Orange Crush 10 - power yes, sounds sort of - input wont work

[DrGonz78]

When you measured did any of the voltages produce a negative voltage?

Perhaps pin 7 is stuck to the pin 8's rail? Also pin5 is stuck to pin 4's voltage rail? I am not sure if that could be the case here or not, maybe. Pin 5 & 7 should have millivolt readings and what we are seeing is similar to the voltages on pin4 & 8.

Disconnect the speaker and measure to check if there is any significant DC voltage on the output of the amp. Place black meter on the negative speaker terminal (or ground) and put the red meter on the positive speaker terminal plug. Do this all with the speaker disconnected.

[greybox]

Modified my post to show negatives in previous post. speakers = no measurements (randomly .1 - usually 0 though)

[DrGonz78]

This is harder to navigate without a schematic... Still I would remove that 4558 IC chip and then power it up to measure where the pins were connected. It is possible that the chip is bad and it would be good to see the voltage readings without the chip in place. For the price of a 4558 chip it is worth just installing a new one to see if it fixes the problem.

[J M Fahey]

That RC4558 looks very dead.

There can be no (or a couple mV ... single digit) between pins 6 and 5 .
Carefully desolder all 8 pins using a good solder sucker, then pull it while cold away from the PCB, it should come out easily.

Do not wiggle parts legs whilke solder is molten, pad to base material is weakest at that temperature and it's very easy to pull that pad with the slightest movement.

If possible, put an IC socket there so if you have to replace that IC later the board does not suffer.

Measure all 8 pins again without the IC present, as suggested above

Although I basically suspect the IC itsel, we *might* have a cracked trace .

+/-15V are reaching that IC normally.
Slightly high, but it might be because of lack of consumption.

[greybox]

I lucked out and actually got the replacement chips today, I ordered them just in case. I will work on it tomorrow and fingers crossed have an orange amp again

[J M Fahey]

 :dbtu:
Just work slow and careful, pamper the PCB, clean old solder well before pulling the IC out.
Just to make sure,measure voltages on all 8 pads without IC to rule out that some weird voltage is coming from somewhere else (besides the +/- 15V on pins 8 and 4, that is).

Oh, and mark which way pin 1 (or the marking notch) goes.
Unfortunately it fits the wrong way too.

[greybox]

WOOHOOO!!!!!! Fixed - new chip in and sounds fantastic (and I upgraded the chip to a TL072)! and because I started troubleshooting with the pots and input jack it has no scratchiness left either!

and just as important I have accomplished my first ever amp fix! (changed the tubes and speaker on my VOX before but other than that nothing else)

Thanks for the help guys!

[DrGonz78]

Congrats on the amp fix!! Isn't a great feeling when you repair something to working condition again? I get a high feeling for about an hour and then I am bummed cuz I don't have to figure the problem any more. Then it is on to the pursuit of more broken amps to fix!!

[greybox]

Amps are all working now, did a pickup swap and strat mod yesterday...now I just have some playing left...what fun is that...

[J M Fahey]

am starting to question whether its better to keep working on it or find a working amp cheap on craigslist

just trying to decide if this is going to become a money pit....

Ahem !!!!  :trouble
The Forum Complaints guy is going to have a few words with you .... as soon as he's finished dealing with another .... complainer ....



:lmao:

[greybox]

I know...it was more just wondering how far down the path I was going to have to go, $5 here, $8 here...I only had $50 into the amp to start with....

[J M Fahey]

Don't worry

As you see, it turned out quite cheap.

The price of servicing is 1% parts and 99% finding which the bad one is.

And (so far) we aren't charging for the detective work

[Roly]

The price of servicing is 1% parts and 99% finding which the bad one is.

And (so far) we aren't charging for the detective work

...although we do often expect a certain amount of effort.    8|