SUNN SR8520 Powered mixer schematic...?

[DrGonz78]

I found something online here that pointed to this schematic, but the PDF file was corrupted. Really a hard schematic to find. If anyone has a copy that would be excellent if they don't mind sharing. Thanks

[Enzo]

I probably have it in large sheet paper form, I'll have to look. ANy scans will be in parts though. So what part are you working on?

Meanwhile, it might be a lot simpler to just call Fender and ask them for it.

[DrGonz78]

You know honestly I might not really even need a schematic, but since it is not passing the dim bulb test I would like to have one on hand. I am not in a rush or anything as this is just another one of many projects that I keep supplying for myself. Right now it is really stage one for this amp. I will need to check the whole thing for any shorts on the power board, BR, or the PT. I hope it's not the power transformer, but usually that has not been the case yet working on amps. This PT looks a bit suspect as far as condition, but we'll see...

Thanks Enzo will probably consult on specific parts later or just call fender. They usually charge for these ones I think...? I will post it if I get it too.

[Steve L]

I have this. Hope it helps.

Fender SR-6520, SR-8520 Powered Mixer Service Manual.pdf

Steve

[DrGonz78]

Thanks a Million Steve!!

Yeah the thing is really really dirty!! The pot slides for the EQ unit on the preamp are missing the metal shafts. The BR is looking fine. There is a 400ohm wire wound resistor where the cement has all sorts of cracks and it measured 470ohms. This thing is a beast so the schematic will definitely be a great help! Thanks again.

[DrGonz78]

Instead of opening a new thread here... I just had a quick question that refers to this current thread. I need your experienced opinion if replacing cement filled wire wound resistors to ceramic style is a good idea. I have found some places to order a new cement filled 400 ohm wire wound but I also have found the like of these...>>>

25J400 Ohmite | 25J400-ND | DigiKey

So is this type of wire wound a good choice to replace this part or should I stick w/ cement filled style that is originally in this amp? My gut says that it is the same thing, but is one better than another? I recently have come across the ceramic styled one's on a few older amps and I guess they are the same...Thanks guys.

[Jazz P Bass]

There is a reason for the different resistor types.
They both accomplish the same thing with different spec's.
Some of the cement types are rated 'flameproof'.
Some of the enamel types will have a derating curve.
Temperature, humidity, tolerance, overload rating.
I am not an engineer.
But I would have to think that they know what they are doing. (hopefully)
So any time I would like to choose a replacement (whatever), my first line of attack is the components datasheet.
Then ask 'why' was this particular part chosen over any other.

[DrGonz78]

Hey thanks Jazz for the great advice! This was a thought that crossed my mind in thinking on this too. Will look at data sheet to understand these components better and will probably stick with the original type part. Funny that on mouser and digikey that this part is hard to find, but found it on a car/home audio type parts store website.