Orion HCCA 225 Digital Reference with Low Output

[0ldSch00lf00l]

I picked up a barely working Orion HCCA 225 Digital Reference on a trade and it has extremely low output.

Thus far I've checked the SMP60N06-18s in the Power supply section as well as the 2n6491s and the 2n6488s and nothing appears to be shorted or open. Rail voltage is where I think it should be at 22.5 volts.

I guess I am off to troubleshoot the audio section next but I did have a couple of questions. What are the chances that there are bad capacitors blocking the audio signal from passing through the amp? Also, if I decide to replace the SMP60N06-18s, would the IRF3205 be a viable substitute?

 

[Perry Babin]

Remove the two muting transistors (2N5639 near the audio op-amps). Does that help?

 

[0ldSch00lf00l]

Removing the muting transistors worked like a charm.

What do I need to do to solve the problem?

 

[Perry Babin]

What is the DC voltage on the third pad for the muting transistors?

 

[0ldSch00lf00l]

-10.83 and -10.89

Also, by third, I am assuming you mean the squares since these are reversed as mentioned in your repair tutorial.

Edit: After testing the JFETS that I pulled, it appears that they are both shot.

 

[Perry Babin]

It appears that the FETs are defective. -11 volts should have them switched completely off (allowing audio to pass). On a gen 2 225 I have here, the muting is essentially completely defeated at -3v.

 

[0ldSch00lf00l]

Thank you for the help kind sir!

 

[Perry Babin]

If you order replacements, order extras.

A side note, it's good to see that you took time to find that orion page and read it.