ECA 008 - speaker noise


ECA 008 - Speaker Noise

Continuous speaker noise on 8580 mod 111 and mod 311 (ECA008)

 

PURPOSE:
To provide instructions for identifying and replacing 8580 model 111 or 311 system planar boards that cause erratic speaker operation or noise when a Math coprocessor is installed.

Machines Affected
Model
80-111 serial # below 6019000 see physical check!
80-311 serial # below 6502022 see physical check!

PHYSICAL check:
  1.  Suspected planar boards (FRU P/N 90X7390), can be identified  by checking the part number of the planars and of the PAL in  location U26. Good planar boards can be identified by P/N  15F7979, 15F7982 and 15F7985. These however must have U26 part  P/N 15F7988.
  2.  Down level P/N are 15F6603, 15F6606 and 15F6727.  these will have U26 with a P/N 90X8011.
  3.  Check for the installation of the 80387 Math Coprocessor.  The location of the Math Coprocessor can be found in the PS/2  model 80 quick reference manual on page 39 or the HMR on p3.10.  If a Coprocessor is installed and the planar is identified as  listed above,replace the planar board as instructed in the  detail section of this ECA:.
  4.  If any other P/N than those listed above or there  is no Coprocessor installed, no further action is required.

The 8580 speaker makes a crackling noise and/or short beeps. The worse case condition is the speaker turns on continuously and cannot be reset. Only 8580 models 111 and 311 with an 80387 Math Coprocessor installed are affected.

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