I have this Weconic amp which lights up both LEDs power and protection.
Voltage on FETs 1: 0 2: 12,38V 3: 0, voltage on output transistors: 1: 0,18V 2: 0,18 (0,42 on some of them) 3: 0,42.
I removed rectifier diodes. Then protection LED did not light up.
Voltage on FETs 1: 3.64 2: 11,80 3: 0
Reinstalled rectifiers checked that they are OK, put them back in right places, they are identical (not -><- and <--> but both are ->->)
Voltages on power supply chip (tl494cn):
01:0.02
02:4.7
03:4.68
04:0,18
05:1,41
06:3,30
07:0
08:12,4
09:0
10:0
11:12,40
12:11,68
13:4,87
14:4,87
15:4,87
16:8,69
I read from Dr. Zeus's Hifonics Zeus ZXI6406 thread (http://www.diyaudio.com/forums/car-audio/180935-hifonics-zeus-zxi6406.html) that pin 16 8V means that something triggers overcurrent protection.
I tried to trace what is connected to pin 16 - opamp KIA4558 near the TL494CN through diodes (see attached photo)
I lift one leg of each diode and now I can switch the amp on without it going into protection.
Voltages on FETs 1: 3,30 2: 11,10 3: 0, output transistors 1: 0,02 2: 25 3: 0,02
All four channels produce good audio. Amp does not draw current (I am using 12V lamp as a current limiter, lamp does not even glow).
Nothing gets hot. Only weird thing was that sometimes after switching off the amp, there were some sparks near one of the rectifiers.
Made some big resolution photos of the amps guts and tries to photoshop them together, that did not go so well but the photo is here:
http://mote.planet.ee/weconic/weconic_vx-4260.jpg
At the moment I dont know what to do next.
Found german site which has photos of the same amps guts:
I see that someone has tried to repair my amp before and I see that output transistors are different, on german site photo they have metal back but my amp has plastic back transistors (2SD998, 2SB778). Using wrong replacement could cause something like this?
Voltage on FETs 1: 0 2: 12,38V 3: 0, voltage on output transistors: 1: 0,18V 2: 0,18 (0,42 on some of them) 3: 0,42.
I removed rectifier diodes. Then protection LED did not light up.
Voltage on FETs 1: 3.64 2: 11,80 3: 0
Reinstalled rectifiers checked that they are OK, put them back in right places, they are identical (not -><- and <--> but both are ->->)
Voltages on power supply chip (tl494cn):
01:0.02
02:4.7
03:4.68
04:0,18
05:1,41
06:3,30
07:0
08:12,4
09:0
10:0
11:12,40
12:11,68
13:4,87
14:4,87
15:4,87
16:8,69
I read from Dr. Zeus's Hifonics Zeus ZXI6406 thread (http://www.diyaudio.com/forums/car-audio/180935-hifonics-zeus-zxi6406.html) that pin 16 8V means that something triggers overcurrent protection.
I tried to trace what is connected to pin 16 - opamp KIA4558 near the TL494CN through diodes (see attached photo)
I lift one leg of each diode and now I can switch the amp on without it going into protection.
Voltages on FETs 1: 3,30 2: 11,10 3: 0, output transistors 1: 0,02 2: 25 3: 0,02
All four channels produce good audio. Amp does not draw current (I am using 12V lamp as a current limiter, lamp does not even glow).
Nothing gets hot. Only weird thing was that sometimes after switching off the amp, there were some sparks near one of the rectifiers.
Made some big resolution photos of the amps guts and tries to photoshop them together, that did not go so well but the photo is here:
http://mote.planet.ee/weconic/weconic_vx-4260.jpg
At the moment I dont know what to do next.
Found german site which has photos of the same amps guts:
An externally hosted image should be here but it was not working when we last tested it.
I see that someone has tried to repair my amp before and I see that output transistors are different, on german site photo they have metal back but my amp has plastic back transistors (2SD998, 2SB778). Using wrong replacement could cause something like this?
Attachments
Last edited:
Post the DC voltage on all of the pins of the 4558.
Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
Check the solder joints of the rectifiers you mentioned sparking, you will need to resolder those.
Pin 1: 1.54
Pin 2: 9.86
Pin 3: 5.58
Pin 4: 0
Pin 5: 9.26
Pin 6: 4.87
Pin 7: 9.88
Pin 8:10.53
Isnt pin 4 supposed to have -10.53V on it?
Pin 2: 9.86
Pin 3: 5.58
Pin 4: 0
Pin 5: 9.26
Pin 6: 4.87
Pin 7: 9.88
Pin 8:10.53
Isnt pin 4 supposed to have -10.53V on it?
Pin 4 is likely on the primary side of the power supply where there is no negative voltage. Pin 4 would be directly connected to the amp's main ground terminal.
Follow the circuit back from pin 5. What's driving that pin?
Does it come from a thermistor or from the audio amplifier section of the amp?
Follow the circuit back from pin 5. What's driving that pin?
Does it come from a thermistor or from the audio amplifier section of the amp?
Pin 5 goes to Q2 (A1266) center leg, first leg of that transistor is connected to leg 12 of TL494 and to the same KIA4558 8th pin. Third leg of Q2 is connected through diode and resistors to audio sections Q221 (C3198L) center leg.
Do Q121, Q221, Q321 and Q421 have their collectors connected together?
If so, reconnect the diodes and anything else that you've disconnected and remove the transistors listed above one at a time to see which channel is causing the amp to go into protect mode.
If so, reconnect the diodes and anything else that you've disconnected and remove the transistors listed above one at a time to see which channel is causing the amp to go into protect mode.
