Unexpected Resets with the DSP-599zx

July 17, 1996
A few of the new DSP-599zx units were shipped without a screw that bonds the 5 volt regulator to the circuit card. This enabled the circuit card to carry away heat it generates. If the regulator gets too hot, it will shut itself off until it cools down and then it comes back on. This has the effect of turning the unit's power off and on, causing it to re-initialize over and over. Ths solution is to add the missing screw as follows:
  1. Read all the steps before your begin.
  2. Remove all connections to the DSP-599zx
  3. Loosen the 4 screws (2 front, 2 rear) that hold the plastic bezels on and remove them.
  4. Remove the 2 screws and plastic washers from the bottom of the case.
  5. Remove the 4 front and 4 rear panel screws.
  6. Pull the front panel out slightly and remove the 2 ribbon cables connected to it. Note the cable connector orientation for proper re-assembly.
  7. Slide the circuit card out of the case towards the rear. Always use appropriate static electricity precautions when handling the circuit card.
  8. The 5 volt regulator is located near the on-card fuse and is labeled U-16. Note the hole in it and the hole in the circuit card.
  9. Install an approximately 3/8 inch long 4-40 machine screw from the card's bottom (foil) side upward through it's hole and the regulator's hole.
  10. Place a 4-40 split-ring lockwasher and nut on the end and tighten it down firmly. Do not use a nut driver or socket to hold the nut when tightening as their wall thickness is often too great to allow clearance between the body of the regulator and the nut. An open ended wrench or pliers will suffice for holding the nut while you tighten the screw. Remember, you are not putting on a car tire here.
  11. Reverse the disassembly procedure and you're all done. Make sure you orient the 2 ribbon cable connectors the same way they came off.
If you are not comfortable with performing this task yourself, send your unit in and we will be happy to do it for you free of charge.

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