Thanks! I replaced that transistor and it was still doing it so I individually disconnected the 3 pin plug with the sense wires to see if it was coming from one of the driver boards and it turns out it was a bad 2SC869 (Q11 on driver board). Also replaced the blue tantalum caps C11 on each side as they were very high esr.
I viewed your video on the SX-1250. I am having an identical problem with my SX 1280. Limiter has a mind of its own. Has been to three expert HI Fi repair shops without a solution. Honestly, I think they simply replaced several caps and transistors without actually troubleshooting it. I am find a similar issue with the current limiting voltage coming into the base of Q-1. In my case, it is shown as 13V. I am getting a constantly fluctuating voltage between 9 and12. If it is as you suggested, the Q-1 is leaking, I should just replace it. However, I cannot locate one. I believe you suggested an alternate. Could you elaborate?
My left side offset i can't keep at 0 volts , it keeps fluctuating under 1 volt. Would bad trimpots cause that? The right side is solid. Man , the regulator board runs hot at 65 volts on these.
@@Iatolaazzahola Google "2sa733 equivalent transistor" You should see a result for AudioKrama.com with someone looking for the same. In the AudioKrama post, there's a link that will take you mouser.com Those 2 sites are your best friend.
Hey sir can you help me pleast 🙏🙏 my 1250pionner is can not open its have a power in transformer and the relay is turn on but the relay of both left and right power amp is can not switch's and the pre amp in the selector like am pm aux is no power the pre amp is ni supply what would I do thanks sir
If the main power relay is turning on when you are turning on the receiver but the speaker protection relays do not turn on, it probably means that you have DC on one or both of your amplifier channels preventing the unit from coming out of protection. Take your meter on DC volts and measure to see that you have zero volts output on the input side of the relays. If you don't have close to zero volts on the input side of each protection relay then they will not turn on to connect the speakers to the amp. This protects the outputs and your speakers in the event that there is some issue with the power amp section
Thanks! I replaced that transistor and it was still doing it so I individually disconnected the 3 pin plug with the sense wires to see if it was coming from one of the driver boards and it turns out it was a bad 2SC869 (Q11 on driver board). Also replaced the blue tantalum caps C11 on each side as they were very high esr.
I’ve got a minty sx 650 doing something similar - hope the circuit is similar.
I viewed your video on the SX-1250. I am having an identical problem with my SX 1280. Limiter has a mind of its own. Has been to three expert HI Fi repair shops without a solution. Honestly, I think they simply replaced several caps and transistors without actually troubleshooting it.
I am find a similar issue with the current limiting voltage coming into the base of Q-1. In my case, it is shown as 13V. I am getting a constantly fluctuating voltage between 9 and12. If it is as you suggested, the Q-1 is leaking, I should just replace it. However, I cannot locate one. I believe you suggested an alternate. Could you elaborate?
Changed it out. Voltage drops from 17.8 to 14 within 5 seconds and receiver goes quiet as it did before. Have any ideas?
My left side offset i can't keep at 0 volts , it keeps fluctuating under 1 volt. Would bad trimpots cause that? The right side is solid. Man , the regulator board runs hot at 65 volts on these.
it is the same for pioneer sx-1980 too?? that my problem now on my sx-1980. thanks
I have a Pioneer Spec-4 doing the same thing, do you suppose this could be the cause?
I've got a 1250 that has just started to do this. I'll be looking here first. Thanks for the video bud.Where did you find that transistor?
Find transistors at Mouser or Digikey websites
@@MrPageplayer , or PAballoonists, what is the 2SA733 equivalent tansistor?
@@Iatolaazzahola Google "2sa733 equivalent transistor"
You should see a result for AudioKrama.com with someone looking for the same.
In the AudioKrama post, there's a link that will take you mouser.com
Those 2 sites are your best friend.
Hey sir can you help me pleast 🙏🙏 my 1250pionner is can not open its have a power in transformer and the relay is turn on but the relay of both left and right power amp is can not switch's and the pre amp in the selector like am pm aux is no power the pre amp is ni supply what would I do thanks sir
If the main power relay is turning on when you are turning on the receiver but the speaker protection relays do not turn on, it probably means that you have DC on one or both of your amplifier channels preventing the unit from coming out of protection. Take your meter on DC volts and measure to see that you have zero volts output on the input side of the relays. If you don't have close to zero volts on the input side of each protection relay then they will not turn on to connect the speakers to the amp. This protects the outputs and your speakers in the event that there is some issue with the power amp section
@@PAballoonists thank you sir. ill try to fix it
0:00 / 2:44
Pioneer SX-1250 Receiver going in and out of protection randomly - FIXED