Another SX-850 cuts in/out

[spadad128]

New Parts List 21 March

Flat Amplifier
AWG-038 C1 647-UKL1H2R2KDDANA
AWG-038 C2 647-UKL1H2R2KDDANA
AWG-038 C5 647-UKL1E4R7KDDANA
AWG-038 C6 647-UKL1E4R7KDDANA
AWG-038 C13 647-UPW1V221MPD6
AWG-038 C14 647-UPW1V221MPD6
AWG-038 C17 647-UKL1H100KDDANA
AWG-038 C18 647-UKL1H100KDDANA
AWG-038 C23 647-UKL1E4R7KDDANA
AWG-038 C24 647-UKL1E4R7KDDANA
AWG-038 C25 647-UKL1E101KPDANA
AWG-038 C26 647-UKL1E101KPDANA
AWG-038 C27 647-UPW1H101MPD
AWG-038 Q1 512-KSC1845EBU
AWG-038 Q2 512-KSC1845EBU
AWG-038 Q5 512-KSA992FBU
AWG-038 Q6 512-KSA992FBU

Power Amplifier
AWH-059 C1 647-UKL1H2R2KDDANA
AWH-059 C2 647-UKL1H2R2KDDANA
AWH-059 C3 647-UKL2A0R1KDD
AWH-059 C4 647-UKL2A0R1KDD
AWH-059 C5 647-UPW1V330MDD
AWH-059 C6 647-UPW1V330MDD
AWH-059 C11 647-UPW1E331MPD
AWH-059 C12 647-UPW1E331MPD
AWH-059 Q1 512-KSA992FBU
AWH-059 Q2 512-KSA992FBU
AWH-059 Q3 512-KSA992FBU
AWH-059 Q4 512-KSA992FBU

Power Supply
AWR-102 C10 647-UHE2A471MHD6
AWR-102 C11 647-UHE2A471MHD6
AWR-102 C12 647-UPW1V222MHD
AWR-102 C13 647-UPW1E102MPD6
AWR-102 C14 647-UPW1E221MPD
AWR-102 C15 647-UPW1J471MHD
AWR-102 C16 647-UPW1E470MDD
AWR-102 C18 647-UPW1H470MED
AWR-102 C19 647-UPW1H470MED
AWR-102 C20 647-UPW1J101MPD
AWR-102 C21 647-UPW1E470MDD
AWR-102 C23 647-UPW1H101MPD
AWR-102 Q5 512-KSC2690AYS
AWR-102 Q6 512-KSA1013YBU
AWR-102 Q7 512-KSC2383YBU

SWITCH ASSEMBLY 94 C1 647-UPW1E221MPD

Tone Amp
AWG-039 C13 647-UKL1H100KDDANA
AWG-039 C14 647-UKL1H100KDDANA
AWG-039 C15 647-UKL1H100KDDANA
AWG-039 C16 647-UKL1H100KDDANA
AWG-039 C19 647-UKL1E101KPDANA
AWG-039 C20 647-UKL1E101KPDANA
AWG-039 C21 647-UPW1H470MED
AWG-039 C22 647-UPW1H470MED
AWG-039 C23 647-UKL1H2R2KDDANA
AWG-039 C24 647-UKL1H2R2KDDANA
AWG-039 C25 667-ECQ-E2224KF
AWG-039 C26 667-ECQ-E2224KF
AWG-039 C29 647-UKL1H100KDDANA
AWG-039 C30 647-UKL1H100KDDANA
AWG-039 C30 512-KSC1845EBU
AWG-039 C30 512-KSC1845EBU

OTHER 532-250
OTHER 588-OF512JE
OTHER 588-OF512JE

Notes:
1. I decided to just replace Q1,Q2,Q3,Q4 on the power amp board.
2. On the power supply board, I have Q5, Q6 and Q7. But, Q6 is not in stock. I'm not sure I really need that one as I think I saw your recommendation that only Q5 and Q7 need to be replaced.
3. C10 on the power supply board is also not in stock (647-EHE2A471MHD6). Looks like I could use 647-EHE2A471MHD instead.
4. All other items are in stock at Mouser
5. The thermal compound (OTHER 532-250) spec shows a dialectric strength of 300v/mil. Is that appropriate, or is there a better product to use?
6. The last two items are 5.1K ohm resistors to use to use when I adjust V1,V2,V3, V4 when I get to that point. I just picked this up from the service manual instructions to make a dummy load for the amp power in jacks.

