SX-780 Refurb BOM to vet

merlynski

merlynski

Curmudgeon Electronicist
I have assembled a BOM for the AF board (GWK-118 only) in the SX-780 for vetting if anyone is willing to look it over. It is not intended to include the STK0050s, the protection relay, front panel controls or the Tuner board parts. I have collected these from multiple posts and old lists on AK. Please look them over and post corrections or additions. Thank you!
ASSY, Capacitance, Voltage, Type, Quantity, Identifier, Mouser number, RPL values, RPL w/Film?, Comment
GWK-118, 0.22, 50, CEA NL, 2, "C227, C228", 647-UKT1HR33MDD, 0.33/50V, y, "RPL Cap Val Does Not Match, Non-Stocked, 2mm lead spacing on rpl cap"
GWK-118, 0.47, 50, CEA, 4, "C401, C402, C403, C404 ", 647-UPM1HR47MDD, 0.47/50V, Y?, "Non-Stocked, 2mm lead spacing on rpl cap"
GWK-118, 1, 50, CEA NL, 2, "C207, C208", 647-UKL1H010KDDANA, 1/50V, y,
GWK-118, 2.2, 50, CEA NL, 8, "C103, C104, C117, C118, C229, C230, C309, C310 ", 647-UKL1H2R2KDDANA, 2.2/50V, y,
GWK-118, 4.7, 25, CEA NL, 2, "C217, C218 ", 647-UPW1E4R7MDD, 4.7/25V, y,
GWK-118, 4.7, 35, CEA, 7, "C201, C202, C324, C325, C326, C327, ", 647-UPW1H4R7MDD, 4.7/50V, (+unmarked position just to the right of C309 and the value was 4.7 uF/35 volt.
GWK-118, 10, 16, CEA, 2, "C318, C405 ", 647-UPW1C100MDD, 10/16V,
GWK-118, 33, 16, CEA, 1, C317, 647-UPW1C330MDD, 33/16V,
GWK-118, 47, 6, CEA, 2, "C213, C214 ", 647-UPW0J470MDD6, 47/6.3V,
GWK-118, 47, 16, CEA, 1, C319 , 647-UPW1C470MDD, 47/16V,
GWK-118, 47, 35, CEA, 2, "C305, C306", 647-UKT1V470MDD, 47/35V,
GWK-118, 47, 50, CEA, 1, C316, 647-UPW1H470MED, 47/50V,
GWK-118, 100, 25, CEA, 4, "C301, C302, C303, C304", 647-UPW1E101MED, 100/25V,
GWK-118, 100, 50, CEA, 2, "C307, C308", 647-UPW1H101MPD, 100/50V,
GWK-118, 220, 6.3, CEA, 1, C406, 647-UPW0J221MED, 220/6.3V,
GWK-118, 220, 16, CEA, 1, C311, 647-UPW1C221MPD, 220/16V,
GWK-118, 220, 63, CEA, 1, C315, 647-UPW1J221MPD6, 220/63V,
GWK-118, 470, 6.3, CEA, 2, "C105, C106", 647-UPW0J471MPD, 470/6.3,
GWK-118, 470, 63, CEA, 1, C314, 647-UPW1J471MHD6, 470/63V,
Transistors
GWK-118, 2sc1775, NPN, 4, "Q5, Q6, Q11, Q12", 512-KSC1845FTA, KSC1845FTA,
GWK-118, 2sc1885, NPN, 2, "Q13, Q14", 512-KSC2383YTA, KSC2383YTA,
GWK-118, 2sa912, NPN, 2, "Q15, Q16", 512-KSA1013YBU, KSA1013YBU,
GWK-118, 2sd325R, NPN, 1, Q19, 512-KSC2073TU, KSC2073TU, 863-MJE15032G
GWK-118, 2sb536L, PNP, 1, Q20, 512-KSA940TU, KSA940TU, 863-MJE15033G
GWK-118, 2SD712, NPN, 1, Q25, 512-KSC2073TU, KSC2073TU, 863-MJE15032G
GWK-118, 2sc1384, NPN, 1, Q26, 512-KSC2690A, KSC2690A, Mouser OOS
GWK-118, 2SC2291, dual NPN, 2 (4), "Q9, Q10", 512-KSC1845FTA, KSC1845TFA, match, bent leads
GWK-118, 2sa979, dual PNP, 2 (4), "Q7, Q8", 512-KSA992FBU, KSA992FBU, match,
 
Last edited:
CEA NL types should be replaced by low leakage Nicicon UKL
ecaps in the signal path can be Nichicon, UKW,UKZ,UKA, some like Elna SilmicII
I do not know if I'd replace semis esp the duals C2291,A979, if any the ones in the Power supply
 
rcs16 said:
CEA NL types should be replaced by low leakage Nicicon UKL
ecaps in the signal path can be Nichicon, UKW,UKZ,UKA, some like Elna SilmicII
I do not know if I'd replace semis esp the duals C2291,A979, if any the ones in the Power supply
Click to expand...

Thanks for the reply!
The CEA NL caps in the list above are all in the signal path. Did you mean they should be UKL types? Or would be better as UKW,UKZ,UKA or SilmicII types. Specific suggestions? I did find UKL replacements for all the CEA NL caps at Mouser. I was contemplating switching the signal path CEA NL types all to film caps . . . which would require some creative locating and mounting, but seems doable if I can find film Cs with long enough leads. Which way would you go?
As for dual transistors, I would not feel a need to RPL unless failed, but did want options/opinions just in case. The power supply transistors (esp. regulators) would be an upgrade for longevity purposes, including better heatsinking.
 
merlynski said:
The power supply transistors (esp. regulators) would be an upgrade for longevity purposes, including better heatsinking.
Click to expand...

