Sansui AU-G55X, AU-G50X, AU-G30X and AU-G33X) Disassembly (aid) Notes. - UK Vintage Radio Repair and Restoration Discussion Forum

lloydie_p · 11th Jun 2023, 12:06 pm

Sansui AU-G55X (I suspect applies to AU-G50X, AU-G30X and the AU-G33X) disassembly (aid) notes.

I'm not sure what Sansui was thinking, but I suspect if you are reading this it's either because you have balance pot issues (seems to be common on the G5xX and G3xX series) or you need to clean/fix something towards the front facia of the amp.

For starters don't try to pull the nobs (Treble, Bass, etc..) off to disassemble, they are locked in place! I don't know what Sansui were thinking as I've never seen such "evil" before, for good measure just to throw you off the Volume nob doesn't seem to have this locking mechanism.

Please note I haven't managed to "fully" disassemble the unit (not sure if this is possible) but I have managed to disassemble it to a point where you can access, remove and repair all the PCBs inside the unit.

So the steps are:
Remove the top and bottom covers, normal disassembly logic applies.
Remove the 4 screws at the rear holding the plastic sides in place, again normal disassembly logic applies.

And now for the black magic bit, basically the front (fascia) and the left and right plastic panels together are supposed to be separated from the remainder of the metal chassis, basically like two halves.

To achieve this you will need to cut quite a few cable-ties and disconnect (I initially disconnected more than I need to, so pay closer attention) various cables interconnecting the PCBs on both halves. Thankfully connections are just push connectors so no desoldering. The two tiny PCBs for the power LED and I think what is a bulb for the VU meters need to be just unclipped (one of my blub PCB's clips was already broken... delicate to boot?). The power switch PCB and power cord need (would suggest) to be unclipped from the righthand side (from the rear) plastic panel. Lastly, you'll need to unscrew rear input RCAs from the metal "half" of the chassis. Now after further "finessing", you should be able to cleanly separate the two chassis halves (Plastic and Metal).

Now you should (I've only removed the balance pot PCB so far) be able to access and remove (Plastic slots with clips, gently lever the plastic slots outwards to release the PCB... still fiddley) the relevant PCBs attached to the fascia.

Hope this helps someone and keeps otherwise great Amplifiers working, some say this was Sansui just trying to be cheap, but the effort to create this design, the interconnects, the multi-part heatsinks, the quality parts (a large transformer, 10000uF caps etc...) just doesn't add up, I suspect they were more just trying to save on assembly (time) costs and experimenting with new materials to produce an otherwise decent quality affordable product... but this ultimately backfired.

Me in the future... the Balance Potentiometer (Pot) can be repaired or at least in my case it was the metal wiper towards the rear half of the Pot, it would easily fall out/off once the pot was disassembled, but I don't think this should be the case. Out frustration (reassembled before thinking a clean alone would do the trick) I put the wiper back in place and used my soldering iron (didn't have glue/epoxy to hand) to melt the top(s) of the incredibly small plastic guides that should be holding the wiper in place and so far so good. I would recommend epoxy/glue as if my melted plastic breaks/cracks the guides will probably be non-existent so more complicated repair if even possible.

John_BS · 16th Jul 2023, 2:08 pm

Thanks for posting this. Did you find out how to "unlock" those knobs?

John

lloydie_p · 20th Jul 2023, 11:51 pm

Hi John, I don't think the knobs can be removed or at least without making some type of tool I can't fathom. As each of the boards (PCBs) can be removed from the fascia, once dissemble like I've described, you'll never end up having to line up more two knobs (potentiometers) at time to re-insert/refit the PCBs.

The knobs are held in by 6 - 8 very stiff clips (see image) thus you'd need to flex at least half them to pop the knob out...when I attempted it felt I had a greater chance of breaking them than removing them... but like I said you don't really need to attempt to remove the knobs... unless your trying fix a broken knob.

