Faulty Sansui AU101 speaker switch - diyAudio
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Old 8th January 2014, 12:48 PM   #1
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Default Faulty Sansui AU101 speaker switch

Hi guys

This is my first real post here; forgive me asking rather that answering a question, I have very little knowledge regarding electronics but I am willing to learn and pass on what Iíve learned.

Iím in need of some advice regarding an issue with my Sansui AU101 amplifier. The speaker switching switch is defective; I need to wiggle it up and down just to get music to come out and then jam-it in that position hoping music will remain (it doesnít normally which is a pain).

I purchased the amplifier in this condition (due to cost constraints) thinking I could easily fix it, but I have failed to source any information that may help. I also intended to use it as a electronics learning project.

When music does come out it is surprising good, big soundstage and an overall smoothness, what else has amazed me is the power, I believe it has 15 watts but sounds way more powerful with my speakers (Goodmans magnum Ks 1964 model),easily fills my 25x12ft living room.

Does anyone know if I can source an alternative replacement or would it be possible to take it out of the circuit completely.

Iíve included some pics below of the Sansui AU101 and the problematic switch.

Appreciate any help you can give me

Dean
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Old 8th January 2014, 05:41 PM   #2
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Shame about the damage to what is a clean lines, good looking old amp. (I have one around here somewhere too!) Maybe someone with a wreck of one of that early series can help out, since they were very affordable and popular models back in the early 1970s.

The switch only disconnects the speakers when you want to use headphones alone. This is a very old solid state amp without the fancier features like relays and switched 'phone socket so, as you can see in your own pic, the headphone connections (those 330R resistors on flying leads) are permanently wired to the amplifier outputs (the wires to the centre pins of the switches) The other (lower) wires will connect the outputs to the speaker terminals when the switch is in the on (up) position.

Surely you can still manipulate the switch into the on position and leave it there. I guess though, if the whole toggle pivot is also smashed, you will just have to bridge the upper and lower wire connections on either side and that does the same job as the switch contacts in the on position. Use short lengths of solid tinned copper wire, top to bottom on either side there - it doesn't have to be thick wire for that short run either. So, join blue to black, grey(?) to white. That's all.

Hope this is helpful and take care.
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Last edited by Ian Finch; 8th January 2014 at 05:57 PM.
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Old 8th January 2014, 06:13 PM   #3
Mooly is offline Mooly  United Kingdom
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I'd go along with Ian's suggestion too. If you have the broken bit then I'm sure it will glue back on with the tiniest drop of superglue. At least that would maintain the appearance.

I wonder whether it would be worth removing the broken switch and flooding it with WD40, it just might clean up OK.
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Old 9th January 2014, 05:53 PM   #4
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ďHope this is helpfulĒ are you kidding? I am so grateful for your reply and comprehensive Information/advice to the problem; to be honest I wasnít expecting any reply (shame on me for doubting).

Your advice is clear and precise Ian and itís within my capability, so Iím so grateful for it.

I will look forward to having a go soon, would you mind if I placed a picture of what Iím doing on here so that you can have a check that Iíve done it correctly.

ďSurely you can still manipulate the switch into the on position and leave it thereĒ

Unfortunately I think the switch itself has failed (I will try some WD40 as suggested by Mooly), it will not play ball in any position for long.

Thank you once again Ian you have been a great help


Quote:
Originally Posted by Mooly View Post
I'd go along with Ian's suggestion too. If you have the broken bit then I'm sure it will glue back on with the tiniest drop of superglue. At least that would maintain the appearance.



I wonder whether it would be worth removing the broken switch and flooding it with WD40, it just might clean up OK.
Thank you for your input MoolyUnfortunately I haven't got the piece that snapped off, I guess I could try and make something up

I've got some WD40 so I will have a try thanks.

Thanks again Guys

All the best

Dean

PS will report back soon.
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Old 9th January 2014, 06:55 PM   #5
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Pictures are good

A real long shot but if the screw holes are 19mm apart then something like this might fit. Its not ideal, and its only rated at half an amp, but hey, its only a 15 watt amp and your not likely to be actually operating the switch at full volume anyway. Just a thought.

SLIDE SWITCH MINIATURE DPCO - -- - SLIDE SWITCH, DPDT, GREY, PK10 | CPC
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Old 10th January 2014, 01:34 AM   #6
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Since the paddle switch mounts to a sub-panel, you could adapt something to fit, as there are few, if any products still readily available in that mounting format. (I think Mooly has found it! ) For interest, here's a locally available variant of a common universal switch: Altronics - S1250 DPDT Solder Tail Mini Paddle Switch .
It does have a black, flat paddle actuator, dimensions shown but probably won't fit simply. In the 537 web pages of switches in the Mouser catalogue, you find all sorts - here's some C&K brand datasheets: http://www.mouser.com/ds/2/60/7000ro...ec11-16314.pdf
Measure up and think about it. It could still be surprisingly easy once you have something that works. Just ensure it's a double pole type (DPST or DPDT) and the arc of movement will swing wide enough to function. The original swings from level to ~30 deg. down IIRC. This will be unobtanium but available types may still operate by adjusting mounting position.

I would just slip a piece of dull black card or plastic in there to obscure the old switch and ignore it. It's going nowhere and at the low power, isolated by its output capacitor, shouldn't give cause for concern.
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Old 10th January 2014, 08:14 PM   #7
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Hi Guys

I've gone ahead and bridged the upper and lower wire connections on either side.Could you please confirm that I've done it correctly before I switch the amp on.I appreciate you can't judge my soldering but I guess I'll know if it's not good enough.

Here's the pic.

Click the image to open in full size.

Thanks for suggesting and doing some research on a new switch (I would prefer a new one).I've found one on ebay,could you tell me if this is suitable please.

I 'm sorry I can't seem to copy & paste the link.Here's the item number
eBay item number:
330826001416


The width between the screw holes on the amp is 35mm ,the one on ebay is 24mm so I'll have to adapt.

Guys I really appreciate all your help

all the best

Dean

Last edited by Solderburn; 10th January 2014 at 08:17 PM.
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Old 11th January 2014, 12:34 AM   #8
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Good work, the switch wiring looks OK. Give the black wire a tug with the pliers to be sure.

Unfortunately, the replacement you found has too much bulk located forward of its mounting plate and I guess the paddle will be much narrower. To get it to work, you would need spacing blocks or perhaps tiny, hand made sheet metal "Z" brackets to locate it about 12 mm further behind the sub panel. There is little on the original switch, other than the paddle itself, protruding forward of the plate and this is the difficult requirement, not forgetting to add some vertical offset (lower it) for the different arc of paddle movement.

'Not impossible for a fixit kind of guy but an awkward set of specs. Good luck but meanwhile, enjoy the amp!
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Old 11th January 2014, 06:23 AM   #9
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As above really
There are options but all involve a bit of diy of some sort. I guess the real question is whether the use of headphones is needed. If not then just accept it as it is and perhaps blank the hole off.
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Old 11th January 2014, 06:36 AM   #10
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Quote:
Originally Posted by Solderburn View Post
(I will try some WD40 as suggested by Mooly).....................
..........................
.....................
I've got some WD40 so I will have a try thanks.
.............
Unfortunately Mooly gave a bad advice
As the WD 40 is a little oily and it's NOT the right product to polish the contacts. You must find a cleaner that evaporates rapidly; a mechanical removing ( tissues, ear sticks ?!? ) of the dirt goes together with the spray.

About the switch, I wouldn't have bothered more : a hole on the front panel
doesn't impress me as long the cable redundancy and added resistance associated with it have been removed ---as the HP output.
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