pioneer SA500 left channel fuse blowing Help pleas

[colin.hepburn2]

Hi All
I have just acquired a pioneer SA500 in very good order but there is a problem with left channel fuse blowing at switch on can anyone help with this problem as far as I can find on line it seem to be a common fault too this model I have the schematic for the amps see left channel image

[nightanole]

take a multi meter to Q11 and the other 2sd130 (ithink Q8, i cant read it) odds are one is a 3 legged piece of wire.

[colin.hepburn2]

Q11/Q8 need to come out of circuit to be checked or can thay be checked in place?

[nightanole]

they can be checked in place with the unit off for shorts. If both ring good, then would see if there is a short from b+ to ground with a multimeter while the unit is off. There cant be that much to test, only those 2 outputs, and the 2 outputs that feed it have a direct route to ground in order to blow the fuse. Even if the other parts are toast they have several K to ground so they cant blow fuses.

[colin.hepburn2]

OK thanks
For the pointers the amp is now working just had to replace the presets VR2 and VR3 replaced with multturn 100 ohm reset to same value as the old but still working preset which was 72.4 ohms
The amp is running a bit hot touching the heatsink it’s hot but not unbearable to touch replacing the fuse with meter left channel current seems a bit high at 134.8mA and bouncing up/down right channel 145.2mA does anyone know what the idle current should be for this pioneer SA 500
But the amp sounds very good

[Bonsai]

No, but the standing current sounds a bit on the high side. Try adjusting it down to about 100mA. That should cool things off a bit and then you can assess a bit further. I like Pioneer stuff - very solid.

[colin.hepburn2]

Originally Posted by Bonsai

No, but the standing current sounds a bit on the high side. Try adjusting it down to about 100mA. That should cool things off a bit and then you can assess a bit further. I like Pioneer stuff - very solid.

Hi bonsai
Thanks for that I will adjust it down in the morning I just got the amp going to night so just ran it with my headphones for now sennheiser HD650 this little SA 500 sounds great I also have a healthy pioneer SA2600 in my system driven by a tube pre love this amp as well works wonderfully with the tube pre