EEVblog Electronics Community Forum
Electronics => Repair => Topic started by: IDEngineer on July 13, 2023, 02:39:49 am
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I have an 8562EC that I purchased from The Signal Path guy a while back. Worked great when it arrived, but today when I turned it on all I got was the green power LED and a "click" after a few seconds which sounds like a relay. Turning it off I get another, softer click which is probably the same relay releasing. The LCD backlight flashes briefly at powerup, then is dark. No action results from any front panel pushbuttons.
Is there a known, common failure mode for this SA? I'm getting ready to move cross-country soon so I can't really dig into the unit (and I don't have schematics) but if there's something commonplace I could check it would be nice to resolve it before the unit gets packed up for shipment.
Thanks!
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Found the service manual in PDF form, I'll start digging into that. Further advice welcome!
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Found the service manual in PDF form, I'll start digging into that. Further advice welcome!
Re HPAK service manuals, make sure you check a few versions particularly older ones (going back to the HP days). Some times the older ones have more info in them. e.g. full schematics are sometimes taken out in later versions.
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For any kind of unit that old the first thing is to open it up and check the power supply voltages. Pretty likely some electrolytic capacitor is bad.
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Caps were my first thought. I'm going to connect to the VGA output on the back panel to see if the unit is powering up at all. If not, it's power supply debugging time and hopefully I can find some schematics.
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Finally got some time to start digging into this. First step was to connect an external monitor via the rear panel VGA port. The service manual suggests that this will differentiate between a display problem and something more serious. The LCD backlight is definitely visible when power is applied so it could be just a connector issue.
Connected via VGA, turned it on, and - both displays started working just fine!
Unplugged the VGA connector and the LCD continued to work.
Cycled power and the LCD came right up.
This is strange. I don't think there's an option to "disable internal display" but somehow connecting an external one kickstarted things. I suspect I'll be revisiting this problem in the near future.
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I have fixed a few of these. At the age of these, they are due for new power supply capacitors, a blowout for dust, and a new fan. None of mine were the EC model though. Don't go crazy with ultra low ESR caps or higher voltage ratings than needed on the power supply capacitors. It will oscillate, not start consistently, or not stabilize in some cases. Ask me how I know. ;)
Replace the RIFA safety caps while you're in there too.