Fender Roc Pro 1000 - Problem with channel distortion

[adiorgelis]

Bing Translate: "Ola JM Fahey. I'm even quite understand them ... I don't know if they're understanding me correctly ... I hope so.on expomusic I really wanted to go further on that date I will be working and in addition also the distance and too big, it turns out that doesn't pay much offset.JM Fahey, bought this amplifier already with this problem, and I would love to solve more from what I saw there that probably defective IC8 I'll see if I can it right here in my town and change to see if it will work.The amplifier works perfect the clear channel and yellow channel, plus the red channel does not work in any way:

I prefer the google translate

[52 Bill]

So TP32 voltages are incorrect.

These voltages do not make any sense, or I don't understand what the amp is actually doing when switched.

If I understand it correctly, the clean channel works, the yellow gain channel works, but the red gain channel does not work. Do we know if the red led lights up when turned on? If it does, then we could be looking in the wrong place for the fix.

There are three channel control lines, marked on the schematic as SEL.1, SEL.3 and SEL.4. Each of these lines needs to be switched to -15vdc to turn off a particular channel by way of an fet transistor.

SEL.1 selects the yellow channel by turning off the signal from the red channel, SEL.3 selects the red gain channel by turning off the signal from the yellow channel and SEL.4 selects the clean channel by turning off the signal from both yellow and red channels.

If in fact the clean and yellow channels are working, then SEL.3 is the only line that could cause the red channel not to work. The voltages that we have been given from TP32 must be incorrect, or else the clean and yellow channels would not be switching correctly.

So U8 appears to be working, U9 might be bad or it could just be a bad Q2 jfet not allowing the red channel signal to pass.

We still need better information.

[adiorgelis]

These voltages do not make any sense, or I don't understand what the amp is actually doing when switched.

If I understand it correctly, the clean channel works, the yellow gain channel works, but the red gain channel does not work. Do we know if the red led lights up when turned on? If it does, then we could be looking in the wrong place for the fix.

There are three channel control lines, marked on the schematic as SEL.1, SEL.3 and SEL.4. Each of these lines needs to be switched to -15vdc to turn off a particular channel by way of an fet transistor.

SEL.1 selects the yellow channel by turning off the signal from the red channel, SEL.3 selects the red gain channel by turning off the signal from the yellow channel and SEL.4 selects the clean channel by turning off the signal from both yellow and red channels.

If in fact the clean and yellow channels are working, then SEL.3 is the only line that could cause the red channel not to work. The voltages that we have been given from TP32 must be incorrect, or else the clean and yellow channels would not be switching correctly.

So U8 appears to be working, U9 might be bad or it could just be a bad Q2 jfet not allowing the red channel signal to pass.

We still need better information.

ok, what else could I be measuring to get a conclusion?

ok, o que mais eu poderia estar medindo para chegar a uma conclusão?

[52 Bill]

ok, what else could I be measuring to get a conclusion?

ok, o que mais eu poderia estar medindo para chegar a uma conclusão?

Measure the voltage at the stripe and of CR60 (TP34) in all three modes.

And does the red light turn on when the red channel is selected?

[adiorgelis]

Measure the voltage at the stripe and of CR60 (TP34) in all three modes.

And does the red light turn on when the red channel is selected?

** com o multimetro em dc, preto no chassi, medindo o IC9 oitavo pino (TP34) **
with the multimeter in dc, black chassis, measuring IC9 eighth pin (TP34)
clean - 15.92 (negative)
yellow 16.17
red -16.17 (negative)

CR60
clean -16.07 (negative)
yellow 16.25
16.30 red (negative)

[52 Bill]

CR60
clean -16.07 (negative)
yellow 16.25
16.30 red (negative)

These voltage are correct.

Does the red light go on when the red mode is selected?

[adiorgelis]

These voltage are correct.

Does the red light go on when the red mode is selected?

the problem is not just her turn, actually more distortion red does not work when I I trigger a red distortion it is clean, and the volume of the red channel rather than work with the panel drive tube, it works with the panel channel clean, nullifying all part of the panel drive tube.

** o problema não é só ela ligar, mais na verdade a distorção vermelho não funciona, quando eu aciono a distorção vermelho ela fica clean, e o volume do canal vermelho ao invés de funcionar com o do painel drive tube, ela funciona com o painel do canal clean, anulando todo a parte do painel drive tube. **

[52 Bill]

the problem is not just her turn, actually more distortion red does not work when I I trigger a red distortion it is clean, and the volume of the red channel rather than work with the panel drive tube, it works with the panel channel clean, nullifying all part of the panel drive tube.

When you switch to the red mode, does the amp actually switch back into clean mode? Do the front panel lights switch into clean mode?

[adiorgelis]

When you switch to the red mode, does the amp actually switch back into clean mode? Do the front panel lights switch into clean mode?

in reality the sound is clean and all is on the equalization panel clean when selected the red channel.

seems to have a short piece or broken when it switches to the red channel was to play the signal in a certain place not more it comes back to the clean channel


**na verdade o som fica clean e toda a equalizacao fica no painel do clean, quando selecionado o canal vermelho.

parece ter uma peca em curto ou rompida pois quando muda para o canal vermelho era pra jogar o sinal em determinado lugar mais nao ele volta para o canal limpo**

[J M Fahey]

** com o multimetro em dc, preto no chassi, medindo o IC9 oitavo pino (TP34) **
with the multimeter in dc, black chassis, measuring IC9 eighth pin (TP34)

^^^ Multimeter set to DC, black probe to chassis, measuring IC9 pin 8 (TP34)

clean - 15.92 (negative)

yellow 16.17
red -16.17 (negative)

CR60
clean -16.07 (negative)
yellow 16.25
16.30 red (negative)

Amigo adiorgelis, em toda medição indica a unidade; por caso

16.30 V red (negative)

^^^ please *always* write units by each number .

[g1]

Pin8 is supply pin, I think there may be some confusion about pin numbering of the IC's.

[52 Bill]

Now I'm totally confused. Juan, would it be possible for you to ask the original poster to describe exactly what is happening with his amp? It sounds like he now is saying that the red channel switches correctly but it just sounds clean?

Please help!

[adiorgelis]

Now I'm totally confused. Juan, would it be possible for you to ask the original poster to describe exactly what is happening with his amp? It sounds like he now is saying that the red channel switches correctly but it just sounds clean?

Please help!

eu gravei um video para fica mais facil de entender

I recorded a video for it is easier to understand

Problem Fender Roc Pro 1000 - YouTube

[52 Bill]

eu gravei um video para fica mais facil de entender

I recorded a video for it is easier to understand

Problem Fender Roc Pro 1000 - YouTube

What I guess is happening, is when the amp is switched into red mode, it switches back to clean mode. If the voltage readings that you gave us are correct, this should not be happening.

At this point the only thing that I can suggest is to have someone qualified in your country look at the amp and test all of the switching system components, diodes, ICs and all of the fets. I have no way to really help you from a distance with the unfortunate communication problems. Sorry.

Maybe somebody else here can help more than I can.

[adiorgelis]

What I guess is happening, is when the amp is switched into red mode, it switches back to clean mode. If the voltage readings that you gave us are correct, this should not be happening.

At this point the only thing that I can suggest is to have someone qualified in your country look at the amp and test all of the switching system components, diodes, ICs and all of the fets. I have no way to really help you from a distance with the unfortunate communication problems. Sorry.

Maybe somebody else here can help more than I can.

Ok, obrigado por tentar ajudar.
Ok, thanks for trying to help.