Yes : Torroidy 500VA, 240V primary, dual 18V secondaries Cx: 10nF Cs: 150nF Rs: 7Ω / 7Ω
Maybe these ones ?
Cs 150nF
Cx 10nF
For the resistor :
Rs 7R
If not, what do you recommend?
Thx !
Cx 10nF -->OK (871-B32529C3103K189)
Cs should be 150nF not 6.8nF....??? I don't understood (871-B32529C3682J289)
Cx 10nF -->OK (871-B32529C3103K189)
Cs should be 150nF not 6.8nF....??? I don't understood (871-B32529C3682J289)
There are a great number of parts to choose from that have the recommended capacitance and physical size ... however... if you go by Mark Johnson's words, there is one characteristic he finds worth mentioning.
Page 7 in the attached document - 'Guidelines for selecting CRC snubber components'.
If you're able (and willing) to go through the spec sheets and pick parts using that recommendation, then you're better at it than I am.
If that's all Greek to you (HA!) like it is to me ... I'd personally pick one of the parts previously mentioned and know that it will work properly. Hint: the parts that I and 6L6 listed are parts that Mark lists in the BoM for the Quasimodo jig. Thus, they are the parts that I personally put in my Quasimodo jig and in my snubbers. I find both 6L6 and Mark to be very reliable in providing excellent recommendations.
Page 7 in the attached document - 'Guidelines for selecting CRC snubber components'.
If you're able (and willing) to go through the spec sheets and pick parts using that recommendation, then you're better at it than I am.
If that's all Greek to you (HA!) like it is to me ... I'd personally pick one of the parts previously mentioned and know that it will work properly. Hint: the parts that I and 6L6 listed are parts that Mark lists in the BoM for the Quasimodo jig. Thus, they are the parts that I personally put in my Quasimodo jig and in my snubbers. I find both 6L6 and Mark to be very reliable in providing excellent recommendations.
Check post # 1,358 of the Quasimodo thread. It shows you exactly how to calculate the amount of power dissipated in each snubbing resistor. I personally have always found that 0.6 Watt resistors were sufficient to snub every one of the solid state amps I built. I perform the calculations and the answer is always: Your Snubbing Resistor Dissipates XXXX Watts, where XXXX is a number that turns out to be waaaay less than 0.6. Always. Every time; for the solid state amps I've built. And I love extra safety margin so I spend the extra pennies to get 0.6 watt resistors, and I sleep soundly.
Suitable resistor types, sold at Mouser, include (TE Connectivity series LR1F) , (Vishay MRS25) , (Vishay MBB02) , (Yaego MF0207) , (Yaego FM0207) .
All of those have body diameter = 2.5 mm , body length = 6.5 mm . Some are very slightly smaller but not a lot smaller, since they do have to dissipate 0.6 watts to meet their own specs.
Hi there. A question for this thread: I'm trying to narrow down where some problems might be occurring. I have built a power supply consisting of transformer, recifiers and the filter board. With no amplifier boards connected I am reading 25v DC plus and minus. Everything seems to be fine. However when I connect either Aleph J or F6 to it, I'm either burning fuses or my mosfets are like immediately at 200 degrees F and starting to smoke. I have checked and rechecked and even rebuilt my amp boards in the case of the F6. Is a reading of 25v DC (with no amp circuit connected) enough to prove that nothing is wrong with my power supply? Or is there something else I should check before I can conclusively say that its not my my PSU? (I don't have a dim bulb tester. I'm getting one.) Thank you for any help!
It's a fairly straightforward process to rule out the PS. Do you have a pair of power resistors, say 25 ohms? They should be about 25W. And perhaps on a heat sink. Disconnect PS from boards. The connect one to each power supply rail and the other ends connect to each other (The center or common) Then measure across each with your DMM, where each one will be less than the unloaded voltage. When keeping your DMM at the center between resistors, one will be +24V to 25V, the other -24V to -25V. IF that checks out, and the voltage remains stable for some time, or until the resistors get too hot, the power supply is good. I think one thing that might cause what you describe is a power FET contacting the heat sink, as in a bad insulator. Have you checked this?
@pestoman Since you are having no problems without a load, and voltage measures what you are expecting, it’s reasonable to think that the PSU is ok.
However… the questions posed by @roger57 are good, and if you can do his suggested troubleshooting, please do.
That said, go to the F6 or Aleph J thread (whichever you are trying to hook up) and post a bunch of well-lit, in-focus photos there so we can have the hive mind start the debugging process. Do this as soon as you can.
However… the questions posed by @roger57 are good, and if you can do his suggested troubleshooting, please do.
That said, go to the F6 or Aleph J thread (whichever you are trying to hook up) and post a bunch of well-lit, in-focus photos there so we can have the hive mind start the debugging process. Do this as soon as you can.
I would like to highlight the importance of bulb tester, it will tell you if there is a short somewhere, it will save you money of all the MOSFET's that smoke due to short. Do a resistance check If all joints are ok(board and non-board) , check between mosfet leads and chassis to make sure there is no short.
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Hi, I will soon start assembling my Aleph J.
- Is the switch in a correct position ?
- Are the 18V outputs of the transformer in the right place on the PSU? Can the 2 black wires be interchanged? Blues too?
- Is the speaker protector circuit properly connected?
1) The switch is good.
2) the secondaries look good. I assume one secondary is black-black, the other secondary is blue blue. You generally want to wire them in phase with one another.
Set a multimeter to ohms. if the circuit is closed (you get an ohm reading) between two wires, then you have the wires for one secondary. If you get an open reading, then you have the wrong two wires.
Typically you have four wires in a row. Say Black1-Black2 Blue3-Blue4. Black 1 would be the start of one seconary, blue 3 would be the start of the second. This will help you get them in phase. The way you have the lines drawn should put them in phase.
3) I do not know about the DC delay as I like to live my life in fear. The two lines would read around 18vac with a voltmeter.
2) the secondaries look good. I assume one secondary is black-black, the other secondary is blue blue. You generally want to wire them in phase with one another.
Set a multimeter to ohms. if the circuit is closed (you get an ohm reading) between two wires, then you have the wires for one secondary. If you get an open reading, then you have the wrong two wires.
Typically you have four wires in a row. Say Black1-Black2 Blue3-Blue4. Black 1 would be the start of one seconary, blue 3 would be the start of the second. This will help you get them in phase. The way you have the lines drawn should put them in phase.
3) I do not know about the DC delay as I like to live my life in fear. The two lines would read around 18vac with a voltmeter.