oscilloscope Problems - please help

Hello everyone, My oscilloscope has gone wrong. Was going fine then it suddenly went out of focus for no reason. The focus knob hardly has an
effect, its majorly out of focus
any ideas ?
many thanks!
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Dear Barry Hobbs:

Post to a different newsgroup, one that deals in electronics. Because "take it to the repair shop" is the obvious answer. "For no reason" indicates one of the components inside has failed due to age, voltage spike, etc. Not sure how up you might be on troubleshooting electronics to the component level.
David A. Smith
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What kind of signal are you looking at? It could be a lot of things. You can't just connect most oscilloscopes to a source and expect them to automatically give you a perfect signal without any adjustment.
It may not be blurry; it might just be out of range or not triggering properly. Your signal may be too high a frequency. If you try to scrunch 30,000 waves onto the little screen, they will appear as a blur. There is usually a frequency range knob of some sort (one of the major knobs). Try switching this knob (probably higher) and see if anything improves. If you can get it to a point where you see the waves, but they are racing by too fast to see, then that is your trigger. There's probably a "trigger" or "sync." control that will freeze the wave. If you are using an old scope, there may also be a knob within the center of the frequency range knob that can fine tune the sweep and slow the wave down. Also, take a look at the other major knob, amplitude range, and make sure that your signal is not simply too large and going vertically off the screen.
Hope this helps.
Don Kansas City
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Helo, thanks for your help. Im sure the blur is not due to a signal being of a high requency, or anything along those lines because it is not just the signal lines that are like it, the scope also displays other data such as the time division, and these are also out of focus. It was working perfectly before it suddenly died, and it was doing nothing at the time
Thanks,

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By the way, its an Iwatsu SS 7636 350MHz 4 channel

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Dear Barry Hobbs:

URL:http://www.iti.iwatsu.co.jp/e/sales_e.htm ... contact phone numbers and email addresses. They might know who does service.
I assume the cable set(s) are in good shape? And you have run this on different power circuits (just in case you've got line noise mucking with things)?
David A. Smith
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If it is a generic out of focus problem affecting everything, it is most likely to do with the EHT voltage. Not a good place to try and do your own fault-finding!
Bruce.
Barry Hobbs wrote:

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Barry Hobbs wrote:

Yeah. Same thing happened to me once. Then it happened to my computer screen, and my calculator, and even my newspapers. I got my first pair of eyeglasses for my 43rd birthday, and the scope's been just fine ever since.
KG
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