You're going to have to (with all transistors tightly clamped down), measure the DC voltage across every emitter resistor. With the bias pots fully CCW, I'd expect all to read 0.000v DC with the amp on. If you find one or a group of emitter resistors with significantly higher voltage (0.005v, for example), you will know where to start troubleshooting.
I see. That makes sense.
I will do it now. Thanks.
====
And a question for you Perry (if you can answer me), i was studying on your fantastic website:
This is the scenario of my amp, that is right? And all class AB amps i've opened. I see a lot of NPN and PNP transistors working together.
From far as i know, every transistor have its own dissipation, current and voltage capability.
This is just an example. But, it is possible to install more transistors in paralell to allow the amp to work better in lower impedances? I know this will not increase the power of the amp since that depends on the entire circuit.
But, from what i think, it will increase the output current. And output current is the most important thing when we work with lower impedances.
What you think? I'm just crazy or that makes sense for you?
I will do it now. Thanks.
====
And a question for you Perry (if you can answer me), i was studying on your fantastic website:
This is the scenario of my amp, that is right? And all class AB amps i've opened. I see a lot of NPN and PNP transistors working together.
From far as i know, every transistor have its own dissipation, current and voltage capability.
This is just an example. But, it is possible to install more transistors in paralell to allow the amp to work better in lower impedances? I know this will not increase the power of the amp since that depends on the entire circuit.
But, from what i think, it will increase the output current. And output current is the most important thing when we work with lower impedances.
What you think? I'm just crazy or that makes sense for you?
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It's not generally as simple as adding more parallel transistors. With more power transistors, you need stronger drive circuits. With more output transistors, you need more power supply transistors. With more current you need to upgrade other various components. it's best to use an amp as it was designed. If you need it to do something other than what it was designed, buy/use a different amp.
I can understand it.
I have so many old school Fosgate's and two extremely huge Orion's (with tons of transistors) here with output completely blown (maybe even the power supply transistors, like this Kicker).
I just was thinking on a method to make them more tought. Even if it is costly.
Too bad is not possible. It is the life.
Thanks!
I have so many old school Fosgate's and two extremely huge Orion's (with tons of transistors) here with output completely blown (maybe even the power supply transistors, like this Kicker).
I just was thinking on a method to make them more tought. Even if it is costly.
Too bad is not possible. It is the life.
Thanks!
Perry,
On this test i will run the amp on about 7.5v volts because of the current limiter (a big variable resistor i have).
This is a problem on this test?
On this test i will run the amp on about 7.5v volts because of the current limiter (a big variable resistor i have).
This is a problem on this test?
And i forget to say. The noise on the toroidal reduced by 50% when i removed the faulty output transistor.
Perry,
Here is the results:
Thanks.
Here is the results:
An externally hosted image should be here but it was not working when we last tested it.
Thanks.
Hi,
Should i buy new output transistors and change them all from the upper side of the amplifier?
Please, let me know. I don't know what to do now.
Thanks.
Should i buy new output transistors and change them all from the upper side of the amplifier?
Please, let me know. I don't know what to do now.
Thanks.
For the amp to be reliable, you will have to (At the very least), replace all of the output transistors in parallel with the one that failed. You will also need to replace all of the emitter resistors for those transistors. If this came to me for repair, I'd replace all outputs and all emitter resistors in that channel. I'd use 1% tolerance emitter resistors.
Does the amp produce audio now that the defective output has been removed?
Does the amp produce audio now that the defective output has been removed?
Perry,
Just to me understand, the upper side have blown transistors and the lower side is OK?
What you think is happening on the upper side?
0.000v is normal on the lower side? That means the FETs are OK?
I will do that on the resistors, thanks for the tip. I will buy 1% tolerance emitter resistors today.
About change everything, i was thinking to change all 24 bipolar transistors for BOTH sides since i will be using this amp on BRIDGE mode.
The problem i see right now is to buy NOT fake transistors.
Just to me understand, the upper side have blown transistors and the lower side is OK?
