One more thing........
So if you have the right voltage, but not the right current you can still do the same trouble shooting checks, like what is talked about in this whole thread?? If so then, when I hook up that voltage to the amp, the power light(LED) should come on, right?? Well when I did it, it did not come on, plus I noticed that when I conected the remote lead, the voltage on the PS went down and the amps went up, so as I know that means their is a short, right??
I know I am probley killing you with all these little tiny problems, but Im still learning and I do thank you for your help. Im good at all the book work and doing our labs for class, but when it comes to trouble shooting stuff Im in the dark....
So if you have the right voltage, but not the right current you can still do the same trouble shooting checks, like what is talked about in this whole thread?? If so then, when I hook up that voltage to the amp, the power light(LED) should come on, right?? Well when I did it, it did not come on, plus I noticed that when I conected the remote lead, the voltage on the PS went down and the amps went up, so as I know that means their is a short, right??
I know I am probley killing you with all these little tiny problems, but Im still learning and I do thank you for your help. Im good at all the book work and doing our labs for class, but when it comes to trouble shooting stuff Im in the dark....
If the supply can only deliver 6 amps, you probably don't need the fuse (but you still need to have the transistors clamped to the heatsink).
The power light won't come on until you apply remote voltage.
How far did the voltage drop?
How much current did it draw?
Did the current draw decrease after a few seconds?
What parts have you replaced?
Did you check the output transistors to determine if any are shorted?
The power light won't come on until you apply remote voltage.
How far did the voltage drop?
How much current did it draw?
Did the current draw decrease after a few seconds?
What parts have you replaced?
Did you check the output transistors to determine if any are shorted?
I just checked the output transistors, and 2 of them are bad. I know the power supply transistors are the (75339p), but there is only 4 of them, then there is 2 rectifiers right next to them. Then on the other side of the amp are 4 more transistors and I think they are the output ones. They are marked (SSP45N20A) and like I said after doing the test 2 of them are bad.
I cant do any more test with the DC power supply because I don’t own one so its back at school but I’m going to head in their tomorrow and get some work done on this head unit my working on. But when I did hook it up today, I ran both the remote and +B from the same lead, and then one lead to the ground from the power supply. As I remember it started out at 12.5V, before I hooked it up, then as soon as I hooked up the remote lead it dropped maybe 2 to 3V, and the current went up to 4A.
Yes when I did the test the transistors where clamped down, all I did was take off the top of the amp, I did not take off the clamps holding the transistors on the side of the amp. But what is that white type of paper under the transistors?? It has some sort of white paint, or something coming off of it???
I cant do any more test with the DC power supply because I don’t own one so its back at school but I’m going to head in their tomorrow and get some work done on this head unit my working on. But when I did hook it up today, I ran both the remote and +B from the same lead, and then one lead to the ground from the power supply. As I remember it started out at 12.5V, before I hooked it up, then as soon as I hooked up the remote lead it dropped maybe 2 to 3V, and the current went up to 4A.
Yes when I did the test the transistors where clamped down, all I did was take off the top of the amp, I did not take off the clamps holding the transistors on the side of the amp. But what is that white type of paper under the transistors?? It has some sort of white paint, or something coming off of it???
I've been using IRF3415s in place of the SSP45N20As. They are more readily available. Replace all 4.
The material under the transistors is an insulator. It's silicone rubber with a fiberglass core (generally). The white grease is a thermally conductive compound that's used to fill tiny imperfections in the surfaces to promote better heat transfer.
The material under the transistors is an insulator. It's silicone rubber with a fiberglass core (generally). The white grease is a thermally conductive compound that's used to fill tiny imperfections in the surfaces to promote better heat transfer.
I thought it might be something like that. Well I went through and did a couple more quick test on Q110, I just did it with a DMM, on the diode test setting and had ground on BASE and positive on COLLECTOR, and instead of getting no readings, it shot out some crazy numbers, so I went though and found Q119, Q115, Q116 were all the same way. I also checked out almost all others around the board and they all seem to be fine. So I believe all the problems are all in that same area. I also think that D112 is also bad, but I could be wrong their. I’m going to take it back in to school tomorrow and test all the resistors in that area but I need a magnified glass(which we have a super nice one at school) and check out the values of them and do some more test then order parts from my good friends at Digi-key.....
