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SX-1250 Right Channel Distorted.

Stevesmullen

Stevesmullen

Well-Known Member
Hey Guys.
I just aquired a Mint SX-1250 that has supposed distortion in the Right Channel.
The Unit came from a shop that the customer declined the work,the work order parts list states that it needs (4) 22,000mf 80volt caps and some misc caps.
I didnt bother to hook speakers up to it yet just hooked up the dim bulb tester first to make sure that nothing was pulling to much current (all was okay there)
Plugged the unit in to wall power with all the covers off and tested voltage at the 4 main cap terminals.
The left side checked good at +65 and -65 vdv but the right side had -42 and +65 vdc.
All the caps are just starting to leak but didnt make a mess yet.
"Mark" Can I power up the Amp with the 4 main caps unplugged to test for supply voltage?? I WONT DO ANYTHING without approval first:D I would think that it would be okay to do with out a load because if Im right the caps are there to store power for the OPs.
What are the part#s for the 4 Caps and what other caps should I replace to freshen this unit up?
Thanks Steve
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Stevesmullen said:
Hey Guys.
I just aquired a Mint SX-1250 that has supposed distortion in the Right Channel.
The Unit came from a shop that the customer declined the work,the work order parts list states that it needs (4) 22,000mf 80volt caps and some misc caps.
I didnt bother to hook speakers up to it yet just hooked up the dim bulb tester first to make sure that nothing was pulling to much current (all was okay there)
Plugged the unit in to wall power with all the covers off and tested voltage at the 4 main cap terminals.
The left side checked good at +65 and -65 vdv but the right side had -42 and +65 vdc.
All the caps are just starting to leak but didnt make a mess yet.
"Mark" Can I power up the Amp with the 4 main caps unplugged to test for supply voltage?? I WONT DO ANYTHING without approval first:D I would think that it would be okay to do with out a load because if Im right the caps are there to store power for the OPs.
What are the part#s for the 4 Caps and what other caps should I replace to freshen this unit up?
Thanks Steve
Click to expand...

Don't disconnect anything to test.

Did the protection click on when you took the readings? Either way you can check the dc offsets now, (but the -42 may be upsetting that channel) along with the power supply readings: (+/- 65v, +/-25v, +13.5v & +5.4v, I think you have the hang of finding and measuring the raw dc input and regulated dc outputs, schematic is on page 78 of 94 in the pdf). You will see the power supply voltages are adjustable, DON'T for now....

Any other parameters are useless until we get the supples settled, so mostly we wait until the 4 big caps have been replaced.

Obviously that -42v cap has to be replaced, then the unit powered back up and thoroughly checked out.

Since the big caps are starting to leak, order and replace all 4. While you are waiting for the big ones, start making up a list of all the electrolytic caps in the unit, for a recap. Use the manual, and if somebody has posted or posts a list, that's gravy. Otherwise, YOU'LL be the guy with the posted list.

An excel type spreadsheet would be a good way to generate the list. Comrade_boris has done one for the 850 that should give you a HUGE headstart on finding the caps vs parts numbers etc..
http://www.audiokarma.org/forums/showthread.php?t=163029
I'll give some pointers on the nichicon - mouser search later.

Once you think you have a list of parts & values (BUT NOT the mouser numbers) together, then I'll take a look at it, and we'll see what changes are needed. Bascally any value below 0.1 uf probably isn't an electrolytic. you will start to recognize the codes pretty quickly in the service manual's parts lists....

The physical work necesary (and the risk) to get at the tone and control boards is the same for just deoxiting, or recapping those boards. We'll have a better idea with the correct voltages what is involved. Then get the other recap caps. And maybe replace the bias and offset trimmers on the amps as well, they're both 500 ohms...

THis link:
http://www.audiokarma.org/forums/showpost.php?p=171612&postcount=10
will get you going on the caps, also a quick fleabay search using this string:
(35000uF,22000uF) (80v,100v)
copy and past it as a search term

will come up with two current listings.

They are BOTH EchoWars approved values, the soft start circuit allows higher capacitance...
(p.s. both the 1050 and 1250 use 22000uF 80v caps, but the 1250 uses FOUR..)


