No amplifier on Stern Meteor (SB-300)

Brought home a Meteor and all is working except the sounds.

Adjusting the volume knob at the bottom of the cab is not producing any white noise, so it seems like the amp is the issue.

I am getting no vdc at TP2 (should be 11.9) but am getting 5vdc at TP4.

I checked and reseated all connectors on the sound board and the MPU ribbon cable connections, and checked all fuses on the rectifier board.

Can you help me diagnose the issue? How can I determine if it's a capacitor issue or something else, like a connection?

#2 5 years ago

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Quench

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Quoted from westofrome:
I am getting no vdc at TP2 (should be 11.9)

Are you getting 12V at the wire pin 6 of connector J2 at the sound board? From there it goes through a 2 ohm resistor to TP2 on the board.

#3 5 years ago

???

westofrome

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Quoted from Quench:
Are you getting 12V at the wire pin 6 of connector J2 at the sound board? From there it goes through a 2 ohm resistor to TP2 on the board.

I will check when I get home, but as I read the schematic, the voltage would flow from TP2 out to J2-6, so if it isn't on the test point it wouldn't be on the pin? Would I then test the components up the chain (V12, C7, R5, C1, etc)?
sb300 (resized).PNG

#4 5 years ago

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Quench

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Ignore that arrow at pin 6 on the schematic - it's not indicating flow.
12 volts comes in on that pin and/or pin 5 (since they're wired together on the board). It then goes down stream to TP2 then onto produce the 10V supply via the VR1 zener diode at TP3.

I saw your connector image in the Meteor club thread - you have double wires at pin 5 which should have 12 volts on it. Also check the back of the sound board at J2 in case the pin header has cracked solder joints.

#5 5 years ago

???

westofrome

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Quoted from Quench:
Ignore that arrow at pin 6 on the schematic - it's not indicating flow.
12 volts comes in on that pin and/or pin 5 (since they're wired together on the board). It then goes down stream to TP2 then onto produce the 10V supply via the VR1 zener diode at TP3.
I saw your connector image in the Meteor club thread - you have double wires at pin 5 which should have 12 volts on it. Also check the back of the sound board at J2 in case the pin header has cracked solder joints.

Got it, thanks! Will check and report back tonight. How can I read the schematic to determine direction of the current?

#6 5 years ago

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Quench

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Quoted from westofrome:
How can I read the schematic to determine direction of the current?

I guess it comes from experience. There's no other source of power going to the sound board that can generate 12 volts for the amplifier so it has to come externally. It's listed as 11.9VDC which is one of the voltage rails coming from the rectifier board.
It's just unfortunate about the direction of that arrow on the sound board schematic.

SternPower.jpg

4 months later

#7 4 years ago

???

westofrome

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Hi folks, getting back around to trying to solve the missing sound on Meteor...

So I actually get about 16vdc on pin 5 of J2 (where the two red wires are joined). Does this being high present a problem, and if so how can I fix it?

I reflowed solder on the 5/6 pins of the header and repinned the red wire connector. I know the 16vdc is making it through because I also get the 16v on the bottom leg of the R1 resistor.

Still nothing on TP2.

Still no sound.

Any advice on what to do next to troubleshoot this?

Thanks!
Dave

pasted_image (resized).png

#8 4 years ago

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westofrome

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One more thing, I just checked TP3 on the rectifier board and also am getting 16vdc there. The F3 fuse tests for continuity. Is this an issue with the BR2? Thanks again for any help-
Dave

#9 4 years ago

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Quench

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Quoted from westofrome:
I also get the 16v on the bottom leg of the R1 resistor.

Still nothing on TP2.

Looks like that R1 resistor might be open circuit.
With the machine OFF, disconnect that J2 connector from the sound board.
Set your multi-meter to low resistance mode.
Put one meter lead on one leg of that grey R1 resistor and the other meter lead on the other leg of that resistor. You should measure 2 ohms.
Next, read the resistance of TP2 with respect to ground. You might have a short circuited (faulty) amplifier chip at U1 which caused that resistor to blow if the R1 resistor measures open circuit (R1 is a 2 ohm 1 watt resistor).

OP
Quoted from westofrome:
One more thing, I just checked TP3 on the rectifier board and also am getting 16vdc there.

It won't read 11.9 volts as stated in the schematics on a working machine and is typically higher - anywhere from 14.0 - 16.5 volts because capacitors on that supply rail store voltage. If the transformer in the game is wired for 110VAC, changing it to 115VAC will bring the TP3 voltage down a touch (resulting in slightly reduced power consumption and heat). Take precautions if doing it that the machine disconnected from the wall.

#10 4 years ago

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westofrome

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Thanks again for your help.

Looks like that R1 resistor might be open circuit.
With the machine OFF, disconnect that J2 connector from the sound board.
Set your multi-meter to low resistance mode.
Put one meter lead on one leg of that grey R1 resistor and the other meter lead on the other leg of that resistor. You should measure 2 ohms.

I get OL on the multimeter in this test.

Next, read the resistance of TP2 with respect to ground. You might have a short circuited (faulty) amplifier chip at U1 which caused that resistor to blow if the R1 resistor measures open circuit (R1 is a 2 ohm 1 watt resistor).

TP2 to ground measures about 9 M ohms - crazy high?

Where to go from here? Replace R1? Or replace R1 and U1?

#11 4 years ago

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Quench

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Quoted from westofrome:
TP2 to ground measures about 9 M ohms - crazy high?

Where to go from here? Replace R1? Or replace R1 and U1?

I measure about 1M ohms at TP2 to ground on a loose SB-300 board I have here.

R1 is open circuit so replace it first.

#12 4 years ago

???

westofrome

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Quoted from Quench:
I measure about 1M ohms at TP2 to ground on a loose SB-300 board I have here.
R1 is open circuit so replace it first.

Thanks again, I have a resistor kit coming tomorrow and will give it a shot - it's got 10 2 ohm 1w in case the first one blows...

Appreciate you sticking with me on this, let me buy you a drink, or a tourney entry, if you'll be at Allentown.

#13 4 years ago

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westofrome

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Replaced R1 and the sound is back!

Well, about 99%. When I first turn on the machine and start a game, I only get the low "rumble" tones. About one minute into playing, I get the higher-pitched tones, like the spinner. Is this a matter of cold solder joints that need touching up?

#14 4 years ago

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Quench

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Quoted from westofrome:
Is this a matter of cold solder joints that need touching up?

Possible, look for them with a close visual inspection.

Tackle thermal problems using thermal control via a hair dryer or freeze spray.
Most air duster in an aerosol can expel cold air. If you have some, freeze sections of the sound board then power up and keep doing it until you can localize the thermal issue to a component.

1 week later

#15 4 years ago

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westofrome

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Just to close the loop on this, some sounds took a minute to come on and some sounds were missing altogether.

The solution was to reset the Alltek MPU - a tip I found in another thread. This 100% fixed all the audio issues and now all sounds come on immediately.

Thanks again for your help!

#16 4 years ago

JJZ

janus

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11y 51,600 545 12 10

OP
Quoted from westofrome:
Just to close the loop on this, some sounds took a minute to come on and some sounds were missing altogether.
The solution was to reset the Alltek MPU - a tip I found in another thread. This 100% fixed all the audio issues and now all sounds come on immediately.
Thanks again for your help!

Thank you for this. I have a meteor that's having the exact same issues as your's. Looking forward to finally fixing this.

#17 4 years ago

???

westofrome

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