mtx blue thunder 500xd

[bdgf2004]

would LM833 be an acceptable replacement for NE5532P?

[bdgf2004]

http://datasheet.octopart.com/NE5532...eet-150397.pdf

http://datasheet.octopart.com/LM833N...heet-26455.pdf

[bdgf2004]

does anybody know the value of R118?

this one is discolored and im getting 839 ohms with it out of the circuit.

[Perry Babin]

You can't always predict what a substitute op-amp will do. The circuit in which it's being used and the decoupling of the power supply at the IC are only two of the issues that can make a replacement unsuitable. You can try it for testing but I'd suggest ordering the original (especially if this is for a paying customer).

I don't have the value of the resistor. What is the voltage across the resistor?

What are the dimensions of the body of the resistor (length and diameter)?

[bdgf2004]

i haven't attempted to power up the amp yet because upon opening it i saw numerous parts damaged and sevel others have direct shorts. it appears to be all around the preamp area.

so far i have:

R??---475 OHM
R??---1000 OHM
R118--- ??
Q61---MPSA06
Q62---MPSW56
Q63---MPSA06
Q65---MPSA06
U1,U2,U3---NE5532
D61---1N5233B
D25---T4148
D61---1N5233B
D62,D63,D64,D65---1N4746A

I MAY BE IN OVER MY HEAD!!!

[bdgf2004]

R118 is a 2 watt

[Perry Babin]

With all of those parts burned, you'll need to find someone with an identical amp.

If you decide to repair it, you'll need to change the transistors used as regulators to a different type or mount them under the board, against the heatsink. This was a huge problem in the MTX 500d (see corresponding page on the DVD).

[bdgf2004]

i actually have 2. both appear to have the same problem.

luckily i have been able to identify all the damaged parts so far besides R118

[bdgf2004]

i also have a working 2-ch same series amp packed up somewere. maybe i'll have look in it but i imagine it would be completely different inside.

[Perry Babin]

I'd start with a 2k resistor in place of R118 if you can't find the correct value. You can calculate a usable value when you get the amp up and running.

If you have all of the values of the other components, there's no reason that you can't repair them unless you don't feel that they're worth the effort.