power amp bias oscillating

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I have recently found my 600 watts power amp, in 1 ch the bias is either near zero or when turned up oscillating slowly rising from 0.3ma to perhaps more then 100ma at which point presumable the protection circuit cut the current off back to near 0.
The amp hass npn/pnp complmentary double differential input feeding a cascode stage. The cascode transistors obtain bias with the base connecting to the CCS transistor, that derived ref voltage from the input pairs double transistors CCS.
I suspect the oscilation may be from the CCS, but not sure if it is the input diff amp's CCS or the cascode amp's CCS.
Any advise on how to detect it, and if a 100 ohm at the base of the CCS will eliminate the oscillation...

tks

Wlee

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Topic - power amp bias oscillating - wlee 06:12:44 10/09/08 (2)

RE: power amp bias oscillating - budm 09:42:07 10/09/08 (1)

RE: power amp bias oscillating - wlee 17:46:53 10/09/08 (0)

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