(solved) Grace m802 Display Going Blank

[BrianJSiegel]

I recapped the electrolytic caps in both the external power supply and the unit itself but the problem still persists. Upon powering up the Grace m802, the display is goes fully black (pixels) then goes blank shortly thereafter. What could be causing this? I haven't been able to find any documentation really on the unit. Really need some help if you guys have any ideas.
-Brian

 

[chilidawg]

Was the display behaving like that prior to recapping?
Did you check the voltages before you recap?
What was the reason for a recapping? Bad caps?

After recapping an external power supply, you should abuse it close to a full load for at least an hour or two without shutting it down BEFORE you hook it up to the unit that it's supposed to give the power to.

During that test, you check for stability for both output voltages and current, and also for any thermal abnormality like a part (or parts) overheating way too fast.

Sometimes a wrong recapping job like choosing a very low ESR electrolytic cap to replace a general purpose electrolytic cap will make a circuit behaves differently.

 

[Khron]

Display going fully black points towards it not getting initialized, which means that whatever microcontroller / processor is driving it, is not booting up (properly).

Good question about whether it did that (also) before the recap or not.

 

[BrianJSiegel]

Was the display behaving like that prior to recapping?
Did you check the voltages before you recap?
What was the reason for a recapping? Bad caps?

After recapping an external power supply, you should abuse it close to a full load for at least an hour or two without shutting it down BEFORE you hook it up to the unit that it's supposed to give the power to.

During that test, you check for stability for both output voltages and current, and also for any thermal abnormality like a part (or parts) overheating way too fast.

Sometimes a wrong recapping job like choosing a very low ESR electrolytic cap to replace a general purpose electrolytic cap will make a circuit behaves differently.

The owner said he was experiencing the blank screen with increasing regularity until it happened every time it powered on. I was hoping recapping would fix it - some of them were bulging slightly.

 

[BrianJSiegel]

Turned out to be a bad AT111 Controller Card. Grace was wonderful and sent me a working one. Just thought I'd wrap this one up in case anyone has the same issue
-Brian

 

[boji]

Smoked a few pins on my M905's controller MCU while customizing the control surface. Mr. Vallejo was kind enough to grant me an RMA and swap in a new chip. Great customer service.

 

[BrianJSiegel]

Smoked a few pins on my M905's controller MCU while customizing the control surface. Mr. Vallejo was kind enough to grant me an RMA and swap in a new chip. Great customer service.

No kidding, they have perhaps they best customer service I have ever received from anybody. Great quality gear AND great customer service...almost unheard of LOL