I've got a Space Shuttle System 9 with a similar problem. Low sounds and no speech. I know the volume control on the speech board is the mix between system sounds and speech. You should be able to google search and find the manual. I was just reading a thread here with the schematic for the speech board for the comet. I know when I unplug my speech board and jumper pins 3 & 4 the volume for the system sounds are pretty loud so I know it's something on the speech board. Anyone have a link to a thread on diagnosing the speech boards for us?

Good Luck Tim!

Where are you ordering from?

Looks like R13 on the speech board should be a 2.7K.

s1 (resized).jpg

s2 (resized).jpg

Sorry, R14 should be a 10k.

I recently got a logic probe and was testing around on U2 & U3. I know I seen somewhere on Pinside what to look for when using the probe. Anyone know the hi and lo states for these chips? I remember you need to be in sound diagnostic mode when testing them.