Please check this revised list and then I will order. Your help is very much appreciated.

 

[spadad128]

SX-850 Caps and Transistors

Mark,

Your capacitor spreadsheet was very helpful and I used your format to try to figure out what transistors I needed. I added that page to your capacitor spreadsheet for SX-850 transistors. This spreadsheet is incomplete so should not be used as is. I'm sending it to you if there is any info you can use from it. Thanks.

 

[spadad128]

Normally at this point I would post a list of all the parts you mentioned. Can't right away, but if you post the list before closing the order I'll check the list, and if you don't know what transistors replace what, post the aaa-999 board number, part number (c9, q3 etc) and part number or values to make it quicker and I'll check/upgrade the list to eliminate any problems I spot.

Mark, my thread fell off the radar, probably because I didn't reply correctly. Anyway, to summarize, you have guided me through recapping the PS board and new caps and transistors in the preamp board on my SX-850. Then I had some pops in the left channel, we determined it was the 726's for the amp board, so I am ordering the 726's and caps for the amp board, as well as caps and some transistors for the PS and also caps for the tone amp boards.

If you could give my list a quick look before I order, I would appreciate it. It is post #21 of this thread. I've been following your advice to Sm1tty on his SX-850 and that has provided a lot of info. Thank You!

 

[mattsd]

FYI, for the caps it would help if you included the cap values for the original and replacement caps along with the board number and cap number, like this (this is from my own list, it hasn't been updated to reflect current stock):

Power Amp Board (AWH-059)

AWH-059: C1: 2.2uF 25v CSSA: 647-UKL1H2R2KDDANA 2.2uF 50v
AWH-059: C2: 2.2uF 25v CSSA: 647-UKL1H2R2KDDANA 2.2uF 50v
AWH-059: C3: 1uF 25v CSSA: 647-UKL1H010KDDANA 1uF 50v
AWH-059: C4: 1uF 25v CSSA: 647-UKL1H010KDDANA 1uF 50v
AWH-059: C5: 33uF 16v CEA: 647-UPW1C330MDD 33uF 16v
AWH-059: C6: 33uF 16v CEA: 647-UPW1C330MDD 33uF 16v
AWH-059: C11: 330uF 10v CEA: 647-UPW1A331MPD 330uF 10v
AWH-059: C12: 330uF 10v CEA: 647-UPW1A331MPD 330uF 10v

Also, C15 and 16 on the tone amp are 2.2uF 25v caps, not 10uF 25v caps. But other then that, it looks alright to me.

 

[spadad128]

Thanks for the response and advice. You are right about C15 and 16 on the tone amp being 2.2uF 25v caps instead of 10uF 25v caps. I'll order those instead. Appreciate the help!

 

[markthefixer]

q6 ksa1013 512-KSA1013YBU is in stock - typo perhaps?

3. C10 on the power supply board is also not in stock (647-EHE2A471MHD6). Looks like I could use 647-EHE2A471MHD instead.

neither number responds on mouser, i can't look up the volts and uf for c10 right now to come up with an alternative.

what the HECK is an 647-ehexxxxxxxxx??????

i don't have time to solve puzzles right now... sorry.... life intervenes this month too

 

[spadad128]

ehe[/B]xxxxxxxxx??????

my apologies for the typo. It should have been AWR-102 C10 647-UHE2A471MHD6. But, with your help and mattsd's help, I have all the information I need to place the order. Thanks to both of you!

 

[spadad128]

Received parts today and am ready to start work on amplifier board. I've been following the dialog between sm1tty and MTF (and other posts) and am confident I can move ahead on this, knowing what the pitfalls are. And, I know MTF is very busy now, so think I will be OK. If I get in trouble, I'll beg for help!

 

[markthefixer]

Received parts today and am ready to start work on amplifier board. I've been following the dialog between sm1tty and MTF (and other posts) and am confident I can move ahead on this, knowing what the pitfalls are. And, I know MTF is very busy now, so think I will be OK. If I get in trouble, I'll beg for help!

:sigh: good luck... although luck shouldn't enter into it.

hard to know where the knowledge gaps are (to fill) with no or minimal feedback.


I gotta get that "master thread" written some day...

sigh... it's getting very very late and I am truly tired.

