As miksi and me correctly found out R19, R20 installed are standard Yageo SMD2010 resistors and not Vishay as I specified to the producer of PCB. Vishay resistors are current pulse proved type and Yageo are obviously not.
R19, R20 faces current pulse at the power on sequence when C14, C15 are empty of charge. This happens only when SMPS400A180 is used since this power supply starts with full +/-45 V voltage at the moment when TL494 starts to oscillate mosfets on primary. DC voltage on secondary goes from zero to max in a matter of micro seconds so the current pulse to charge C14, C15 is higher than R19, R20 resistors can withstand.
In classic linear power supply rising of the secondary smoothed DC voltage is slow, also the charge current for C14, C15, so there should be no problem with R19, R20.
R19, R20 faces current pulse at the power on sequence when C14, C15 are empty of charge. This happens only when SMPS400A180 is used since this power supply starts with full +/-45 V voltage at the moment when TL494 starts to oscillate mosfets on primary. DC voltage on secondary goes from zero to max in a matter of micro seconds so the current pulse to charge C14, C15 is higher than R19, R20 resistors can withstand.
In classic linear power supply rising of the secondary smoothed DC voltage is slow, also the charge current for C14, C15, so there should be no problem with R19, R20.
Shipping the caps is expensive (I am already doing it for a couple people), and there is not much agreement on the caps anyway ...
Seriously, anyone else can organize a GB for capacitors, why should LC have to do all the work?
Because of the following post by LC:
"Since we are in vendors forum I'll go full blast on VSSA marketing and therefore promote new Alu-chassis made especially for VSSA and SMPS400A180 modules in dual mono configuration. Here are some pictures of a second VSSA amplifier assembled, from now on with official commercial name Lakner Oné The most transparent amplifier."
Let all the Elcos and MKTs be made available on his site from where they can be ordered easily. Actually, he can now offer all the parts for DIYer's and Fully assembled and tested Amps for those who like it that way.
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You have a point, I'm still looking at this the old way not as a business. My apologies, and I will shut up now... on this subject, anyway... well, for a little while at least...
... oh, forget that, I'm having too much fun to stop now...
Hi gannaji,
I agree with you, it would be nice to have some sort of VSSA shop, with best and cheapest parts, and cheapest shipping.
But I cannot understand how people believe that it will be cheaper to buy some (quite heavy) parts from Europe or America, including shipping back in Asia where they are actually produced (and accordingly imported from, with all the taxes/VAT/customs/etc included ).
Don't you agree it will be cheaper to organize local "group buy"? or my logic is failing somehow, perhaps...
I agree with you, it would be nice to have some sort of VSSA shop, with best and cheapest parts, and cheapest shipping.
But I cannot understand how people believe that it will be cheaper to buy some (quite heavy) parts from Europe or America, including shipping back in Asia where they are actually produced (and accordingly imported from, with all the taxes/VAT/customs/etc included ).
Don't you agree it will be cheaper to organize local "group buy"? or my logic is failing somehow, perhaps...
R19 and R20 are easy to replace even with leaded resistors soldered between the two electrolytics positive legs under the PCB.. , there is plenty of space in there for a 1W resistor.You can even replace the 10 ohms SMD with two 20ohms SMD`s one on top the other in paralel.
LC..
What type resistors were used in positions R5 and R6, Their properties are very important to sound .
Thank you..
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On Hypex datasheet, it was mentioned that output DC voltage is proportional to the mains input voltage which is specified at 180V AC min. DC power apears 3-4 sec after switch on and does that very fast so maybe soft start with prolonged hold on time >4sec would be beneficial, but now am inclined to replace R19 and R20 SMDs with something more resilient to impulse currents like ivanlukic did. There is plenty of space indeed. Those already replaced are combination of 4 pcs 10ohm 1206 10+10||10+10.
R5 and R6 are probably the same Yageo type SMDs as R19 and R20 judging by the type of letters on them. I have some 1k Vishay Dales CMF series laying around but for now I want to resolve ¨current¨ problems. Replacing R5 and R6 would be a part of further tweaking...it is (almost) never ending story for DIYers.
LC thank you for grounding schematic.
R5 and R6 are probably the same Yageo type SMDs as R19 and R20 judging by the type of letters on them. I have some 1k Vishay Dales CMF series laying around but for now I want to resolve ¨current¨ problems. Replacing R5 and R6 would be a part of further tweaking...it is (almost) never ending story for DIYers.
LC thank you for grounding schematic.
Thanks,
but what we need is :
- 2200µf 6,3v
- 1000µf 50v.
Still not available, even at headfishop. Panasonic FC caps are so widely available, we just have to pick them up
Mouser has both FG Nichicons now.
2200µf 6,3v is found in the mounting note provided by LC.
I've seen recently that Mouser has re-stocked 1000µf 50V FG Cap, so both are now available, but now epcos (10µf 63v with 15mm and the right footprint is not that simple to find either) are no longer available. Shipping costs are likely to be greater than capacitors price... the whole cap set is available at digkey : one shot order, on shot shipping cost.
There is no MKT cap available at Mouser that fit the VSSA footprint...
I've seen recently that Mouser has re-stocked 1000µf 50V FG Cap, so both are now available, but now epcos (10µf 63v with 15mm and the right footprint is not that simple to find either) are no longer available. Shipping costs are likely to be greater than capacitors price... the whole cap set is available at digkey : one shot order, on shot shipping cost.
There is no MKT cap available at Mouser that fit the VSSA footprint...