So thanks again for all your help so far.....
And if their is anything else I should keep my eye out for or any pointers you have that would be nice... Thanks....
So thanks again for all your help so far.....
And if their is anything else I should keep my eye out for or any pointers you have that would be nice... Thanks....
Hey Perry,
Well I finally got the output transistors put in yesterday, and I went back to class today to do more trouble shooting. Remember when I said that the DC power supply at my school only put out 6A, well that is true but only at 6V.
When I did my testing today, I put the output voltage at 13.28V, and I was only getting 585mA. So I dont know how I'm going to do my testing on this amp. But I did go through a check the voltage at the LM311 and the Q110.
LM311
pin1= 0.00V
pin2= 3.730V
pin3= .615V
pin4= REF
pin5= 4.61V
pin6= 4.57V
pin7= 4.34V
pin8= 4.70V
Q110
1 base= .017V
2 emitter= 0V
3 collector= 10.28V
Now since I can't even get any real amps going through the amplifier, what else can I do for trouble shooting?/
Thank you in advance for your help, and all the help you have giving so far, and by the way my teacher really liked your web page too......
Well I finally got the output transistors put in yesterday, and I went back to class today to do more trouble shooting. Remember when I said that the DC power supply at my school only put out 6A, well that is true but only at 6V.
When I did my testing today, I put the output voltage at 13.28V, and I was only getting 585mA. So I dont know how I'm going to do my testing on this amp. But I did go through a check the voltage at the LM311 and the Q110.
LM311
pin1= 0.00V
pin2= 3.730V
pin3= .615V
pin4= REF
pin5= 4.61V
pin6= 4.57V
pin7= 4.34V
pin8= 4.70V
Q110
1 base= .017V
2 emitter= 0V
3 collector= 10.28V
Now since I can't even get any real amps going through the amplifier, what else can I do for trouble shooting?/
Thank you in advance for your help, and all the help you have giving so far, and by the way my teacher really liked your web page too......
It appears that the amp's power supply wasn't producing full rail voltage. With the black probe on chassis ground, what is the DC voltage on pin 4 of the LM311?
If it's near -50v, measure the voltage on the LM311 again.
Pin 8 of the 311 should have ~12v (pin 4 as the reference point) if the power supply is producing the proper rail voltage.
If it's near -50v, measure the voltage on the LM311 again.
Pin 8 of the 311 should have ~12v (pin 4 as the reference point) if the power supply is producing the proper rail voltage.
Ok here is the thing. When I set up the DC power supply, I hooked it up to a DMM, just to see what voltage I had it set at (I always do that just to double check.) And it was at 13.28V, but once I hooked it up to the amp the voltage reading from the power supply dropped to around 10V.
Well tomorrow I'm going to head to my friends house and use his DC power supply, and test what you said.
But how will I have a reading of -50V, I only ask because since there is very little current go into the amp from the power supply I would think that it couldn't produce a high voltage like that??
And what else do you think I should look for???
Well tomorrow I'm going to head to my friends house and use his DC power supply, and test what you said.
But how will I have a reading of -50V, I only ask because since there is very little current go into the amp from the power supply I would think that it couldn't produce a high voltage like that??
And what else do you think I should look for???
The voltage probably dropped to 10v on the 6A supply because there was a problem causing excessive current draw. Insert a 10 amp fuse in the B+ line to protect the amp in case it is drawing excessive current.
Double-check all of your solder connections to be sure there are no solder bridges.
The -50v will be produced by the power supply if everything is working properly. If there is no excessive current draw, you don't need significant current to produce high voltage.
Double-check all of your solder connections to be sure there are no solder bridges.
The -50v will be produced by the power supply if everything is working properly. If there is no excessive current draw, you don't need significant current to produce high voltage.
The power supply doesn't go to 6A, only 600mA.
On the power supply at my school, on the left bottom you can hook up to it but only get a max of 6V, with 3A. But then on the right side you can plug into it can get a max of 25V at 600mA........
