Arcam Alpha 9 amplifier

I've had this amp for a long time, around twelve years. The input selector knob has had an issue for quite some time and I've had enough. Basically the amp will often cut out one channel, and it can be corrected by twiddling this selector, sometimes with painful precision needed. Also even though it doesn't have a push/pull action, pushing on it sometimes helps. I took some photos which you can see at

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The input selector is in the bottom left of photo 1, with a close-up in photo

  1. It's motorized as it can be moved by remote control. I've tried squirting switch cleaner through the holes, but no improvement. It appears to be a sealed unit made by Alps. Is my only option replacement? Can anyone here tell me anything more than people discussing it at
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    and
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Also, the lid has been off for ages, and I forgot whether the thin foam square piece goes over the caps as in photo 3 or over the transformer as in photo 4.

Any advice appreciated.

--
TD
Reply to
TD
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As this has been a chronic problem, you might throw the warranty of implied merchantability at Arcam. That is, the quality of the switch is unacceptable for its intended purpose, and switch -- or even the entire unit -- should be replaced at no cost to you..

Reply to
William Sommerwerck

Thanks, but I don't think that after ten years, that argument will wash.

--
TD
Reply to
TD

implied

unacceptable

be

But that's the point. If you've had this problem over most of the life of the unit...

Reply to
William Sommerwerck

TD wrote in message news:gv1hr4$b04$ snipped-for-privacy@news.eternal-september.org...

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My wrestling with an Arcam, steer well clear, is the lesson Long term finecky poor function switch contacts Motorised switch for R/C use and also manual front panel knob. I would not fancy desoldering that one by conventional means. No broken pins or lifted tracks/pads. Desoldered the motor and straightened the bent over pins while melting solder before hot-airing apart the whole switch mechanism. Drilled out the copper rivet holding front sub-pannel to pcb, replaced with nut and bolt. Remove ASIC / PIC IC for safety All conductors covered in black corrossion, but does all come apart quite safely, after labelling. I tested the switches and also that bending the wipers had not produced trouble with extra back torque and driving round via the motor. Now its all soldered in, the safety clutch operates in one position, too much back torque. I had tested before fixing the metal casing back into place around the switch sections and there must be some sort of additional strain/misalignment. Took apart to separate the clutch, packing out under the

2 springs, with hindsight should have had less packing or just one attended to as now too much pressure. Position 6, Tape 2, triangle ident is "TDC" down to pcb and diamond to motor side Pair of contacts, inside, is between that triangle and diamond. If pin 1 is on motor side of each switch wafer then pin 6 to pin 12(common) in position 6. The 2 pin wafer has very fine contact pads. This wafer must be oriented relative to the other 3 so that the dedent action from the main shaft leaves a bt of leeway to the 0 side of position 1 and same leeway to 7 side of position 6. Eventually found the first problem to be the second cog is worn No broken teeth as such , just frayed/feathered tooth tips , in a very low torque drive, reduction drive. And the feathering/bunching eventually causes the gear train to stall. It is attached, co-axial, to a fine pitch worm drive, with no salvaged eqivalent around. Turned the worm plus cog assembly around on the axle and glued a salvaged 1mm pitch cog to the other end. One possible solution. Fix the whole switchbank rotated 90 degrees, with the motor uppermost, and bridge ribbon connect the 23 active lines. Leaving the original hidden underside of the wafers exposed so can add a bit of relative rotation if required. Its switching line level signals, so stray signal pickup from extra wire should be no observable problem. Check each stage of motor/cog replacement. Try motor plus first 2 cogs driven from the amp board before connecting the main shaft etc . All wafers must be in a valid postion or the remote will not work. Nedds a good 3V on a DVM The BA6109 is pulsed and current limited. If its not possible to find a suitable cog/cogs it may be possible to turn the worm gear around, fill in part of the end of the spiral , form a "pulley" in that and set a rubber band around it. Cut into part of the junk metal that slides over carying the main shaft and mopunt a motor and pulley in a different position.
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modified Arcam Alps switch/servo mechanism O is original worn cog, B is bracket, P motor pulley and A is the Ned Kelly aperture for the drive band. When first trying out it would not move reliably to the next dedent position. Because of through hole plating, or now , the lack of it on the common line there was a break so not sensing the 1 of 6 posistion. I increased the size of the motor pulley, from the size in the pic as the r/c process was timing out going from 1 to 6 or 6 to 1. All the front panel switch shafts are weak , with the front panel removed. and will easily break. Final job - heat the Al dome of the control knob to release from the plastic core, hot melt heated and reset 1/4 turn around. IR R/C coding approx timings, repeat 110mS, 1 bit .83mS, 1 pulse 26uS ident code 101AB011 then function code AB=01 or 10 on alternate key presses. propbably some errors in some of these data, reading off scope display 1/ code 8001, where 8 = 8 repeats of 01 2/ 700101 3/ 600101 4/ 70011 5/ 6001101 6/ 6001011 vol-/ 400110101001 vol+/ 400113 pause (CD)/ 0011010010113

