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N* Horizon Motherboard Repair

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  by Bill Degnan - 12/07/2008 19:57
Power leads on Northstar Horizon Motherboard

see page 31 of manual "Horizon Computer System Double Density" through page 37.

Power Leads
reset - grey (thinnner)
GND - black (thinnner)
-16V - yellow
GND - black from 11,000 uf cap.
+16V - orange
GND - 180,000 uf cap 1st wire
GND - 180,000 uf cap 2nd wire
+8v - red wire
+8v - other red wire

Drive A is not getting 5V (it's 1.3-2v)

Board is not sending the 5V to drive A

Had to determine whether 5v may also not be getting the controller cards - therefore the board is not bad, nor are the CPU cards.

Red wire coming from mother board +5v with P8 connector.

Need to replace the 7805 inside heatsink, 6030B, the front-most 7805.

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