Having same issue. I got tired of it and haven’t looked into it further in a couple of weeks. Very annoying. Will be following this thread.

Check the DIP Switch settings on the sound board. If they're set for no speech, you'll get the scenario where you have sound and no "silent pause" where speech should be.

He already indicated he’s moved the dip switches to match with the manuals position. As have I.

I have some experience with these boards. Do you have the ability to read the speech roms to confirm they are good? What about replacing the capacitors or the two LM1458 amps? That's about all else that ever fails on these boards...

You can also order one of these and be done with it if you don't want to shotgun it:
http://pinballpcb.com/products/replacement-system-6-7-9-speech-board/

Follow the schematic and verify the dip switch settings are making it to the PIA correctly. If they are, I’d replace the PIA.

If there was a gap in the sound test where the voices should be, I’d suspect the caps or op amps on the voice board but since there isn’t a gap, it isn’t even trying to play voice and that can be caused by bad dip switches, bad PIA, bad CPU or bad ROMs.

Not sure about op, mine has had all caps replaced. I have not changed my sockets yet. The sound dipswitch is working as I can get it to go back and forth between “tones” and “music”

Suspect a faulty ribbon cable between the speech board and sound board.

Send a photo of the sound and speech board

What revision is the speech board you acquired? If it's from the Sys9 era, it may be factory jumpered for different ROM chips which were larger than Firepower's... you'll have to jumper the Sys9 speech board to support the earlier roms, or burn larger roms with the FP sounds. Of course if it's a SYs6 speech board you should be OK.

Every WMS Sys6 + speech game I 've acquired has had bad OEM speech roms; not sure why those tend to go rotten. If you have the means (a rom burner) I would definitely verify they are good before chasing your tail. If you don't have a rom burner, try swapping them into a known good speech board (in another game) if you have access to that.

I've yet to have a ribbon cable go bad, but you can tone them out end to end. A little tricky but worth the effort to solve that variable.

Bad speech roms will cause the sound test to skip the attempt with no blank/pause as well. The boards could be perfectly fine and functional otherwise.

Test your roms first and check back: You can download the rom images from ipdb. Read the physical ones with your GQ4X4, and compare to the ipdb image, one at a time. They need to be perfect before you proceed any further.

Your roms are in the correct sockets... But, your speech board has "Scanbe" sockets. I would replace those 3 sockets before worrying about too much else. They are notoriously faulty. It's tricky to replace them if you've not done it before. It may be easier to just buy the Pinballpcb sound board linked above if you've not replaced sockets before. Your speech board is repairable but it comes down to how much patience and time do you have?

Also note the SIP style sockets that were replaced on your main sound board. I would strongly suggest that type if you do replace them.

Incorrect Speech Roms
Speech Roms shown are for BLACKOUT Game# 495-1 495-2 495-3
The speech Roms needed are 497-1 497-2 and 497-3

No Speech will be produced using with Rom 3 at IC 12

Blackout speech Roms are triggered by Sound Rom 2 software