Amplifier output got shorted on right channel, Left channel is now louder than right

[Jazz P Bass]

Well versed post, Brad1.
Solid state output sections can be a bear and they will bite you.
It may well assist the OP to build a 60 watt 'lamp limiter' to help with voltage checks.
And yeah, Google can be your friend.

[S1L03T]

That was a good read and some good advice, thank you for that, i have done a little research and my first attempt on any amp was to trace back the circuit from the output. Hopefully this electronics place can get me these bits, they seem to be pretty rare.. How do i find out what resistors they are when they are burnt and you can't really get the color code off of it?

[Jazz P Bass]

I posted the schematic & the Service Manual above.
All of the information that you need is right there.
No?

[S1L03T]

I have the schematic too, but i don't quite understand how to reference things to the parts list?

[Steve Conner]

Maybe resistors that look just like the old ones are rare, but they don't need to look the same to perform the same function.

The PCB layout diagram you posted earlier has details of the parts printed right on it. The resistances and power ratings of the resistors are given, "0.47R 5W" and so on.

I'm starting to think soundguruman might have been right for once in his career. ;-)

[S1L03T]

Yes for the ceramic resistor i understood that, what about the other resistors? the ones that have 220 (FS) is that fail safe? What is the 220?

[Jazz P Bass]

220 ohm's is the resistance.
1/4 watt (unless noted differently) is the wattage.
FS is designated (by the schematic note) as 'Fail Safe'.
Not knowing exactly what this is, I would assume a 'fusible' resistor is called for.
This type will most definitely go open when overstressed.
The alternative is a 'flame proof' rating.
Most major parts houses have drop down menus where you can pick the value, wattage & features.
Here is an example from DigiKey: Resistors | Through Hole Resistors | Digi-Key

[S1L03T]

Hmm i was thinking it was 220 ohms.. These resistors are bluey/greenish in color and look like a normal resistor

[Steve Conner]

I must admit, when doing repairs, I replace those "fusible" or "flameproof" resistors with ordinary 1/4 watt metal film resistors. The slightly larger size that are sold as 0.6 watt in some places.

My justification (excuse?) is that I've burnt out plenty of them and never seen one catch fire yet.

There are some exceptions for high voltage circuits or circuits connected directly to the mains, but this isn't one of them.

[soundguruman]

Well you see,
resistors contain smoke. When you let the smoke out, it won't work anymore.

[Jazz P Bass]

Hmm i was thinking it was 220 ohms.. These resistors are bluey/greenish in color and look like a normal resistor

The bluey/ greeny's are fusible.
In catastrophic failures, you 'want' certain parts to go open.
In select places they help keep the flames from occurring.
I don't know if it is a lawyer thing.
You certainly can put in whatever you feel like but I would like to think that amp manufacturers have gotten a little smarter over the years.

[S1L03T]

Okay so i measured the one that is pretty black, it measured 221 ohms :S

[Jazz P Bass]

It would help everyone if you could identify the components by the schematic designation.
The black resistor could be stated as R737 or whichever.
Inform us of what components you have found shorted or stressed (blackened)
I have found it helps to highlight the failed components on the schematic.
That way you get an idea of the path of distruction, which may assist you in identifying other failed, stressed components.
You have a wonderful schematic with just about every voltage labeled (this is indeed rare)
Google (or Search this forum) for' lamp limiter'.
Build one.
It will help when you first power up the unit, by limiting the current draw of the amplifier, after the new parts are installed.

[km6xz]

How about making a list of the parts, by part designation on the PC board which you have tested to be bad and post that. It is a relatively simple output stage and the extent of the damaged parts will probably turn out to be output transistors and a few resistors. A good thing is that there was no high current pulled before you shorted the output or the protection circuit would have been active and would have opened the speaker relay.
Do not take any more parts out unless you know why and can prove it is defective. If you have a meter with a 2K ohms range, measure the resistance between all the leads of the power transistors and write them down:
Transistor Q713
pin 1<>pin2= .600
Pin 2<>Pin3= 200
pin1<>pin3= .600 for example

When done, reverse the red and black test leads and do it again and write those down and post them. Also measure the resistance of the large "ceramic" resistors. They should read very low.
The transistors are not critical in value, there are many which will work but they need to be the same pin connections and polarity.

You have a good working channel which is the same exact circuit but laid out a little differently on the pc board so match the readings of parts on the good channel with the bad channel by looking on the schematic for which is the equivalent part between the two channels( for example Q713 and Q714 have the same purpose and value but the opposite channel.
Good luck

[S1L03T]

The resistor i tested was one of the blue/green fail safe ones. The parts i pulled are at an electronics store at the moment. I have one of the ceramic resistors here that i've tested all the ranges except "200" that has a beep function as well all show 0 ohms. This 200 range shows 00.7 This ceramic resistor has labelled on it MPC71 0.47k. I assume its mean't to show that reading??