intense-tavda said:
Anytime you see a burned gate resistor, you are looking at a
blown Mosfet. Anytime you can measure voltage across a gate
resistor, you have a blown Mosfet.
😎
So I removed the mosfets, also the ones that got hot, and I put the pcb back to the psu, I did put on my amplifier and the pcb started to burn. On the side where the three mosfets were wich get hot, the connectionstripes burned through. So now I have to buy a new pcb with new parts I think.
Teake
Teake
aleph5 help
Hello there!
I wil put a new pcb together, with all new parts.
Do the condensators silver mica's 10PF, 680PF and the WIMA MKP10 0,047UF have polarity? And in what order do I put the pcb together, the mosfets last?
Teake.
Hello there!
I wil put a new pcb together, with all new parts.
Do the condensators silver mica's 10PF, 680PF and the WIMA MKP10 0,047UF have polarity? And in what order do I put the pcb together, the mosfets last?
Teake.
The Mica condensators have no parity.
When you put together to board, do it "by height of components", that means first resistors etc. That way you have room to solder and to place the components.
Leave the Mosfets for last, and use a anti static device before handling those.
After mounting everything without the mosfets, check the DC voltages as defined in the servicemanual by Mr. Nelson.
Then mount the 9610 fets, and check AC reactions.
Then mount the power mosfets AND mount to a heatsink.
Power on and pray..... (or use a light bulb in the power supply, as advised by Netlist)
Greetings and good luck,
Harry
When you put together to board, do it "by height of components", that means first resistors etc. That way you have room to solder and to place the components.
Leave the Mosfets for last, and use a anti static device before handling those.
After mounting everything without the mosfets, check the DC voltages as defined in the servicemanual by Mr. Nelson.
Then mount the 9610 fets, and check AC reactions.
Then mount the power mosfets AND mount to a heatsink.
Power on and pray..... (or use a light bulb in the power supply, as advised by Netlist)
Greetings and good luck,
Harry
Hi there
I made my new pcb and will now put it on the psu. Now i have some grounding questions. First time I put, from the pcb (KKpcb),
two grounding wires, one to the rca socket and one to floating ground, then i connected the ground from the xlr to the rca with a wire, what i didnot do is put a wire between the rca/xlr and put it to floating ground. Is it nessecery to do this. So the middle ground in the scedule from KK from out the pcb I did put it straight to the rca socket, or do i have to put it only on the ground from the wire, wich i don,t have, I only connected ungrounded teflon coated wire. See KK scedule. Will I get some shorting problems this way?
I made my new pcb and will now put it on the psu. Now i have some grounding questions. First time I put, from the pcb (KKpcb),
two grounding wires, one to the rca socket and one to floating ground, then i connected the ground from the xlr to the rca with a wire, what i didnot do is put a wire between the rca/xlr and put it to floating ground. Is it nessecery to do this. So the middle ground in the scedule from KK from out the pcb I did put it straight to the rca socket, or do i have to put it only on the ground from the wire, wich i don,t have, I only connected ungrounded teflon coated wire. See KK scedule. Will I get some shorting problems this way?
Hi Teake,
The circuit has normally three ground connections:
-One from the RCA ground and XLR ground to the central (non)floating ground. Purpose: ground the signal, AND deroute all quirks that the cable shield picked up straight to the ground, and not along the PCB board.
-One from the (non)floating ground to the PCB. Purpose: making sure the signal is in the middle of the plus and minus voltage, so swings can be accepted in both directories.
-The third wire in the schematics is connected from PCB to internal cable. Purpose: only to ground only the shield from the internal cabling. This shield is NOT connected to the connectors.
I myself only installed the XLR connector. Remember the jumper you have to place on the XLR connector when using the RCA connector. Some people use a switch to connect the minus from the balanced input to ground when using RCA. Up to you.
Always connect via the central (non)floating ground, not from-to via the PCB. This way immunity to RF problems is much larger.
Greetings,
Harry.
The circuit has normally three ground connections:
-One from the RCA ground and XLR ground to the central (non)floating ground. Purpose: ground the signal, AND deroute all quirks that the cable shield picked up straight to the ground, and not along the PCB board.
-One from the (non)floating ground to the PCB. Purpose: making sure the signal is in the middle of the plus and minus voltage, so swings can be accepted in both directories.
-The third wire in the schematics is connected from PCB to internal cable. Purpose: only to ground only the shield from the internal cabling. This shield is NOT connected to the connectors.
I myself only installed the XLR connector. Remember the jumper you have to place on the XLR connector when using the RCA connector. Some people use a switch to connect the minus from the balanced input to ground when using RCA. Up to you.
Always connect via the central (non)floating ground, not from-to via the PCB. This way immunity to RF problems is much larger.
Greetings,
Harry.
Thanks Harry
But I have no shielded cable to rca or xlr only teflon coated silver coated copper wire. So how will I connect the third ground cable, or can I leave it away? Greetings Teake.
But I have no shielded cable to rca or xlr only teflon coated silver coated copper wire. So how will I connect the third ground cable, or can I leave it away? Greetings Teake.
Hi Teake,
You should have some sort of shielding on your internal cabling. When you use unshielded teflon coated cable, you could do the same as I did, and twist it together "Kimber Cable" style.
As said, the only function for the third connection is the shielding of the internal cabling. So when you just twist these together you would not need this connection.
Greetings, Harry
You should have some sort of shielding on your internal cabling. When you use unshielded teflon coated cable, you could do the same as I did, and twist it together "Kimber Cable" style.
As said, the only function for the third connection is the shielding of the internal cabling. So when you just twist these together you would not need this connection.
