Post by John RobertsonPost by cfhatprovidedotnetThe MOV is rated at 45 to 50 volts, so it did it's job!
it saw the 100v and FRIED, which is *exactly*
what it is supposed to do! This forces a fuse implosion,
which is what you want too. But when a MOV goes,
it GOES HARD AND VIOLENT. but that's what it's
supposed to do. it was preventing over voltage to
the coils in the game. Nothing else should have
fried, as the 43 volt coil power is unregulated, and
the bridge should be able to handle the 100v you
gave it.
They had ALL the fuses out. Nothing should have happened...
If the MOV blew because it was connected to the 230VAC, that would have
destroyed the transformer - that winding can't handle more than about
500MA after all.
It might be the MOV is somehow hooked up to the line voltage...
John :-#)#
Post by cfhatprovidedotnetYou can run without the MOV, but probably a good
idea to install a new one!
Also when i do a rectifier (transformer) board replacement,
after I'm done, you should *always* *always* *always* hook
the input connector up to 120 volts and test *all* the voltages.
Look at the schematics to get the exact two pins on the
input power connector. Frankly this takes all of about 1 minute
to do. All you need is two alligator clips on the rectifier board
connector 120vac pins. Or use the game's input plug (don't
attach the other two connectors.) And then use the test points
to check the voltages (6vdc, 240vdc, 15vdc, 6vac, 43vdc.)
If you had done that, problems would have been avoided...
(though that MOV would have still blown up!)
Post by John RobertsonPost by LexingtonVAPinLong story....
Punchline is that the zener labelled as VR1 in the original board caught
fire.
Two of us were called into the pinball museum to rescue a Bally Paragon.
Another person tried to 'upgrade' the rectifier board to a new after-
market one. We were told the voltages were 'wrong' after the upgrade.
We found that the HV was low and the solenoid V was ~ 100 V.
A quick look and it appeared that a pair of wires off the transformer
from the HV and the solenoid AC were switched. We didn't see any
damage, but there was a smell that bothered us. Maybe the transformer?
So we rewired the board correctly from the transformer. Double-checked
everything.
Wanted to check the AC coming out of the transformer. Removed fuses F1
- F5.
Turned it on. The zener in the VR1 location burned up and caught fire.
VR1 is NOT a zener, it is supposed to be a MOV and it is also supposed
to be after fuse F4.
Post by LexingtonVAPinI have not figured out how voltage could have gotten to VR1 with the
fuses removed.
Either you or the board designer made a mistake, or you missed something
the previous 'tech' did. Can you get the aftermarket board's
installation instructions?
Post by LexingtonVAPinAny suggestions on where to go from here?
I highly recommend Pinhead's Bally/Stern rectifier board that we sell
(here in BC) and you might be able to get from Player 1 or perhaps
Toronto Pinball (Hamilton) of The Church Of The Silver Ball in
Missisagua (I think).
Ours is here and you can download the manual which gives you all the
wiring info which may apply to your rectifier board IF the designer
followed Bally/Stern labeling.
https://flippers.com/catalog_oc/bally-stern-replacement-rectifier-board-p-2678.html?search=pinhead
Post by LexingtonVAPinMaybe if multiple bridges were shorted. If BR3, ground to AC on the
fuse was shorted, and the HV diode from ground to AC was shorted.
We removed BR3 and replaced it because it seemed to test shorted.
But
Post by LexingtonVAPinthe removed bridge tested fine in the diode test.
Wiring problems...
Post by LexingtonVAPinThis after-market board has a small bridge in place of the HV 1N4004
diodes in the original.
That shouldn't matter IF it is rated at a high enough breakdown voltage.
John :-#)#
--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
(604)872-5757 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."
I said Zener. This is a weird aftermarket board. The other tech I was
working with, who knows his stuff said he looked it up and it was a
Zener (60V if I recall correctly). But maybe we were both in shock as
that is the first time I have ever seen a board torch like that.
I have requested a schematic from the manufacturer. I don't recall the
name, but it was one I have never heard of before.
As to all of the precautions about wiring.....
Come on guys, we didn't do the initial mistake. As I said:
"Another person tried to 'upgrade' the rectifier board"
We were called in to mop up the mess.
"Either you or the board designer made a mistake, or you missed
something the previous 'tech' did."
Anything is possible. But we went over each and every connection. We
are not newbies on this, but have been doing electronics all of our
lives - between us 70 years. Did we miss something? I would bet my
left nut that we didn't. I found the two errors, moved the two wires.
Then we both went back through and checked every single connection. I
checked it. He checked it. Then I went back through it again. Traced
the wire back to the secondary numbers on the transformer. Compared
that to the letters on the schematics. Three times.
#2 to E3, #6 to E4, and on down the list.
"Also when i do a rectifier (transformer) board replacement,
after I'm done, you should *always* *always* *always* hook
the input connector up to 120 volts and test *all* the voltages."
Exactly. We do that also. And that was what we were doing. Only the
120 VAC was connected. As you know, on these Bally boards, that comes
into the rectifier board, through a fuse and back out to the primary of
the transformer. Then the secondaries come back into the board. Pulling
all five fuses should have kept the voltage away from that [MOV / Zener
or whatever]. There is no bleeping way that MOV should ever have had
any voltage across it.
"If the MOV blew because it was connected to the 230VAC"
How would 230 VAC get to that MOV? On the other side of the removed F4?
That is my question!
"It might be the MOV is somehow hooked up to the line voltage... "
Only if the transformer was shorted internally. Even then, the removal
of the fuse should have prevented that MOV from seeing any power.
Here is my only theory so far:
* This board uses a small bridge for the HV, but the equivalent of CR4
or CR3 shorted.
* The diode inside the bridge of BR3 that goes from ground to the
(empty) F4 side of the MOV is also shorted.
"If the MOV blew because it was connected to the 230VAC, that would have
destroyed the transformer"
When we came in to test the pin, first thing we did was disconnect all
outputs from the rectifier board. We tested the TP's on the rectifier
board. Saw ~100 V DC at TP5 and turned it off.
We thought we smelled something funky. We could not tell where from be
feared it was internal to the transformer.
Which is why I need to get 120 VAC hooked up to the primary and then
measure all the secondaries. Without understanding why that board
fried, the only thing I can think to do is to unsolder all the wires to
that fried board, put small wire caps on the end of the wires to keep
them from shorting, then measure one pair at a time.
--
http://orcalcoast.com/