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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Reply to
N_Cook

"TD" wrote in message news:gv1hr4$b04$ snipped-for-privacy@news.eternal-september.org...

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It sounds as though either the contacts in the unit are oxidized or that they have lost their spring and the switch is just worn out. If the switch sits in the same position year after year, only a very very tiny amount of surface area on each contact is actually touching the other contact surface and is protected from oxidation. So when you go to switch to a particular setting rather than having let's say half a horizontal mm of area to choose from you might have a tenth of a mm or less, hence you must painstakingly find the spot on the switch where the metal is bare. You mention you've cleaned the switch. You might try having a go with a product called DeOxit made by a company called Caig. Otherwise I've used other brands from electronics stores, even Radio Shack sells a variant. I've repaired many many many products just by properly cleaning up the switches and pots. If the switch is sealed (or there just aren't access holes to the innards where you need them), it is quite possible to drill small access holes to the interior of the switch through which to squirt DeOxit. Use the thin straw that comes with the can to blast a lot of cleaner in there, then operate the switch a good 50 times or so. This should remove the oxidation to a degree that the switch is workable. Next let it dry overnight. The next day spray with Faderlube or other cleaner/lubricant also sometimes called "tuner spray". These products contain a small amount of lubricant which will coat the contacts and prevent their immediate re-oxidation, plus generally lubricate the works. I find that I generally have to use both products for any sort of long-term results.

Just a helpful suggestion for next time: when you take photos of your equipment, use the close-up mode, generally denoted by a flower on the wheel selector on the camera somelace... otherwise you get blurry photos such as yours. Also, it's nice to have some tight-in shots of the problem area. As you neglected to post a shot of the face plate, there's no way for me to determine which is the problem switch. You might also consider editing the photo with Adobe Acrobat, or even MS Word or other text editor, to add some circles, arrows, and relevant text. It just makes it easier for others to understand your problem and gives you a lot better shot at useful unit-specific responses.

Dave

Reply to
Dave

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Hello,

This is a fairly common problem on these amps, as well as others (Creek, Yamaha) that use this Alps switch. Spray cleaning rarely helps for very long, and taking the switch apart requires lost of patience and good desoldering, as it must come off the board. Just changing the switch, if you have a new one on hand is a 1.5 to 2 hour job.

If you use only one input on your amp, then you can use the tape monitor input as the tape monitor input bypasses the switch.

As to the white square damper, it was originally glued to the underside of the lid. My suggestion is to throw it away, but you can re-glue it if you want to.

Regards, Tim Schwartz Bristol Electronics

Reply to
Tim Schwartz

I own a Peavey Tube Fex guitar processor with a motorized switch similar to what you have. I used some Caig Deoxit on the switch which controls the tube preamps. The Peavey is 14 years old and the switch now works well. Deoxit might be worth a try in your case. Make sure you get it inside. Removing that switch and replacing it is an hour or so job at best from what I can see.

Reply to
Meat Plow

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