Amplifone Fireworks

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I'm at a loss.

The deflection board has been rebuilt with new caps, all new transistors and voltage regulators, upgraded diodes and no modifications.

The bottle caps are substituted with 15003G and 15004G which are compatible upgrades.

The U07s and U57s are now ZTC653s and ZTX753s, again, confirmed compatible upgrades.

Question is, where does this board get its power from - is it from the game board or the HV board? The problem is that the spot killer remains off for about 5 seconds and then comes on followed by a smoked R35. Post-apocalypse diagnosis has resulted in the aforementioned parts all shorted out.

I'm thinking that perhaps the power going to the board could be the issue, but I'm nearing the end of my bandwidth on this one.
 
When you installed the ZTX's, did you install them backwards with respect to the original transistors?

You need to. They have the reverse pinout from the 07/57's.

The round side needs to face down, not up.
 
Where did you get the power transistors? A lot of the ebay ones are fake and only last a few moments.
Bought locally through an electronics shop. No concerns but yes, I did order BU406Ds from eBay and as you mentioned, they were mislabeled who knows what!
 
When you installed the ZTX's, did you install them backwards with respect to the original transistors?

You need to. They have the reverse pinout from the 07/57's.

The round side needs to face down, not up.
Sure did! I noticed the leg positions were backwards on the schematic vs the replacements and did reverse install them. No idea why the board keeps blowing. When it does, I go through everything once again to replace all the components that failed, not just the ones that smoked.
 
Thanks all for the suggestions and replies. Thai board is a mystery for sure. It may not even be the board that's the problem, but more like the end result of a problem coming from somewhere else besides the deflection board.
 
Have you tested the output voltages that the game board is outputting? (And what game is this?)

If not, measure the DC and AC voltages on the XOUT and YOUT test points on the game board, with the game board in test mode, and the monitor UNPLUGGED. (Power the board up with the test switch ALREADY flipped on before you apply power. This will force self-test to run, and display the result screen, even though you won't see it.)

The DC values on XOUT and YOUT should be between -1 and +1V. And the AC values on both should be somewhere between 2 and 4V.

If either DC value is stuck at 2 volts or more (positive or negative), or if either AC value is zero, then there's problem with the game board. And you'll have to fix that before reconnecting the monitor again.
 
Have you tested the output voltages that the game board is outputting? (And what game is this?)

If not, measure the DC and AC voltages on the XOUT and YOUT test points on the game board, with the game board in test mode, and the monitor UNPLUGGED. (Power the board up with the test switch ALREADY flipped on before you apply power. This will force self-test to run, and display the result screen, even though you won't see it.)

The DC values on XOUT and YOUT should be between -1 and +1V. And the AC values on both should be somewhere between 2 and 4V.

If either DC value is stuck at 2 volts or more (positive or negative), or if either AC value is zero, then there's problem with the game board. And you'll have to fix that before reconnecting the monitor again.
Amazing amount of advice, thank you. No, I have not tested the game board voltage - this is why I was starting to question the voltage source for the deflection board. It's a Star Wars upright.
 
No problem.

You might want to download and spend time with this doc. It explains how to bring up a 6100 color vector monitor (the model used in Tempest and other games), and walks you through a process that should catch most major issues before they cause damage. The general procedure is the same for Amplifones, in terms of the major steps, and the order to do them in:


If you have any specific questions about any of it, post them here.
 
No problem.

You might want to download and spend time with this doc. It explains how to bring up a 6100 color vector monitor (the model used in Tempest and other games), and walks you through a process that should catch most major issues before they cause damage. The general procedure is the same for Amplifones, in terms of the major steps, and the order to do them in:


If you have any specific questions about any of it, post them here.
Test results at the test points on the vector board are:

12V is 12.1V

5V is 6.98V

X is 1.073VDC and 1.617VAC

Y is -0.89VDC and 1.766VAC

All done in test mode. Looks like we're on the right path...!
 
On the vector board between the +5V test point and the nearest ground test point
 
I'd sanity check that measurement, make sure you were using the right test point and GND.

And test your DMM. (Test it on a 9V battery, or your 12V car battery, or something else with a known voltage.)

I'm surprised the board would even work if it's actually at 7V. The AR normally can't even go that high. So if it is that high, your AR likely has issues.
 
Ok. That makes it pretty clear. Wow.

Turn that voltage down using the pot on the AR, immediately.

You should also replace the 2N3055 bottlecap transistor on the AR, as it's likely damaged. Normally the AR's adjustment range should be roughly 4 to 6V, for the min to max travel of the pot. So the fact that it's 7V means something else is likely wrong with the AR. And the 3055 should be replaced on any AR anyway (even if still working). They all have 10,000+ hours on them, they fail often, and they are a high risk part because when they fail short they will send 10+ volts to the game board, damaging it. But if you replace it, you'll be good for another 40 years.

Get a replacement 3055 from arcadepartsandrepair.com or Digikey. Not ebay, Aliexpress, Arcadeshop, Amazon, or any other untrusted source. There are a lot of counterfeits of these out there, and we've seen them damage game boards. It's the most critical part in the entire cab, so you want to be 100% sure you have a legitimate part.

Also, check R29 and R30 on the AR. If either is burned, replace it. They are 10 ohm, 1/4 watt. Do NOT use 1/2 watt.
 
The plot thickens....

The pot at R8 does register resistance change when tested with the DMM, but turning it does not affect any voltages on the AR or on the vector board at all - they remain constant and at the 6.98V.

I tested the bottle cap and it appears fine at this time but I'll replace it for good measure.

As for the board's voltages not being impacted by turning the pot, that's another issue.
 
Ok. That makes it pretty clear. Wow.

Turn that voltage down using the pot on the AR, immediately.

You should also replace the 2N3055 bottlecap transistor on the AR, as it's likely damaged. Normally the AR's adjustment range should be roughly 4 to 6V, for the min to max travel of the pot. So the fact that it's 7V means something else is likely wrong with the AR. And the 3055 should be replaced on any AR anyway (even if still working). They all have 10,000+ hours on them, they fail often, and they are a high risk part because when they fail short they will send 10+ volts to the game board, damaging it. But if you replace it, you'll be good for another 40 years.

Get a replacement 3055 from arcadepartsandrepair.com or Digikey. Not ebay, Aliexpress, Arcadeshop, Amazon, or any other untrusted source. There are a lot of counterfeits of these out there, and we've seen them damage game boards. It's the most critical part in the entire cab, so you want to be 100% sure you have a legitimate part.

Also, check R29 and R30 on the AR. If either is burned, replace it. They are 10 ohm, 1/4 watt. Do NOT use 1/2 watt.
I took measurements on the power brick and getting:

Pin 1-3 14VDC

Pin 6-7 18.4VAC

Pin 8 7VAC

Pin 9 4.7VAC

Pin 10 14VAC

Pin 11 6.8VAC

Pin 13 27.7VAC
 
See the wiring diagram in the Star Wars schematics for how to test the power brick voltages. AC voltages must be tested between two pins, not from one to ground.

1760031981143.png


Also, the 2N3055 can test ok and still be bad, if it isn't tested under load.

Also, you may have a bad LM-305 regulator (the tin can thing on the AR). But replace the 3055 first, as that needs to be done anyway, then see where you are at. The LM-305's don't go bad often enough to warrant always replacing them, but they can go bad. I would also NOT plug the game board into that AR until you get the voltage situation figured out.

And be sure to test all other resistors for the 5V regulator circuit, which you can do in-system. (Compare against another AR if needed.)
 
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