Orion 2500d weak output

[807tubenut]

Amp's ran fine for 4 or 5 years now, 2 days ago I was playing some tool, when the bass dropped out significantly, Got the amp apart today, cant find any issues with it, the 7812 and 7912 produce there + and - 12v, nothing but the driver cards gets warm, I measure about 15mv dc on the speaker terminals, adjusting the pot on the audio driver card varies this, but produces no change in output or idle current draw (about 2.5amps idle)

[Perry Babin]

Did the bass drop and remain clean or did it begin to distort well before it generally does?

Have you checked the speakers?

[tauro0221]

Hi,
Did you tried another input device?

[807tubenut]

It dropped and remained clean, tested a different input device, speaker is a orion hcca 12.2, pulled the soft parts out just now and inspected, no issues with the speaker, tested another amp in the 2500's place, all is well.


I think I can hear a faint humm, but it could be hashing noise from my bench top power supply.

[Perry Babin]

Confirm that all of the output transistors have full rail to rail swing on the drains.

[807tubenut]

105v across the rail totals, individual variances from the tranfo's secondary, referencing CT is about 50~55v with a input range from 13.8 to 15.1v

[Perry Babin]

Do you have rail to rail oscillation on ALL of the output transistors?

[807tubenut]

Ill check that in the morning!

[807tubenut]

Db-r was not interested in fixing this amp, I was not interested in sending it to amp medics, so he called me a *******.


Ill sit it on the shelf and buy a sundown 4500 to replace it.




And wont bother Db-r again, He's just to busy to help these days.