Iwatsu SS-5711

[elebish]

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.

Only an old fashion cap checker that checks for leakage at 600 vdc will work. An ESR meter (I have one), will not find this problem, besides they only work on values of 1 Ufd or above. Ed.

 

[Sinewave]

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.

Hi Ed, I think I'll replace as many poly caps as I can then in that case. Previously, I did replace 19C51 and 19C52 when I replaced some electrolytics in the power section, as one also had a split.

 

[elebish]

Hi there.

I have an Iwatsu SS-5711 scope, which has just developed a focus issue.

It's not had much use in recent years. Othewise, appears to work just fine apart from keeping a trace in focus.

It'll start sharp, then go out of focus, I can 'chase' it into focus, but it'll wander again. Have tried the astigmatism but it'll go out of focus again.

I think somewhere I may have the manual for it, but I don't think it'll be a service manual.

Thanks.

I have a 5711 Iwatsu that had the same problem. Replace 19C68 (.01@630v) and 19C64 (.047@630v) on the Z axis board then readjust focus 1, focus 2 and astig. Ed.

 

[elebish]

Let me know if replacing 19C64 and 19C68 fixes your problem. Ed.

 

[elebish]

Do you have the schematic? What symbol does it show for this device? (normal diode, schottky diode, zener diode, etc...)

That meter looks like a good tool. Probably out of my price range though

It's a fast switching schottky! Ed.

 

[Sinewave]

I've been slow, not fitted the components yet, but I do have them.

 

[Sinewave]

I'm trying to check 19C43, I can see it on the schematic, but I just can't find it on the board. Is it on the same board as the rest of the CRT Z amp board?

 

[Sinewave]

Just found it, replaced it.

So tonight and it's taken me a long time to do (have a 1 year old son which keeps me busy) I've replaced all you suggested and it works!

Nice crisp sharp trace!

Thank you very much for your help. I'd love to be able to return the favour.

 

[elebish]

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.

Replace 19C43 and 19C64 with like values (630 vdc) and readjust 'focus 1, focus 2 and front panel focus. These caps are known to break down with voltages less than rated as the years go by. Ed.

 

[elebish]

Just found it, replaced it.

So tonight and it's taken me a long time to do (have a 1 year old son which keeps me busy) I've replaced all you suggested and it works!

Nice crisp sharp trace!

Thank you very much for your help. I'd love to be able to return the favour.

When one gets to be my age, being useful to others is reward enough! Ed.

 

[Sinewave]

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.

For the sake of it, I'd make the 2.5kv test as I have a probe, but I'm unsure where to test. The photo in the manual doesn't show crt pin 2 very well, so since it all works, I'm leaving it well alone.

 

[elebish]

Let me know if replacing the 2 caps remedies the problem. It should but you may have to readjust focus 1 and 2 and the front panel focus along with the astig adjust. Adjust the front panel focus to the center position before making the other adjustments, then the front panel focus should be pretty much centered when properly focused. Collapse the sweep and you should have a nice round dot when adjusting the astig. Ed.

 

[Sinewave]

Let me know if replacing the 2 caps remedies the problem. It should but you may have to readjust focus 1 and 2 and the front panel focus along with the astig adjust. Adjust the front panel focus to the center position before making the other adjustments, then the front panel focus should be pretty much centered when properly focused. Collapse the sweep and you should have a nice round dot when adjusting the astig. Ed.

I'm not sure if it were those two caps alone, but the focus is nice now, I'll just have to centre the focus and make the other adjustments inside to make it focused with the front panel focus control centred.

 

[elebish]

I'm pretty sure those 2 caps were your problem as they were my problem. Do not over adjust the intensity pot on the Z axis board. Ed.

 

[rasantos]

Very nice Mr. elebish!

Thank you!

I was just seeking for help and found this thread. My workplace SS5711D oscilloscope has the same issue. I hope it will be the same solution. The line which should have -297V (from HV board) is presenting just -56V. It may be due to 19C68 capacitor if its leaking current, but I will check 19C64 as well.