I have delt with the seller before and it beats 150.00 or more from industrial sources.
 
markthefixer said:
Any other parameters are useless until we get the supples settled, so mostly we wait until the 4 big caps have been replaced.

Obviously that -42v cap has to be replaced, then the unit powered back up and thoroughly checked out.

Since the big caps are starting to leak, order and replace all 4.
Click to expand...
That is what I was thinking other than wondering if I could check supply voltage (which I will not do at this point).And yes the Protection relay did click once.
I would like to get the oder in tommorrow if possible at least for the main caps,but I will get busy on the rest tonight.
Thanks Steve
 
Stevesmullen said:
That is what I was thinking other than wondering if I could check supply voltage (which I will not do at this point).And yes the Protection relay did click once.
I would like to get the oder in tommorrow if possible at least for the main caps,but I will get busy on the rest tonight.
Thanks Steve
Click to expand...

BEFORE ordering, CHECK the physical dimensions for fit. The closer the diameter is to original, the less futzing around to mount it, and of course, TOO Tall is baaaad...
 
markthefixer said:
BEFORE ordering, CHECK the physical dimensions for fit. The closer the diameter is to original, the less futzing around to mount it, and of course, TOO Tall is baaaad...
Click to expand...
I was also wondering about the size knowing that most newer caps are physically smaller.
I will get going on this.
Thanks Steve
 
Absolute best cap for the job...United Chemi-Con (Nippon Chemi-Con) #36DA223F100CD2A, 22,000µf 100V, 63mm x 118mm (2.5" x 4.625"). About $27 each from Newark.

There are others, but this is the King.
 
Thanks EW.
I dont have the SM loaded on my home computer and I still cant get in so I will just have to start the list off of the unit itself.
Steve
 
Hey Mark.
Here is a rough draft of the Caps in Notepad for now,I will update it as we go and fiqure out eactly what we will be ordering.
These are the Caps that are Physically on the Boards.
SX-1250 Capacitors
Main Power Supply Caps (4 Large ones)
qty4) 22,000uf 80volt Radial (dimensions) 2.5 inches X 4.75 inches (screw posts)
Newark Part# 36DA223F100CD2A @ $27.00 each EW's Choice

DC Power Supply Board (AWR-106-A) Mouser part #s
C1,C2 (qty2) 220uf 80volt Radial
C15,18,19 (qty3) 47uf 10volt Radial
C17 (qty1) 220uf 16volt Radial 647-UVZ1E221MPH @ $0.35 ea nichicon vz
C16 (qty1) 22uf 10volt Radial
C9,C10 (qty2) 100uf 35volt Radial 647-UPW1H101MPD $0.50 100uf 35V
C11,C12 (qty2) 47uf 80volt Radial
C7,C8 (qty2) 22uf 50volt Radial 647-UHE1H220MDD $0.15 22uf 50V
C5,C6 (qty2) 47uf 35volt Radial
C13 (qty1) 1000uf 25volt Axial

Power Amplifier Boards AWH-048 (total includes both sides) Mouser part#s
C15,C16 (qty4) 470uf 80volt Radial 647-UPW2A471MHD @ 1.92 ea nichicon pw
C2 (qty2) 10uf 16volt Radial 647-UVZ1V100MDD @ $0.06 ea nichicon vz
C5 (qty2) 220uf 16volt Radial 647-UVZ1E221MPH @ $0.35 ea nichicon vz
C11(qty1) 0.22uf 10volt Radial
Protection Circuit Board AWM-091 (Mouser part#s)
C4 (qty1) 100uf 16volt Radial (100/35) 647-UPW1V101MPD $0.15 protection circuit timing capacitor
C5,C6 (qty2) 100uf 50volt Radial (100/50) 647-UPW1H101MPD $0.50 protection circuit voltage regulator
C1,C2 (qty2) 470uf 6.3 volt Radial (470/16) 647-UPW1C471MPD $0.52 protection audio input.
C3 (qty1) 4.7uf 25volt (4.7/50) 647-UPW1H4R7MDD $0.23 protection circuit ac power on signal integrator

