Its true what they say about sega vectors

Kalan714

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Had some friends over last night and one of them noticed a burning smell so instinctively i went to my Segas and noticed my eliminator screen went black so i shut it off and it smelled pretty bad. So I looked for the problem this morning and found this board on the monitor.

20130127_085703.jpg


Luckily i have a spare monitor and its still works great but im taking a long look at selling it.
 
Well at least that looks like a small and easy board to reproduce....

I would be very interested to know 'exactly' what failed that did that, and if a bulletproof rebuild, similar to the goals of the Amplifone overhaul, would prevent that.
 
Finding out why it failed is as important as repairing the damage.

When Resistors burn, it is normally an indication that something is drawing too much current.

I would look at the high voltage side and the Fly back transformer.
 
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Yep, thats pretty common when the deflection transitors fail. Make sure you get the EXACT resistors, and the X and Y boards are different. If you get larger resistors, it will clip the screen. Those are the sample resistors for the production circuit.
 
Yup, and the same thing happens on other vectors, so it's not just Sega's problem... if you lose deflecting transistors on a 6100, it burns up resistors over near the low voltage area, if you lose deflection transistors on a cinematronics, it burns up resistors on the left side of the board, etc.
 
Did the fuses at F600 and F700 blow? What rating are they?

I'm very interested in why this failed as I have 3 G08s currently. I just repaired one, am deep into the second, and on more in the queue...
 
Did the fuses at F600 and F700 blow? What rating are they?

I'm very interested in why this failed as I have 3 G08s currently. I just repaired one, am deep into the second, and on more in the queue...

Your fuses are likely blowing because your getting DC from the output stage. Now, as to why your getting DC on the output stage.. Id guess one of your MPS u10 or u56s are fried.

The few times Ive worked on these, I pull the board from the frame completely, and dont even hook up the deflection transistors until I get a nice looking waveform on the scope.
 
The few times Ive worked on these, I pull the board from the frame completely, and dont even hook up the deflection transistors until I get a nice looking waveform on the scope.

Excellent idea. I'm doing this now that I started testing my second one. Thanks for the tip!
 
Either that or test the power transistors right from the start.

I agree with not hooking them up until you have sane output from the rest of the board.

Kerry
 
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