Hey guys im back at this project. It's my old school rockford fosgate punch 150. The problem is the left channel is not working. I remember a while back I replaced NE5532P ic's to see if that would work. The amplifier still powers on and plays through one channel. What do I check? It's missing a driver transistor (D40D8) hard to find those. Has anyone fixed these?
Btw what year is this one from?
Btw what year is this one from?
You should check, the FET output that faulty channel, to see if they are short, or open, also resistors, capacitors, and check voltages at different points.
I see a fuse missing on that side of the amp, and there is a resistor 1/4 watt, which has a suspicious color ...
I've seen on ebay, a seller who has these transistors (D40D8) and seems reliable.
It is this:
http://www.ebay.es/itm/HARRIS-TO-20...851?pt=LH_DefaultDomain_0&hash=item5655cf0ff3
I see a fuse missing on that side of the amp, and there is a resistor 1/4 watt, which has a suspicious color ...
I've seen on ebay, a seller who has these transistors (D40D8) and seems reliable.
It is this:
http://www.ebay.es/itm/HARRIS-TO-20...851?pt=LH_DefaultDomain_0&hash=item5655cf0ff3
I removed the fuse because that channel had DC on it. I'm guessing maybe just replace all the components in that channel? The outputs are BJT 2N6487 & 2N6490. I can use 2N6491 & 2N6488?
If you got DC on the speaker output of the channel, because there is a blown fet, check them.
I prefer to do the replacement, always identical to the original parts of the amplifier.
If you replace those with equivalent FETS, it may not work properly, you have to adjust the bias, or, burn a few minutes ..
I prefer to do the replacement, always identical to the original parts of the amplifier.
If you replace those with equivalent FETS, it may not work properly, you have to adjust the bias, or, burn a few minutes ..
They're bipolar transistors? I'm guessing early Fosgate used bipolar outputs in these early amps? Seems a lot different from all the other amps I've worked on..
Sorry, if I referred to as FET output transistors, (is the usual,) I think they are just power transistors, "plain" I'm not sure if they are bipolar or not ....
I noticed some time ago a 75HD, but I remember, yes, were mosfet output transistors, specifically IRF 540 or 640'S ....
Anyway, I will repeat, that would try to replace them with the originals, the same channel that is in the works.
I noticed some time ago a 75HD, but I remember, yes, were mosfet output transistors, specifically IRF 540 or 640'S ....
Anyway, I will repeat, that would try to replace them with the originals, the same channel that is in the works.
Using the DMM diode test function, check the devices (diodes, NPNs and PNPs) for open in the reverse direction and 600 +/-100 mV in the forward direction. You may need to lift one end of the base emitter resistor or lift the base of each device to get a valid measurement. If they all look good, remove the op amp (on my schematic it’s marked U3) and post a list of all the voltages. Install a socket for U3 incase needs replacing.
I worked for a company who made discrete op amps in 1969 and repaired over 70 amplifiers in one day by troubleshooting with only a DMM. The next day the company shipped over $10,000 worth of op amps. I made $28 a day minus taxes about $17, then the laid me off.
Let me know if you need the schematic.
I worked for a company who made discrete op amps in 1969 and repaired over 70 amplifiers in one day by troubleshooting with only a DMM. The next day the company shipped over $10,000 worth of op amps. I made $28 a day minus taxes about $17, then the laid me off.
Let me know if you need the schematic.
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Central semiconductor makes a cross chip for both that work great. Even better you can contact them for free samples. They sent me 16 for free to try and that is what I installed in the power 650.
CEN-U07 is D40
CEN-U57 is D41
When you get them check them against the originals. I will have to verify if the d40 is the cen-u07 or the other one
CEN-U07 is D40
CEN-U57 is D41
When you get them check them against the originals. I will have to verify if the d40 is the cen-u07 or the other one
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