Help with Orion HCCA250 dead

[pergo]

thank you Perry,

now i've remount the amplifier with all fets, and with chassis.

without 2N6488, the current draw starts at 1.2A..then, after 10 second, it goes on drifting until 5A.

but, with a new 2N6488, the amplifier stays at 1,3A @idle forever, but there's a little zzzzzzzz (noise).

i check with o-scope, and there's some zzzzzz (the waveforms goes quickly left-right-left-right like no-triggering)

I think, it's regulation.


How can i remove zzzzz noise? All new capacitors with low ESR?

[Perry Babin]

I don't know what's causing the noise so I can't really offer any suggestions but there shouldn't be any noise. If it was the regulation, the voltage on the collectors of the MPSA06 driver transistors would be pulsing up and down (not related to the frequency of oscillation).

If you don't see any high frequency ripple on the filter capacitors, they're not likely to be the problem.

The idle current was likely at 5A without the 6488 because the amp was producing more than the working voltage of the rail caps and they were beginning to leak.

Email me.
babin_perry@yahoo.com

[pergo]

thank you Perry,

i make some test.

the noise decrease when i've lower input voltage, like 11V.
When i increase voltage (like 14,4V) the noise increase.

but, there is a very low high frequency noise.

i had same problem with my first diy-car-SMPS, when wrong compensation in feedback, caused the same noise.

The ripple is 50mV...too much for me

Same problem with some old PPIs 2150AM.

I know (from Eva and luka in this forum) that is cause by having only capacitor filter after toroid (no inductance). So, or you ad more capacitance (or better capacitor with low ESR and high ripple current), or add an inductance, to have an LC filter and better regulation.


This amplifier is a HCCA250 v2.0 Digital Reference. How old is? 10 years? More?

Maybe the original capacitor are not fully 100% efficent?


thank you


ps: Email sent

[pergo]

Amplifier done and rock solid.

The low audible noise it only at idle, and it is very very low noise at high frequency.

I've discussed with Perry and probably are the old caps not fully 100% efficent.

No problem, if Morpheus want, he will replace it with some new Panasonic FM, for better regulation, filtering e low ripple.

The amplifier works perfectly in each condition (4ohm, 2ohm, 1ohm, 0,5ohm) and never heat a lot.

Very very good amplifier.


Special thanks to Perry for the costant professionalism, and to Morpheus for having trust in me


Best regards!
Ciao!