williams comet system 9 power supply +5 volts reads 8 HELP

[hawk007]

hello everyone.....I am at a loss.  My power supply for my comet says all voltages are good but the 12 volts+ is a little low at 11.57 and the +5 is at 8 volts?  I have replaced both voltage regs. twice and the cap at c-10 and the bridge rectifier.  But still the same thing?  Please help!

[Ken Layton]

Caps C7, C8, or C9 may be open. IC1 or the resistors around it may be bad.

[hawk007]

thanks sooo much i will replace thiose now and let you know how it goes.. Thanks soooo much

[hawk007]

o.k. i replaced all that stuff and a couple diodes as well and still high 5 volts. All resistors test good and voltage regs have been replaced three times now and still the same thing.  5 reads 8 or 9 and not 5 volts!  Help !!!!

[Ken Layton]

Doesn't this board use a mica insulator between the regulator transistor and the heat sink?

[hawk007]

some do but some have a nonconductive material gasket that isolates the reg from the heat sink but still transfers heat.  mine is not shorted or connected to the heat sink at all i checked that for continuity already.  Any other ideas for me?

[hawk007]

i am ordering a new rotten dog power supply for 75 bucks.  But someone must have encountered this problem before and fixed it and i want to fix this thing.  I will not surrender!

If any more ideas p-lease help!  I am not putting this to a landfill so i will hang onto it til we fix it and i will post what finally fixes the problem.

Thanks to everyone for your help