It's somewhat more stable. With a simple resistors/zener/current boost transistor, the voltage will vary slightly as the load varies. This circuit has feedback and can compensate for changes in the load. This may be important in this amp since the fans are driven off of this supply.
With a less complex circuit, you could compensate to some degree by passing additional current through the resistor/zener circuit but that would dissipate significant power with this much rail voltage.
With a less complex circuit, you could compensate to some degree by passing additional current through the resistor/zener circuit but that would dissipate significant power with this much rail voltage.
Well this amp came back to me, +15V supply fried again, replaced R116, R118, Q106, Q107, Q110 , the 15V Zener and the Mosfet with a STP24NF10. I have placed a 2amp fuse in series with the Source terminal of the Power Mosfet and it keeps blowing, im afraid to connect the Mosfet directly to the board in case it fries everything again. Is the 2amp fuse too small on the source terminal, or should it be drawing less than 2 amps?
I would Love to get this amp out of my hair.
I would Love to get this amp out of my hair.
It appears that there is an intermittent problem. With the fuse in series with the regulator FET, you should push on various parts of both circuit boards to see if you can make the fuse blow. If that doesn't do it, heat various parts of both boards with a heat gun to see if that makes the fuse blow.
Well, the amp seems to have all the same issues as when it first came into me. The class-D stage op-amps are fried, found R421 near the servo op-amp was 10k instead of the 2k it's supposed to be, R118, and R203 on the x-over board are gone again. The input noise cancellation stage near the RCA's seems to be fine this time though.
On the 3120's, all the terminals check out fine according to your diagram for testing the 3120's, except, pins 2-3, both 3120's read .013V no matter what polarity I check them when on diode check.
The 15V regulator is running at 18amps, so im going to piggy back another 15V zener off the Source to common on the regulators Mosfet. I could not get anything weird to happen by poking at components, or heating things up with the heat gun. I have to make a whole new parts order, so once that comes in i'll power up the amp once more and go over almost every resistor.
Im learning more with this amplifier alone than I have in school over the last year haha.
On the 3120's, all the terminals check out fine according to your diagram for testing the 3120's, except, pins 2-3, both 3120's read .013V no matter what polarity I check them when on diode check.
The 15V regulator is running at 18amps, so im going to piggy back another 15V zener off the Source to common on the regulators Mosfet. I could not get anything weird to happen by poking at components, or heating things up with the heat gun. I have to make a whole new parts order, so once that comes in i'll power up the amp once more and go over almost every resistor.
Im learning more with this amplifier alone than I have in school over the last year haha.
Fans work great, I pulled Q405 , do you know what that transistor is? On it it says C1TVA, I would like to find a diagram on it, I believe it's shorted since the two terminals that are on one side both test .013V no matter what polarity.
How do you find the replacement transistors? I can't for the life of me pull up anything related to the part # C1TVA.
How do you find the replacement transistors? I can't for the life of me pull up anything related to the part # C1TVA.
It's a JFET so the terminals are going to appear nearly shorted unless something turns it off.
I think it's something similar to an MMBFJ111 but I can't find a j111 with a c1 mark.
Generally, you can find the part numbers for SMD parts by googling:
SMD codebook
There will be 2-3 sites that will have the codes.
I think it's something similar to an MMBFJ111 but I can't find a j111 with a c1 mark.
Generally, you can find the part numbers for SMD parts by googling:
SMD codebook
There will be 2-3 sites that will have the codes.
Well if you look at the picture I attached, the go-no-go tests come out as follows:
Pin1(+) Pin2(-) =0.13V
Pin1 (-) Pin2(+) =0.13V
Pin3(+) Pin1(-) =0.65V
Pin3(-) Pin1(+) =O.L
Pin3(+) Pin2(-) =0.65V
Pin3(-) Pin2 (+) =O.L
When I looked up the SMD Code book and looked up C1t it referenced a BCW29 PNP transistor which like you say doesn't seem right.
Pin1(+) Pin2(-) =0.13V
Pin1 (-) Pin2(+) =0.13V
Pin3(+) Pin1(-) =0.65V
Pin3(-) Pin1(+) =O.L
Pin3(+) Pin2(-) =0.65V
Pin3(-) Pin2 (+) =O.L
When I looked up the SMD Code book and looked up C1t it referenced a BCW29 PNP transistor which like you say doesn't seem right.
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