Marantz 4400 oscilloscope does not display - AVS Forum
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post #1 of 4 Old 02-29-2012, 02:53 PM - Thread Starter
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My 4400 works great except for the oscilloscope. When i turn it on it is a faint orange color, but none of the functions (such as FM tuning) show up on the scope rendering it useless. I can provide a picture if needed. I do not want to replace this unit, it has great sentimental value. When it worked it was green color as far as I recall.
The attachment is how it should look, I get no green color now
I appreciate any suggestions, I am willing to take off the cover and 'tinker' if necessary.
LL

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post #2 of 4 Old 02-29-2012, 03:12 PM
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Not that I have any suggestions for you on it, but dang that is a cool oldie but goodie ya got there.
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post #3 of 4 Old 02-29-2012, 07:58 PM
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I don't have the absolute answer for you but at almost 40 years old it's possible that the CRT has burned out and obviously you'll need a new one. Not sure where to get a replacement or if any would be available NOS or used. I recently came into possession of a 4400 in need of restoration.

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post #4 of 4 Old 02-29-2012, 08:00 PM
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You'll have to get it serviced unless you know how to do it yourself. There is high voltage (~kV) on the tube so don't mess with it if you don't know what you're doing. The bad news is it could be very hard to find replacement parts... Orange glow could mean the filament is OK but the HV supply or sweep circuits have fried.

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