KAS 297b blank screen

[Top Heavy]

I recently had what I suspect was a power surge which caused a failure of the HSI as well as a blank screen on the KAS 297b (altitude preselect). The HSI issue was corrected with a rebuilt module but the KAS 297b screen is still blank. I have no problems with the King 150 autopilot. It passes the test and works fine. Could this be something as simple as  a bulb in the lighting system for the screen? I would greatly appreciate any insight for troubleshooting this problem.

[LANCECASPER]

The display is a gas discharge so there's not just a light bulb that controls it. There aren't many, but there are a few shops around that will still test these and might be able to replace a component on the circuit board. I've heard good things about these people: https://www.bevanrabell.com/    Their number is 316-946-4870.

The KAS297B has a pin connector on back which is not difficult to unplug. You might talk to them and if they can look at it send it off.

Worst case secenario, they come up for sale from time to time on Ebay in good working order and are pretty much plug and play 

http://www.ebay.com/itm/KING-KAS-297B-ALTITUDE-PRESELECT-/281986258466

 

[Top Heavy]

Thanks. It looks pretty easy to remove. Maybe, I can get an idea about the extent of the problem by visualizing the circuit board. it does not seem to have it's own circuit breaker. Do you know if it's power supply is tied into the same circuit as the autopilot?

[Marcopolo]

Top,

 

   The altitude pre-select should be on its own 1 amp inline fuse behind the panel.  Power is usually supplied from the Auto Pilot circuit breaker with the inline fuse as 1 amp protection.  This is how the installation manual has it laid out.

 

Ron

[LANCECASPER]

1 hour ago, Marcopolo said:

Top,

 

   The altitude pre-select should be on its own 1 amp inline fuse behind the panel.  Power is usually supplied from the Auto Pilot circuit breaker with the inline fuse as 1 amp protection.  This is how the installation manual has it laid out.

 

Ron

Nice, if that's the case that fuse may have protected it.

KAS-297B-INSTALL-MANUAL.pdf

[Top Heavy]

Thanks for the "heads up" regarding the in line fuse. I will take a look at it tomorrow. That would be a gift from God if that is the problem.

[Top Heavy]

Ron,

   I looked behind the panel and could not locate the fuse. Any thoughts on where it is typically located? I would think it would be immediately proximate to the pin connector to the unit itself

[Marcopolo]

On 7/24/2017 at 5:34 PM, Top Heavy said:

 I looked behind the panel and could not locate the fuse. Any thoughts on where it is typically located? I would think it would be immediately proximate to the pin connector to the unit itself

Hi Top,

 

  Sorry for the delay, was enjoying airventure and not mooneyspace for a while.  If you haven't already resolved this issue then the next easiest step would be to check pin 18 for power and pin 19 for ground.  If no power on pin 18 then tracing it to its source will be necessary, hopefully while tracing the wire you'll run across a blown 1 amp fuse.

 

Ron