(Topic ID: 274360)

Fish Tales DMD Controler Board Fuse F602 Blowing

By Evangelist

1 year ago



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  • 6 posts
  • 4 Pinsiders participating
  • Latest reply 1 year ago by Schwaggs
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#1 1 year ago

You don’t need a multimeter to confirm some of these components need changing....

IMG_20200727_191727 (2) (resized).jpg

I changed the components highlighted (Q4, Q5, Q6, D4, D4 & R5) in yellow except BR2 as I have tested it and it seems fine.

IMG_0157 (resized).jpgIMG_0158 (resized).jpg

BR Test using Multimeter in Diode testing mode gets a reading of between 0.5v to 0.7v for :
==> -ve MM lead on either the AC legs & +ve MM lead on the -ve DC leg of Bridge Rectifier BR2
==> +ve MM lead on either the AC legs & -ve MM lead on the +ve DC leg of Bridge Rectifier BR2

IMG_20200802_143428 (resized).jpg

All looking good and thought I was on for a quick easy fix but put it back in the game with the DMD unplugged and fuse F602 blows straight away.

FYI I have tested it in another machine so it's definitely the DMD Controller Board.

==> Is it possible that the Bridge Rectifier (BR2) can test ok but at higher voltage cause issues??

==> Are there any other components which could cause F602 to blow which I have not yet replaced??

I think I will be replacing BR2 just in case.

Thanks in advance for any suggestions

#2 1 year ago

C9 which is a .1 uf @ 500 volt ceramic disc capacitor.

C7 which is 150 uf @ 160 volt electrolytic. I use a 220 uf @ 160 volt as a replacement.

Definitely replace that bridge rectifier anyway. It's dirt cheap.

#3 1 year ago
Quoted from Evangelist:

You don’t need a multimeter to confirm some of these components need changing....
[quoted image]
I changed the components highlighted (Q4, Q5, Q6, D4, D4 & R5) in yellow except BR2 as I have tested it and it seems fine.
[quoted image][quoted image]
BR Test using Multimeter in Diode testing mode gets a reading of between 0.5v to 0.7v for :
==> -ve MM lead on either the AC legs & +ve MM lead on the -ve DC leg of Bridge Rectifier BR2
==> +ve MM lead on either the AC legs & -ve MM lead on the +ve DC leg of Bridge Rectifier BR2
[quoted image]
All looking good and thought I was on for a quick easy fix but put it back in the game with the DMD unplugged and fuse F602 blows straight away.
FYI I have tested it in another machine so it's definitely the DMD Controller Board.
==> Is it possible that the Bridge Rectifier (BR2) can test ok but at higher voltage cause issues??
==> Are there any other components which could cause F602 to blow which I have not yet replaced??
I think I will be replacing BR2 just in case.
Thanks in advance for any suggestions

In one direction, you should get .5-.7 in the other, you should get infinite. If its bad, you might get 0. You didn't list the measurement in the other direction.

As Ken said, replace both of the filter caps C4 and C7. It could have failed shorted.

1 week later
#5 1 year ago
Quoted from KenLayton:

C9 which is a .1 uf @ 500 volt ceramic disc capacitor.
C7 which is 150 uf @ 160 volt electrolytic. I use a 220 uf @ 160 volt as a replacement.
Definitely replace that bridge rectifier anyway. It's dirt cheap.

BR2 replaced and found C9 was shorted so replaced it... DMD working now like it did in 1994.

Thanks

#6 1 year ago

Congrats on the fix!

This is an example why you don't overfuse a circuit. If you would have simply tried a larger fuse in that circuit, you could have burned traces off that board making the fix more difficult and messy!

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