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Fishtales Loud Humming

Optimus Prime

Optimus Prime

Registered
Joined
Mar 8, 2016
Messages
101
Location
Ireland
Hi Guys,

hoping you can help me out with this, bought this a few weeks ago, have taken it apart and cleaned it inside and out. putting it back together now.

Originally a load of lights where out, needed an eject hole switch and the eject mech itself wasnt working. a bumper light is broken too and a few fuses out. I changed a load of other stuff like legs, side rails, plastics etc anyways.

last week while working on it i had this loud humming noise. i tracked it down to the wrong bulb in one spot. changed that and the hum was gone. all good.

today i fixed the eject hole lever for video mode etc, it was pretty much just stiff so cleaned it down etc. and its working great. but when i turned the machine back on its making this loud hum again. ive gone around removing loads of lights from and turning it on testing but the noise is still there. I didnt touch anything today before it started other than the eject hole assembly thing and the coil, removing them.

If i remove the cables from the sound board it goes away. Is it an earth issue? ive checked from the earth on the plug to various parts of the pin and it gets connectivity on my meter.

any help appreciate.. video of the humming noise below.

 
Sgt GrizZ said:
Had that on a Flintstones. IIRC I had to change a capacitor (?) on the sound board ...let me try and remember exactly what it was.
Click to expand...
Thanks, if you remember let me know, its doing my head in at this stage trying to figure out! cheers
 
Those caps are easy to make a right mess of.
Ask me how I know........
If I was doing them again I'd cut them off instead of trying to get them off in one.
 
Don't make me nervous ! Haha

Considering I haven't a clue how to do them anyways. I capped a game gear once and it didn't work after it.

I'll give it a go though. Might swap the getaway sound board in first see if it works. Would that be a good indicator if that's the issue ?
 
would there be a high risk to me damaging anything in the getaway by putting the broken soundcard in there? (if it is broken)

Ill get a chance to try it the weekend. Thanks
 
I put the fishtales sound board in the getaway and it didnt work, it wasnt a hum though, the dmd was all messed up with dots on it and no lights came on. I put the getaway one in fishtales and it worked, i could hear the music etc where i cant when the fishtales soundboard is in because of the hum.

I had a look on the underside of the fishtales soundboard and where the two caps are and the black tower thing is, not sure what its called, there seems to be either bad solder joints or some sort of leakage?? im not sure.. what do you guys think?

www.gamersireland.ie_wp_content_uploads_2017_fishtales_fishtalessoundboard.jpg
 
The problem here is that when the old capacitors were removed it's highly likely that the plating through the board was also removed. This means that the solder doesn't easily flow trough to the component side of the board where you need to connect to two solder pads/traces. So it's likely you have poor connection to the tracks under the body of the capacitor. The quick fix is to work out where the hidden pads go to and add a jumper wire to replace the connection. You can also use a meter to test for continuity between these points first.
 
Fixed it!!

It was one of either two things, i did both these before turning it on and the humming was gone.

1. Put washers on the screws behind the sound board so the connections behind there for the earth where bigger\more secure.

2. Removed the transformer and scrubbed the leg where it touched the earth braid with steel wool.. it was a bit rusty looking and cleaned up well so it may have been a bad earth to the transformer causing it?

Its working great now though! Just waiting on a part to fix the middle pop bumper and its 100%!

Oh while replacing the switch in the rod\caster thing that launches a ball i noticed it had a light in it. think i read the early ones had lights in the launcher??
 
Nice 50hz hum you had there. Your problem was likely the transformer leg - noise of that specific tone is generated by the AC side of the power circuitry. Not coincidentally, in America and other places with 60hz AC frequency, the sound is correspondingly 60hz.

Here's 50hz...

Compare to 60hz (jump to about two thirds in)...
 
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