Quad 303 Heatsink Runs Hot after Service

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10-Feb-2018 05:51 PM

beadlesabout

beadlesabout

Posts: 10

Just hooked up my recently serviced Quad 303. Before the service the heatsink ran barely warmer than blood temperature. Now it gets quite hot!

Sounds amazing though. 

Any ideas why it might be warmer now? 

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11-Feb-2018 06:59 PM

beadlesabout

beadlesabout

Posts: 10

Think I'll phone the engineer in the morning. The frame around the heatsink and the shroud for the transistors is nearly too hot to touch after 30 mins of music at normal volume. Must be something wrong :(

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12-Feb-2018 12:54 AM

EJP

EJP

Posts: 1443

Send it back for correction. He has over-biased it. The correct bias setting is described in the service manual, and it should stay stable under no-signal conditions over a period of at least ten minutes. If it runs away, the temperature will also be running away. The heatsink cover should be no more than slightly warm to the touch.
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