Hi, I just finished recapping my SX-1050. It sounds awesome, but it has one issue. The protection circuit relay is now buzzing as it engages - sound is possibly caused by arcing. Could it be a coincidence that it started with the recap and I need a new relay, or does it sound like something recap related?
SX-1050 Protection Relay Buzzing After Recap
- Thread starter kidcoma
- Start date
Are you sure it's the protection relay, and not the soft start Relay? Make absoutely sure.
Did you replace Q7 and C6 on the protection board. Could be you aren't getting enough pull in voltage to "snap" the points together fast enough.
Then there is the possibility that the points on the relay are bad. Replacement is the best way to fix that.
This from the following thread http://www.audiokarma.org/forums/showthread.php?p=6759577#post6759577 by MARK THE FIXER.
Did you replace Q7 and C6 on the protection board. Could be you aren't getting enough pull in voltage to "snap" the points together fast enough.
Then there is the possibility that the points on the relay are bad. Replacement is the best way to fix that.
This from the following thread http://www.audiokarma.org/forums/showthread.php?p=6759577#post6759577 by MARK THE FIXER.
I haven't checked the prices on these, but they are probably higher now, as the post was from May 2013.
More info:
Protection Circuit Voltages:
Location - Measured (schematic)
Pin 2 - 13V (13V)
Pin 3 - 6.8V AC (8V AC)
Pin 12 - 61.9 (60V)
Q7 Base - starts around 0V - goes to 8.5 after relay engages (9.2V)
Also - upon inspection it appears the sound is caused by vibration in the relay, not arcing.
Protection Circuit Voltages:
Location - Measured (schematic)
Pin 2 - 13V (13V)
Pin 3 - 6.8V AC (8V AC)
Pin 12 - 61.9 (60V)
Q7 Base - starts around 0V - goes to 8.5 after relay engages (9.2V)
Also - upon inspection it appears the sound is caused by vibration in the relay, not arcing.
Sorry, I was writing my last post while you responded. It's the relay on the protection circuit board (that's the soft start I presume?), not the surge killer relay. I did not replace Q6 and Q7.
Sorry, I missed the part where you said the protection relay is PCB mounted - so yes, it is the protection relay.
Another observation: if I turn the amp on and off and on again within a second or so, the relay engages quickly/properly. If I wait a few second it will go through the scenario that causes the vibration.
Another observation: if I turn the amp on and off and on again within a second or so, the relay engages quickly/properly. If I wait a few second it will go through the scenario that causes the vibration.
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I figured it out. I was looking at the schematic and C6 - the 47uf/50V cap - looked like it may be a suspect. So I tested the continuity between the adjacent components - low and behold I wasn't getting a connection between C6 and R28. Turned out that the pad that C6 was soldered to had come off the board and disconnected from the rest of the trace. I soldered in a jumper wire and voila!
good show. My next question was gonna be about c6 & Q7.
