Restoring an SX-1050 questions

NealinNevada

THE Bozak Museum of NV
Good evening folks...I just got an SX-1050 on Thursday night for $100 in pretty good cosmetic shape, but with a couple of small issues. The first obvious problem is that I would have to turn the volume knob back and forth to get the right channel working. Once I got it working by jiggling the volume control the unit worked beautifully, until I changed the volume...then the right channel would drop out and I would have to jiggle the volume control to get the right channel working again. I figured it was oxidation, so all the switches and pots will get the treatment. I started the pot cleaning by dropping the board which contains the volume pot (the board also contains the balance and a punch of toggle switches. I then saw a volume control I have never seen before...it is a square pot with small screws in each corner (see picture below). I stopped at that point for some advice of those who have walked this way before me. How do you clean a pot like this? Do I have to open it (I don't see any openings to spray into)? What do I need to look for when I open the pot (if that is the way to clean it)? Any advice on this pot in particular and any hints in general for cleaning all the switches and toggles would be most appreciated :thmbsp:!
 

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Deoxit and faderlube everything but the pot first, and check the pot's solder connections.]

THEN see if the problem persists. If so, then the risk of opening / disassembling the pot is justified.

I haven't opened (or needed to) one of those models to inspect the internals, but the next step up "pots" (stepped attenuators with switches and thick film printed and trimmed resistors) with ceramic substrates are gold plated - thus NOT needing attention - and risky because that ceramic substrate is brittle.

I do not know what the substrate on that part is, and the very dirty 1280 that I just shipped had NO problems with that exact pot - and it wasn't worth the risk of opening it just to satisfy my curiosity.

I DID have to remove, open and clean (with a soft pink eraser) all the lever switch contacts on that 1280, they resisted Deoxit and I wasn't going to spend several days deoxiting until it cut through the corrosion layers. So one of your lever switches could be getting just enough vibration from the volume control's actuation to make and break contact.

Removing the switches isn't for everybody - lots of tricky desoldering as well as pins that were bent to hold the switches in before wave soldering, and THEN there is the matter opening the switches without destroying them OR LOOSING PARTS...

The lever switch contacts are just above where they are soldered into the pc board, you will see a moving block of white plastic, this block has channels cut into it lengthwise to clear the stationary contacts, and recesses for the moving contacts.

Luckily when you spray deoxit right into the cracks at the bottom it gets everywhere, including where it needs to be.
 
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Thanks for the info Mark...Where would you try to spray the de-oxit in that volume pot (in my first post picture)? On other pots I have always found a place to spray the de-oxit into...in this pot it seems like a sealed unit with no place to spray into. I don't want to take the pot apart unless absolutely necessary...In fact, I might try to find a replacement pot first BEFORE I took the old one apart (just to know I have a replacement on-hand before my inevitable screw up).
 
...Where would you try to spray the de-oxit in that volume pot (in my first post picture)?.
If this pot really needs to get cleaned, it has to be desoldered from the board, and the long screws removed so you can gently pry it apart just enough to get some Caig Faderlube shot into it. Not a fun job, and with the way the pot contact pins are soldered in, it is very easy to destroy the foil traces on the PC boards.
 
If I recall that sticker on the back can be punctured and allow access for the deoxit to be sprayed through, that may or may not have been the volume control.
 
that is an ALPS type of pot. Most can not be taken apart. Sometimes you can get DeoxIt into the unit from where the connectors enter the the unit, but most of the time not. I found the best way to service these is to drill a small hole in the side with a hand drill. I describe the process here...
http://www.geocities.com/cdkands/AU717-7

Some folks really dislike this approach, but I have done this many many times with 100% success. With a sealed unit there is little else you can do. Even though there are little nuts and bolts in each corner, the problem is that many of these types of pots have a retaining clip on the center shaft. Removing the nuts and bolts allows the unit to pried apart, allowing a needle applicator to be forced into the small opening between the sections. There is far more chance of damaging the unit with this approach then by drilling a small holes for a needle applicator.

Check for access from the bottom first, you might get lucky and have access.
 
The vol. pot is used on the SX-1250 and 1050. There is a label on the back of the switch that you can punture thru and spray deoxit into the pot. You'll need to spray it all around the side, top and sides. Work the hell out of the pot and let sit for awhile then do it all over again and let sit for ~12-24 hrs. then use a bit of Faderlube and work it in. Had the same problem with my 1250 and worked like a charm the second time around when I recapped the board.
 
I'm going to follow Mark's advice and clean/lube all the other switches and pots first, then see if the problem persists. If it does, then I can follow the suggestions of going through where the label is (thanks, I ASSUMED :no: the label was on a solid surface, but after reading mhk87's and Eagle1's posts I checked the pot and there are definitely openings under the sticker to try deoxit in). I looked at the solder joints on the board and they look good under a hand lens. I won't be able to start this until next week due to a full plate of jobs I have, but I will report back after I get into it.