Equilzer amplifier assembly AWF-021 replacement electrolytic capacitor parts numbers:
from mouser.com
647-UPW1E471MPD $0.68 470uf 25V C11,C12 (in stock) f/b cap
647-UPW2A3R3MDD $0.31 3.3 uf 100V C17,C18 (in stock) f/b cap
647-UHE1H220MDD $0.15 22uf 50V C25,C26,C30,C31 (in stock) coupling cap
-----
647-UPW1J221MPD6 $1.05 220uf 63V C27,C28 (in stock) pwr supp
OR
647-UPW2A221MHD $1.48 220uf 100V C27,C28 ** PREFERRED ** (in stock) pwr supp
-----
647-UPW1H101MPD $0.50 100uf 35V C29,C32 (in stock) pwr supp
__________________

All Caps are Polarized unless noted
Just storing info here until we have a final list.Then I will put it into the proper format.I will keep updating this post.
 
Hey.
I talked to Newark this morning and they have the 22,000 100volt Caps in stock no problem.
As far as the other caps we needed to know the grade and the tolerance,Im not sure if EW or Mark has the part#s or were going to fiqure that out.There are so many options I just want to make sure that I get the right ones and that we get the part#s right on the spreadsheet so that we dont have to do this again in the future.Should we use Mouser Part#s for the rest of the caps for the Spreadsheet for when people want to put in small orders?
I would also like to do the same for the SX-1050,I could probobaly find most of the #s in the posts and what I have copied and saved.Check post#8 for changing updates.
Steve
 
Stevesmullen said:
Hey.
I talked to Newark this morning and they have the 22,000 100volt Caps in stock no problem.
As far as the other caps we needed to know the grade and the tolerance,Im not sure if EW or Mark has the part#s or were going to fiqure that out.There are so many options I just want to make sure that I get the right ones and that we get the part#s right on the spreadsheet so that we dont have to do this again in the future.Should we use Mouser Part#s for the rest of the caps for the Spreadsheet for when people want to put in small orders?
I would also like to do the same for the SX-1050,I could probobaly find most of the #s in the posts and what I have copied and saved.Check post#8 for changing updates.
Steve
Click to expand...

That's why EchoWars says for replacement caps:
Use Panasonic FC or FM, and Nichicon PW or HE
which now translates to:
Use Panasonic (digikey) FC or FM, and Nichicon (mouser) UPW or UHE
THAT takes care of almost ALL the details... (sometimes there are two sizes of the same cap value, usually taller/thinner and more $$)

Looks like you are on the right track...
(don't forget things like the C11 0.22 uf 10v caps for the overcurrent detector on the amp card)
 
Hey Mark.
C11 is miss labeled on the schematic I dont think that it is electrolytic,it looks like a mylar or something.
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Stevesmullen said:
Hey Mark.
C11 is miss labeled on the schematic I dont think that it is electrolytic,it looks like a mylar or something.
Click to expand...

They are tantalum electrolytic capacitors. You don't want to pass audio through them, plus they have a terrible tendency to short, fail out short, and overvoltage short...

They are supposd to be long term stable.... but.....:scratch2:

So we generally get rid of ALL tantalum caps....

With those amp caps in that position you have the opportunity to go non-polar.

edit: glenn beat me... yup. plenty of room for those there...

edit:edit: Hey!! what's the number of that big square transistor sticking up about an inch away, between the cap and the transistor on the heatsink?????
 
markthefixer said:
edit:edit: Hey!! what's the number of that big square transistor sticking up about an inch away, between the cap and the transistor on the heatsink?????
Click to expand...
Q8 part# (100) on the top row then (A899 A).
Could I get some Mouser part#s for the 7 remaining Caps on my list?
Unless it is to much of a pain then I will keep searching the Posts.
Thanks Steve
 
Here's how to search mouser.com:

for example a 220uF 80v radial:

first page search box, type in: 220uf nichicon upw and hit the search button.

it will come back with a page showing 33 matches, click on the "stocked" checkbox, then go through the voltage rating selection box and click on 100v.(63 is too low and 160 is too high...)
To highlight more than one box, hold down the control key and click on each of them,
or click one, scroll down to another box, hold the shift key and click on the bottom one to highlight everything in between.


