Upgraded Single Board PCM1794 NOS DDDAC

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#181
emyeuoi (CCS x 2)
carlsor (CCS x 4)
juancho (CCS x 4)
crazyfrog (CCS x2)
mk57 (CCS x 8) + parts
SimonJ (CCS x 2) + parts
PET-240 CCS x 4 + parts
sterlingmck (CCS x 4) + parts
zz1969 (CCS x 8) + parts
kurand (CCS x 4) + parts
mbcoffman (CCS x 2) + parts
Myint67 (CSSx2)+ parts
tuyen (CCS x 8) + parts
Brumjam (CCS x 4) + parts
mr_whocares (CCS x 2) + parts
tods (CCS x 8) + parts
IanS1 (CCS x 4) + Parts
dwjames (CCS x 2) + parts
titus2002 (CCS x 8) + parts
Total CCS= 82
Parts = 70
 
#182
emyeuoi (CCS x 2)
carlsor (CCS x 4)
juancho (CCS x 4)
crazyfrog (CCS x2)
mk57 (CCS x 8) + parts
SimonJ (CCS x 2) + parts
PET-240 CCS x 4 + parts
sterlingmck (CCS x 4) + parts
zz1969 (CCS x 8) + parts
kurand (CCS x 4) + parts
mbcoffman (CCS x 2) + parts
Myint67 (CSSx2)+ parts
tuyen (CCS x 8) + parts
Brumjam (CCS x 4) + parts
mr_whocares (CCS x 2) + parts
tods (CCS x 8) + parts
IanS1 (CCS x 4) + Parts
dwjames (CCS x 2) + parts
titus2002 (CCS x 8) + parts
Chanh CCS x 24 + parts
Total CCS= 106
Parts = 94
 
#183
emyeuoi (x1)
PET-240 x2 + 2 set JFETS + 2 set Susumu
Myint67x 3, + 3set JFEct + 3set SuSumu
Juancho x2 + 2 sets JFETS + 2 sets Susumu
Sterlingmck x2 + 2 set JFETS + 2 set Susumu
BDL x1 + 1 set JFETS + 1 set Susumu
mbcoffman x1 + 1 set JFETS + 1 set Susumu
carlsor x1
naimster x2
kurand x1 + 1 set JFETS + 1 set Susumu
brettlb x1
SimonJ x1 + 1 set JFETS + 1 set Susumu
JanGr. (x1)
ed linssen x1 + 1set JFETS + 1 set Susumu (+ 2 sets of CCS parts )
tuyen x1 + 1 set JFETS + 1 set susumu
mr_whocares x1 + 1 set jfets + 1 set susumu
dwjames x1 + 1 set jfets + 1 set susumu

PCB= 23
Parts= 17
 
#184
emyeuoi (CCS x 2)
carlsor (CCS x 4)
juancho (CCS x 4)
crazyfrog (CCS x2)
mk57 (CCS x 8) + parts
SimonJ (CCS x 2) + parts
PET-240 CCS x 4 + parts
sterlingmck (CCS x 4) + parts
zz1969 (CCS x 8) + parts
kurand (CCS x 4) + parts
mbcoffman (CCS x 2) + parts
Myint67 (CSSx16) + Parts
tuyen (CCS x 8) + parts
Brumjam (CCS x 4) + parts
mr_whocares (CCS x 2) + parts
tods (CCS x 8) + parts
IanS1 (CCS x 4) + Parts
dwjames (CCS x 2) + parts
titus2002 (CCS x 8) + parts
Chanh CCS x 24 + parts
Total CCS= 120
Parts = 108
 
#185
CCS “Parts” Instructions and Clarification

The parts from me will consist of three (3) 2SK208 “O” SMD JFETs ($4.00USD). If you want the “R” version then you are on your own to get them. The CCS mini-boards will be sent to you by emyeuoi.

I will test each 2SK208 to determine what resistance is needed for them to operate at 0.40ma from a 2.4V source. From this I will recommend what Susumu SMD fixed resistor value is needed to work with a 500 ohm trimmer pot to achieve the needed resistance. You will have to obtain your own trimmer pot which can have the adjusting screw on top or off to the side depending on your DAC installation space requirements. A trimmer pot doesn’t fit well in a letter envelope. A 1K or 2K pot will also work if that is already what you have on hand. The measured voltage across the two "TP" test points can be used to determine the current through the CCS circuit. I will provide what voltage reading represents 0.40ma for the recommended Fixed resistor.

After you install the fixed resistor and trimmer pot, the pot can be adjusted so that the trimmer pot and fixed resistor together equal the test resistance before mounting the CCS mini-board on the DAC board. After turning on the power the pot can be adjusted further to achieve 2.7V across the Rload resistors if needed. If you are using non-standard Rload resistor values, then measure the Rload Voltage before removing the 6K resistor and adjust the CCS to match this.

