info
Google Groups no longer supports new Usenet posts or subscriptions. Historical content remains viewable.
Dismiss
Whitestar - Monopoly - Way too loud!
141 views
Skip to first unread message
John Robertson
Apr 9, 2021, 1:24:17 AM4/9/21
to
Anyone here looked into how WhiteStar board sets the audio volume? As
near as I can figure out it is data buried in SD0 to SD7 data between
the audio 6809E, the Basement 2K chip, and the DAC. Where I can't figure
out is the steps in the audio - are they simply data or is one of the
serial latches responsible?
My problem is the game sound (while pretty clear) is WAY too LOUD! Only
with one bar above zero is the sound OK, and that is loud for a small
arcade. Add any bars to the volume and distortion kicks in and the
volume goes up enough to be annoying/painful.
So, I'm trying to figure out how audio volume is done digitally...I do
have a request in to Stern tech, but not sure if they know these older
(for them) games that well.
By the way, audio is controlled between 3800h and 3BFFh on the main MPU.
I worked that out with my Fluke 9010A today. Not exact memory locations,
but the audio enable was active for most of the calls to memory in that
range.
Thanks!
John :-#)#
--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
(604)872-5757 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."
near as I can figure out it is data buried in SD0 to SD7 data between
the audio 6809E, the Basement 2K chip, and the DAC. Where I can't figure
out is the steps in the audio - are they simply data or is one of the
serial latches responsible?
My problem is the game sound (while pretty clear) is WAY too LOUD! Only
with one bar above zero is the sound OK, and that is loud for a small
arcade. Add any bars to the volume and distortion kicks in and the
volume goes up enough to be annoying/painful.
So, I'm trying to figure out how audio volume is done digitally...I do
have a request in to Stern tech, but not sure if they know these older
(for them) games that well.
By the way, audio is controlled between 3800h and 3BFFh on the main MPU.
I worked that out with my Fluke 9010A today. Not exact memory locations,
but the audio enable was active for most of the calls to memory in that
range.
Thanks!
John :-#)#
--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
(604)872-5757 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."
Todd Scott
Apr 9, 2021, 6:30:30 AM4/9/21
to
John,
I had the same problem with a game. I did this service update and it helped a lot. Todd Scott
https://sternpinball.com/wp-content/uploads/2018/10/sb133.pdf
I had the same problem with a game. I did this service update and it helped a lot. Todd Scott
https://sternpinball.com/wp-content/uploads/2018/10/sb133.pdf
Kerry Imming
Apr 9, 2021, 7:12:21 AM4/9/21
to
On 4/9/2021 12:24 AM, John Robertson wrote:
> Anyone here looked into how WhiteStar board sets the audio volume? As
> near as I can figure out it is data buried in SD0 to SD7 data between
> the audio 6809E, the Basement 2K chip, and the DAC. Where I can't figure
> out is the steps in the audio - are they simply data or is one of the
> serial latches responsible?
>
> My problem is the game sound (while pretty clear) is WAY too LOUD! Only
> with one bar above zero is the sound OK, and that is loud for a small
> arcade. Add any bars to the volume and distortion kicks in and the
> volume goes up enough to be annoying/painful.
>
> So, I'm trying to figure out how audio volume is done digitally...I do
> have a request in to Stern tech, but not sure if they know these older
> (for them) games that well.
>
> By the way, audio is controlled between 3800h and 3BFFh on the main MPU.
> I worked that out with my Fluke 9010A today. Not exact memory locations,
> but the audio enable was active for most of the calls to memory in that
> range.
>
> Thanks!
>
> John :-#)#
>
The audio data is written in parallel to U23 and U24 and then serially
> Anyone here looked into how WhiteStar board sets the audio volume? As
> near as I can figure out it is data buried in SD0 to SD7 data between
> the audio 6809E, the Basement 2K chip, and the DAC. Where I can't figure
> out is the steps in the audio - are they simply data or is one of the
> serial latches responsible?
>
> My problem is the game sound (while pretty clear) is WAY too LOUD! Only
> with one bar above zero is the sound OK, and that is loud for a small
> arcade. Add any bars to the volume and distortion kicks in and the
> volume goes up enough to be annoying/painful.
>
> So, I'm trying to figure out how audio volume is done digitally...I do
> have a request in to Stern tech, but not sure if they know these older
> (for them) games that well.
>
> By the way, audio is controlled between 3800h and 3BFFh on the main MPU.
> I worked that out with my Fluke 9010A today. Not exact memory locations,
> but the audio enable was active for most of the calls to memory in that
> range.
>
> Thanks!
>
> John :-#)#
>
shifted into U26, the digital-to-analog converter (DAC). I can't
imagine a problem in SD0-SD16 that could corrupt the audio data without
causing other problems on the CPU.
The service bulletin that Todd pointed out decreases the gain of the
main amplifier (TDA2030) and seems like a good thing to try.
U30 is a low-pass filter and probably set to a gain of 1 (no
amplification). If something went wrong with it or the R16, R17
resistors it could amplify the signal and probably cause distortion but
I would suspect that to only affect the left or right channel.
- Kerry
John Robertson
Apr 9, 2021, 11:24:23 AM4/9/21
to
I agree it is hard to see how a data error would not cause serious
distortion too, but it is the volume that is simply way too high.
I'll try my logic comparator on U23, 24, and 26 just to be sure.
Weird!
Thanks,
John Robertson
Apr 9, 2021, 1:49:24 PM4/9/21
to
On 2021/04/09 4:12 a.m., Kerry Imming wrote:
Thanks for the clue! It turned out to be a bad DAC - the TDA1543 was
putting out too high a reference voltage. Normally this is -1.7VDC, but
here it was at +2.5! Now the reference voltage does not change depending
on the volume, but - of course - it does set the gain on the L&R Op Amps
U30A/B.
Volume is normal now, and regular adjustment range.
John Robertson
Apr 9, 2021, 3:03:31 PM4/9/21
to
Kerry Imming
Apr 9, 2021, 9:59:32 PM4/9/21
to
Vref failed but I'm glad you found it.
- Kerry
0 new messages