Then click on "apply filters".

it will come back with just: 647-UPW2A221MHD ........

the next example is the 47uf 10v radial.

on the TOP search box (starts a NEW search) type in 47uf nichicon UPW and hit the search button.

it will be slightly confused and offer two capacitance selections, click on 47uf
and then on "stocked" and 10v 16v 25v 35v and hit "apply filters"
To highlight more than one box, hold down the control key and click on each of them,
or click one, scroll down to another box, hold the shift key and click on the bottom one to highlight everything in between.


it will come back with 5 choices in 4 voltages... pick the 10v part (for now, a higher voltage might be recommended for the power suppply after I check)

647-UPW1A470MDD6

and so on...

the 0.22 doesn't get a hit on 0.22uf nichicon upw or 0.22uf nichicon upw but it does on 0.22uf nichicon

It will then give 2 choices:

Passive Components
• Aluminum Electrolytic Capacitors (48)
• Film Capacitors (8)

we will click on "stocked" again and then we will remember what EchoWars said about film capacitors here, and click on the • Film Capacitors (8) link

it will ask us:
Film Capacitors
• Polyester Film Capacitors (7)
• Polypropylene Capacitors (1)

BUT we will see only one part number is actually in stock: 647-QXK2G224KTP
 
Thanks.
I will get on the web site,just knowing the brand will be helpful.
Newarks web search was even more confusing than Mousers when you dont know the difference between all the options.
Steve
 
markthefixer said:
That's why EchoWars says for replacement caps:
Use Panasonic FC or FM, and Nichicon PW or HE
which now translates to:
Use Panasonic (digikey) FC or FM, and Nichicon (mouser) UPW or UHE
THAT takes care of almost ALL the details... (sometimes there are two sizes of the same cap value, usually taller/thinner and more $$)

Looks like you are on the right track...
(don't forget things like the C11 0.22 uf 10v caps for the overcurrent detector on the amp card)
Click to expand...

I didn't (and don't) leave you hanging.............^^^^^^^^^^^^^^^^^^^^^ :D

when I googled the BIG number 36DA223F100CD2A EchoWars posted, the first page had a Newark link that went straight to it....
 
Hey Mark.
Well My New 22,000mf 100 volt caps came in today. :banana:
They do fit exactly as the originals with the exception that the terminal screws are 8/32 on the originals and 10/32 on the replacement Caps I just had to enlarge all the terminal and bridge holes slightly but other than that they fit great.
After getting them in and double checking all of my connections I flipped the switch with the Dim Bulb tester (sure lights that sucker up compared to the smaller units) all looked good so I went to wall power and tested the voltage at the caps and it was perfect at +65 and -65 vdc.
From there I checked the Power Amplifier DC offset and Idle current both of which were either right on or very close,then I checked the Stabilizer (power supply) voltage and it was right at -64 and +64 vdc.
Finally Hooked up the HPM-100s and let it rip.:banana:
It sure does sound good,I just wish that I could have heard it before the new caps to hear the difference.
I still need to clean and lube the pots and switches and Completely Recap the power Supply board and the Power Amp Boards yet.
Tommorow I will put it up against the SX-1080 and see how I like the sound quality between the two units.
I will also make some time and get the SX-1250 Complete Recap list organized and look up the missing caps.
I just had to play for a little bit.
Thanks Once Again for your help.
Steve.
 

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Hey Mark.
Here is the Partial SX-1250 Capacitor Spread Sheet,there were alot of Mouser Part#s that were out of stock so I had to look up the next available.
Please let me know if you see any errors as I would like to get a order in Tuesday for the 850 and 1250.
Thanks Steve
 

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Stevesmullen said:
Hey Mark.
Here is the Partial SX-1250 Capacitor Spread Sheet,there were alot of Mouser Part#s that were out of stock so I had to look up the next available.
Please let me know if you see any errors as I would like to get a order in Tuesday for the 850 and 1250.
Thanks Steve
Click to expand...

It would be helpful to note where the axial capacitors are...

Other than that I can see where and why the decisions were made...

You are definitely on the right track.

Of course there are a lot of caps to go....
 
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