 

[spadad128]

MTF - I'm making great progress. I carefully detached those fragile thermal diodes you warned me about and following your instructions, dropped the amp board awh-059 low enough to work on it without detaching any of the other wires. I replaced Q1,Q2,Q3,Q4 and the elecrolytic caps. I did not remove the output transistors to apply new thermal compound. Maybe that's a mistake, but I cannot see any signs that this unit has been driven hard. The power supply board does not show any heat stress like you've mentioned in other threads.

I used the information you provided to sm1tty to set the bias and idle current. I started with the dim bulb tester to get things close. Then, I put it on the variac starting at about 60v and carefully went back and forth between VR3 and VR4 tweaking them over and over as I increased the voltage. The protection kicked in at 85V and stayed in and there are no more pops in the speaker!

As you have said before, "life intervenes" in my case it was "wife intervenes". So, I haven't made as much progress as hoped but that's OK. I am delighted that with your guidance, I have been able to solve the underlying problem. You led me right to it, I would not have known where to start without your help. Next, I have to rework the tone amp and control boards and then want to replace the caps and Q5 on the power supply board. I already have those parts, so it's just a matter of a few blocks of time.

As for experience, I have little, all of the other electronics work I have done is on tube equipment, again with the help of others, schematics and trial and error. I'm trying to learn as I go, for me fixing things is like solving a puzzle, but I don't really understand electronics very well. I've never repaired a solid state piece before and was scared to try it, but you have enough information posted here, that I decided to give it a try. The info is all there in bits and pieces if you take the time and look hard enough. You could easily write a book with the info you have posted. I also bought a new soldering iron (Hakko 936) that is temperature controlled as I was afraid I would run into problems with the circuit boards if I didn't use the proper equipment. That helped a whole bunch, a very worthwhile purchase even though it set me back about $100.

I'll keep you posted as I tackle the rest of the work. I am delighted with the results so far. It was your advice/guidance that gave me the courage to do something I've never done before and I have learned a lot in the process. Many thanks!

 

[spadad128]

Finished the flat amp board awg-038 caps and transistors (except the 2SK30AW's which I am not replacing), re-cleaned the pots and switches while they were exposed. Re-checked the DC offset again just to be sure everything was still OK and it was.

Now, I've run into a difference between the cap specs for C13 and C14 in the tone amp board awg-039. The service manual shows 10uF 25v CSZA. For replacements, I got UKL1H100KDDANA 10uF 50V from Mouser. But the old caps on the board are actually 2.2uF 50v. There is no name brand on the old caps just a rectangular symbol and "LR" on each cap. They may have been replaced previously but I could not tell it from the solder connections. My inclination is to replace C13 and C14 with the correct 10uF caps instead of 2.2uF caps. Do you agree?

 

[markthefixer]

double post... see below:

 

[markthefixer]

sorry, no I have checked several manuals and they all show 2.2uf

and I checked the various spreadsheets I have collected and all have the 10/2.2 error.

the 2.2 is correct, and if the 10 is used, unwanted rumble could become a problem with saturating the transistor when the bass is turned up. we can't depend upon the previous stages to cut it enough.

you can leave the old ones in for now, and upon your next order get them and put them in. They're not buried deeply, there on the bottom level of the front panel.


better let whomever actually posted the list (that actual author of that post) that you pulled know so it can be corrected.

looks like dec of 2010, although a 2008 text file also had it.

 

[spadad128]

I should have checked more myself. I have two SX-850 manuals. One from HiFi Engine shows 2.2uF 50v on the schematic, but didn't have a foil view or schematic. The other SX-850 manual I have shows 10uF 25V on the foil view, schematic and parts list. Then, I have a SX950 manual which shows 2.2uF 25v on the foil side and schematic, but 10uF 25v on the parts list.

I have a couple extra 2.2uF 50v caps because I ordered a few extras just in case, now I'm glad I did. I'll put these in and will also pass the info along to the person who helped finalize the list. Then, I will start work on the Power Supply board caps.

Know how busy you have been, thanks for doing all the research to help me out.

 

[spadad128]

Dare I say Mission Accomplished?

Completed replacing caps on Power Supply board and replaced Q5 with a KSC2690AYS.

Unit sounds great. Dead silent when it is supposed to be silent and the tone controls work better than they have since I've owned it. I am very pleased with the results. I'll use it some more before buttoning it up, but I believe everything is working as it should and much better than it has in a long time. I am ready to declare "Mission Accomplished".

Thanks to everyone who helped me with this. A special thanks to MTF, I would not have tackled this except I read so many of his posts I convinced myself that I could do it. I appreciate his knowledge, patience and his attention to details.