Haunted House "Sound board issue?"

(Topic ID: 206257)

Haunted House "Sound board issue?"

By Boltronix

1 year ago

Topic Stats

  • 6 posts
  • 4 Pinsiders participating
  • Latest reply 1 year ago by Boltronix
  • Topic is favorited by 1 Pinsider


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#2 1 year ago


Yes the 30 VDC is only used for the amplifier (LM379S).
All others voltages +/- 12vdc are for D/A converters (1408) and pre-amp. (LM741).
The A7 board (speech/sound power supply board) produce the regulated +/- 12 volts for converters, and the +30 volts for the amplifier.

The sound board had receive later some modifications:
On september, 1981, the "On-target newsletter" announce an improvement to provide higher volume level for sound/speech. They remove and replace some discrete components around the LM379S. Nothing very important here (they also improve the stability for the speech generator - but not installed on HH).
But, on july/aug. 1983, as the LM379S was no more produced, Gottlieb replace it by a TDA2002, mounted on a piggy-back. Of course, as the TDA2002 doesn't support the 30 VDC, they also made some modifications on the A7 power board. Only the "high-voltage" section was changed, to reduce the 30 VDC to 18 VDC to be compliant with the TDA2002 specifications.

Finding a LM379S today is very difficult. When the amp is dead, we use solutions based on LM1875 or something similar.

#4 1 year ago

Note that the replacement of the rare LM379S has already been discussed here.
An there is a wiki (from chrishibler) for replacing by a LM1875 :

I know a guy in France that has some LM379S in stock (about 15€ here). But to my mind, the LM1875 is better and more modern.

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