Recapping SX-950

[gmahoog]

Finished up the caps, including the bypass caps, deoxit treatment and got it all back together. I haven't been able to crank it yet, but I can tell that it is much cleaner with a lot more punch than it use to have.

It's been a cool project and I really enjoyed working on it. In a way I'm kind of bummed out that I'm done.

Thanks to everybody here, not only contributors to this thread, but also the entire AK community. There is such a wealth of knowledge in all these threads.

Especially thanks to mattsd.

Now on to my SX-780.

Regards,
Dave H.

 

[mattsd]

Congratulations! :thmbsp: I hope you enjoy it for a long time to come!

 

[day67]

I'm at work, no SM to refer to so I have to ask blindly, are any of the "C" capacitor numbers like "C 12" (just for example) on any of the various boards inclusive of tantalum caps? I know these are recommended to be replaced and am wondering if they are included in the caps list here. Thanks!

 

[mattsd]

Yes, they are inclusive of the tantalum caps and are included in the cap list.

 

[dukja]

Here is a list of transistors that should be replaced as preventive maintenance

Power Supply Board (AWR-101)

Q5: 2SC1318: 512-KSC2690AYS
Q7: 2SC1318: 512-KSC2383YBU

Power Amp Board (AWR-059)

Q1-4: 2SA726: 512-KSA992FBU

Flat Amp Board (AWG-038)

Q5-6: 2SA726: 512-KSA992FBU

Equalizer Amp Board (AWF-011)

Q1-2: 2SA726: 512-KSA992FBU

Thanks for the BOM for SX-950. I have used the list from the 1st page of this thread and then found some additional transistor list quoted above. I wonder if only those transistors need to be replaced? How about other transistors on the same board, for example, Q1-Q4 and Q6 for the PSU board?

Thanks for the explanation!

 

[harleyrider]

Just curious if anyone has used this BOM list recently ? I just aquired 950 and would like to get the parts ordered soon .

Thanks

 

[mattsd]

Everything in that BOM is in stock, I just checked. The only thing I'd check before ordering is the equalizer amp board, sometimes it has a couple of 100uF 6.3v caps on it that's not listed in that BOM, they are in the middle of the board. Also while you're in there you might as well replace the 2SC1312 and 1313 transistors on the EQ and tone amp boards, replacement for those the 512-KSC1845FTA. There's four on the EQ board and two on the tone amp board.

 

[harleyrider]

Q5 & Q7 same replacement or not ?

That's a little bit overkill, a KSC2383YBU would work just as well, but the 940 is okay. The other transistor that should be replaced is Q5, replace it with a 512-KSC2690AYS.

Im in the process of repairing my 950 ,
Question is can i use the 512-ksc2690ays to replace both Q5 & Q7 on the AWR 101 board, both are origianly 2sc1318. I have seen that there was 2 different part #s here to replace the two here that i qusetion. Is there a reason for the 2 different #s ?

Thanks

 

[markthefixer]

Im in the process of repairing my 950 ,
Question is can i use the 512-ksc2690ays to replace both Q5 & Q7 on the AWR 101 board, both are origianly 2sc1318. I have seen that there was 2 different part #s here to replace the two here that i qusetion. Is there a reason for the 2 different #s ?

Thanks

these two? yes there is,,,,

Power Supply Board (AWR-101)

Q5: 2SC1318: 512-KSC2690AYS
Q7: 2SC1318: 512-KSC2383YBU

q7 just runs the phono preamp, smaller transistor MIGHT be a bit quieter, fit better...

you could try the other...

 

[harleyrider]

thanks Mark , i didnt have any 2383s here but plenty of 2690s that was why i asked .

 

[harleyrider]

Got all my parts today , just seperated them into individual bags per board . Hope to get around to recapping this weekend .

Thanks Mattsd for the BOM it really helps out alot .

