SX-1250 Intermittent loss of signal

[Jackwebb1965]

So my old SX-1250 works, but every so often the left side just cuts out tap the top of the volume knob and it comes back. after awhile the right side will crackle for a couple of seconds then settle down, and work fine. if you adjust the volume knob it crackles on both sides and the left cuts out till again you tap the top. any ideas what is up with it any help would be greatly appreciated

 

[Mr.Heatsink]

It most likely needs Deoxit cleaning. Mentioned in this forum and all the others Marantz, Sansui, Kenwood etc. Look for pot and switch cleaning. You'll have to manually search as the search function is still non op.

 

[Mr.Heatsink]

Welcome to AK btw!

 

[Jackwebb1965]

Hey thanks man for both the warm welcome and the advice. I just had it worked on last year but I'm trying to do all the work myself from here on out

 

[SimplerTimes]

The 1250 has a sealed Alps volume pot. It is rather difficult to get deoxit to the internals. IIRC there is a method involving carefully drilling a hole in the housing but I’ve never done it myself. There are threads here on AK on how to do it though, or maybe someone more knowledgeable can chime in…

 

[kwayde]

You'll have to pull the board the volume control is on, remove the control from the board, loosen the small bolts that hold it together enough to slide small pieces of cardboard in the gaps to be able to spray in some Faderlube (Deoxit F5). I used small pieces of a cereal box. Don't totally remove the bolts, just watch the small nuts to see where you want to stop loosening without it coming apart.

Spray the cleaner in the gaps you just made, pull the cardboard out and rotate the control back and forth about four dozen times. Put the cardboard back in then blow dry the control. I used a hair dryer set at no heat. The control is good to go, but while you have it this far apart you'll want to clean the rest of the controls.

This link will help with how to deoxidize the unit: https://audiokarma.org/forums/index.php?threads/the-idiots-guide-to-using-deoxit-revisited.207005/

The second pic shows where somebody tried to clean the control by just tearing off the label stuck to the back and spraying cleaner in that area. That didn't help a bit. I cleaned it good and taped the back of it to seal it up.

View attachment 2858973

 

[Jimbo40]

Try this first.
Work all controls back and forth though there entire range of motion 10 20 or 30 times.
Concentrate on volume, balance, tape Mon, tone but do them all.
Don't be violent slamming them on the stops.
You should have significant improvement after that.
If things change or improve then the pots were dirty.
Cleaning these pots is not as simple as just spraying them like the usual. These are sealed and need to be desoldered and carefully cracked open.
If nothing changes it could be a cold cracked solder joint.
Please post your findings

 

[koolkat62]

I have to clean mine too. I really would like to take it apart to do it tho..in order to really clean it throughly and just do it once for another 20 years or so. Is this possible?