KMD-150

[Don]

I am looking for a schematic of the KMD-150. If you have one you'd like to part with or know of a source for one, let me know. Thanks

[Bob Martin]

Originally Posted by Don

I am looking for a schematic of the KMD-150. If you have one you'd like to part with or know of a source for one, let me know. Thanks

Don,
Clarifying you are looking for the internal operating schematic of the KMD 150, something one would use to work on the unit itself.
As opposed to a wiring schematic one would use to install the unit.
I have the install docs and would also like to have a internal schematic for working on the unit. Hope there is one available. I can change a battery but after that I'm lost. :-)

[Walt]

Even if you do find one, chances are it won't do you much good. "Modern" avionics repair generally consists of checking the power supply then replace the defective board. Generally speaking, custom made IC's combined with surface mount technology make "repair" impossible.

[tkatc]

Walt,
Don's problem is that dreaded internal battery. He has replaced it but unsuccessfully. He suspects there is a bad connection elsewhere that keeps the new battery from properly connecting. Perhaps you some advice for him?

Also, does Honeywell still support this product? I need an updated database as the PHL class bravo changes this month.

[Scrabo]

Originally Posted by Don

I am looking for a schematic of the KMD-150. If you have one you'd like to part with or know of a source for one, let me know. Thanks

PM me your email - I might have something for you

[fl-mike]

Originally Posted by Walt

Even if you do find one, chances are it won't do you much good. "Modern" avionics repair generally consists of checking the power supply then replace the defective board. Generally speaking, custom made IC's combined with surface mount technology make "repair" impossible.

Walt,
I have to disagree with you on this. With modern surface mount components, the increase in component reliability makes a large percentage of board failures more mechanical in nature. A good visual inspection of the board with a magnifier or microscope (and an ohm meter helps too) will often reveal a crack in a solder joint, or a shorted or burned component. Replacement of a (simple) SMT component can often be easier than a thru-hole, if you have a suitable soldering iron. Because the components are often not labeled, having a schematic and/or bill of material become more important.

That being said, I still grumble about having to do everything under a magnifier these days. Dang kids and their 0402 resistors!

[Don]

Walt, I would normally share your opinion but there's a pilot on the field with me that works as an electrical engineer for the feds and does this sort of stuff with experimental aircraft. When I told him what was wrong, he was essentially certain he could fix it, if he could get the schematic. Either he can or he can't and it won't cost much to find out.

[Walt]

Originally Posted by Don

Walt, I would normally share your opinion but there's a pilot on the field with me that works as an electrical engineer for the feds and does this sort of stuff with experimental aircraft. When I told him what was wrong, he was essentially certain he could fix it, if he could get the schematic. Either he can or he can't and it won't cost much to find out.

Hey, don't get me wrong, I'm all about tinkering with electronics, sometimes you can get lucky and spot the trouble without a schematic. I was a bench tech for quite a few years on the "old" stuff where you actually trouble shot down to component level and fixed things.

However, I have a number of modern avionics maintenance manuals and they don't even have schematics in them anymore as they are now considered "proprietary". If the com section doesn't work the "trouble-shooting guide says "replace the com board", thats it

Add that to the fact that it's almost impossible to figure out what the component is with the prints make repair unlikely unless you're very lucky.