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#1
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Tektronix tds510a Image expands, then tube shuts off
I have a VGA tube that was pulled from an old Tektronix TDS510A. It's now being used as a little monochrome VGA monitor. Discovered a weird issue after its been running for a while. The picture slowly expands, then the screen goes blank.
I am driving it with a 640x480 VGA signal at 60Hz refresh Never seen this before. Could it be capacitor related? video of issue Video is without crt turning off. Last edited by Devicemodder; 01-05-2024 at 08:49 PM. Reason: Fixed link to video |
#2
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Hi to all,
Hi Devicemodder, i watched your short video, operation looks OK. As you don't show the picture expansion & fade, it's hard to diagnose anything. Questions: does just the Windows computer content display disappear & screen stays lit or does the CRT brightness die? In traditional TV, image expansion & decrease in brightness usually points to a dying EHT rectifier. In the schematic you posted, EHT rectification seems to be included in the Flyback transformer (modern "split-diode" transformer technology). To assess if the transformer is at fault (or not) additional data is needed: - the schematic showing the CRT, its type & hopefully electrode voltage. Something might be drifting & driving the CRT to cutoff, blanking the display. How is the Tektronix VDU powered; own power supply, bench PSU,...? Have test gear: multimeter, HV probe,...? If possible, a new video showing the "expand & fade" fault, For anyone interested, the TekTronix TDS-510A digital Scope service manual* (284 pages/4Mb) is on TekWiki: https://w140.com/tekwiki/images/5/52/070-9704-02.pdf *didn't see schematics. TekTronix TDS-510A wiki main page: https://w140.com/tekwiki/wiki/TDS510A Best Regards jhalphen Paris/France Last edited by jhalphen; 01-23-2024 at 05:28 AM. |
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Looks like it runs on 12 VDC. See top L of manual. Be sure thats not creeping up first. After that hoz / HV may be iit. Would need that part of schematic.
73 Zeno LFOD ! |
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Quote:
I have the service manual for the scope that the tube came from. I'll check the schematics and report back. The Tektronix display is powered from a 24VDC wall adapter as i don't have the rest of the scope. I just have the VDU. And the expand is shown in the original video. watch the windows taskbar, and you'll slowly see it going offscreen. Last edited by Devicemodder; 02-16-2024 at 12:01 PM. |
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CRT Model: 678PAMGLX
Here's the service manual i got the schematics from: https://files.catbox.moe/owboca.pdf page 370. I'll try to make a new video of the fadeout and expansion. Only test equipment I habe is a multimeter and a scope (not the one this tube came from) Last edited by Devicemodder; 02-16-2024 at 12:51 PM. |
Audiokarma |
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