks like I now solved all problems. For people who want to repair or adjust a Tek 271X SA, be carefull, it is not an easy job without the right gear. You need a second SA, a scope with more as 100 MHz BW, a 100 MHz and 10 MHz standard, a 0-60 dB attenuator (or a good 100 MHz generator with attenuator) and a powermeter.
    Instead of a second SA you can use the FFT of a DSO. One adjustment needs a scope in XY mode and 1X probes. A DSO can do it but it is much more easy on an analog scope. This is the beatnote adjustment of R620. The manual tells you to find the zerobeat using the XY but is very unclear. You need to connect P100 again. Above R620 are the 3 solderpoint. You need the most right one. But the manual talks about a cap. It tells you to turn the marker/freq knob for low zero beat. But you need the knob under it which lets you move the trace manual. The value for the DAC is 1100 on my SA. Just start at 1000 and then go 100 up, if the frequency uincrease you go down to 900. If it gets lower you go up.


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