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| Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Oscilloscope problem.
I have a Hung Chan 6502 20MHz cro that is proving rather difficult to
repair. Apparently it is also known as a Protek 6502. The fault is that the trace is only just visible with the brightness on full. This one has me baffled. Any advice would be greatly appreciated. Cheers, Dan |
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#2
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Oscilloscope problem.
On 8/26/07 4:13 PM, in article
, "Dan Stephen" wrote: I have a Hung Chan 6502 20MHz cro that is proving rather difficult to repair. Apparently it is also known as a Protek 6502. The fault is that the trace is only just visible with the brightness on full. This one has me baffled. Any advice would be greatly appreciated. Cheers, Dan I'm not at all familiar with that scope, but....... Do you have access to the crt cathode, aka Z axis, control? Maybe you have a link, jumper, or other Z axis option mis-set. |
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#3
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Oscilloscope problem.
On Aug 26, 6:13 pm, Dan Stephen wrote:
I have a Hung Chan 6502 20MHz cro that is proving rather difficult to repair. Apparently it is also known as a Protek 6502. The fault is that the trace is only just visible with the brightness on full. This one has me baffled. Any advice would be greatly appreciated. Cheers, Dan Do you have a schematic? Check the various voltages on the CRT. If you have a high-voltage probe, measure the accelerator voltage - carefully! H. R.(Bob) Hofmann |
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#4
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Oscilloscope problem.
Dan Stephen wrote in message
... I have a Hung Chan 6502 20MHz cro that is proving rather difficult to repair. Apparently it is also known as a Protek 6502. The fault is that the trace is only just visible with the brightness on full. This one has me baffled. Any advice would be greatly appreciated. Cheers, Dan Is the trace equal illumination over the whole trace or is there an X-axis gradation in the brightness of trace? Is the trace constant in brightness or wavering? Did it suddenly emerge as a problem or gradually over time? Is the trace of the correct geometry, X and Y sense, for a test signal input ? if it is correct then not an EHT problem I would suspect leakage/failure in something in the blanking/un-blanking area (eg opto-coupler high R resistor) or a "sub bright" preset failure. -- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on http://home.graffiti.net/diverse:graffiti.net/ |
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