bally freedom ss, power issues

cadillacman

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I have a ss bally freedom here.. went through the mpu, driver, power boards a few years ago. Been perfect untill now.

One day, powered on and mpu not booting( led not on or blinking) and displays are blank of course but can see a orange dot so i know they have h.v.

A test of the power supply shows .400v at tp3. Other voltages are correct. Checked and rechecked fuses, all check good. From what ive checked, this tp3 is supposed to be around 12 volts dc. I back tracked to the rectifier(br2) and i have no ac to the rectifier. This is supposed to be supplied with 12vac from the transformer. I pulled up the board form the transformer, and i see no broken connections. I have no ac even at the fuse.

I think i have a bad transformer, do you guys agree? Ever see one fail like this?
 
did that two years ago lol but i guess it cant hurt. DO you think its shorted ro something and thats pulling down the ac? From what i remember the replacement rectifiers were special ones that were fatter/higher rating then the original. I gotta remember where the hell i got them from now.. if it ends up indeed bieng the rectifier i guess ill need to add a fan in there.
 
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Replaced the rectifiers. Same prob. I knew there wasnt anything wrong with them.

Even with br2 out, all i get is 1.5vac across the ac terminals.

DO i replace the transformer yet or is there something else im missing. Checked and rechecked fuses again.

Im about to hack a atx ps in here. ALL i need is a good clean 12v.
 
To test the transformer winding I would desolder the wires going from the transformer to the back of the rectifier board for that winding (connections E11 and E12) and check right at the wires coming out of the transformer. If you still don't see the proper voltage at those points with AC applied you've got a bad transformer winding.

Replaced the rectifiers. Same prob. I knew there wasnt anything wrong with them.

You could have just tested the bridges. Would have saved some time/money.

Even with br2 out, all i get is 1.5vac across the ac terminals.

Like I said above I would isolate the wires coming out of the transformer and check the voltage there. Could prove to be a bad solder joint where those wires connect to the rectifier board or something. If you still see a reading of 1.5vac with the winding isolated that would definitely be an unusual problem but not impossible. At that point you've concluded that your transformer is the source of your problem.

Im about to hack a atx ps in here. ALL i need is a good clean 12v.

If I were going to do that I would just bypass the existing +5VDC regulator all together. You could remove +5 section from the regulator/driver board, connect TP1 and TP3 together (should do this anyway) and apply the +5VDC from the switcher to one of those points. You could also wire the switcher in at the rectifier board as you've suggested.

With all that said I would still advise against it because it could introduce other problems. Switchers don't become stable as quickly as linear power supplies so your MPU might decide that it doesn't want to boot half of the time. Or at all. This is a problem with bench testing MPUs. I can only imagine it would be a lot more annoying in a machine that you were trying to play. A solution would be to lengthen the reset which is documented on pinrepair.com. You can either add a capacitor to the existing reset circuit to lengthen the reset or replace the circuit all together with something like a Dallas DS1811.

It's something to consider if you can't find a transformer for a reasonable price.

That should pretty much cover it :)
 
im pretty sure i have already rung out the wires between the board and the transformer, but i will again. I might have a deal on another ps. Either way im getting it. But its worth retesting one more time.

Yeah, i wont be hacking it unless i absoultely have to. Thank you lindsey.
 
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sorry this is old but im going thru this with my first SS machine a Bally Night Rider, are you saying to join TP3 and TP1 on the rectifier board?
 
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