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Old 14th November 2007, 02:27 AM   #21
jol50 is offline jol50  United States
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I set the bias, have it on both channels so it is lowest 1.2mv and high of 1.8. Was close as I could get and be over 1mv, sometimes the lowest shows 1.1. Still have a difference in the speaker terminals, the 'warm' side is 2.2mv dc and the other 1.2 at rest. I played about 5 songs at low volume into 8ohms and both channels made a little heat, just enough to tell they were not cold. The power supply sink stayed cold.

Just on my bench, so if that looks ok (?) guess it is time to wrap it up and try it on a sub with some power. The transistors are just on the blocks; the bottom case is the rest of the heat sink. Seems like a cruddy cooling idea to me but it is easier to work on that way.
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Old 14th November 2007, 02:44 AM   #22
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I think it's OK.
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Old 14th November 2007, 03:01 AM   #23
jol50 is offline jol50  United States
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I owe you. Now I know a little bit about bias.

Maybe tomorrow I can dig out my spare 12" and see what it does. Sure would be nice if it is fixed.
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Old 16th November 2007, 02:29 AM   #24
jol50 is offline jol50  United States
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Put it all back together and ran it on a sony 12" sub, at measured ~12v off a boat battery w/only a 2a charger on it. Ran it rattling stuff in the room for a couple songs, then lower for a few more. Felt a little bit of heat in outputs and power supply had none. Seems to sound good. I have about 1mv across leads for bridged sub at rest. Now looking at a junk amp I have that will not shut off with trigger.
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Old 16th November 2007, 02:43 AM   #25
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The amp sounds like it's working properly. The audio section of this type of amp (class AB) is going to run warmer than the power supply. When pushed hard, it will get hot. When at idle, it should be only slightly warmer than room (trunk) temperature. In most cases, the power supply FETs will run much cooler than the audio section.

Start a new thread if you need help with a different amp.
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Old 16th November 2007, 03:29 AM   #26
jol50 is offline jol50  United States
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That is just what I have with the Sony.

These others, I have a box of them with assorted problems. I'll have a go at them as time permits and if I can't come up with anything (entirely possible) I might be back if you don't mind. I have to search more first but it looks like remote circuit problems are not that common.
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Old 16th November 2007, 05:58 PM   #27
jol50 is offline jol50  United States
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Think I fixed it! It was just an oversolder on a transistor that tied two legs together. Well I think it will work, it played ok before and now the light goes on/off with the remote. Have to put back in case to test w/sound. What a butcher job; there must be a whole roll of solder on this little board and it is covered with some cloudy residue of some kind. It was that way since day one, bet it never got used. Too bad its only worth $20 or so. It's a 190x1rms sub amp.

Another item saved from the landfill! That makes two in one post! and a great ending to this planet saving thread, what more could I ask for...LOL! (the landfill is my running joke with friends every time I fix discarded junk)
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