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Author Topic: Broken Laney AOR, with gutshots.  (Read 4017 times)

SG Thrasher

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Broken Laney AOR, with gutshots.
« on: June 28, 2008, 12:14:52 PM »
Hey guys, I bought this '87 AOR 3012 combo a few months ago and I haven't played it much because I think my GH smokes in in the tone department. Anyway, It's a friday night and I had nothing to do so I dusted off the AOR and gave it a cranking, I was running it at about 3/4ths of the master and it started to drop in volume for 5-7 seconds at a time before coming back again for a few minutes.
On the 5th or 4th volume drop I look around the back to check the valves and smoke starts pouring out of the front. I unplugged and opened her up to find this...


I'm not completely knowledgeable of the components within the amp so I was just wondering if any of you guys could tell me what part it is that has failed, why it could have failed and how easy is it to get replaced/fixed.

It's not worrying me too much because I have the GH but it's nice to have a backup.

Thanks in advance, Baz.
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Will

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Broken Laney AOR, with gutshots.
« Reply #1 on: June 28, 2008, 12:23:35 PM »
Sounds similar to what happened to my JCM900 at a guess.
Marshall replaced some caps, and the valve sockets, apparently the caps had blown, and there was no limit on the current to the valves
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gwEm

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Broken Laney AOR, with gutshots.
« Reply #2 on: June 28, 2008, 12:24:25 PM »
this looks like a high power rating resistor getting too hot - easy and not expensive to replace the resistor itself.

but the question is why has this component failed (most likely a short circuit, as will says maybe caused by something else failing) - could be a lengthy fault finding sessions, but necessary i think.
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bobthemerciful

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Broken Laney AOR, with gutshots.
« Reply #3 on: June 29, 2008, 01:35:32 AM »
I agree with gwem. I have the circuit diagram for the AOR100 if it's of any help to you. PM us if so  :D
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HTH AMPS

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Re: Broken Laney AOR, with gutshots.
« Reply #4 on: July 08, 2008, 12:42:30 AM »
It's connected right after the diode bridge, and is marked as a 1k resistor so it's got to be R17 on the schematic... http://www.schematicheaven.com/newamps/laney_aor100_series2.pdf

When you replace this resistor, make sure there is a gap between the resistor body and the PCB to stop burning like whats happened in your amp.  You will get a 3w wirewound resistor from Maplins easily enough.

That 1K is feeding the channel switching circuit - does the channel switching still work?

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