I mentioned that for an additional $0.50USD each I can supply the recommended fixed resistor. This will NOT be the test resistance but a lower value that will require a trimmer pot. For those purists who want only one or two SMD resistors in their CCS circuit and no trimmer pot then the final resistance needed will have to be determined AFTER the 2SK208 is soldered onto the CCS board and AFTER a pot is used to adjust the Rload voltage to 2.7V. The heat from soldering a JFET device can slightly alter its operating characteristics.

For those who are not ordering Buffer board parts from me I intend to send these tiny parts in a flat letter envelope with no customs or special mention unless you request this. Postage and envelope should be no more than $4USD to Europe from the USA. Total for three 2SK208’s, three fixed resistors, and postage for parts for one pair of CCS boards would be $9.50 USD. Parts for up to 4 pairs of CCS boards will also fit in a letter envelope.
 
Last edited:
#186
Myint67 said:
emyeuoi (CCS x 2)
carlsor (CCS x 4)
juancho (CCS x 4)+parts
crazyfrog (CCS x2)
mk57 (CCS x 8) + parts
SimonJ (CCS x 2) + parts
PET-240 CCS x 4 + parts
sterlingmck (CCS x 4) + parts
zz1969 (CCS x 8) + parts
kurand (CCS x 4) + parts
mbcoffman (CCS x 2) + parts
Myint67 (CSSx16) + Parts
tuyen (CCS x 8) + parts
Brumjam (CCS x 4) + parts
mr_whocares (CCS x 2) + parts
tods (CCS x 8) + parts
IanS1 (CCS x 4) + Parts
dwjames (CCS x 2) + parts
titus2002 (CCS x 8) + parts
Chanh CCS x 24 + parts
Total CCS= 120
Parts = 110
Click to expand...
 
#187
emyeuoi (x1)
PET-240 x2 + 2 set JFETS + 2 set Susumu
Myint67x 3, + 3set JFEct + 3set SuSumu
Juancho x2 + 2 sets JFETS + 2 sets Susumu
Sterlingmck x2 + 2 set JFETS + 2 set Susumu
BDL x1 + 1 set JFETS + 1 set Susumu
mbcoffman x1 + 1 set JFETS + 1 set Susumu
carlsor x1
naimster x2
kurand x1 + 1 set JFETS + 1 set Susumu
brettlb x1
SimonJ x1 + 1 set JFETS + 1 set Susumu
JanGr. x1 + 1 set JFETS + 1 set Susumu
ed linssen x1 + 1set JFETS + 1 set Susumu (+ 2 sets of CCS parts )
tuyen x1 + 1 set JFETS + 1 set susumu
mr_whocares x1 + 1 set jfets + 1 set susumu
dwjames x1 + 1 set jfets + 1 set susumu

PCB= 23
Parts= 18
 
#188
emyeuoi (CCS x 2)
carlsor (CCS x 4)
juancho (CCS x 4)+parts
crazyfrog (CCS x2)
mk57 (CCS x 8) + parts
SimonJ (CCS x 2) + parts
PET-240 CCS x 4 + parts
sterlingmck (CCS x 4) + parts
zz1969 (CCS x 8) + parts
kurand (CCS x 4) + parts
mbcoffman (CCS x 2) + parts
Myint67 (CSSx16) + Parts
tuyen (CCS x 8) + parts
Brumjam (CCS x 4) + parts
mr_whocares (CCS x 2) + parts
tods (CCS x 8) + parts
IanS1 (CCS x 4) + Parts
dwjames (CCS x 2) + parts
titus2002 (CCS x 8) + parts
Chanh CCS x 24 + parts
BDL (CCS x 2) + parts

Total CCS= 122
Parts = 114
 
#189
emyeuoi said:
Dear All,

carlsor kindly highlight to me that the 2SK208, as per datasheet, need to be flipped.

Thanks carlsor to catch it 🙂

Attached the new layout of the CCS circuit.

Tomorrow I will close the GB and in few days I will send you a PM with the final amount including handling/shipping. Please reply to the PM with your paypal account and the exact shipping address.

Thanks and Happy New Years to all of you and your families.

Enrico
Click to expand...

