Star wars Amplifone no high voltage

newkid3

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Hello all, i have a star wars i am trying to get working. It has the Amplifone monitir. I have replaced all caps and every diode and transistor on that board. All i get is neck glow no high voltage. Any help i would greatly appreciate. I really would like to get this monitor working so i can move on with the game. Any ideas or suggestions or questions please let me know. Thanks
 
Post a clear photo of the PCB, front and back. List the tools you have at your disposal and what you feel your skill level is. This will help us help you.
 
Let me know if these pics will work. I have all tools that a tv repair shop would have. My friend has had a tv repair shop for 23 years. The game is at his shop.
 

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Let me know if these pics will work. I have all tools that a tv repair shop would have. My friend has had a tv repair shop for 23 years. The game is at his shop.

Those will do fine. However if it's at a shop that has dealt with TV's for 23 years, you should just need a copy of this manual. Work through the HV circuit like any other.

http://arcarc.xmission.com/PDF_Moni...Printing Amplifone 19in and 25in Color XY.pdf

Should be a routine fix over there. May the force be with you :)
 
That is the thing he has done everything he can think of and still no high voltage. That is why i asked on here. Thinking the people on here would have more experience on these arcade monitors. He said we get the -24 and +24 actually they are a little high about 30 volts.it has all new caps new flyback all new diodes and all new transistors. All resistors were checked and they are correct. R17 pot was replaced. Also the diode resistor modification was done sometime in the past. We get neckglow (filment voltage) anything you could think of?
 
It's really a pretty straightforward circuit so there's no magic secret that only us arcade guys know :) If the 24v regulators are OK, 24v +/- should be the output. If the output(s) are high, change the regulator associated with it. The LED should not be lit, if it is, the HV protection is tripped. See the manual for adjusting this. Check the 555 timer for oscillation at it's output pin. Check for oscillation at the input to the bu406d. Check for flyback oscillation at the primary tied to the bu406d. Step through the circuit with a scope until you isolate an area of dropout.

It's a standard flyback drive. The 555 sets the frequency, it's pumped through a coupling transformer into the drive transistor fed by -24v where it is in turn coupled to the flyback primary. The opposing side of this primary is coupled to a ferro resonant 'can' (MC1) and then coupled to +24v. It's a giant 48v loop. Don't let it psych you out.
 
Replace w1 with wire, like a leg off a cap or diode. Check the wires going to the focus block assy. Meter the B+ and see if you have anything.
 
We replaced the W1 with a wire. We checked the wires going to focus one of the wires was not connected inside rubber boot. Still no change. We get neck glow and also B+ at 181 volts no high voltage.
 
We replaced the W1 with a wire. We checked the wires going to focus one of the wires was not connected inside rubber boot. Still no change. We get neck glow and also B+ at 181 volts no high voltage.


If you have B+ and HTR then you have primary drive and at least two secondaries of the FBT. Are you sure there is no high voltage? Is that being measured at the anode cup with a probe? If you don't that only leaves about 5 things to check.

1) Focus block
2) c10
3) r18
4) r17
5) p102/j102 needs to be connected to the DAG GND.

Ie. the third primary of the FBT is open internally or externally.
 
Thanks for everyone's help so far. Our board is a version 2 and does not have a R18. That is one problem our board is different than anything we can find. We can not find a version 2 manual schematics
 
Thanks for everyone's help so far. Our board is a version 2 and does not have a R18. That is one problem our board is different than anything we can find. We can not find a version 2 manual schematics

r18 is there to program a minimum adjustment for r17. If you're doesn't have it, ignore it and check the rest.
 
Ok we get 24 volts up to collector Q5 that is where the voltage drops off. Nothing beyond that.
 
C10 checked good. R17 checked good and is a new pot. There is no R18. p102/j102 is connected to the DAG GND. Is there anyway of checking the focus block?
 
Ok we get 24 volts up to collector Q5 that is where the voltage drops off. Nothing beyond that.

Q5 isn't on the list right now. If your HV shutdown was active, you wouldn't have heater or B+ either. You need to look at the return path for the HV secondary. Electricity needs a return path. It's either open in the FBT or outside the FBT. Add pins 6+7 of the FBT to the list, they need to go to GND. Make sure the pads on the bottom where those pins are soldered are not cracked where they meet the trace.
 
On the focus block if i go from the purple wire to the red wire it is open. This should not be open should it?
Any way to test it for sure? If it is bad can a replacement be found? Thanks
 
I can put the brightness in any position and it is still open
 
Pins 6&7 on FBT are connected to ground good. It all had just been resoldered with new FBT. Can not find anything wrong. We have checked everything that has been mentioned. It is about to drive us crazy.
 
Everything you posted to date leads me to believe that particular secondary is open somewhere. Remove the flyback from the PCB and inspect where the pins enter the potting compound. Take a meter impedance reading from pin 6 to the anode and pin 7 to the anode with the flyback out. Post those. Even better, use a ringer on that winding.
 
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