Are the rail voltages present? The +/- 15 volts to the preamp?
Check the voltage between speaker and power ground. It should be 0 volts. If not the zero ohm resistor/jumper is open.
Check the voltage between speaker and power ground. It should be 0 volts. If not the zero ohm resistor/jumper is open.
i pulled it apart and it has a blown 5402 diode, several capacitors, the power supply is shorted, a cap id blown on the class d board. the 4r7 resistor in the remote curcuit is burnt. Its so many componts, I may leave this one a parts amp.
What your describing is a result of under rated power cables and improper fusing, It's not uncommon to see this in the repair department. There may be a burnt trace on the bottom side. This will require replacing all four IRFZ46N's, Three 2200uf/25v caps, maybe a smaller value cap in the same area. P39-4.7 ohm is tied to Q17-2SB772 and Q3_2N4403 which may be shorted. Possible RP87-0 ohm resistor and repairing trace. Possible a shorted output.
This is your call and I think the daughter boards are worth salvage, among other things.
BTW, there is no class D board on this amp. This is a Class A/B amp and does not require a class D circuit. Are you referring to the daughter board in the power supply section, or the Input/Preamp board?
This is your call and I think the daughter boards are worth salvage, among other things.
BTW, there is no class D board on this amp. This is a Class A/B amp and does not require a class D circuit. Are you referring to the daughter board in the power supply section, or the Input/Preamp board?
I removed the capacitors, and the diode, the 4.7ohm resistors is burnt and open. All four power supply mosfets. I do have all the required parts. So I'll attempt it. The only reason I said that is I still can't get the other one work. There is also an exploded cap on the daughter board possibly, a 100uf 16v-25v. We'll see how it goes. Maybe it will help me with the other one.
It was a 10uf 25v cp4. I don't have drive at the ps mosfets now. Open pnp drivers? Amp has no power supply mosfets in curcuit and in protection.
What is the locator of the 10uf/25v cap?
Post a tight picture of the daughter board,component side and the bottom side of the main board.
There may be a burnt trace on the bottom side that could be causing no drive.
The edited picture I posted show three arrows.
One arrow shows a zero ohm resistor that tie the other two arrows together. Speaker and Power Grounds. Check the resistor and the two arrows test points with an ohmmeter. You should see near zero ohms between them. If these two points are open it will cause a voltage drop that will cause muting and other issues.
Post a tight picture of the daughter board,component side and the bottom side of the main board.
There may be a burnt trace on the bottom side that could be causing no drive.
The edited picture I posted show three arrows.
One arrow shows a zero ohm resistor that tie the other two arrows together. Speaker and Power Grounds. Check the resistor and the two arrows test points with an ohmmeter. You should see near zero ohms between them. If these two points are open it will cause a voltage drop that will cause muting and other issues.
Attachments
.4 ohms from ground. And the resistor tests .3ohms. I think it's good. The resistor that exploded is "cp4" I replaced it. Along with everything else the 2200 25v power supply capacitors. Amp stays in protection.
Despite me changing the daughter card with the another one, the amplifier stays in protection. As soon as b+ is applied red light only.
The daughter card you used from a different amp may have same issue. Was the swapped daughter card able to turn on the amp, when it was installed in its original amp?
On the daughter card from the amp you are currently looking at, the CP4 was exploded, which is tied to the emitter of Q1-2SB772 and +12v Power terminal, through a P4-221kohm resister. It's possible Q1 has failed. Also, check Q5-MPSA06, Q7-2N4403, both transistor will cause this issue when they fail. An ohmmeter will show a shorted or low value resistance when they fail. There are a several more transistors on that board. I would recommend checking each one.
On the daughter card from the amp you are currently looking at, the CP4 was exploded, which is tied to the emitter of Q1-2SB772 and +12v Power terminal, through a P4-221kohm resister. It's possible Q1 has failed. Also, check Q5-MPSA06, Q7-2N4403, both transistor will cause this issue when they fail. An ohmmeter will show a shorted or low value resistance when they fail. There are a several more transistors on that board. I would recommend checking each one.
No it is from the amplifier I can not get it to stop powering up without remote voltage applied.
On this amplifier the 2sb772 was shorted, I replaced it and the transistor Q7 was open.
I'm going to change the other transistors as well. Unless, will the amplifier power up with out the ps fets in place?
On this amplifier the 2sb772 was shorted, I replaced it and the transistor Q7 was open.
I'm going to change the other transistors as well. Unless, will the amplifier power up with out the ps fets in place?
working, protection light stays on when the ps fets are removed but drive is present, once i obtained drive, replaced the mosfets with irf3205's and tested for audio, clear and present on all channels.
Repaired both now the card that had the cap exploded, also destryoed the 494 as well. Once the components we're replaced now the other amplifier is working. It is missing an output, I used it in another amplifier a while ago, I think that's why I draws a little more current than usual.
So two CX300.4's are working, correct?
One draws a little more current, because it's missing an output? I'm a little unclear what you mean.
You had one that would turn on without remote, have you been able to correct this, and what was the fix?
It might be useful to briefly break down what you did to fix each amp on their relevant forum threads, so that others can gain some insight into how to fix these amps.
One draws a little more current, because it's missing an output? I'm a little unclear what you mean.
You had one that would turn on without remote, have you been able to correct this, and what was the fix?
It might be useful to briefly break down what you did to fix each amp on their relevant forum threads, so that others can gain some insight into how to fix these amps.
yes both are operational, we went through the entire remote curcuit.
Replaced the 4R7 Resistor
Replaced the blown 1N5402 Rectifier Diode
Replace the 2) 2200uF 25v power suppy capacitors
Replaced the 100uf capacitor in remote curcuit.
Replaced 2SB772 (On daughter card was shorted)
Replaced Q3 2N4403
Replaced the 4 IRFP46Z (I used IRFP3205 in place of the originals, only beacuse original transitors i did not have in stock)
Replaced the 4R7 Resistor
Replaced the blown 1N5402 Rectifier Diode
Replace the 2) 2200uF 25v power suppy capacitors
Replaced the 100uf capacitor in remote curcuit.
Replaced 2SB772 (On daughter card was shorted)
Replaced Q3 2N4403
Replaced the 4 IRFP46Z (I used IRFP3205 in place of the originals, only beacuse original transitors i did not have in stock)
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