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Iwatsu SS-5711

Discussion in 'Troubleshooting and Repair' started by Sinewave, Feb 15, 2013.

  1. Sinewave

    Sinewave

    119
    1
    Feb 15, 2013
    Hi Steve,

    The schematic shows it as being a regular diode but what I did manage to pull from the internet searches were coming up with schottky, RF diode - maybe it's just the way searches are when trying to find a needle in a haystack, but just trying to cross reference it to a modern equivalent isn't showing anything.
     
  2. Electrobrains

    Electrobrains

    259
    5
    Jan 2, 2012
    You find some data sheets at http://www.datasheetarchive.com/
    It seems to be a UHF (855MHz) silicon diode. Manufacturer is NEC. Vrrm=5V (!), Vf=0.5V @ I=30mA, C=0.9pF @ Vr=0.9V and some other specs you can see there (if you know Japanese it will help you).
     
  3. Sinewave

    Sinewave

    119
    1
    Feb 15, 2013
    Thanks.

    Is UHF Silicon the diode type? It's just that the 'normal' diode type search is a bit ambiguos. Using the data on the sheet is good, but I'm finding difficulty finding the diode. There are a load on ebay from overseas, though.
     
    Last edited: Feb 25, 2013
  4. Sinewave

    Sinewave

    119
    1
    Feb 15, 2013
    Ok, well the only way I could find any 1SS16 were from a seller in Hong Kong, on ebay of all places, a box of 5 new ones.

    Will bench test them all when they arrive.
     
  5. Sinewave

    Sinewave

    119
    1
    Feb 15, 2013
    Ok well new caps in the power supply and new diode in.

    Unfortnatley, still an out of focus trace.
     
  6. herbgh

    herbgh

    3
    0
    Jan 19, 2012
    same scope similar problem

    my display of the calibrate square wave form on my 5711 is very out of focus..nothing in the way of an adjustment works...Volt meter shows 700+ volts from the voltage doubler circuit that feeds from page 20 to page 19.. should be 500 + and - volts..

    The diodes in the circuit , D5 AND D6 seem to be at fault. Fast recovery types..one measures open and the other measures same resistance both ways..

    Just bought this bugger from an Ebay auction..

    Trying to figure how a failure of this type results in a reading of +700 or so volts? Herb
     
  7. herbgh

    herbgh

    3
    0
    Jan 19, 2012
    forgot to mention that the output of the doubler is 700 volts on one lead and 19 on the other...Herb
     
  8. Gunoi

    Gunoi

    1
    0
    Jun 21, 2013
    Hello.
    I have an SS5711 since 1980 (or so). very happy with it until now. However
    it has developed a similar problem. At power on, the trace is normal for several seconds bt then it de-focuses. badly. I took it apart but I can not find an obvious reason for this behavior. I have no HV probe to check the 2500V source but I assume it is OK as the brightness og the defocused beam is quite OK.

    I have the original instruction manual but it would be useful to find a repair guide or something like this. To my surprise I can not find their European rep to talk to them.
    Does any one have their phone number here in Eu?

    I just wonder what happened whit SINEWAVE repair. The thread ended abruptly and no resolution was to be found.

    Any help would be greatly appreciated.

    Gunoi.
     
  9. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,156
    2,672
    Jan 21, 2010
    Well, we seem to have a collection of people here with the same fault.

    As soon as someone finds the cause, please let us all know :)
     
  10. elebish

    elebish

    177
    12
    Aug 16, 2013
    If you are referring to the p/n ISS16 (D32) as listed on page 19 of the Z axis schematic, that diode is a schottky for fast switching of the unblanking pulse. It has a fwd voltage drop of only .23 volts. I have an Iwatsu SS5711 D scope and also have a focus problem. I found R47 open which is in the emitter circuit of Q16, a 2SA899 PNP transister. I found nothing else so far and hope the CRT is ok. If anyone comes up with a fix, I would appreciate some help. This is the first problem I have had with this scope since I purchased it many years ago. I do have the complete manual for the scope with the DMM and Counter. Thanks, Ed.
     
