need help with this number AWG-042

[pioneersound]

I have a broken bass switch on a 1250 and the control board
panel is AWG-041. Can anyone tell me what AWG-042 is. I really
what this monster fixed

 

[pioneersound]

It's a broken treble stem not bass

 

[Watthour]

"Bass switch" ?

Did you mean the Tone switch or the Loudness switch?

 

[Watthour]

O.K. The Treble pots are standard, dual, center tapped with a slight taper but linear pots can be used. Looks like you need a 100K pot, ACV-167 or ACV-168. I'm not sure if those are on the AWG-042 or not, but you can measure resistance and see if they are close enough to get you running.

DON'T throw away your old pot - They are getting rare and CAN be repaired, broken shaft and all.

 

[pioneersound]

I belive it's the tone switch on the treble side

 

[pioneersound]

The number AWG-041 is the control panel correct?
The number AWG-042 was given to me by a ebayer
that said he dismantled 2 sx-1250s I was wondering
if the number he give me was a single pot number?

 

[pioneersound]

The part # he give me was the flat amp section
no help. I need the tone amp section or single pot

 

[markthefixer]

Watthour is well intentioned, but incorrect... He's basing advice on the way they are drawn in the schematic.

I have been working with these intensively lately over the last few months.


Sx-1250 control amp (tone control) board assembly is AWG-041.

it has two rotary shafts,a lever switch and 2 more rotary shafts sticking out.

the first shaft is 50hz and has 5 positions (-5, -2.5, 0, +2.5, +5) db ACV-165

the second shaft is 100 hz and has 11 positions (-10, -8, -6, -4, -2, 0, +2, +4, +6, +8, +10)db ACV-166

then the lever switch for on(tone adjustable) and off(flat) of circuit.

the third shaft is 10khz and has 11 positions (-10, -8, -6, -4, -2, 0, +2, +4, +6, +8, +10)db ACV-167

the fourth shaft is 20khz and has 5 positions (-5, -2.5, 0, +2.5, +5) db ACV-168

These are NOT pots, they are custom switches with specific resistances between the positions. They will run you a MINUMUM of 35 bucks each on ebay as they actually become available as someone kills a unit for it's parts.

Thus a whole undamaged tone control assembly for a 1250, it's PARTS (acv-165 to 68) which also fits a 1280 AND the 1980, will set you back a minimum of 120 bucks or more. They are getting more rare as unthinking people destroy the shafts - while leaving the resistance and switching functions intact.

I am one of the guys working on a mechanical fix.

Right now, I too need a 5 position mechanism with an undamaged shaft. I am splitting my time many ways including a replacement for something similar which is a 22 step switch with 4 decks tha makes up a spec-1 volume control. I have a few ideas. For both.



The awg-042 board is the flat amp in the 1250,

it has 4 lever switches (tape duplicate, tape mon 1, tape mon 2, ad adapter)

a balance control

2 MORE lever switches (mono/stereo, loudness)

a volume control

one last lever switch (-20db muting)

 

[laatsch55]

I have some of those switches out of an RG-1 Mark, will they work??

 

[markthefixer]

I have some of those switches out of an RG-1 Mark, will they work??

Sorry, completely different.

Someday I gotta dump a bunch of old jpg schematics from old threads before the databases, they are clogging my attachments. Then I can start posting pictures much more frequently.

 

[Watthour]

MTF - Thanks for the correction. I'd read in earlier threads that the controls were interrupted, overlapping, series "contacts" (for lack of a better descriptor) but aside from the detents and fixed values at those detents do you suppose that a typical pot would not operate about the same, except variably rather than in steps?

If they are dual-ganged, concentric shaft pairs I would imagine that finding a suitable replacement would be more of a challenge, but Bournes, Clairostat, and A-B can custom make a lot of stacked specials - for a price. Fat chance that the leads would hit the board in the right places, though.

As for the shaft repair, I've been pondering that and am interested in trying a method whereby the rear stub of the shaft would be chucked in a collet and the pot/switch/control spun in the headstock to carefully and slowly face off the break, center drill, then drill and bottom tap the shaft stub for a screw. The new/donor section would be cut to the correct length, center drilled and tapped to match, then screwed to the prepared stub using LocTite 262 to secure the thread. Making the new end would be FAR easier, and cutting off the usable portion from a Soundesign, Penncrest, or Panasonic unit would be even easier (just picking on them - even new low $ pots could be sacrificed for the shafts).

I'd need good photos/drawings of the back side to determine if a special collet would have to be broached (not really difficult) to lock a flatted or double-flatted shaft. I'd be very hesitant to rely upon the internal stop/travel limit of a control to sustain the torque of machining the face and drilling, even at low feedrates and with small holes.

I'm confident there is a way to save these, or even multiple methods.

 

[markthefixer]

It's the travel range.

Nowhere near the 300 degrees of a standard pot on the 5 step units...

The 11 step unit is 300 degrees rotation.

Probably 15 degrees per step on both, but I haven't measured it yet.

not concentric driven, locked together, single shaft.

The wafers are about 1.5 to 2 inches square.

internal fastening at the shaft is by staking. Body is with bent tabs.

Sometime soon I'm gonna read the resistance between the steps accurately, like I did for the spec-1. Including publishing the info.

I have some stuff coming in from Hong Kong next month, a standard pot form factor, with multiple detents, but implemented as a step switch with individual SMD resistors.

It turns out to be a pc board based wafer with etched on, plated contacts etc. BUT until I get it I will not speculate and burn time.

objective is a quad deck replacement for a spec-1 volume control and the acv-165 through acv-168 dual wafer controls.