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Fish tales loud static hum

B

Body pop

Registered
Joined
Feb 23, 2015
Messages
212
Location
Belfast
Could anyone help me with this please
There a loud him from my fishtales
Backround .it was blowing main fuse ,
Dotmatrix was faulty ,I changed to an xpin control board ,then had to buy a second hand dotmatrix when that didn't fix problem
Changed line filter ,Varistor and thermistor when it started blowing main fuse
Now it's playing ,dotmatrix is working ,but you can't hear the sound /music etc
Just this worryingly loud hum ,that gets so bad ,it sounds like it might blow
 
I had a VERY loud hum on my Jokerz. Tried all sorts before I was pointed in the direction of the bridge rectifiers. There was ripple in the DC circuit which was playing havoc with the sound which needed a pure DC supply.

Dunno if WPC works the same but definitely something worth looking at.
 
Did some post on here with a similar issue ,and tightening the transformer down or hitting it with a hammer solve it:hmm:

PS I am at a pub writing this :tut:
 
The caps look ok on sound board
I'm not sure about the bridge rectifiers ,are they on sound board ?
I took the xpin board out ,and put original in dot matrix was fine
Then I took sound board out ,to look for clues ,when I put it back in dotmatrix was messed up
 
The bridge rectifiers are on the power driver board. You need to check the DC voltages for AC ripple.

Check (and double check) the ribbon cable that goes to the sound board for the DMD issue. VERY easy to have it misaligned by one pin.
 
Only work on the voltages if you are capable and confident that you won't kill yourself or blow your machine up.
 
Thanks mate .
Il check the bridge rectifiers and take it from there
The other thing I was wondering ,could the wrong thermistor cause this ,a guy on pinside had gave me the link for it in USA ,would they be different than ours ?
 
There are thermistors for 110v and 240v so yes you could have the wrong one, i'm not sure but i would have thought a 110v rated one in a 240v wouldn't last long.. I should have a 240v rated one if you need it

More importantly, I see you are in Belfast ! i'm based in Ballyhackamore (near stormont) are you the guy over in Castlereagh Road that does the arcade stuff?
I currently run the Irish pinball league if that's of any interest ? Last meet of the season is in Waterford on the 31st July get in touch if you want to come along, haven't sorted lifts etc yet. Don't let the term 'league' put you off its more jsut a get to gether to play some pinball and talk rubbish.

Anyhow let me know if you need the Thermistor and I will have a look when i get home..
 
I actually just read a good bit of the thread on the league last night .
Sounds great ,I'm getting more into pinballs now ,and have been selling some of my video games and stuff.
Will will make a point of getting down that day ,if heard of you before .so would be good to meet some other enthusiasts .
This is thermistor is
 

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astyy said:
How do you check that Andrew?
Click to expand...
As aaronhicksuk said above. A scope is best but a decent multimeter set to AC volts will pick up voltage ripple in a DC circuit. As stated it should read 0V, any voltage being read is the amount of ripple getting through the bridge rectifiers.
 
Just to clarify a few points. There are varistors, and thermistors. A thermistor goes in line with the supply voltage and provides protection against high currents when you switch on. They are not voltage rated. Varistors protect against over voltage, they connect across the line voltage. If a 110v varistors was fitted it would go short circuit the instant it was plugged into 240v. The fuse would blow. A bridge rectifier passes AC, but it puts the negative AC peaks into the Positive. The ripple is removed after the bridge rectifier by the big capacitor. The capacitor acts to maintain the voltage when the rectified AC drops towards zero. Excess ripple occurs when the capacitor is bad or not connected.
 
pinballmania said:
Just to clarify a few points. There are varistors, and thermistors. A thermistor goes in line with the supply voltage and provides protection against high currents when you switch on. They are not voltage rated. Varistors protect against over voltage, they connect across the line voltage. If a 110v varistors was fitted it would go short circuit the instant it was plugged into 240v. The fuse would blow. A bridge rectifier passes AC, but it puts the negative AC peaks into the Positive. The ripple is removed after the bridge rectifier by the big capacitor. The capacitor acts to maintain the voltage when the rectified AC drops towards zero. Excess ripple occurs when the capacitor is bad or not connected.
Click to expand...


My bad I was talking about varistors. Realised when I got home and hoked out the varistors. Suddenly realised
 
Last edited:
pinballmania said:
Just to clarify a few points. There are varistors, and thermistors. A thermistor goes in line with the supply voltage and provides protection against high currents when you switch on. They are not voltage rated. Varistors protect against over voltage, they connect across the line voltage. If a 110v varistors was fitted it would go short circuit the instant it was plugged into 240v. The fuse would blow. A bridge rectifier passes AC, but it puts the negative AC peaks into the Positive. The ripple is removed after the bridge rectifier by the big capacitor. The capacitor acts to maintain the voltage when the rectified AC drops towards zero. Excess ripple occurs when the capacitor is bad or not connected.
Click to expand...

That's a great explanation thanks for that
 
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