(Topic ID: 116438)

Sound problem and opto switch problems on Metallica

By Jeff_PHX_AZ

9 years ago



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#1 9 years ago

Turned my Metallica on and the sound is very low, volume is set at 45 so it should be loud. Backbox speakers barely have sound and same with the cabinet speakers and my external Polk sub has no sound. Checked all wires, not sure what to check next.

Also have a service notice saying my Grave marker opto is out of service. Don't know what to check as far as sound. Anybody have this issue before, and can help me out? Thanks in advance

#2 9 years ago

bump

I did unplug J10 and plugged it back in, and still very faint sound out of the speakers. What else to do?

#3 9 years ago

You're going to need use a DMM to test some voltage values on the CPU. This has to do with your sound issues ONLY.

Set the meter to DC Volts and auto range. On the upper part of the CPU are the areas you'll need to test. Put the black lead on a known ground or test point that indicates GND.

Using the red lead, directly below U34, check for +12VDC. The test point is labeled +12V. Moving to the right about 3 inches, check for +3.3VDC and +5VDC where indicated. About 2" above the +5V test point is the -12V test point. Unlike B/W WPC driver boards, the test points aren't labeled as such and are very small.

Mark down the values you get and report back.

Unfortunately, most of the Stern PCB's components are surface mounted and if a problem exists that complicates matters.

As for the opto issue, start by following the wires back to the opto board and make sure that they're properly seated.

2 years later
#4 6 years ago

I have this same issue with low volume. I checked all the voltages where you said and the + & -12v test around 13v with the other testing at 3.3 and 5.

1 week later
#5 6 years ago

I just upgraded to latest code and have the low volume issue - did anyone ever find out what was the likely cause?

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