Finally, if none of this works, I will follow the instructions provided by megawatt in the link provided...a question for megawatt or anyone else with experience though. This is an Alps ACV-198-A pot and it only has three sections, not five as in the link megawatt provided. Is there any way to determine which of the sections would need to be drilled for the deoxit treatment?

Once again, I am indebted to everyone for advice and input :thmbsp:!
 
The SX-1050 is one of my personal favorites.:yes: Plenty of power and great looks too!:yes: I've always got to have at least one nice 1050 in the stable.:thmbsp:
 
Thank you to everyone!

In the other room, I have an SX-1050 that is now running perfectly due to the assistance I have received in this thread :thmbsp:. I followed Mark's direction and cleaned all switches and pots on the unit...still no luck, the volume pot would only work intermittently. I then tried Eagle1's suggestion and cut off the paper tag on the back of the volume pot and squirted a bunch of Deoxit and worked the pot a few hundred times, let it sit overnight and tried again...still a balky volume pot. I got out my drill and started the operation described by megawatt, drilled a hole (just big enough to accept the red tube of the deoxit can) in segment #1 and segment #2 of the volume pot. Note: When I squirted into the hole I drilled, you could see Deoxit coming out the back of the pot where I had removed the paper label...so we know that Deoxit got into the pot when I tried Eagle1's suggestion. I then worked the pot a few hundred times, squirted some Faderlube into it and worked it some more. After re-attaching the switches & pots, I plugged it in and IT WORKS PERFECT :banana:!!!

I am now going to put the unit into regular service...move the SX-780 in the kitchen to a spare bedroom and the SX-1050 running EPI 200 speakers becomes the kitchen system. But, before I do that I am going to join Audiokarma as a supporter...MY SINCERE THANKS TO ALL OF YOU!
 
Doing that procedure really calls for a solid depth stop on the drill bit to avoid inadvertently going too deep.
 
Thank you to everyone!

In the other room, I have an SX-1050 that is now running perfectly due to the assistance I have received in this thread :thmbsp:. I followed Mark's direction and cleaned all switches and pots on the unit...still no luck, the volume pot would only work intermittently. I then tried Eagle1's suggestion and cut off the paper tag on the back of the volume pot and squirted a bunch of Deoxit and worked the pot a few hundred times, let it sit overnight and tried again...still a balky volume pot. I got out my drill and started the operation described by megawatt, drilled a hole (just big enough to accept the red tube of the deoxit can) in segment #1 and segment #2 of the volume pot. Note: When I squirted into the hole I drilled, you could see Deoxit coming out the back of the pot where I had removed the paper label...so we know that Deoxit got into the pot when I tried Eagle1's suggestion. I then worked the pot a few hundred times, squirted some Faderlube into it and worked it some more. After re-attaching the switches & pots, I plugged it in and IT WORKS PERFECT :banana:!!!

I am now going to put the unit into regular service...move the SX-780 in the kitchen to a spare bedroom and the SX-1050 running EPI 200 speakers becomes the kitchen system. But, before I do that I am going to join Audiokarma as a supporter...MY SINCERE THANKS TO ALL OF YOU!
By any chance can you describe where you drilled the hole? I'm having the same issue, but I tried the Geocities link but no longer works . Just want to make sure I'm drilling the hole in the right place
 
I usually unscrew the screw out just a bit, then wedge a very fine flat head screwdriver in between sections of the pot. I think there are 3 sections, each one gets a blast of Deoxit. Work the shaft back and forth 50 times then a spritz of faderlube and tighten her back up. Work the shaft again 50 times and you are good to go
 
I usually unscrew the screw out just a bit, then wedge a very fine flat head screwdriver in between sections of the pot. I think there are 3 sections, each one gets a blast of Deoxit. Work the shaft back and forth 50 times then a spritz of faderlube and tighten her back up. Work the shaft again 50 times and you are good to go
Thanks, I wanted to try this also but I wasn't sure if opening might dislodge something inside or cause something to come loose inside. I'll give this a try, my problem is that the volume just comes down I already sprayed the -20 dB switch along with all others but this has had no effect. I figured I would try the volume knob next
 
Don't unscrew to far out as to let the nut fall off into oblivion, just enough to get the straw of the deoxit in there.
 
I have also loosened the screws, spread the sections apart slightly and been successful at getting deoxit into the pot on a 1050. This solved the problem of a dirty pot without the risk of drilling.
 
Great I use this method all the time with 1050 and 1250, easier than de-soldering all those legs.
 
Sometimes I use that method, sometimes I make a hole... Drilling is a bad idea. You will get chips inside. I make the hole with a fine tipped soldering iron and seal it with tape or RTV when done. Holes should be on the top edge near one end.
 
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