Re: Bally -54 Rectifier Voltage Question and other issues

On Aug 28, 9:37 am, Steve Kulpa <steveku...@xxxxxxxxx> wrote:
On Aug 28, 8:59 am, Keroppi <king.kero...@xxxxxxxxx> wrote:

Thanks, that's what I kinda figured needed to happen. Will put the
parts on order (again)...
In the mean time, any recommendations on the 5V side of the board?
Short of buying another whole rebuild kit? My biggest suspect is the
regulator itself. How would I test it? Diode setting? What readings
should I see, and do I need to remove it from the circuit first?-

the 5volt regulator can not be tested w/ a meter in the diode setting,
as it's an integrated circuit, not a transistor.  Best way to check it
is to hook it up, and measure the value at TP5 (11VDC) and TP1 (5VDC)
on the sole/reg board.  If TP5 is low, or pushing 20VDC or more, you
have arectifierboard issue (replace the diodes - use heafty 6A2 or
6A4 diodes).  If TP5 is OK, then TP1 has to be 5VDC + or - 0.25V.  Any
more or less, replace the filter cap (C23) if it's old (12,000 -
15,000uF, 25VDC or more).  If the filter cap is new and TP1 is still
out of spec, get a new LM323K.

If you have issues with the HV regulator or other parts, simply remove
their fuses from therectifierboard BEFORE you turn it on.  You'll
need F3, since that's the fuse for the 11VDC.  The others (besides the
main fuse in the off-board holder) can be removed.  Also, keep in mind
the 11VDC was rectified by the 4 big diodes, not one of the two
bridges.

and DUH, turn the machine off before messing with the fuses

steve
---
Steve Kulpa (cargpb10)
Nolensville, TNhttp://stevekulpa.net/pinball/pinball.htm- Pinballhttp://stevekulpa.net/faces/rgpidx.htm - Faces

Thanks so much for the help Steve. Let me clarify where I am at:

Short of the connectors (they were un-tarnished)....I have replaced
EVERYTHING on the rectifier board, as well as the everything in the 5V
regulator section of the SDU.
On the rectifier: I don't blow any fuses at all. All TP voltages are
within spec except 12V, which measures low 9-10V with J3 unplugged.
Plugging it in took the 12V down to .5V as mentioned earlier.
I started systematically removing all components from the 5V-regulator
circuit to figure out what is bringing the voltage down. This is what
I found: The 12V (TP5) circuit stays @ ~.5V unless I remove BOTH C23
and the LM323K. Everything else can be removed from the circuit and it
stays @ .5V if these are soldered in.
So, I soldered everything back and removed the regulator and C23, and
powered up. the 12V voltage goes hay-wire, climbing up to ~ 24V and
slowly coming back down, checked on the 12V TP of both the SDU and
rectifier, they both match. I can power down and back up and the
process will repeat. If I unplug J3, the 12V on the rectifier goes
back to 9-10V like it was. I assume its fluctuating because there are
other resistors and caps still in the circuit?
I thought maybe there is an off-chance that my new LM323 or cap could
be bad, so since I still have the old ones, I swapped them in. The
result is the same: if I put either item (or both of them) back in the
circuit, old or new, it pulls the voltage down to .5V
The only thing I have not removed is the jumper from the negative
terminal of C23 to ground. I mean, it's just tied ground to ground; it
couldn't possibly be a problem, could it?

To the didoes you speak of: Using the diode test on my DMM, all 4
tested the same (4.9 I think)...but when testing the voltage coming
off of them, CR5 was <1V when CR6-CR8 were all 8-9V each. When the
voltage went up over 20, CR5 was still low, while CR6-CR8 were pumping
all the voltage. Is this by design, or is CR5 suspected to be bad?
These are all new huge, high amp diodes that came in the kit.

Where should I go from here? Thanks again!!
.

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