Would anyone know what teperature of heatsink on Quad 303 running at idle should roughly be? I measure 45c at about an hour of idle. I thought maybe it's a bit too hot so tried bias settings but that didn't change anything.
If you cannot adjust the quiescent current, you have a fault that must be rectified before you use it again.
Which series board have you got and have you replaced anything.
Which series board have you got and have you replaced anything.
I can adjust it but setting it for more or less current doesn't seem to affect the heatsink temp. Sorry don't know the board series, amp is closed right now.
I've had it running for about 10 hours now with music and on idle and the temp sits constant at 45c. So I wonder if thats too high or not because last time I used it years ego, the amp was out of reach behind cabinet so I never checked for temp until now.
I've had it running for about 10 hours now with music and on idle and the temp sits constant at 45c. So I wonder if thats too high or not because last time I used it years ego, the amp was out of reach behind cabinet so I never checked for temp until now.
It is too high and it is overbiased. You should aim for about 5mV across pins 4-6: less if it runs away - watch it for a few minutes.
My (free standing) Quad 303 normally stays on and has not been used today so has been idle for more than 12 hours. The surface temp of the heatsink is about 38-39 centigrade, environment is currently 27,1 centigrade.
So yours is overbiased too. Mine is correctly biased; it has been on for 3 hours and is presently at 18.6 degrees C, much the same as the temperature of the room.
Right now I'm reviewing everything I want to sell, and today I woke up my JVC VN900 which I know quite well and I took the opportunity to raise the temperature of the heatsinks even though it's an amp that relatively cold work in general and also set rather cold (given the size of the heatsink).
Today I have 33°C in the workshop and my amp, which works more in the 25/28° range on the heatsink, operates at 45° today with the same bias.
It would be interesting to check this 303 in September/October.
Today I have 33°C in the workshop and my amp, which works more in the 25/28° range on the heatsink, operates at 45° today with the same bias.
It would be interesting to check this 303 in September/October.
what is your bias set at? Either too high, bias pot not working properly or relatively higher temp in your area.
Thanks, I'll check and clean the pots and try the bias again. It runs at 45c but it's only about 23c in the workshop. Currently winter here in AU. Can't imagine what's it gonna run in summer when we hit high temps and I don't use aircon.
You say it is behind a cabinet. Does the heatsink have room to breath or are you restricting airflow. This will cause the temp to rise.