Their collectors are connected and base and emitter are connected to emitter resistors.
Ended up removing them all and still protection mode triggers.
Ended up removing them all and still protection mode triggers.
A transistor in the location of Q2 rarely fails but it may have here. Try removing it. If it still goes into protect ode, post the voltages on the 4558 again.
Removed Q2, amp does not go into protection but the transistor seems fine. hfe=150, resistances between legs are also like they should be.
What about Q1? It is also connected to Q2.
What about Q1? It is also connected to Q2.
Q2s third leg is connected through a resistor to Q1s center leg. The other legs of Q1 are connected to series of diodes and resistors seen on the photo attached to my first post in this thread.
If you leave Q1 out and reinstall Q2 and the 4 transistors in the audio section. Does it power up and produce audio?
If so, follow back all circuit paths that can drive the base of Q1 and eliminate each one to determine which one is driving Q1 on. Reinstall Q1 when you start trying to eliminate what's driving it.
If so, follow back all circuit paths that can drive the base of Q1 and eliminate each one to determine which one is driving Q1 on. Reinstall Q1 when you start trying to eliminate what's driving it.
With Q1 out of the circuit and the 4 transistors from audio section reinstalled amp does not go to protection and produces audio.
Q1 is connected to Q3 and Q4. Q3 and Q4 are connected to power supply FETs gate resistors. Various combinations with Q1 in and Q3 or Q4 out all end up throwing amp into protection mode.
4 transistors from audio section are identical to Q1. To eliminate the doubt that Q1 could be faulty I removed diode which connected 4 audio section transistors to Q2 and switched one of them to Q1. Still protection mode.
Traced Q1s connections further and found out that one connection goes through diodes, capacitors and jumpers to audio section. The trace makes two connections through small resistors (R163, R263) to outputs of two of the channels and continues to emitter resistors and makes two connections there, also through small resistors (R363, R463). I removed one of the jumpers (J110) and reinstalled all of the other components which I had removed. Amp powers up without entering protection mode. Did not try if it produces audio but I bet it does.
So what is that all about?
Q1 is connected to Q3 and Q4. Q3 and Q4 are connected to power supply FETs gate resistors. Various combinations with Q1 in and Q3 or Q4 out all end up throwing amp into protection mode.
4 transistors from audio section are identical to Q1. To eliminate the doubt that Q1 could be faulty I removed diode which connected 4 audio section transistors to Q2 and switched one of them to Q1. Still protection mode.
Traced Q1s connections further and found out that one connection goes through diodes, capacitors and jumpers to audio section. The trace makes two connections through small resistors (R163, R263) to outputs of two of the channels and continues to emitter resistors and makes two connections there, also through small resistors (R363, R463). I removed one of the jumpers (J110) and reinstalled all of the other components which I had removed. Amp powers up without entering protection mode. Did not try if it produces audio but I bet it does.
So what is that all about?
I thought the 4 you pulled earlier were the ones connected across they emitter resistors. If they were not, they may have been the muting transistors.
If the ones that you disconnected last were across the emitter resistors, they are likely for over-current protection. They can cause the amp to go into protect mode if they're defective, if one of the the emitter resistors is out of tolerance or if there is a fault in one of the channels. Since the amp produces clean audio, it's likely either a defective over-current protection transistor or an emitter resistor that's out of tolerance.
If the ones that you disconnected last were across the emitter resistors, they are likely for over-current protection. They can cause the amp to go into protect mode if they're defective, if one of the the emitter resistors is out of tolerance or if there is a fault in one of the channels. Since the amp produces clean audio, it's likely either a defective over-current protection transistor or an emitter resistor that's out of tolerance.
Sorry, my english is not so good.
This last connection which I was talking about consists only of 4 resistors no transistors.
I added a photo to illustrate. Blue line is the route we were investigating earlier, consisting of Q2 and 4 other transistors.
Red line is the route which is disconnected at the moment.
Photo was taken earlier, the diode which is disconnected on the photo is at the moment in its original position.
This last connection which I was talking about consists only of 4 resistors no transistors.
I added a photo to illustrate. Blue line is the route we were investigating earlier, consisting of Q2 and 4 other transistors.
Red line is the route which is disconnected at the moment.
Photo was taken earlier, the diode which is disconnected on the photo is at the moment in its original position.
Attachments
Do any of the channels have any significant DC (more than 0.1v DC) across the speaker terminals?
If not, reinstall the jumper and disconnect the resistors one at a time to determine which channel is causing the problem.
If not, reinstall the jumper and disconnect the resistors one at a time to determine which channel is causing the problem.
2 channels have 0.00V across their speaker terminals. One channels has 0.02V and one has 0.15V across speaker terminals. That last channel is causing the amp to go into protection. Removed the resistor associated with that channel and protection wont trigger.
I don't think I've ever seen a DC offset circuit that would trip at 0.15v. I'm assuming that that's what this circuit is.
Which channel is this (300 series parts, 400 series parts...)?
Which channel is this (300 series parts, 400 series parts...)?
200 series parts.
Im assuming, if I just leave the resistor out, there is 99% chance that nothing bad will happen to the amp.
Somebody has already tried to fix this. By the looks of it all transistors of 1st and 2nd channel have been replaced or at least taken out of the circuit.
Im assuming, if I just leave the resistor out, there is 99% chance that nothing bad will happen to the amp.
Somebody has already tried to fix this. By the looks of it all transistors of 1st and 2nd channel have been replaced or at least taken out of the circuit.
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