Intellivoice weirdness

So, my original Intellivision (brown unit) seems to work fine.  But it will not operate an Intellivoice consistently.  I've tried two different Intellivoice units.  When I plug an Intellivoice in the unit displays a black screen but after a time can be reset and the game will display, most often with garbled sounds and an attempt at saying, "Mattel Electronics Presents (game name)".  Seems like something is warming up and getting better but not quite making it where it needs to.  Power?  IC?  Any ideas?

Thanks!

How do I fix my spelling error in the topic title?

Thanks!

I fixed it for you. I don't know enough about hardware issues to help you out with your question, though. I hope someone else can.

Haven't delved into repair yet, but it was a bad motherboard.

A bad motherboard on the Intellivoice?

Oops...  More clarity.  Sorry.

Bad Intellivision console motherboard.  Or, to be exact, probably some component on the motherboard.  Probably an easy fix but I didn't have time to delve into it yet.

Ah, I hope you can iron it out.