Mono Slab - no sound

NeXT Computer, Inc. -> NeXT Black Hardware

Title: Mono Slab - no sound
Post by: nullvalue on April 21, 2021, 12:58:09 PM
So I have a monochrome slab with a mono megapixel display. While doing some adjustments I noticed it has a speaker - though I have never heard this nexstation make a sound. I didn't realize that it's only the color display that needs the external soundbox. So what gives? How do I get sound working through the monitor's speaker?
Title: Re: Mono Slab - no sound
Post by: barcher174 on April 21, 2021, 03:41:58 PM
It should just work. You can try enabling the audio check in the ROM monitor to see if its a hardware or software issue.
Title: Re: Mono Slab - no sound
Post by: nullvalue on April 21, 2021, 05:17:40 PM
Hmm "sound out tests" is set to yes. All system tests pass at startup.. What would I typically hear on a nextstation during boot?
Title: Re: Mono Slab - no sound
Post by: barcher174 on April 21, 2021, 10:43:53 PM
A beep. So you know its a problem with the megapixel.
Title: Re: Mono Slab - no sound
Post by: nullvalue on April 22, 2021, 02:42:44 PM
Hmm so I tried a set of headphones plugged into the monitor and I do hear sound through those. Not sure what's up with the internal speaker though...
Title: Re: Mono Slab - no sound
Post by: barcher174 on April 22, 2021, 05:52:14 PM
Hard to say without opening it up.
Title: Re: Mono Slab - no sound
Post by: nullvalue on April 22, 2021, 06:55:12 PM
Some pics: https://imgur.com/a/ly1Kh0o

Everything looks like its hooked up correctly, but quite dusty & dirty. I've pulled the board and will give it a good cleaning. Fingers crossed... Not sure if the pots are bad.. nothing is bulging or looked leaky on this board or the analog board.
Title: Re: Mono Slab - no sound
Post by: nullvalue on April 22, 2021, 08:48:35 PM
OK so that board looks like brand new - but nope still no sound. bummer
Title: Re: Mono Slab - no sound
Post by: barcher174 on April 23, 2021, 08:08:46 AM
First thing I would do is recap the board. Specifically the large through hole cap is used for the audio amp chip. I would then suspect the audio amp chip. I've seen those go bad often when that large cap shorts.
Title: Re: Mono Slab - no sound
Post by: nullvalue on April 23, 2021, 12:03:55 PM
Thank you, I'll give that a shot!

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