Orion Xtreme 800.4 one channel heavily disorted

[Chopperbuilder]

The first photo is pin 1. The second photo is pin 2.

 

[Perry Babin]

Set the vertical amp to 5v/div and repost pin 1.

 

[Chopperbuilder]

Here is pin 1 with the scope at vertical amp to 5v/div.

 

[Perry Babin]

Assuming that pin 3 is clean and you have ± supply voltages, that op-amp may be defective. It could also be that the op-amp is being loaded too heavily.

 

[Chopperbuilder]

Pin 3 is producing no wave form at all, only a flat line.

 

[Perry Babin]

OK. It must be set up as an inverter. The input would be to a resistor feeding pin 2 if that's true.

Do you have an op-amp to replace this one?

 

[Chopperbuilder]

Yes, I have one to replace it with.

 

[Chopperbuilder]

I replaced that op-amp, it didn't change anything.

 

[Perry Babin]

OK, then I'd suspect a driver problem between that op-amp and the outputs. I'll assume that you found the resistor feeding pin 2 and confirmed that you had clean audio driving the op-amp.

 

[Chopperbuilder]

I did find the resistor feeding pin 2 and confirmed I had good clean signal driving the op-amp.

You were correct it was a driver problem between that op-amp and the outputs. I found the A06 driver that was causing the distorted signal and replaced it as well as it's A56 counter part. That channel as well as the rest are producing good clean audio now.

Thank you for your help, Perry.

 

[Perry Babin]

Keep the map of the channels in your notes.

 

[Chopperbuilder]

Will do.

 

[Chopperbuilder]

Anyone happen to know what wattage resistors these are in the attached photo.

 

[twilliar]

1/4 watt if I see the picture resolution correctly. There is vague information online about resistor size in comparison to wattage.

 

[Chopperbuilder]

Thanks, twilliar. I was thinking 1/4 watt too.

 

[Chopperbuilder]

The resistors I have circled in the attached photo appear to be metal oxide. Would it be safe to change them to wirewound?

 

[Perry Babin]

Are they defective?

Wirewound are typically less likely to open under high surge current. This can be good and bad. Sometimes you want a resistor to open more easily to act as sort of a fuse.

Also, the resistors you have are ceramic coated which tends to be flameproof. Replace with resistors that also have a ceramic coating.

 

[Chopperbuilder]

No, they are not defective. I was wanting to replace them with higher wattage resistors. I have another same model amp as this one and it has higher wattage resistors in those locations.