What you think is happening on the upper side?
0.000v is normal on the lower side? That means the FETs are OK?
I will do that on the resistors, thanks for the tip. I will buy 1% tolerance emitter resistors today.
About change everything, i was thinking to change all 24 bipolar transistors for BOTH sides since i will be using this amp on BRIDGE mode.
The problem i see right now is to buy NOT fake transistors.
0.000v on the lower channel is what I'd expect with the bias set fully CCW. I don't know why the upper channel isn't at 0.000. I wanted to know if it produced clean audio to see if the upper channel had any other obvious problems.
To clarify, the outputs are not FETs, they BJTs.
If you're planning on using this on bass, I'd suggest buying a cheap class D amp. They're much better suited for bass.
Side note...
When replacing large numbers of identical parts, it loos better if you find a way to bend all of the leads consistently. If all of the leads are bent precisely the same, the repair will look much better.
This will also be a good time to buy a good soldering iron if possible. The Weller WES51 or something similar would be a good choice.
To clarify, the outputs are not FETs, they BJTs.
If you're planning on using this on bass, I'd suggest buying a cheap class D amp. They're much better suited for bass.
Side note...
When replacing large numbers of identical parts, it loos better if you find a way to bend all of the leads consistently. If all of the leads are bent precisely the same, the repair will look much better.
This will also be a good time to buy a good soldering iron if possible. The Weller WES51 or something similar would be a good choice.
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Hey Perry and friends.
Sorry for the delay. I've bought a nice Classe D amplifier. Everything working perfectly since then.
But, i love this amplifier. I want to get it repaired.
Can you suggest me nice replacement transistors? I can't find anywere the genuine one. Everything i see on Aliexpress/ebay REALLY sounds fake.
Sorry for the delay. I've bought a nice Classe D amplifier. Everything working perfectly since then.
But, i love this amplifier. I want to get it repaired.
Can you suggest me nice replacement transistors? I can't find anywere the genuine one. Everything i see on Aliexpress/ebay REALLY sounds fake.
And i need to let you guys know:
Before install the new class D amp (SounDigital), i've seen problems on the negative connection to the chassis of my car. It was very bad.
I've tested with a amperimeter and a load of 150A and i was seeying about 10.3v of voltage with 3x 60A batteries.
I killed this kicker because of low voltage. I was reading that this old school amps can't stand this. The output starts to get very hot because of the distortion and blows up the power supply and the transistors on the output.
Too bad. Now it's time to fix it.
Thanks for the help.
Before install the new class D amp (SounDigital), i've seen problems on the negative connection to the chassis of my car. It was very bad.
I've tested with a amperimeter and a load of 150A and i was seeying about 10.3v of voltage with 3x 60A batteries.
I killed this kicker because of low voltage. I was reading that this old school amps can't stand this. The output starts to get very hot because of the distortion and blows up the power supply and the transistors on the output.
Too bad. Now it's time to fix it.
Thanks for the help.
For the power supply, I use the IRFP064. For the outputs, The FJA4313 and FJA4213 is what I'd use. Maybe PapaZBill has other suggestions.
Low voltage killed a lot of older amps that didn't have enough deadtime. When the voltage dropped, there was cross conduction between the power supply FETs and the supply failed. For low voltage to kill a properly designed power supply, the voltage has to be so low that the drive circuit cannot drive the FETs fully on. This causes them to overheat if the condition continues.
Low voltage killed a lot of older amps that didn't have enough deadtime. When the voltage dropped, there was cross conduction between the power supply FETs and the supply failed. For low voltage to kill a properly designed power supply, the voltage has to be so low that the drive circuit cannot drive the FETs fully on. This causes them to overheat if the condition continues.
Thanks, Perry.
That makes sense to me.
I will try find those FETs this week. Let me know if you guys have any other suggestions.
Thanks.
That makes sense to me.
I will try find those FETs this week. Let me know if you guys have any other suggestions.
Thanks.
Has something at Kicker changed? Every time I tried to buy parts, I was told they didn't sell parts.
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