Greetings, Harry
Hi Harry
How twist these together, the rcawire and the gnd, without connecting to rcagnd? Greetings teake
How twist these together, the rcawire and the gnd, without connecting to rcagnd? Greetings teake
Correct!
When you want to use it that way make sure that the signal wire is as far away as possible from the transformer.
You can either use one ground wire and "roll" it or use two ground wires and do it Kimber style.
Just be on the lookout for the pickup of hum out of the power supply.
Have Fun, Harry
When you want to use it that way make sure that the signal wire is as far away as possible from the transformer.
You can either use one ground wire and "roll" it or use two ground wires and do it Kimber style.
Just be on the lookout for the pickup of hum out of the power supply.
Have Fun, Harry
Thanks Harry
I did it your way and put the pcb with the mosfets to the heatsink, connected everything and there was again nothing. mosfets did not get hot. I measured the mosfets, and G to D I measured 32,8V for the first three mosfets, and G to S I measured 3,3V for the first three mosfets, for the other three I measured 36,4V on G to D and 0,0V from G to S. What.s happening, it did not burn. It's an new pcb, with al new parts, I soldered everything corect and checked it several times, and it looked good to me, but I won.t give up, I will survive, Greetings Teake, I still have fun.
I did it your way and put the pcb with the mosfets to the heatsink, connected everything and there was again nothing. mosfets did not get hot. I measured the mosfets, and G to D I measured 32,8V for the first three mosfets, and G to S I measured 3,3V for the first three mosfets, for the other three I measured 36,4V on G to D and 0,0V from G to S. What.s happening, it did not burn. It's an new pcb, with al new parts, I soldered everything corect and checked it several times, and it looked good to me, but I won.t give up, I will survive, Greetings Teake, I still have fun.
No fire is better! 
I am a newby too (one Aleph, one pre and one DAC) so first lets check out the simple things:
I guess the most made mistakes with Kristians boards:
1. R17 should be 2K21 and not 221R
2. Mosfets drawing on the silkscreen are correct when mounting on the Backside, and not on the front
3. The heatsinks from the IRF9610 should be pointing to the topside of the board
4. When you use MPSA18 the flat sides should be pointing to the side of the boards
Gate Source on the first three mosfets should be 3,5 - 4,5 V, so that is about allright.
Did you mount 50W 8Ohm resistors on the output for testing?
Did you find your ac testsignal back on R114 (=R12) ?
Did you find 4-5Volts on R114? (=R12 on Kristian)
Greetings, Harry
I am a newby too (one Aleph, one pre and one DAC) so first lets check out the simple things:
I guess the most made mistakes with Kristians boards:
1. R17 should be 2K21 and not 221R
2. Mosfets drawing on the silkscreen are correct when mounting on the Backside, and not on the front
3. The heatsinks from the IRF9610 should be pointing to the topside of the board
4. When you use MPSA18 the flat sides should be pointing to the side of the boards
Gate Source on the first three mosfets should be 3,5 - 4,5 V, so that is about allright.
Did you mount 50W 8Ohm resistors on the output for testing?
Did you find your ac testsignal back on R114 (=R12) ?
Did you find 4-5Volts on R114? (=R12 on Kristian)
Greetings, Harry
Hi Harry
I had 3.3V on R12. The mosfets I connected with 4cm teflon coated silver wires to the pcb, from the pins of the mosfets to the back of the pcb, just on the same way as when I should put them straight to the back of the pcb. Greetings Teake
I had 3.3V on R12. The mosfets I connected with 4cm teflon coated silver wires to the pcb, from the pins of the mosfets to the back of the pcb, just on the same way as when I should put them straight to the back of the pcb. Greetings Teake
Hi there!
Is it possible that my problem is the heatsink isolation from the irf 9610. I did not do that. But I did put a heatsink on them. And now, when I try the amplifier out, I did not mount the pcb on the heatsink with some distenceparts and the heatsink of the irf 9610 is touching the amplifierchassis. Do I create a short? Is the irf9610 dead, or all irfs? I don,t know.
Thanks Teake.
Is it possible that my problem is the heatsink isolation from the irf 9610. I did not do that. But I did put a heatsink on them. And now, when I try the amplifier out, I did not mount the pcb on the heatsink with some distenceparts and the heatsink of the irf 9610 is touching the amplifierchassis. Do I create a short? Is the irf9610 dead, or all irfs? I don,t know.
Thanks Teake.
Hi Teake,
All mosfets mounted to the heatsink should have Mica isolators, and use non-conducting "poo".
The IRF9610 do not need heatsinks, they run fine on their own within the Aleph 5.
When you did mount them on the heatsink unisolated, I am not sure whether they are still alive.
If you check passdiy.com you can find a simple method to match mosfets, using a powersupply and resistors. I would use this method to check the Mosfets.
Maybe somebody else from the forum has a better method?
Greetings, Harry.
All mosfets mounted to the heatsink should have Mica isolators, and use non-conducting "poo".
The IRF9610 do not need heatsinks, they run fine on their own within the Aleph 5.
When you did mount them on the heatsink unisolated, I am not sure whether they are still alive.
If you check passdiy.com you can find a simple method to match mosfets, using a powersupply and resistors. I would use this method to check the Mosfets.
Maybe somebody else from the forum has a better method?
Greetings, Harry.
Remember:
On Kristians boards the power mosfets are drawn mounted on the backside of the board, the IRF9610 are drawn mounted on the front of the board.
On Kristians boards the power mosfets are drawn mounted on the backside of the board, the IRF9610 are drawn mounted on the front of the board.
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