SX-950 Repair Question

[goat67]

Hello
I am working on this unit and the Power Amp assy AWH-050 has a few fried resistors and bad pre driver transistors on one channel. After I repair this board I am wondering can I power this up with out the power transistors installed ?

Thanks in advance

 

[EchoWars]

Hello
I am working on this unit and the Power Amp assy AWH-050 has a few fried resistors and bad pre driver transistors on one channel. After I repair this board I am wondering can I power this up with out the power transistors installed?

No problem.

 

[goat67]

Thanks EW

 

[goat67]

Another question regarding an SX-950
I need a bass control pot ACV-136 and I was wondering if anyone knows what type of taper used is.
I found specs on a Bourns pot I think will work PDB182-K525K104
http://www.bourns.com/data/global/pdfs/PDB18.pdf

Measuring the existing one I get these readings going from full CCW to CW in circuit

Pin 1-2 in KOhms
0 - 5.5 - 14 - 23 - 33 - 39 - 45 - 50 - 54 - 56 - 57

Pin 2 - 3
57 - 56 - 54 - 50 - 43 - 38 - 30 - 22 - 14 - 4.3 - 0

Thanks in advance

 

[markthefixer]

The schematic lists it as 100k, the B following the 100k in the schematic indicates the resistance taper. B is usually linear, while A = CW Audio (logarithmic). C = CCW Audio (logarithmic), and then there's variations on the tapers (a1, a2, a3 etc...)

http://en.wikipedia.org/wiki/Potentiometer


The acv-136 parts donor list:

sx-636, sx-737, sx-838
sx-859, sx-950
sx-980, sx-1080
sa-7500
sa-8500ii

What makes yours somewhat unique is the eleven detents in the rotation. Your replacement will NOT have the detents.

 

[goat67]

Mark
I do not understand why you do not think this is not right with the detents the
the part number from the data sheet says eleven detents
what Im I missing BTW typed this in from a Fn Iphone

 

[EchoWars]

Five clockwise and five counterclockwise. Add the '0' position, and you have eleven.

 

[markthefixer]

Mark
I do not understand why you do not think this is not right with the detents the
the part number from the data sheet says eleven detents
what Im I missing BTW typed this in from a Fn Iphone

So it does, a dash K5(11 detents)25........ I didn't look far enough... can you find it in stock anywhere? Because Bourns isn't going to sell you just one, distributors buy from Bourns in quantity what sells a lot (sort of a catch 22) and resells them.

 

[goat67]

Mark
As far as buying them that is the reason for the question on the taper now that I know it is a B type which is what I thought but wanted to get the expert advice I can check.
So I will look for a PDB182-K525K-104BX X signifies the type of B taper I think all would be OK but just a B would be original.
Well I will let you know how it turns out.