When I hooked up the amp, I made sure to have a fuse inline with the +B, and the remote lead going to the PS. I'm ready to pull my hair out.....This whole trouble shooting thing is tough with out a schematic, I hope it gets easier later on once I get more knowledge about the whole electronics game. Well I know that when the voltage drops like that and the current goes up that it's a short. I think I brought this up earlier a couple post ago, before I replaced the output transistors, the amp was doing the same thing, as soon as I put voltage into it, the voltage reading on the PS dropped to 10V. But I couldn't tell if the current went up because it was already at it's full reading (I hope that makes sense??) I just figured that the voltage dropped because it was such a big load, like it wanted to take more current to try and run the amp but couldn't so the voltage dropped, for some reason that doesn't sound right.... Ughhh this amp is driving me crazy.....
On the power supply at my school, on the left bottom you can hook up to it but only get a max of 6V, with 3A. But then on the right side you can plug into it can get a max of 25V at 600mA........
When I hooked up the amp, I made sure to have a fuse inline with the +B, and the remote lead going to the PS. I'm ready to pull my hair out.....This whole trouble shooting thing is tough with out a schematic, I hope it gets easier later on once I get more knowledge about the whole electronics game. Well I know that when the voltage drops like that and the current goes up that it's a short. I think I brought this up earlier a couple post ago, before I replaced the output transistors, the amp was doing the same thing, as soon as I put voltage into it, the voltage reading on the PS dropped to 10V. But I couldn't tell if the current went up because it was already at it's full reading (I hope that makes sense??) I just figured that the voltage dropped because it was such a big load, like it wanted to take more current to try and run the amp but couldn't so the voltage dropped, for some reason that doesn't sound right.... Ughhh this amp is driving me crazy.....
He said that the max output is only 3A. I just headed over their so I can see if that Clarion HU that I was working on is fixed or not, since it only needs 3A to run it.
But back on this topic, so since the current rating is so low on the PS at my school, is that why the voltage dropped so much once I hooked the amp up to it?? Or should I be looking around for a short somewhere??? Because I did notice that a couple of the resistors looked really bad.....
But back on this topic, so since the current rating is so low on the PS at my school, is that why the voltage dropped so much once I hooked the amp up to it?? Or should I be looking around for a short somewhere??? Because I did notice that a couple of the resistors looked really bad.....
R39 looks bad, but could still be good, same with
R33
R37
**** These are for the remote turn-on via the speaker level input. The amp will work even if these have failed.
R628 & R629 look really bad, but they might still work, those two look the worst.
**** These generally only fail or appear damaged when the power supply FETs fail. These must be within tolerance.
Q110
Q116
Q115
Q119 all look to be in pretty bad shape too.
**** I don't remember these failing. They may simply run hot or run hot when the amp is in protect mode.
R33
R37
**** These are for the remote turn-on via the speaker level input. The amp will work even if these have failed.
R628 & R629 look really bad, but they might still work, those two look the worst.
**** These generally only fail or appear damaged when the power supply FETs fail. These must be within tolerance.
Q110
Q116
Q115
Q119 all look to be in pretty bad shape too.
**** I don't remember these failing. They may simply run hot or run hot when the amp is in protect mode.
Hey Perry, well now that I'm on break from school and my Fluke DMM just came in the mail. I hooked the amp up to my car and tested the LM311.....
pin1= 0.00V
pin2= 45.1V
pin3= 1.88V
pin4= REF
pin5= 11.95V
pin6= 11.95V
pin7= 11.11V
pin8= 12.16V
I also checked pin4 with black prob on the chassis ground, and I got a reading of 51.1V
I also checked the Q110
base= .026V
emitter= o.ooV
collector= 51.2V
I dont have a speaker yet to hook up to it, but I think it might work now, or am I reading these numbers wrong??
pin1= 0.00V
pin2= 45.1V
pin3= 1.88V
pin4= REF
pin5= 11.95V
pin6= 11.95V
pin7= 11.11V
pin8= 12.16V
I also checked pin4 with black prob on the chassis ground, and I got a reading of 51.1V
I also checked the Q110
base= .026V
emitter= o.ooV
collector= 51.2V
I dont have a speaker yet to hook up to it, but I think it might work now, or am I reading these numbers wrong??
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