Orion XTR 1500.1

[allaroundsound]

Amp turns on, shows rail voltage, but does not produce audio. When the subsonic filter button or phase 0/180 degrees is pressed, the test woofer jumps. The woofer also jumps when turning the gain pot. All of these tests are done with NO rca input. I've also noticed a possible continuity problem when testing main ground to rca shielding.

Any starting help would be welcomed.

 

[Perry Babin]

Check all of the 10 ohm resistors on the outputs of the various regulators. In a similar amp, they commonly open.

 

[allaroundsound]

are you referring to smd style resistors on the driver boards?

 

[Perry Babin]

I don't have anything on this amp but the smaller version has a problem with the 10 ohm resistors on the output of the various regulators. They are highlighted with green arrows in the attached photo. They won't be exactly the same in your amp (or may not even exist in your amp). I think that there are at least 8 of them and maybe more.

 

[allaroundsound]

I believe that my tone generator had a dead batt at first test. The amp has output, sounds clean, still has turn off pop and pop when adjusting gain or depressing phase and subsonic.

 

[Perry Babin]

Are you turning it off by removing remove voltage (but leaving B+ and ground connected)?

 

[allaroundsound]

removing only remote turn on.

 

[Perry Babin]

Does the relay disengage precisely when you remove the remote voltage?

 

[allaroundsound]

All pins that I've tested that are driven by this circuit seem to be losing voltage at the time that I remove remote turn on

 

[Perry Babin]

Do you hear the relay disengage precisely at the point when you remove remote voltage?

 

[allaroundsound]

I know its frustrating, but i must recall what i said earlier concerning clean audio. I now have the Orions input connected to a source unit along with a ported 10" enclosure. At medium listening volume there is a constant humm underlying the music. The music itself sometimes sounds like its only half there. The preamp level problems stated above seem to be isolated to gain, bass eq, phase 0/180, and subsonic. When the subsonic or phase buttons are pressed in either direction i see the 95 volt +/-rail's jump to 135 volts then settle back down. The amp shuts down and turns back on occasionally after this voltage spike.

Thanks

 

[Perry Babin]

Are you sure that the rail voltage goes to positive AND negative 135?

If you can reproduce the fault, monitor the DC voltage with the black probe on the negative rectifier output and the red terminal on the positive rectifier output to see if the voltage goes from 190v to 270v.

 

[allaroundsound]

Ill reassemble and test In the morning

 

[allaroundsound]

pos rectifier output is 30volts. Neg rectifier output is -30volt. When metering them i get 60volts. i didnt see any of the voltages specified above. ps when the subsonic is used im monitoring peaks in rail voltage approaching 200 volts for positive and negative power supply transistors. Hope this may develop a clue...Thanks

 

[allaroundsound]

What information can I provide to proceed with this repair? Thanks in advance.

 

[Perry Babin]

What make/model meter? It's likely that high frequency noise is causing your meter to give skewed readings.

 

[allaroundsound]

Fluke 81438

 

[Perry Babin]

I don't think that the voltage that you're reading is significant.

Is the only problem with the function of the amp the hum?

Does the hum go away if you ground the signal source RCA shield to the amp ground?

 

[allaroundsound]

it it permissible to post a youtube link on this forum?

 

[Perry Babin]

Yes. I don't have the patience to watch videos that people post but it may be useful for someone else that can help.