I have read all the threads. I think that Jamie have let the board damaged from a lit to a lot. At first, you only need replace the FET and the resistors around FET.
Because the resisitors drive FET,if remove them from the board to check them,the FET will not be damaged,then you can measure FET,if the resistance of D pole to the S pole is about 09l,and S to D ia about 0.5L,then it is OK.Your focus should be placed on measurement and replacement of the resistor, I think so.
Perry do you mean power up the amp and check? I checked in diode test and got 0.83v on the small board and 0.64v on the main board.
Jekat I checked the R41 resistance and it is 10 ohms like it should be. Is that what you mean?
Jekat I checked the R41 resistance and it is 10 ohms like it should be. Is that what you mean?
Jekat, so in the future if I want to check fets as if they were out of board all I have to do is remove the gate resistors?
Because the small board seemed damaged I focused on that and the top side of the main board. I just realized the R41 resistor was connected to the D26 diode from the bottom of the board. I checked D26 and there is a short so I know I need to replace that. I'm going to do that now if I can get the same one. D26 is connected to a large piece of copper in the board that supplies a bunch of resistors, capacitors and a couple transistors. I checked the transistors and they seem ok. I checked some of the capacitors and resistors but there's a lot so I think I should just replace the diode as long as I won't do damage by turning on the amp after if something else is wrong.
I got a IN5819 1amp diode, the FR105 1amp one I'm replacing says its a fast recovery diode. The guy at the store said it would work but he didn't know if the new one was fast recovery. It doesn't say fast recovery on the data sheet so I'm not completely sure. I'll take his advice though and install the new one and see if the amp powers up.
I installed the diode and small board and the amp didn't go into protect! I guess I had the answer the whole time, I just was looking in the wrong spot. Now to figure out why the fets seem ok but there is no speaker jack voltage. I'm going to do my best to figure it out, do you have any suggestions Perry?
Speaker jack voltage?
You should have next to no DC voltage on the output terminals of the amp.
Anything over 0.050 vdc most times (not always) indicates a problem.
Do you have relay engagement and audio at the terminals?
You should have next to no DC voltage on the output terminals of the amp.
Anything over 0.050 vdc most times (not always) indicates a problem.
Do you have relay engagement and audio at the terminals?
Ok thanks for the advice, I thought it seemed weird that there was so much dcv in the amp but not at the terminals. I can hear the relay click and the amp doesnt go into protect but there is no sound. Do you have any ideas? I've been checking around but I haven't found anything. Does it seem normal to get 19.5k ohms between pins 1-3 of the output fets but 73.8 and 70dcv on pins 1 and 3. The middle one isn't readable because it is very jumpy. Is that because of the 12v regulator mentioned by Perry? I remember reading about unrectified signals and I'm thinking the middle pin is not readable because of the type of signal.
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The relay connects the audio signal to the output terminals when its engaged.
Do you have oscillation on one side of the output chokes and audio on the other?
Do you have oscillation on one side of the output chokes and audio on the other?
Sorry my experience is low but I think I do have oscillation on one side of the choke and audio on the other. I believe the chokes are the red coils? I have an unreadable (with multimeter) audio signal on the outside by the fets and a readable (multimeter) oscillating signal on the inside.
OK if the audio is going through the chokes, and the relay is engaging you need to find where between the relay and the output terminals you are losing the signal.
I believe there are some small resistors and diodes near the output terminals. Check those to make sure they are OK.
I believe there are some small resistors and diodes near the output terminals. Check those to make sure they are OK.
If this amp is the same layout as the BXi2607 which it should be check Q225 and Q226 to see if they are shorted, which would also make the diodes test abnormally.
I think that it is complicated, for example，when you checked the R41 resistance and it is 10 ohms,then we can judge this resistor is good,as we know that the resistance of a resistor is not reduced when it's damaged.As far as FET does not work, the main reason is the control signal is not available to the gate.
There have been so many failures, I suggest you use the oscilloscope take a measurement of the signals of G pole and D pole.If the signal amplitude of G-pole is relatively stable and considerable,then view the signal amplitude of D pole can be driven enough.
There have been so many failures, I suggest you use the oscilloscope take a measurement of the signals of G pole and D pole.If the signal amplitude of G-pole is relatively stable and considerable,then view the signal amplitude of D pole can be driven enough.
Ok thanks jekat I'll look into an Oscilloscope to test the signal properly.
I checked the Q225 and Q225 and Q226 had OL on every pin so I replaced it (A1266) with PN2 907A with advice from the electronics store. Do Q225 and Q226 need to be equal pairs as far as replacement?
When I power up the amp it now goes straight into protect, I'm suspecting the IC (IC1) which is after Q226. I get 0 resistance on pins 11-12 and I get 0.00dcv on pins 9 10 13 14 15 16 with the amp in protect.
I checked the Q225 and Q225 and Q226 had OL on every pin so I replaced it (A1266) with PN2 907A with advice from the electronics store. Do Q225 and Q226 need to be equal pairs as far as replacement?
When I power up the amp it now goes straight into protect, I'm suspecting the IC (IC1) which is after Q226. I get 0 resistance on pins 11-12 and I get 0.00dcv on pins 9 10 13 14 15 16 with the amp in protect.
Q225 and Q225q1 are in the working status of the push-pull.Best to replace them with a consistent model.
In addition, the chip IC1 will not be easily damaged,I think.
In addition, the chip IC1 will not be easily damaged,I think.
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I do believe someone correct me if I am wrong that Q225 and Q226 are used for DC offset protection???
I've heard with d-class amps you shouldn't substitiute many things so I wasn't sure about substituting. Do you mean Q225 and Q226 should be consistent with the original or with matching replacements? The electronics sales person said sometimes Japanese parts are hard to find and it would be easier and equal to use these american ones.
Sorry, by push pull do you mean the positive and negative of the speaker output section?
Sorry, by push pull do you mean the positive and negative of the speaker output section?
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I just wanted to say thanks to you three for your help. I wish I could be of more help. I'm soaking it all in though but there is a lot of different things to learn with electronics, from vocabulary to parts to testing to systems .......... I had this amp given to me broken so it's just for learning off of mostly.
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Do you think the reason the amp powered up with a bad Q226 and it goes into protect now is beacuse I didn't also replace Q225 with it's counterpart transistor? The originals were K819 and K820 and the guy at the store gave me something different but similar for Q226. Q225 is still the K... transistor.
Perry maybe? Or anyone else?
Perry maybe? Or anyone else?
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