Which transistors are the power supply transistors and regulators? I have a blown up version of the schematic that I am studying. I am trying to learn how to follow the signal path and where the different sections of the amp are (pre amp, protection, power amp, ect..). I would like to high light the signal path and different sections with a big high lighter on my schematic for learning purposes.

I am also in the process of a restoration. What transistors did you end up replacing? And how did it turn out?
 
Kingbleu said:
Which transistors are the power supply transistors and regulators? I have a blown up version of the schematic that I am studying. I am trying to learn how to follow the signal path and where the different sections of the amp are (pre amp, protection, power amp, ect..). I would like to high light the signal path and different sections with a big high lighter on my schematic for learning purposes.

I am also in the process of a restoration. What transistors did you end up replacing? And how did it turn out?
Click to expand...

Actually I only replaced the protection relay, the relay transistor, the STK modules (hbrown/rcs16 kits), and the two main power supply caps. It sounded so good that I never felt the need to go further. I did reflow the solder on the power supply transistors: Q19, Q20, Q25.
.

EDIT: Also a massive round of Deoxit treatments
 
Last edited:
Consider hanging something like this on Q25:

240_series.jpg
 
merlynski said:
GWK-118, 47, 6, CEA, 2, "C213, C214 ", 647-UPW0J470MDD6, 470/6.3V
Click to expand...

Hi Merlynski and thank you very much for putting the list together as I am slowly recapping one of this these days. This is helpful
I got confused with the value of the line quoted above as originally is a 47 uF cap and the list reads "470/6.3V", however the reference number "647-UPW0J470MDD6" points CORRECTLY to a 47 uF 6.3V Nichicon cap.
thanks,
 
TelRay said:
Hi Merlynski and thank you very much for putting the list together as I am slowly recapping one of this these days. This is helpful
I got confused with the value of the line quoted above as originally is a 47 uF cap and the list reads "470/6.3V", however the reference number "647-UPW0J470MDD6" points CORRECTLY to a 47 uF 6.3V Nichicon cap.
thanks,
Click to expand...
That is exactly why I posted it as a BOM to be vetted, thank you for your sharp eye and reply! I have corrected it.
 
I like to use kemet film caps for anything 4.7uf and under, and they (generally) come with normal lead length so generally no trouble with fitting those so they are suitable for any of the CEANL caps, otherwise an electrolytic nichicon UKL, if i am not happy to spend the extra, i certainly dont hear any difference between a film cap and a electrolytic
And just my opinion, I dont like using the elna silmic caps simply because they are pretty big, and have had a few that were difficult to fit as they have thick leads and are sometimes bigger than the original cap.

https://www.mouser.ie/ProductDetail/ON-Semiconductor-Fairchild/KSC2690AYS?qs=ljbEvF4DwOMCKgoJMAQEOQ==
KSC2690AYS in stock at mouser

2sa912 = 512-KSA1220AYS (I used this on the SA8500II i am working on, per Marks BOM, but not sure if correct for your needs)

For the dual transistors, i opened up the common hole (again on the sa8500II) a bit to allow both leads to fit into the single hole and allowed me to solder in position, which made life a bit easier.
 
Last edited:
As I am approaching the TONE section I need to start taking some decisions.
I see that on your list you have gone for electrolytics. Maybe it was a cost decision (WIMA and ORANGE DROPs being more expensive) or the project was a REFURBISH more than an UPGRADE.
I took the liberty of putting your list side by side with an "upgraded" one so that differences (in both quality and price) can be easily spotted.

upload_2020-8-4_21-25-6.png

let me know what you think.

Best,
 
That is exactly why I posted it as a preliminary BOM to be vetted. Thanks for your input.
I ended up doing just a repair on that SX-780: Custom STK units (hbrown/rcs16 units) and a new relay, some trace repair, and replacement of failed relay driver transistor. The original BOM was created and refined from others here on AK. I have since then moved to liking film caps for values 10µF and under (if they will fit).
I ran out of time, as that one was a Wedding gift for my son. I have another SX-780 in the queue that will get a resto-mod upgrade, including film instead of e-caps in the signal path.
 
that's an awesome wedding gift! :)
i guess my approach might be a bit extreme, but... why not?
if you check the prices you'll see that the "high end" solution might be 3x more expensive.
Will it sound 3 times better? probably not :)
 
TelRay said:
that's an awesome wedding gift! :)
i guess my approach might be a bit extreme, but... why not?
if you check the prices you'll see that the "high end" solution might be 3x more expensive.
Will it sound 3 times better? probably not :)
Click to expand...
The next SX-780 resto-mod will be an over-the-top upgrade, so I might just HAVE to use some of your suggestions |:rflmao:|
 
You must log in or register to reply here.

Similar threads

Awesomeaudio
Pioneer SX-750 BOM list Complete and Updated.
2
Replies
39
Views
4K
Spenser
Spenser
merlynski
SX-1050 BOM AWG-020? - answered
Replies
4
Views
401
merlynski
merlynski
DrTim
SX-737 caps plus vetting help 3/18
Replies
2
Views
377
DrTim
DrTim
Stevescivic
SX-1050 Cap and transistor list
Replies
2
Views
2K
Stevescivic
Stevescivic
moschops
SA-8100 Cap List
2
Replies
35
Views
8K
EC1
E
Back
Top Bottom