can the PS use a too-high secondary transformer?
i have some great toroidal transormers kicking around but they have
45-50V secondaries. is there some way to use these for the ucd400s?
i have seen some PSUs thta used a zener to drop a few volts, but don't
know how much can be done that way.
andrew
i have some great toroidal transormers kicking around but they have
45-50V secondaries. is there some way to use these for the ucd400s?
i have seen some PSUs thta used a zener to drop a few volts, but don't
know how much can be done that way.
andrew
Or if you're not comfortable attempting that you can always drop a few volts using power rectifiers in series, that'd take several of them though.
Had you considered zener + a pass transistor? Basically, regulate it.
Salut,
Chris
Had you considered zener + a pass transistor? Basically, regulate it.
Salut,
Chris
Bruno or JP
UCD 400AD
Is it possible to run the above module with 40VDC? I have some torroids 300VA 27.5V. Want to use them as monoblocks.
If yes, is there any down side to sound quality other than decreased output?
Thanks
UCD 400AD
Is it possible to run the above module with 40VDC? I have some torroids 300VA 27.5V. Want to use them as monoblocks.
If yes, is there any down side to sound quality other than decreased output?
Thanks
40Vdc will be no problem, sonic performance will be the same.
However the charge time of the bootstrap capacitor will be increased so you can hear some small popping noise when the amp switchs on.
For the rest it will work ok!
Jan-Peter
However the charge time of the bootstrap capacitor will be increased so you can hear some small popping noise when the amp switchs on.
For the rest it will work ok!
Jan-Peter
damping factor
Hey, I was just wondering what the damping factor on these modules is. thanks.
Hey, I was just wondering what the damping factor on these modules is. thanks.
Bruno or JP
UCD 400AD
While looking down at the top side of the module, "T" sink at top and input/output connectors at the bottom, what are the values & watt rating for the two top side resistors located at the bottom right side of module?
Thanks
UCD 400AD
While looking down at the top side of the module, "T" sink at top and input/output connectors at the bottom, what are the values & watt rating for the two top side resistors located at the bottom right side of module?
Thanks
What is the purpose of D25 on the UcD400 pcb?Unfortulately, I broke the diode with my tweezer when replacing C26. Should I order a new module?
Thanks.
Thanks.
If you mean polyswitch also known as NTC thermistor then yes. They are only suitable for class-a amps or PA amps where constant, small dynamic range material is played.
The diode is in the current protection section, and must be placed for prper working. This diode is a 12V zener. The anode is connected to minus power rail.
Size is SOD110.
Regards,
Jan-Peter
tomahack said:
🙂 Relax, this is BZX284-C12 cost about $.05.
Yes i do. I take NTC from the ATX SMPS (no marked just a 2 pin green tablet, intensive soldering efforts help you to clean green compound&pins) and put this into the PTC_for_Degaussing_TV (3 pin black box with two tablet inside, as a heater one, and other is a PTC as switcher) instead the PTC tablet. Resume -very neat 3 pin softstart device. So when we turning ON the trafo, then NTC are cold and have 5ohm resistance, over 10 sec NTC come warmer and .3Ohm now. But i'll try to buy 10-20Ohm NTC for this purpose, because trafo primary have 2.5Ohm, and how much effectively it will work, i don't know so far.
Attachments
Everything working fine now...thanks a lot.
I replaced coupling caps with polypropylene 2,7uF, change 22uf 50V and 470uF for Panasonic FC's.
I replaced coupling caps with polypropylene 2,7uF, change 22uf 50V and 470uF for Panasonic FC's.
I have an old version of UCD400 and recent I bought the new version. Can I bridge them together?
Not quite a UCD question, but here goes:
I have just "finished" my UCD400 dual mono amp and now find that the transformers buzz extremely loudly...
I have tried temporarily adding an LC Audio DC filter and this *reduces* the buzzing a little, but not completely. Now the peculiar thing is that the buzzing seems to be quite a bit less if I only have one of the torroids wired up instead of both of them...
Are there any other things to consider when trying to remove torroid hum?
I have tried each torroid on it's own and both hum quite a lot without a DC filter, but are somewhat quieter with the filter. Both together are quite loud both with and without the filter. The torroids are perhaps a few cm apart in a single case with the leads facing each other, moving them around very slightly doesn't make any obvious difference.
Also there is no buzz while the softstart is working, the humm only starts once the softstart relay clicks out. I read here that the loud on the secondaries can influence hum - in my case I have a dual bridge of MBR10100 and some caps (no bypassing) - is this likely to be contributing to my problems?
http://www.diyaudio.com/forums/showthread.php?s=&threadid=2080
The annoying thing is that whilst all my other amps have hummed a little, adding in the DC blocking circuit has so far stopped the problem. This tends to suggest that either these torroids are both rather useless, or it's something to do with the new style of powersupply I am using which is triggering it?
