Fender Rumble 500 Bass amp I only hear the fan nothing else ?

[Jam]

Ok I made a clip and I did p102 pin 5 ground and pin 8 was + and I hooked up a guitar pedal and guitar and I get nothing coming out? You dont power up right?

[Jam]

I did the pin102 and did 5 ground and pin 8 + and I hooked up a pedal and guitar and I dont get anything? I dont power up right?

[g1]

Yes you would need to power up.

[J M Fahey]

Of course you need to power up to test, how do you think it would amplify a signal otherwise?

[Jam]

So I did it with power on Lol and I got a loud signal

[Jazz P Bass]

So the ICE module is good.

Now you have to go through the signal path of the Fender & find just where it is failing.

From Post #23: "A signal inserted into the Input jack should show up at the Send/ Return jacks.
The Send could be used to 'send' it to another amp.

You could try putting a signal into the Return jack.
That will bypass the preamp.

The AUX jack will bypass all of the above.
It goes through U7 4 times before it enters the ICE module.
There is a limiter ic on that circuit.
If that is bad it will confuse your readings.

Note: there are excellent test points marked on the schematic that should assist you. "

[J M Fahey]

Fully agree

One excellent place to inject signal is, as JPB noticed, Aux In , either Left or right, itīs the same.

I guess you used Guitar> 9V powered pedal (which?) > P102 connector.
Now we will again use the trusty "Pedal-as-Preamp" to inject signal into Aux In, you will need to solder a plug or miniplug or RCA connector or whatever does the Aux In need. Please state which one fits.

To get a constant signal and free you fom playing the guitar while measuring at the same time, downloas a constant 440Hz or 1 kHz tone MP3 from http://www.mediacollege.com/audio/to...6bit_30sec.mp3 or http://www.mediacollege.com/audio/to...6bit_30sec.mp3

Play it through computer/MP3 Player/Smartphone into the pedal which you use as a preamp and into Aux In ... you might even play it *straight* into Aux In without the pedal, by making the proper Earphone-to-standard plug cable.

A standard Earphone out typically supplies between 100 and 200 mV output signal, injecting that into Aux In you should get about twice as much at TP30/43/31/32

The one you do NOT get is where the problem is.

We are talking mV AC so your multimeter must have a 200mV AC scale or at least a 2000mV AC (2VAC) one which you will actually use.
$10 multimeter 200VAC minimum scale is NOT suitable for such low voltages, itīs practically deaf to audio signals, so get a good one. Shouldnīt cost more than $30 or $40.

EDIT: almost forgot: those very useful 440 or 1000 Hz tone MP3 last 30 seconds, you must set your player to "repeat" so it sends you a continuous tone, so you donīt have to push "play" every 30 seconds.

[Jam]

Sorry to ask but I'm getting confused on tracing. Do I clip ground to amp and have my meter on vac ? I'm getting some off the wall readings and is it fine to use the test points? The preamp part so small

[Jazz P Bass]

"Do I clip ground to amp and have my meter on vac"
Answer: Yes.

If you want to test the preamp, jump to the Send jack.
Or try Sending that to another amp.

[Jam]

Ok so far I did a signal inserted into the Input jack and out of send to another amp and I got signal. When I sent a signal in aux I get a weak noise coming from speaker. When I try to get reading with meter it seem to float alot?

[J M Fahey]

Problem with that amp is that is has a long, twisted and tortuous signal path zigzagging all over the place, to boot with lots of questionable ribbon connectors in the path.

As Enzo often says, itīs not always "a bad part" by any means, you can easily have all good parts but poor connectors, cracked solder or even tracks can drive you crazy.

Basically you hav 3 signal paths trying to feed that ICE module.
You already know the "long" one, from input jack, does not work.

So letīs test the middle one (from FX return jack) , blue path; or the short one from aux in jack red path.
Both merge in U7c so after it I use purple colour.
Inject signal either in the blue or red path and follow it.

I donīt care whether a TP suggests , say, 358mV AC and you actually have 150 or 200mV there, thatīs a working stage which simply got somewhat less drive signal; I DO care about it having no signal at all, or, say, a couple mV muffled or buzzy audio which mean a poor/open/shorted path or a dead part.

Ok, so do the testing and report.

Signal "should" look fine up to a certain point and die after it, it certainly does not reach ICE power.

[Jam]

Thanks again So I got some reading

The aux send
tp30 1.330 vac
tp43 1.057 vac
tp31 0.762 vac
tp32 2.6 mvac

The fx return
tp27 0.838
tp28 2.4 mvac
tp30 2.8 mvac
tp43 2.4 mvac
tp31 636.6 mvac
tp32 2.4 mvac

[Jam]

Sorry but I had a quick question on the schematic it shows R105 having a resistor a 33k my preamp does we're R105 has no resistor their? I also notice a couple spots were their missing is that normal?

[J M Fahey]

Thanks again So I got some reading

The aux send
tp30 1.330 vac
tp43 1.057 vac
tp31 0.762 vac < normal
tp32 2.6 mvac < probably TL074 dead . Strike 1

The fx return
tp27 0.838
tp28 2.4 mvac
tp30 2.8 mvac
tp43 2.4 mvac
tp31 636.6 mvac
tp32 2.4 mvac

TP28 must have practically same value as TP27 so signal disappeared in the middle.
Either bad connector/cable or dead TL074 , strike 2.
First read DC voltage on all its pins and post it here, just in case, but next step will be to replace it so get one ready.

[Jam]

So I decided to come back to this amp. So I replace u7 and now I have 46vdc on pin 4 and and -61vdc on pin 11 and o on the other's. Do I have my meter on the wrong setting? thanks for any info