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Author Topic: Yamaha G100 410 - Series 1 - Low Volume / Surges when turning off.  (Read 2759 times)

ryanckelso

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Re: Yamaha G100 410 - Series 1 - Low Volume / Surges when turning off.
« Reply #30 on: May 18, 2020, 09:29:32 AM »
To add to the previous post:

I went through the board with the audio probe connected to a separate amp that I know works well.

There is audio at points 5, +CO and even on the white cables connected to the speakers.

So I think the MA board is now working fine - it is amplifying between TR13/14 - TR17/18 and TR19.

I guess the issue is that the speakers are not being driven for some reason to create the sound.

I looked back at an old post to test the AC voltage on the speakers.

Unfortunately there is a 0V reading which I presume is the problem now to create the movement in the cones / generate audio.

All help appreciated!

g1

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Re: Yamaha G100 410 - Series 1 - Low Volume / Surges when turning off.
« Reply #31 on: May 18, 2020, 05:19:23 PM »
What are you using to create signal and what level are you applying when you inject straight into the MA board?
On the MA board there are 2 power resistors, .47ohm 2watt.
Measure the DC mV across each of them (one probe to each end).

Enzo

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Re: Yamaha G100 410 - Series 1 - Low Volume / Surges when turning off.
« Reply #32 on: May 18, 2020, 05:33:20 PM »
Remember, it is all about the CIRCUIT, not the parts.   You report you have signal all the way to the white wire to the speaker.  OK, keep going.  Is there audio right on the speaker terminal with the white wire?  Is there audio on the other speaker terminal?  If so, the ground is missing.  Current ONLY flows through the speaker if there us a complete circuit out to the speaker and back.  Is there continuity, and I mean zero ohms, between the negative speaker terminal and the E (earth) on the MA board?   It is not enough to get signal TO the speaker, we also need a return path.   Just like an effect pedal won't work if we only connect ONE snap on the battery.

And did we test the speaker?  Unplug the speaker from the board, and touch a 9v battery to the speaker terminals for a brief moment.  A working speaker will pop or thump when you do this.  A silent speaker is a dead speaker.

ryanckelso

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Re: Yamaha G100 410 - Series 1 - Low Volume / Surges when turning off.
« Reply #33 on: May 20, 2020, 09:21:11 AM »
Hi All,

Just to let you know, it was the earth connection back to the board.

Some of the cables became disconnected. I sorted this and now it plays!

Heck it gets LOUD!

Thanks for all your help.

joecool85

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Re: Yamaha G100 410 - Series 1 - Low Volume / Surges when turning off.
« Reply #34 on: May 21, 2020, 07:58:33 AM »
Hi All,

Just to let you know, it was the earth connection back to the board.

Some of the cables became disconnected. I sorted this and now it plays!

Heck it gets LOUD!

Thanks for all your help.

Glad to hear you got it sorted!  Seems like it almost always ends up being a simple thing in the end.   :dbtu:
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