Krell KSA 50 PCB

[Jan Dupont]

Pavel

That was my next question

I will continue the layout using a 10*30 mm aluminium "prism".

 

[Upupa Epops]

Continue : Basic lengh of this PCB is for two transistors and next lengts are multiples of basic ( PCB must have cutoffs for transistors ). Standard prism is made by aluminium or copper, high end version with supersound by goldplated copper .

 

[Jan Dupont]

Pavel

I'm not quite sure what you meen by "( PCB must have cutoffs for transistors )"
Do you meen cutoffs for each set of two transistors???

 

[Upupa Epops]

Yes, sure. PCB is screwed to prism on the beggining of prism, next is cutoff for two transistor and on the end again screwing to prism. This is " basic length " and it is multipled n-times. Across the screw come current from PCB to prism. Is this clear now ?

 

[Jan Dupont]

It should be clear now

 

[Upupa Epops]

P.S. : Current from prism to transistors come directly to bootom side of transistor, not to colector pin, so you don't need feeder on PCB.

 

[Jan Dupont]

Thanks

 

[Upupa Epops]

P.P.S. : Make this PCB common for both polarity - who will can, may this cut on axis ( on output " line " ). This solution have advantage, 'cos you can try it " burn " outside of chassis, free on table.

 

[Jan Dupont]

Pavel

I understand the part about common PCB polarity layout
However this part I don't get "who will can, may this cut on axis ( on output " line " )"

 

[Upupa Epops]

My last ( I hope ) notice : In the prism must be also hole, inside which is insulated screw, by which is prism screwed to heatsink. Best place for it is common coaxial hole ( on PCB and prism ) on beginning and end of basic lengh, beside hole for " current connection ".

 

[Jan Dupont]

Pavel

I understand the part about common PCB polarity layout
However this part I don't get "who will can, may this cut on axis ( on output " line " )"

 

[wim]

If anybody has problems to get the transistors wich are not from Onsemi (2SC3955, 2SC2240 and 2SA970, i found a supplyer in Holland (NEDIS). These transistors are cheap.

In the partlist are resistorvalues that can't be bought (shops dont sell them. Can i take the closest value for it?

Onother question, what are ZD101 and ZD102 (ZD9841)? google dont know them, and my local internetstores dont know them too.

Are there substitutes?

 

[Jan Dupont]

win

Sounds fine... Lets have some prices

I have specified the original resistor values, which of some are quite special.... If you buy a handful of resistors at the nearest desired value, you might be able to find some very near the stated value using a standard multimeter
However 100R or 101R doesn't make a difference, however you will get a better amp if you match all resistors

As I recall, the Zeners are 24V (is that right??)..... Get some standard 2W zener, and it should work perfectly...

 

[Jan Dupont]

Here is an Output Board that should satisfy most
Later will come 2 more in different layouts
One will be after Pavel's design suggestions

 

[wim]

Prices from the "not Onsemi" transitors, inclusive VAT.
Dealer is Nedis (internatioal dealer) Prices in Euro from website Nedis Netherlands:

2SC2240:
quantum 5 25 40
price each 0,29 0,18 0,12

2SA970:
quantum 10 30 60
price each 0,17 0,1 0,07

2SC3955:
quotum 2 18 35
price each 0,75 0,51 0,36

 

[Elso Kwak]

Nedis

Prices from the "not Onsemi" transitors, inclusive VAT.
Dealer is Nedis (internatioal dealer) Prices in Euro from website Nedis Netherlands:

Hi Wim, I don't want to spoil the fun but Nedis is notorious for delevering faked parts and second sourced parts......Or even no-name parts.
BEWARE!

 

[wim]

Thanks Elso, for this intresting info!!!

I did not know that.

No way tot see or the parts are real or fake i gues?? Than i drop mines in the ashtray and look for anoter supplier.

 

[Upupa Epops]

2 SC 3955 is not " industry standard ", is not made by many firms, only by Sanyo.

 

[Elso Kwak]

Fake or Real?

Thanks Elso, for this intresting info!!!

I did not know that.

No way tot see or the parts are real or fake i gues?? Than i drop mines in the ashtray and look for anoter supplier.

Hi Wim, I dunno but I will scan some real ones.
Don't laugh Jocko! [inside joke]

 

[wim]

Thanks Elso, later today i will have a look at my transistors and tell the results.

I know for now that they did not deliver second cource parts, on the orderbillthey write:

2SC3955-SAN,
2SC2240-TOS
2SA970-MBR

Tiill later on