Re: Tek 485 - Intensity at Max, Cannot Adjust Down


EB4APL
 

Hi,

It smells like a DC restorer problem. The best test is to replace the
diodes unless you have facilities to test the leakage at high voltage,
the circuit is very sensible to diode leakage and a DMM test usually is
not enough. Since anyway you have to remove them, it is safer to
replace them. Another suspects are the restorer's capacitors.

On 21/03/2016 at 0:26, otrfan01@... [TekScopes] wrote:

Hi,


I have been working on a non-functional 485 that I picked up. I
discovered that the inverter was cycling rapidly on and off. I
resolved an issue that was shorting out the +15V power line, which
restored all power supply voltages to their correct levels.


Now, the trace is very bright (enough that if it is moved down onto
the screen, it will occasionally trip the protection circuit and cause
the power supply to cycle). The intensity control has no effect.


I have checked the DC restorer diodes with my DMM - all appear OK.


Would anyone familiar with this type of problem be able to advise next
troubleshooting steps?


Thanks, Wayne




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Posted by: otrfan01@...
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