11th Jun 2023, 12:06 pm	#1
lloydie_p Diode Join Date: Jun 2023 Location: Croydon, Greater London, UK. Posts: 2	Sansui AU-G55X, AU-G50X, AU-G30X and AU-G33X) Disassembly (aid) Notes. Sansui AU-G55X (I suspect applies to AU-G50X, AU-G30X and the AU-G33X) disassembly (aid) notes. I'm not sure what Sansui was thinking, but I suspect if you are reading this it's either because you have balance pot issues (seems to be common on the G5xX and G3xX series) or you need to clean/fix something towards the front facia of the amp. For starters don't try to pull the nobs (Treble, Bass, etc..) off to disassemble, they are locked in place! I don't know what Sansui were thinking as I've never seen such "evil" before, for good measure just to throw you off the Volume nob doesn't seem to have this locking mechanism. Please note I haven't managed to "fully" disassemble the unit (not sure if this is possible) but I have managed to disassemble it to a point where you can access, remove and repair all the PCBs inside the unit. So the steps are: Remove the top and bottom covers, normal disassembly logic applies. Remove the 4 screws at the rear holding the plastic sides in place, again normal disassembly logic applies. And now for the black magic bit, basically the front (fascia) and the left and right plastic panels together are supposed to be separated from the remainder of the metal chassis, basically like two halves. To achieve this you will need to cut quite a few cable-ties and disconnect (I initially disconnected more than I need to, so pay closer attention) various cables interconnecting the PCBs on both halves. Thankfully connections are just push connectors so no desoldering. The two tiny PCBs for the power LED and I think what is a bulb for the VU meters need to be just unclipped (one of my blub PCB's clips was already broken... delicate to boot?). The power switch PCB and power cord need (would suggest) to be unclipped from the righthand side (from the rear) plastic panel. Lastly, you'll need to unscrew rear input RCAs from the metal "half" of the chassis. Now after further "finessing", you should be able to cleanly separate the two chassis halves (Plastic and Metal). Now you should (I've only removed the balance pot PCB so far) be able to access and remove (Plastic slots with clips, gently lever the plastic slots outwards to release the PCB... still fiddley) the relevant PCBs attached to the fascia. Hope this helps someone and keeps otherwise great Amplifiers working, some say this was Sansui just trying to be cheap, but the effort to create this design, the interconnects, the multi-part heatsinks, the quality parts (a large transformer, 10000uF caps etc...) just doesn't add up, I suspect they were more just trying to save on assembly (time) costs and experimenting with new materials to produce an otherwise decent quality affordable product... but this ultimately backfired. Me in the future... the Balance Potentiometer (Pot) can be repaired or at least in my case it was the metal wiper towards the rear half of the Pot, it would easily fall out/off once the pot was disassembled, but I don't think this should be the case. Out frustration (reassembled before thinking a clean alone would do the trick) I put the wiper back in place and used my soldering iron (didn't have glue/epoxy to hand) to melt the top(s) of the incredibly small plastic guides that should be holding the wiper in place and so far so good. I would recommend epoxy/glue as if my melted plastic breaks/cracks the guides will probably be non-existent so more complicated repair if even possible. Attached Thumbnails

16th Jul 2023, 2:08 pm	#2
John_BS Octode Join Date: Dec 2008 Location: Wincanton, Somerset, UK. Posts: 1,786	Re: Sansui AU-G55X, AU-G50X, AU-G30X and AU-G33X) Disassembly (aid) Notes. Thanks for posting this. Did you find out how to "unlock" those knobs? John

20th Jul 2023, 11:51 pm	#3
lloydie_p Diode Join Date: Jun 2023 Location: Croydon, Greater London, UK. Posts: 2	Re: Sansui AU-G55X, AU-G50X, AU-G30X and AU-G33X) Disassembly (aid) Notes. Hi John, I don't think the knobs can be removed or at least without making some type of tool I can't fathom. As each of the boards (PCBs) can be removed from the fascia, once dissemble like I've described, you'll never end up having to line up more two knobs (potentiometers) at time to re-insert/refit the PCBs. The knobs are held in by 6 - 8 very stiff clips (see image) thus you'd need to flex at least half them to pop the knob out...when I attempted it felt I had a greater chance of breaking them than removing them... but like I said you don't really need to attempt to remove the knobs... unless your trying fix a broken knob. Attached Thumbnails