USSEnterprise
Experienced Member
On both the motherboard and the disk drives. What voltages should be found at these connections. Its a 16-64 with original PSU
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IBM 5150 Power Supply voltages
- Thread starter USSEnterprise
- Start date
Chuck(G)
25k Member
Just what the documentation says, +5, -5, +12, -12. That -5 is very important to the old 16-64K mobo memory--and not all third-party PSUs supply it.
You can measure the voltages directly on the expansion card ege connectors, all referenced to position B1:
B3 = +5
B5 = -5
B7 = -12
B9 = +12
On the disk drives, Black = gnd, Yellow = +12, Red = +5. No negative voltages there.
You can measure the voltages directly on the expansion card ege connectors, all referenced to position B1:
B3 = +5
B5 = -5
B7 = -12
B9 = +12
On the disk drives, Black = gnd, Yellow = +12, Red = +5. No negative voltages there.
USSEnterprise
Experienced Member
I have +5, -5, +12, but the wire that is supposed to have -12 reads -10.49.
Chuck(G)
25k Member
That's not too serious in and of itself. Mostly, the -12 is used to supply power to any RS232 serial port drivers. The voltage isn't terribly critical. +5, -5 and +12, however are used by the DRAM on this model.