Lafayette SQ-W service procedures

[Quadchuck]

Has anyone used the Lafayette service manual procedures for aligning SQ-W decoder, and has the results matched what the manual says?
Seems detail is a bit thin.

 

[furui_suterioo]

I just received an SQ-W from Japan which I won for 1yen. It powers on but there is nothing from the main outputs or rec. out. I left it powered on for several hours no change and all the capacitors still feel cold to the touch, it was sold as "junk" so I expected problems but it still looks pretty clean inside. Should I just start replacing the blue caps? Suggestions welcome, thanks.

 

[DuncanS]

I just received an SQ-W from Japan which I won for 1yen. It powers on but there is nothing from the main outputs or rec. out. I left it powered on for several hours no change and all the capacitors still feel cold to the touch, it was sold as "junk" so I expected problems but it still looks pretty clean inside. Should I just start replacing the blue caps? Suggestions welcome, thanks.
View attachment 81957

They actually look in good condition, may be the large one nearest the lower rotary switch isn't (a bit of brown gunk on its top), if they've seriously gone bad they're normally puffed up at the top and lots of gunk. If you're getting no output from any channel it'll most probably be the power supply.

 

[Doug G.]

Right. Don't shotgun. I have found capacitors actually seldom are bad in these types of equipment. The first thing to do is check voltages from the power supply.

Doug

 

[bill114]

I used an SQ-W for many years (I have 2) till I got my SMv3 earlier this year. First, get the service manual from hifi engine. The most common problem to start with is the electrolytic caps on the output board (EPO-193). Those are most likely the culprit for no output. They may look ok but they're not. Both of mine had that problem. Also it couldn't hurt to refresh the power supply caps which are on the same board as well as the rectifier diodes which caused hum on both of my units. I also replaced the p.s. voltage regulator. Of course, you'll want to confirm that the proper power supply voltages are present for proper operation.

 

[par4ken]

The larger capacitor beside the selector switch looks brown on top, that would be most suspect. The power regulator is a very simple design. Referencing the schematic it's easy to check all the voltages.

https://www.hifiengine.com/manual_library/lafayette/sq-w.shtml

 

[furui_suterioo]

Thank you everyone for your replies.
In regards to changing out the large caps on the EPO-193 board, would there benefit to using some film capacitors or be best to stick with electrolytic caps?
Thanks

 

[DuncanS]

Thank you everyone for your replies.
In regards to changing out the large caps on the EPO-193 board, would there benefit to using some film capacitors or be best to stick with electrolytic caps?
Thanks

For the power supplies you won't get film caps with the same Capacitance value as the Electrolytics

 

[bill114]

Thank you everyone for your replies.
In regards to changing out the large caps on the EPO-193 board, would there benefit to using some film capacitors or be best to stick with electrolytic caps?
Thanks

Use 'lytics for the p.s. and film for the rest