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Post by mastertech on Jul 15, 2015 14:15:48 GMT -5
I always try to refrain from the words "general purpose" since it means different thinks to different people. That transistor is a 2sc2240. So you can use that or something that crosses with it based on the datasheet. www.rcscomponents.kiev.ua/datasheets/2sc2240.pdf |
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Post by danno27 on Jul 18, 2015 12:19:39 GMT -5
Yeah, I picked up that datasheet, but I don't know if there is anything wrong with it though, I get a .68 reading RED to BLACK flat side down... on pins 3 to 1, and 3 to 2... I'm assuming this is good? 680 mV drop?
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Post by mastertech on Jul 18, 2015 13:15:17 GMT -5
Ok, and if you reverse your leeds on those pins you should get no reading at all. Then you have to test both ways between 1 and 2.
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Post by danno27 on Jul 18, 2015 17:31:53 GMT -5
Yes, I reversed the polarity... no reading at all. just 0L... I'm ready to wrap this project up and give it a test and hope it doesn't go up in a puff of smoke  |
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Post by danno27 on Jul 27, 2015 15:10:11 GMT -5
Just got the fuses in finally, so I can plug in and test this amp... Is there anything I need to check before I hook my speakers up to this? Its the first think I attempted to repair so I'm a little nervous to plug this into 120V A/C. Two of the output transistors did not align with the screws on the heatsink, and I left a 2mm chip in one of the output transistors while nudging one of them to fit one of the heatsink screw holes. Should I desolder and see if I can fit it with the heatsink better. I got them to lay in the heatsink though, hopefully it will transfer heat properly? The only odd thing I did with it was combine and 510 and 47 ohm resistors to make close to a 560 because I didn't have any 560 ohm resistors. Kind of twisted the leads to make one resistor.
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Post by mastertech on Jul 27, 2015 16:07:09 GMT -5
I assume you mean you connected those 2 resistors in series and not in parallel?
No speakers connected until you try to turn it on and it does not go into protect.
Also, if it turns on and does not shut down and the output relays latch on you should check the speaker outputs for any DC voltage first.
If that is ok then you can connect a speaker.
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Post by danno27 on Jul 27, 2015 16:41:40 GMT -5
I assume you mean you connected those 2 resistors in series and not in parallel?
Damn, yes end to end would be parallel... I did it wrong, I would need to solder two resistors together making them longer in length. I have to go back and fix that.
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Post by mastertech on Jul 27, 2015 17:50:34 GMT -5
Just google series and parallel. You want series. Double check with your ohm meter to be sure.
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Post by danno27 on Aug 5, 2015 15:42:25 GMT -5
Just tested this power amp and the left channel is considerably lower than the right... Tested with my multimeter, no DC voltage... It pretty much matched all the others. I had a tone with a tone generator and all frequencies with my multimeter matched the tones coming out of the tone generator on my iPhone. The output relay clicked, no protect mode. Light indicates normal operation.
The left channel was the one I was trying to fix. Is there some other step I needed to do to make this match the right? Or was my repair attempt a waste? I tried a known good speaker, swapped it for the right and left, same thing, left channel is lower than other 4 channels. I don't know if this was how it was when I got it. What would cause this?
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Post by mastertech on Aug 6, 2015 0:00:58 GMT -5
Most of these receivers have individual channel output level adjustments in the menu. Maybe that channel output level is just turned down lower then the others.
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Post by danno27 on Aug 6, 2015 11:00:03 GMT -5
No, I turned both the same, and channel 2 is much lower than 1.
There is a trimpot on each amp board, maybe this needed to be adjusted?
Is that something to do with biasing? Idle current...
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