Can someone please help choosing parts to build a copy of the LC Audio DC filter (the one I am using is borrowed from another amp). I clearly need just a tranzil and a capacitor, but I'm not sure what are sensible specs? The LCAudio diagram is here, but the choice of capacitor seems very large?
http://www.lcaudio.com/index.php?page=12
What ripple current do I need for a my capacitor? How do you size a tranzil appropriately?
Thanks
I have just "finished" my UCD400 dual mono amp and now find that the transformers buzz extremely loudly...
I have tried temporarily adding an LC Audio DC filter and this *reduces* the buzzing a little, but not completely. Now the peculiar thing is that the buzzing seems to be quite a bit less if I only have one of the torroids wired up instead of both of them...
Are there any other things to consider when trying to remove torroid hum?
I have tried each torroid on it's own and both hum quite a lot without a DC filter, but are somewhat quieter with the filter. Both together are quite loud both with and without the filter. The torroids are perhaps a few cm apart in a single case with the leads facing each other, moving them around very slightly doesn't make any obvious difference.
Also there is no buzz while the softstart is working, the humm only starts once the softstart relay clicks out. I read here that the loud on the secondaries can influence hum - in my case I have a dual bridge of MBR10100 and some caps (no bypassing) - is this likely to be contributing to my problems?
http://www.diyaudio.com/forums/showthread.php?s=&threadid=2080
The annoying thing is that whilst all my other amps have hummed a little, adding in the DC blocking circuit has so far stopped the problem. This tends to suggest that either these torroids are both rather useless, or it's something to do with the new style of powersupply I am using which is triggering it?
Can someone please help choosing parts to build a copy of the LC Audio DC filter (the one I am using is borrowed from another amp). I clearly need just a tranzil and a capacitor, but I'm not sure what are sensible specs? The LCAudio diagram is here, but the choice of capacitor seems very large?
http://www.lcaudio.com/index.php?page=12
What ripple current do I need for a my capacitor? How do you size a tranzil appropriately?
Thanks
Hi,
Wouldn't think of helping ya copy LC's dc filter thingy.
I think the best solution if you have a DC problem at your mains is to get yourself an isolation transformer. If you hunt around plitron's website in some "secret" forum section they offer a 2000VA isolation xformer for ~200$. That will balance the mains and it'll be DC free, I don't think you can beat that solution.
To comment on your supply from what I know of it, those are schottky diodes you're using. Definitely bypass them, they aren't soft recoveries.. even if they were I'd bypass them anyway. I dont' think it'll help your hum issue though.
You could try moving them around more than a little, stack them on top of one another maybe, turn them 180 or 359... see what happens.
The rounded core of Jan-Peter's old toroidal xformers would help reduce hum by keeping the windings tighter to it, also epoxy potted ones like from plitron will help keep the wires still, as would possibly the addition of a magnetic shield around it, mu-metal, that's if you can get them to do it without doubling the price, they wouldn't do it for me.
Actually I wasn't impressed with them, an extra 50% for the shielding because they haven't had to make one with it yet (that is it's not in stock) so it's extra paper work, but they have to "custom" make it anyway because the plain jane ones aren't stock either, and a 4 to 5 week lead time. I wasn't going to pay an extra 75$ for a metal band.
Don't even ask them about their narrow band units.. apparently it's not for us mere mortals. Seems like great stuff if they can ever do it at a reasonable cost though.
Cheers,
Chris
Wouldn't think of helping ya copy LC's dc filter thingy.
I think the best solution if you have a DC problem at your mains is to get yourself an isolation transformer. If you hunt around plitron's website in some "secret" forum section they offer a 2000VA isolation xformer for ~200$. That will balance the mains and it'll be DC free, I don't think you can beat that solution.
To comment on your supply from what I know of it, those are schottky diodes you're using. Definitely bypass them, they aren't soft recoveries.. even if they were I'd bypass them anyway. I dont' think it'll help your hum issue though.
You could try moving them around more than a little, stack them on top of one another maybe, turn them 180 or 359... see what happens.
The rounded core of Jan-Peter's old toroidal xformers would help reduce hum by keeping the windings tighter to it, also epoxy potted ones like from plitron will help keep the wires still, as would possibly the addition of a magnetic shield around it, mu-metal, that's if you can get them to do it without doubling the price, they wouldn't do it for me.
Actually I wasn't impressed with them, an extra 50% for the shielding because they haven't had to make one with it yet (that is it's not in stock) so it's extra paper work, but they have to "custom" make it anyway because the plain jane ones aren't stock either, and a 4 to 5 week lead time. I wasn't going to pay an extra 75$ for a metal band.
Don't even ask them about their narrow band units.. apparently it's not for us mere mortals. Seems like great stuff if they can ever do it at a reasonable cost though.
Cheers,
Chris