PAPA'S KOAN ....... was Papa's Surprise

as some of you already know for preceding story : http://www.diyaudio.com/forums/pass...high-end-off-topic-thread-67.html#post2264960 ...... I'm blessed with Papa's Suprise ...... ( where is that "notworthy" smiley when you need it ..... ;) ) .

there is rest of story .
I'm certainly one of not many , having opportunity to dismantle FW chassis in pieces ; as Papa likes AR2 , he didn't put usual Donut and caps in it , probably counting on fact that Vladimir will bring it all the way on his shoulder ( not having enough trust in Air baggage departments ) ......
anyway - little jewel box is even without these few parts heavy enough ...

so - to have Papa's Surprise Amp in working condition I had to do few things :

.... install new Donut ; what I already had on my shelf is just right (to squeeze in ) size - 4x18Vac/800VA ; according to that - decision to use 2 Graetzs per channel is logical , same as dedicated filter bank per channel .
so - 2x18Vac windings , two bricks , 4x 33mF/25 Panas , along with 2x 0R1 in CRC ; all that per channel
I didn't want to make new holes in bottom plate , so nice Cu plate is cut and bent , to serve as donut and bricks holder . I also made new filter pcb ( wisely sprayed in black ) , while Papa's original one , along with two finest original FW Chinese Porcelain 35A bricks will end in some less demanding project ( maybe some HP amp ) .

power wiring is made from finest quality cut-in-dust LS cable , produced by local factory

Donut squeezed in sandwich (top & bottom ) of soft rubber ; my usual praxis for all toroids ; you can rotate it few degrees and move about 5mm side wise , but it's secured completely

so - few pics for start ( I'm lazy bstrd , so random order is my native state)
 

Attachments

  • back.jpg
    back.jpg
    29.7 KB · Views: 2,580
  • bottom blur.jpg
    bottom blur.jpg
    48.8 KB · Views: 2,537
  • front.jpg
    front.jpg
    44 KB · Views: 3,933
  • Graetzs.jpg
    Graetzs.jpg
    74 KB · Views: 2,546
  • IEC2.jpg
    IEC2.jpg
    70.8 KB · Views: 2,501
  • IEC.jpg
    IEC.jpg
    77.2 KB · Views: 1,347
  • side blur.jpg
    side blur.jpg
    40 KB · Views: 1,999
  • shield.jpg
    shield.jpg
    84.8 KB · Views: 930
  • PSU.jpg
    PSU.jpg
    85.3 KB · Views: 917
so......

Papa sez :rofl: that pcbs are from early pre-production ; meaning that pcb itself is right as schematic posted in first post in famous F4 thread ; later and final iteration have few changes - mainly with goal to save and secure tiny fragile input Jfets from excessive input signal which , in case of amplitude greater than actual F4 working voltage , will burn them in silent puff :rofl:

I had dilemma few days - leave it as is , counting on fact that I don't need much of input amplitude for my spks ...... or to tweak pcb a little and make it according to final schematic ; naah ....... as Papa sez in one e-mail - " I though that you will put something else in that case " , decision was made - I'll leave present as is , but I must play with it a little ; so - every butcher detail you'll see on pics is made as change to that schm .

electrolytics are my fave - Elna 470uF/35V/125C :rofl: , maybe because I have few kilos of them ;
bypasses on two Elnas in power filtering are 100n/some-film-who-really-care-which-type ; bypasses on two signal carrying Elnas are 10n MKC - polycarbonats

one funny thing is - major-trouble issue for Vladimir , and also major-laughing issue for me - fact that front plate was badly scratched in transport (probably bubble-wrap slipped and back side of zip in Samsonite made those scratches ) ,exactly where Papa's Surprise sticker is put , on pics in linked post above ;
I had instantly cunning plan ( I'm pretty often in Baldrick mode) to send front plate in capable hands of local Metal Guru - Leonardo ( nick on Baby Diya) ;
said and later managed - Leo cleaned existing elox , brushed , made new elox and Fugly! new logo .
possible similarity with existing FW logo is pure coincidence , of course , and your's Mighty ZM is responsible for that coincidence :rofl:

I know that my fave Dutchie Jaccovitty is dumb as Dutchie Whale , so here is link to wikipedia - meaning of Koan ..... for his eyes and education only :clown: : K?an - Wikipedia, the free encyclopedia

why "Koan" ?

just because Papa's crumbs , thrown in ZM's direction , are usually 3 times stiffer than his usual PassDiyA crumbs ...... :clown:
 
as I said - I'm lazy bstrd ......

so - 'nuff typing ; now random pics
 

Attachments

  • channel.jpg
    channel.jpg
    36.1 KB · Views: 1,372
  • channel-both-2.jpg
    channel-both-2.jpg
    46.6 KB · Views: 1,006
  • channel-both.jpg
    channel-both.jpg
    54.9 KB · Views: 879
  • channell-part.jpg
    channell-part.jpg
    36.4 KB · Views: 923
  • front.jpg
    front.jpg
    15 KB · Views: 866
  • front-WS2.jpg
    front-WS2.jpg
    67.5 KB · Views: 710
  • pc-setup.jpg
    pc-setup.jpg
    57.6 KB · Views: 778
  • full.jpg
    full.jpg
    24.4 KB · Views: 4,481
  • front-WS.jpg
    front-WS.jpg
    38.7 KB · Views: 761
  • Like
Reactions: 1 user
more.....

pics
 

Attachments

  • PK-action.jpg
    PK-action.jpg
    24.2 KB · Views: 2,042
  • PK-off.jpg
    PK-off.jpg
    27.6 KB · Views: 207
  • topless-2.jpg
    topless-2.jpg
    48.2 KB · Views: 426
  • topless-3.jpg
    topless-3.jpg
    67 KB · Views: 713
  • topless.jpg
    topless.jpg
    64.2 KB · Views: 836
  • tweak-1.jpg
    tweak-1.jpg
    57.6 KB · Views: 624
  • tweak-4.jpg
    tweak-4.jpg
    51.2 KB · Views: 462
  • tweak-3.jpg
    tweak-3.jpg
    41.6 KB · Views: 411
  • tweak-2.jpg
    tweak-2.jpg
    42.9 KB · Views: 354
tip :

if you want to save surface around screw holes from damage , use plastic washers ;

if you don't have plastic washers handy - DIY them - from roentgen foils :rofl:

all you need are ( what's proper word) - hole making tool and scissors .

funny - I have full box of these foils in A3 format, scavenged from local health center ...... they're good for many things in electronic :clown:
 
Dumb as a Dutch Whale. Now I will have to remember that phrase.
.....

but remember that that phrase is reserved for my Dutchie Whale , as expression of love ; but don't tell him that - he's spoiled too much already :rofl:

....
How does it sound?

exactly as proper F4 ;)
usual FW job - honest amp , no bigger than life ; I can't ask for more

......
I wish I could afford all that copper to use for brackets and such.
....

try at junkyards ; that piece is surplus (sort of ) from little local factory