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Rotel RA-980BX
Rotel RA-980BX
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Old 9th January 2016, 12:42 PM   #1
Carlosraj is offline Carlosraj  United Kingdom
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Default Rotel RA-980BX

Hi,

I am having a problem with this amp. This amp does not have a balance pot but individual volume pots. The problem is the right channel is much softer than the left. If I set the left channel level at quarter, I have to set the right channel level at more than half to make it sound balanced. I checked the volume pot (50KA X 2) and it is OK. I removed the 2 links between "pre out" and "main in" and plug a signal into the 'left main in" and 'right main in' and the left sound louder than the right. I guess it means that it has nothing to do with the "pre out". I checked all the components on both the power amp boards, all seem to be OK except that resistor R669(10 ohms, 3 watts) has blown, but this resistor is on the left channel which is working OK. I am confused. Can this resistor be the problem. Please help.

Thanks

Carlos
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Old 9th January 2016, 02:14 PM   #2
JonSnell Electronic is offline JonSnell Electronic  United Kingdom
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That sounds like the amplifier has reduced gain and the 'good' channel has a burnt out Zobel resistor. Check the feedback decoupling capacitor.
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Old 10th January 2016, 12:37 PM   #3
Carlosraj is offline Carlosraj  United Kingdom
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Quote:
Originally Posted by JonSnell Electronic View Post
That sounds like the amplifier has reduced gain and the 'good' channel has a burnt out Zobel resistor. Check the feedback decoupling capacitor.

Will do. Thanks

Carlos
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Old 11th January 2016, 11:03 AM   #4
Carlosraj is offline Carlosraj  United Kingdom
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Quote:
Originally Posted by Carlosraj View Post
Will do. Thanks

Carlos
Hi JonSnell,

On checking again, I realised that I have overlooked another resistor that has also blown. R620 (562 ohms) on the problematic channel was open, after replacing it now the amp is back to normal.

Many Thanks

Carlos
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