Just need to order new lamps now , i think there the same as my SX 1250 ? If so ill order enough to do both . Any part #s on the lamps and place to get them from ?


Thanks again

Chris

 

[harleyrider]

Caps directional or not ?

Qustion about the 667-ECQ-V1H224JL2 caps that will be replaced on AWM-062 C1, C2 and AWG-039 boards C25, C26.

Are they directional ? There are + signs on board and the original caps have the + symbol. I dont know how to determine + or - on the new replacemnt caps .

Thanks


Chris

 

[harleyrider]

I was hoping to get something back on this so I can complete this board Thanks

 

[goat67]

Film caps do not have polarity so it does not matter which direction you put this cap in.

 

[harleyrider]

Film caps do not have polarity so it does not matter which direction you put this cap in.[/QU


Thanks , now i can move on .

 

[harleyrider]

sx 950 parts replacement questions ?

Ok well i have replaced everything i could from the BOM list provided in this thread.

Question 1

AWR 101 Board

Location C14 , schematic and list calls for 220 at 10 v
mine had a 47 at 25v looked original ?
But i replaced it with the new one per schematic 220/10v.
just curious why it was there?

Question 2

AWR 101 Board

Location C12 , schematic and list calls for 1000 at 35v
mine had a large can ,2200 at 35v again looked original?
Replaced with the new one per schematic and BOM list 1000/35v.

I know we can go up on voltages a bit bit the microfardas ?


So i now need to complete this

(2) 100/6.3v caps for the EQ board New part # ?

(6) 512-KSC1845FTA for the EQ and Tone amp boards

The lamps to replace , Part #s ? Does Mouser have these ?

And on back order are the caps to complete AWR 101 Power supply
647-UPW1V470MED 47/35v (3)
667-EEU-FC1H470 47/50v (1)

Could use some help on replacement #s (?)

Would like to get a order in asap if possible .

Thanks


Chris

Thanks

 

[tsd71]

Harley is your 950 dual voltage because mine is, I recapped awhile ago and the regular 950 manual differed with what I had on the boards. Some of the caps were different like yours is. If you have a dual voltage selector on the right rear of your unit it might differ from the regular version. I usually try to replace what is there with the same value especially if they are original caps.

 

[harleyrider]

Harley is your 950 dual voltage because mine is, I recapped awhile ago and the regular 950 manual differed with what I had on the boards. Some of the caps were different like yours is. If you have a dual voltage selector on the right rear of your unit it might differ from the regular version. I usually try to replace what is there with the same value especially if they are original caps.

Thanks , but this one isnt Dual voltage .

 

[ricohman]

Normally with with these old pots it only takes a small nudge to make a big change because of the dust and dirt that have built up inside of them, so be careful. And yes, sometimes they need changed just because of how dirty they get or the resistance element wears down in one area. Sometimes Deoxit can clear the dirt and then it works just fine, but make sure it gets Faderlube afterward, otherwise the element will break down because the Deoxit takes out the lube that was already in there.

Great thread at the perfect time.
The DC offset in my sx950 is under 10mv but both seem to jump up or down by 1-2mv. So not dead stable.
Anyways, I've been reading the service manual and it does not list measuring this or any way to adjust.
All it lists is adjustments to the power amp in 10 steps. Does this procedure also set the offset?.:scratch2:

 

[Freezer7Pro]

Great thread at the perfect time.
The DC offset in my sx950 is under 10mv but both seem to jump up or down by 1-2mv. So not dead stable.
Anyways, I've been reading the service manual and it does not list measuring this or any way to adjust.
All it lists is adjustments to the power amp in 10 steps. Does this procedure also set the offset?.:scratch2:

Yes. The VR1 and VR2 potentiometers are for adjusting the DC offset, VR3 and VR4 for bias. You can make your life a little easier by jamming your meter probes into the speaker outputs (making sure that whichever speaker group you choose is ON!) when setting the offset, rather than probing directly at the board.