Hi Enrico,
I don't understand why on the 246 the Drain (pin2) is on Ground and with the 208 the Gate (pin3) is on Ground. Do I see it wrong?
Ed
 
#190
Hope not too late:
emyeuoi (CCS x 2)
carlsor (CCS x 4)
juancho (CCS x 4)+parts
crazyfrog (CCS x2)
mk57 (CCS x 8) + parts
SimonJ (CCS x 2) + parts
PET-240 CCS x 4 + parts
sterlingmck (CCS x 4) + parts
zz1969 (CCS x 8) + parts
kurand (CCS x 4) + parts
mbcoffman (CCS x 2) + parts
Myint67 (CSSx16) + Parts
tuyen (CCS x 8) + parts
Brumjam (CCS x 4) + parts
mr_whocares (CCS x 2) + parts
tods (CCS x 8) + parts
IanS1 (CCS x 4) + Parts
dwjames (CCS x 2) + parts
titus2002 (CCS x 8) + parts
Chanh CCS x 24 + parts
BDL (CCS x 2) + parts
Sovereign1 (CCSx40 +Parts

Total CCS= 126
Parts = 118
 
#191
If not too late
emyeuoi (x1)
PET-240 x2 + 2 set JFETS + 2 set Susumu
Myint67x 3, + 3set JFEct + 3set SuSumu
Juancho x2 + 2 sets JFETS + 2 sets Susumu
Sterlingmck x2 + 2 set JFETS + 2 set Susumu
BDL x1 + 1 set JFETS + 1 set Susumu
mbcoffman x1 + 1 set JFETS + 1 set Susumu
carlsor x1
naimster x2
kurand x1 + 1 set JFETS + 1 set Susumu
brettlb x1
SimonJ x1 + 1 set JFETS + 1 set Susumu
JanGr. x1 + 1 set JFETS + 1 set Susumu
ed linssen x1 + 1set JFETS + 1 set Susumu (+ 2 sets of CCS parts )
tuyen x1 + 1 set JFETS + 1 set susumu
mr_whocares x1 + 1 set jfets + 1 set susumu
dwjames x1 + 1 set jfets + 1 set susumu
Sovereign x2 + 2 sets JFETS + 2 sets Susumu

PCB= 25
Parts= 20
 
#196
emyeuoi (x1)
PET-240 x2 + 2 set JFETS + 2 set Susumu
Myint67x 3, + 3set JFEct + 3set SuSumu(request for pre solder if available)
Juancho x2 + 2 sets JFETS + 2 sets Susumu
Sterlingmck x2 + 2 set JFETS + 2 set Susumu
BDL x1 + 1 set JFETS + 1 set Susumu
mbcoffman x1 + 1 set JFETS + 1 set Susumu
carlsor x1
naimster x2
kurand x1 + 1 set JFETS + 1 set Susumu
brettlb x1
SimonJ x1 + 1 set JFETS + 1 set Susumu
JanGr. x1 + 1 set JFETS + 1 set Susumu
ed linssen x1 + 1set JFETS + 1 set Susumu (+ 2 sets of CCS parts )
tuyen x1 + 1 set JFETS + 1 set susumu
mr_whocares x1 + 1 set jfets + 1 set susumu
dwjames x1 + 1 set jfets + 1 set susumu
Sovereign x2 + 2 sets JFETS + 2 sets Susumu

PCB= 25
Parts= 20
 
#197
Myint67 said:
Myint67x 3, + 3set JFEct + 3set SuSumu(request for pre solder if available)
Click to expand...

Hi Myint67,

I have no problem to pre-solder your boards but carlsor should send your parts to me.

Anyway, please note that I CAN'T test the board without the remaining through hole parts and I will only perform a continuity test pin to pin.

The cost to pre-solder the SMD parts including continuity test will be 12USD by board.

Regards,
Enrico
 
#198
Hi Guys,

After an Acko S03 failure due my poor smd soldering skills plus the groupbuy is now in the hundred quantity, I decided not to proceed with this delicate mod concerns I could do more damage to my DDDAC which deems very satisfactory to my ears right now. 😉

I know I will kick myself later, but...., can't risk it with my skills!

So the order as it stands
emyeuoi (CCS x 2)
carlsor (CCS x 4)
juancho (CCS x 4)+parts
crazyfrog (CCS x2)
mk57 (CCS x 8) + parts
SimonJ (CCS x 2) + parts
PET-240 CCS x 4 + parts
sterlingmck (CCS x 4) + parts
zz1969 (CCS x 8) + parts
kurand (CCS x 4) + parts
mbcoffman (CCS x 2) + parts
Myint67 (CSSx16) + Parts
tuyen (CCS x 8) + parts
Brumjam (CCS x 4) + parts
mr_whocares (CCS x 2) + parts
tods (CCS x 8) + parts
IanS1 (CCS x 4) + Parts
dwjames (CCS x 2) + parts
titus2002 (CCS x 8) + parts
BDL (CCS x 2) + parts
Sovereign1 (CCSx40 +Parts

Total CCS= 102
Parts = 94
Click to expand...
 
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