You can put the CPU into your F-14 game after switching the ROMs. This should isolate your issue to the CPU or a connector issue.
(Topic ID: 231590)
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Quoted from Brijam:I just did - 4.8v not good enough I take it? What should it be?
Should be 5.0 volts. Pull off 1J-17 connector from the CPU board and retest the 5 volts on the connector itself (grey wires). If it stays the same, then there is a trick to increase the output, if it is 5 volts now then you may need a new connector and header pins on 1J-17.
Quoted from Brijam:I guess the upgrade didn't go as planned.
Your upgrade is fine, but there are some tolerances on some parts that can affect the output. Now you output is steady at 4.8 which is good but too low. There is a resistor that gives a reference voltage to the voltage regulator chip which affects the final output. If you replace this resistor R-8 on the power supply with a different value you can raise the voltage output level. Give me some time and I can calculate a new value for you to raise the output .2 volts.
Here you go, use a 1% metal film 5.23k resistor like this to replace R-8 on the power supply.
ebay.com link: 4 pcs 5 23k ohm 1 4W 1 Metal Film Resistors
This will bring up the voltage to @ 4.96 volts.
Quoted from Jr99svt:Wouldnt it be better to find the cause of the issue, rather than mask it?
I always want to fix the issue and not install a band aid, but as he stated, he has rebuilt the power supply, retested voltage with CPU disconnected with no increase in voltage. Meaning the CPU isn't dragging down the voltage and no loss at the connectors. Not much left but to change R-8.
You can check the output of your F-14 power supply. If its closer to factory specs then swap the F-14 power supply into Pinbot and then retest the outputs again. If the outputs drop then you have a cabinet wiring issue. If the outputs remain the same then the problem has been isolated to the Pinbot power supply.
Quoted from Brijam:I don't remember if the BR was replaced but I don't think so.
Snap a pic of the power supply, I maybe able to tell if it has been replaced.
Quoted from Jr99svt:There is nothing in the 12v circuit on the power supply, other than the bridge rectifier, with 2 Caps nearby.
Last time I checked this is a unregulated half wave rectified,(BR1 bridge) filtered (C-10 cap) power supply. If 12 volts is not made on the power supply where does it come from?
1 week later
Quoted from Brijam:Both fuses read 10.43VAC and so does the pin on the power connector. I’m reading 120VAC input to the transformer so it looks like I need a new transformer?
This is what a step down transformer does, 120 volts AC in 10 volts AC out. Nothing wrong here.
Quoted from Brijam:Snap a pic of the power supply, I maybe able to tell if it has been replaced.
Bridge rectifier is original and so is Q-5 transistor. It looks like only the caps were changed, but with the wrong type of caps.
Quoted from Jr99svt:Unless he measured incorrectly,
Not incorrectly, just one winding at a time. When you add both winding's together you have 20.86 volts AC. Its called a center tap transformer.
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