• Please note that Audiokarma will be offline briefly for updates early on Monday morning, September 28th.

SX-850 SX-950 Fix for Phono Crackle

Stevesmullen

Stevesmullen

Well-Known Member
I was asked for The Recap List for a SX-950 and this is all that I could get access to tonight to fix the Phono section when it has the common crackle that the SX-850/950 get.Replacing the transistors and caps has fixed 3 of them for me.
Steve
 

Attachments

Register to hide this ad
Stevesmullen said:
I was asked for The Recap List for a SX-950 and this is all that I could get access to tonight to fix the Phono section when it has the common crackle that the SX-850/950 get.Replacing the transistors and caps has fixed 3 of them for me.
Steve
Click to expand...

my ears were burning, then I opened the text file, and lo and behold saw my OWN typing, so here's the rest of the story:

edit, I would now use:
2x 5989-100V1.0-F 1.0uf 50v polyester film caps at $0.53 ea
instead of:
2x 647-UPW1H010MDD @ $0.23 ea for C1, C2 1uF 50V input coupling, signal path


markthefixer said:
This is a very well known problem, there are transistor problems, so they need to be replaced.... while you're in there, re-capping will just add a few bucks onto the parts costs, and the results will please your ears...

The parts are on the phono amp board, labeled awf011. Download the sx850 AND the sx950 manuals, the 850 and 950 are close enough alike that the 950 manual will help make up for the poor 850 manual.

For parts in The USA:
www.mouser.com , mouser.com parts numbers:
during checkout, first class mail shipping becomes available for about 4 bucks
this place has no minimum order, or surcharge.

2x 512-KSA992FBU @ $0.06 ea PNP low noise high gain af amp ecb lead-layout fairchild for Q1 & Q2
4x 512-KSC1845EBU @ $0.06 ea NPN low noise high gain af amp ecb lead-layout fairchild for Q3, Q4, Q5 & Q6

2x 647-UPW1H010MDD @ $0.23 ea for C1, C2 1uF 50V input coupling, signal path
2x 647-UPW1H3R3MDD @ $0.23 ea for C11, C12 3.3uF 50V output coupling, signal path
1x 647-UPW1V101MPD @ $0.15 ea for C17 100uF 25V(35v) + power filter
1x 647-UPW1V221MPD @ $0.56 ea for C18 220uF 16V(35v) - power filter
2x 647-UPW0J331MED @ $0.39 ea for C7, C8 330uF 6V internal filter

All have been checked and are currently in stock.

BE CAREFUL INSTALLING THESE TRANSISTORS, the lead layout is different!!
the original parts are BCE and the fairchilds are ECB...
thus in both the center lead IS the collector (c) but the two on the outside are REVERSED!!!!!
That means the flat on the transistor will face in the other direction.

The capacitors have the minus terminal marked with a minus, the longer lead is plus.

Change each part one at a time. Lead arrangements on EVERY part mentioned are critical and non-negotiable.

Good luck, watch out for the heat sensitive capacitors, the ones with the clear plastic ends...

Of course, holler if you need more detailed help. Although even if new to this, open the bonnet (their words, not mine) and bottom and study it with the manual (at least LOOK at every manual page, later on you can say "oh yeah, I saw something like that") so it isn't alien territory.

Do you have desoldering / soldering equipment ?
Click to expand...
 
The 1845--992 combo sounds great in that phono application. I've also used them a few more times in pre-amp sections of various receivers.
Appreciate the update on the 1uf input caps.
 
Stevesmullen said:
I was asked for The Recap List for a SX-950 and this is all that I could get access to tonight to fix the Phono section when it has the common crackle that the SX-850/950 get.Replacing the transistors and caps has fixed 3 of them for me.
Steve
Click to expand...

Stevesmullen said:
Here's what I have for the SX-850/950 Capacitor list.
Click to expand...

drat, I MISSED that, and I had a copy of the file!!! Did you or I enter that? What about the xls spreadsheet version? Or was that your, mine or someone else's creation? I'm going to try to get that list down to all upw's and film caps if possible.
 
markthefixer said:
drat, I MISSED that, and I had a copy of the file!!! Did you or I enter that? What about the xls spreadsheet version? Or was that your, mine or someone else's creation? I'm going to try to get that list down to all upw's and film caps if possible.
Click to expand...
I think that I put that list together or I updated someones,Im pretty sure that I also did one for a SX-1050.
I really like the one that bisonguy did it turned out really nice,that would probobaly be pretty easy if you (MTF) had the same Program that he used.
We will let you slide with missing that as you are probobaly enjoing the warm weather that you should be getting.:D
Steve
 
Stevesmullen said:
MTF or EW Where is the difference in the components between the 850 and 950 to get the extra wattage?
Click to expand...

THAT is one of those questions that sounds innocent enough - and requires a LOT of work to track down, especially on an old creaky computer that hates to have two big pdf files open at the same time. They may share preamp stuff a lot, but not the power amp and possibly the regulated power supply.
 
markthefixer said:
THAT is one of those questions that sounds innocent enough - and requires a LOT of work to track down, especially on an old creaky computer that hates to have two big pdf files open at the same time. They may share preamp stuff a lot, but not the power amp and possibly the regulated power supply.
Click to expand...
Good enough for me given that im sure you have much better things to be doing ??:D
 
Stevesmullen said:
Good enough for me given that im sure you have much better things to be doing ??:D
Click to expand...

Yeppers, I think ya have a vested interest there.... :D

I'm busier than a 9 tailed cat in a room full of rocking chairs..... stuff IS moving along.....

Although I had an unpleasant surprise when I checked out the nice temps today, I had run and connected some 50 ' or so of 3" pvc piping last year to collect three gutters worth of roof runoff and direct it out back in the yard, the pvc pipes were was exposed by the loss of snow, and it turned out to be thoroughly shattered by internal ice expansion. All that work last year...:tears:

I'm kicking myself about not thinking about ice buildup inside.

Before today, I was patting myself on the back about the fact that of all the nearby houses, mine was the only one without icicles hanging (some were HUGE) from the gutters.
 
Here's the xls, all zipped up...

PLUS
Here is the mouser BOM import for the list:

---- cut and paste the enclosed ---------
598-DSF050J|2
598-DSF050J224|5
598-DSF050J474|1
647-upw1h010mdd|5
647-UPM2A1R5MDD|3
647-upw1h2r2mdd|6
647-UPW1H3R3MDD|3
647-UPW1H4R7MDD|8
647-UPW1H100MDD|12
647-upw1v330mdd|2
647-UPW1E470MDD|5
647-UPW1H470MED|4
647-UPW1A101MDD|2
647-UPW1E101MED|5
647-UPW1H101MPD|3
647-UPW1J101MPD|1
647-UPW1E221MPD|3
647-UPW1V221MPD|3
647-upw1c331mpd|4
647-UPW0J331MED|2
647-UPW1J471MHD|1
647-UPW2A471MHD|2
647-UPW1E102MPD6|1
647-UPW1V222MHD|1
------ end of cut and paste ---
current prices put it at 26.21 ... 84 capacitors,
nichicon upw's, one UPM cap and stacked films for the sub 1uF caps...
 

Attachments

I too have a phono section that needs recapping. All the parts are in stock at Mouser, except for 512-KSC1845EBU.

Is a suitable replacement: KSC1845FTA?
 
You must log in or register to reply here.
Back
Top Bottom