  11. elebish

    elebish

    177
    12
    Aug 16, 2013
    I also have a SS5711D scope with a similar problem that just developed. My problem seems to be in the Z axis circuit. Resistor 19R47 was open and replaced but still the same problem.
    A quick way to check those electolytics is to jumper them with like values and watch the screen. You might try reading the crt K voltage. Should be a neg 2450 volts dc. The focus voltage is approx +480 vdc depending on scope settings. Anode should read approx 20k volts dc. You will really need the schematics for this, page 19 and 20.. Ed.
     
  12. elebish

    elebish

    177
    12
    Aug 16, 2013
    I have the same scope with the same problem. The problem turned out to be a leaky capacitor on the Z axis board on the bottom of the scope. The capacitor is 19C64, a black radial leaded .047 @ 600 vdc. It's located near the hole in the pcb where the red wire that goes to the crt side pins is located. You might want to check resistor 19R47 which was burned open on mine. I do have the complete manual. Ed.
     
  13. elebish

    elebish

    177
    12
    Aug 16, 2013
    Capacitor 19C64 is your problem. It's a .047 @ 600 vdc. It's on the Z axis board. I just replaced mine. Scope works fine now. You might want to check 19C43 (.047 @ 250 vdc), 19C51 & 19C52 & 19C63 (.1 @ 200 vdc, all 3), 19C68 (.01 @ 630 vdc). This will be easy since you have the board removed. That schotky diode is not your problem. It should read .23 v when checked in diode mode. Ed.
     
    Last edited: Aug 22, 2013
  14. Sinewave

    Sinewave

    119
    1
    Feb 15, 2013
    Fantastic. This is still on my bench, I'll check out what you've suggested and report back. Thanks.
     
  15. elebish

    elebish

    177
    12
    Aug 16, 2013
    Gen Info SS5711

    Just some info: The capacitors are Polyester, general purpose types. If your enhancement button doesn't work as it should, you might want to replace IC 1 and IC 2, (74LS08 and 74LS74). These "logic" IC's will switch the trace to a higher brightness when the sweep is turned higher and when the enhancement button is pressed. You may have to touch up focus 1 & 2 and the auto focus adjustments on the bottom of the scope after the components on the Z axis board are replaced. An ESR meter will not work with the capacitors I called out to be replaced since the values are smaller than 1 uF. Ed.
     
  16. Sinewave

    Sinewave

    119
    1
    Feb 15, 2013
    Thanks for the info. I'm just coming back to this now. An unfinished project, out of many to do around the house.

    I didn't buy an ESR meter in the end. I have measured with an LCR and found some values were different, some considerably, but no difference was made.

    I'm hoping the components you have suggested to try, will sort the problem. I'll begin by removing them and ordering some replacements, then I'll see what happens.
     
  17. Sinewave

    Sinewave

    119
    1
    Feb 15, 2013
    I've just taken 19C64 out, has a nice long split in it with gunk leaking out of it, so a leaky capacitor both physically and electrically. I'll take a look at the others, I don't have one of these in stock so I'll make an order up Monday with a few things on them. Thanks again Ed.
     
  18. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,156
    2,672
    Jan 21, 2010
    Sounds like you two guys have found similar faulty components. Best of luck with this repair, you may be helping more people than just yourselves. :)
     
  19. elebish

    elebish

    177
    12
    Aug 16, 2013
     
  20. elebish

    elebish

    177
    12
    Aug 16, 2013
    You must also replace 19C68 (.01 @ 630 v). They are supposed to be rated at 630 but are marked 600v. This is a common problem in this model scope. Those caps develop leaks at voltages above 200. I just fixed 2 of them. High voltage to this crt anode is 20k, higher than any scope I have used. This is why this scope has a better defined focus than any other but comes at a price as the years go by. Ed.
     
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