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Old 21st September 2013, 01:22 AM   #1
almc224 is offline almc224  Puerto Rico
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Default 2db maybe more lower channel?

This is my second post. The previous situation is all cleared up, thanks guys. But I'm still not out of the woods.

Again, I have a set of Bose 901, Crest AMP 900V, Gemini PA-7000, Sony CD/DVD deck. The problem is that when I play music one channel is a lot lower then the other one. When I use the balance, the right is loud and clear, the left one is very low, you almost can't hear it. But when I use the headphones, both channels run fine. Tomorrow I'm installing new RCA wires. Can anyone help, once again, thanks.
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Old 21st September 2013, 02:17 AM   #2
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Default Just Standard Diagnosis Procedure....

You need to swap channels of signal connecting/speaker cables to determine where the fault is.
Most likely one output of the Gemini mixer is faulty....look inside for cracked solder joints at output terminals for a start.

Dan.
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Old 21st September 2013, 04:12 AM   #3
almc224 is offline almc224  Puerto Rico
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Thank you mate. I was wondering, has anyone in this forum, or on the net have a diagram of this Preamp? I once had one, but my computer went down and it was deleted. BTW, I check their website, no go.
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Old 21st September 2013, 03:11 PM   #4
almc224 is offline almc224  Puerto Rico
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Well, this morning I changed all the RCA wires, still the "B" channel is down. Headphones are good though, both channels working. Question, Is their a video in You Tube or in this forum with this procedure? Even though I've been working with music and equipment. This is my first time I'm going into an electrical equipment like this to give service. I do have pictures, or I can even post pictures of the inside of my Preamp.
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Old 21st September 2013, 03:20 PM   #5
almc224 is offline almc224  Puerto Rico
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Here are some pictures:

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.
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Old 21st September 2013, 03:22 PM   #6
almc224 is offline almc224  Puerto Rico
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Feel free to make any pointers and observations, once more, thanks.
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Old 21st September 2013, 04:01 PM   #7
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I need much bigger photos please.

Dan.
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Old 21st September 2013, 05:02 PM   #8
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You've told us that this preamplifier will drive headphones but somehow the signal from the preamplifier to the amplifier and speakers is down - almost dead in one channel, right?

It seems obvious but this does indicate that the problem is in the amplifier/speakers so why are you focused on the preamplifier? Is it because you swapped inputs to the amp. and both amplifier channels worked the same?

As Max Headroom pointed out, if there is a fault in the preamplifier, it will likely be in the internal connections to the connecting sockets. As it drives phones, there isn't much that could be wrong there that isn't loose connecting wires, broken soldering etc.

Tracing circuit problems though, does require the schematic which is not free on the net so few will be able to help you, unfortunately.
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Old 21st September 2013, 05:28 PM   #9
almc224 is offline almc224  Puerto Rico
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The reason why I state that its a PreAMP, I've already taken the AMP to a Certified technician and he told me the AMP was fine.

The reason why I think its the PreAMP, I try it on mono and it works fine. In Stereo where the problem is.

Here is the AMPs pdf Crest V900 AMP

Here is the PreAMP pdf Gemini PA-7000

I use the Bose 901 Factory active EQ.
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Old 21st September 2013, 05:50 PM   #10
AndrewT is offline AndrewT  Scotland
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Swap the speakers.
Is the fault in the same channel?
Swap the amplifiers.
Is the fault in the same channel?
Swap the pre outputs.
Is the fault in thew same channel?
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