Question about SX-650 sub list

[quaddriver]

For the GWH-101 board....

2SC1438 I have seen threads with KSC1845F or the beefier KSC2383Y. Is there a preference I should follow?

Also, on the GWR-101 board....2SC1647. I have seen KSC1616 (circa 2015) but lately KSC2383Y. Since I have a drawer of 2383's (O and Y) is that ok?

Also, since I am in here, its a biotch to get in here, I was leaning heavy to pulling the working A798s for matched sets of KSA992's.....depending on where and when you look for that, sometimes its a 'leave it' item, other people practice shoot on site....

please advise?

 

[zebulon1]

Don't use the KSC1616's they are not robust enough.
2SC1438, If they test okay leave them, otherwise the KSC1845 will work, so will the KSC2383.

 

[quaddriver]

Don't use the KSC1616's they are not robust enough.
2SC1438, If they test okay leave them, otherwise the KSC1845 will work, so will the KSC2383.

ok thanks for the info. the machine works just fine, but since I got it used I was doing a recap and looking at problem areas - like the relay pull in, beefier trans in the power supply...1438 is VAS here? since I am in there is an 1845 good insurance or would you not waste the solder?

 

[markthefixer]

ok thanks for the info. the machine works just fine, but since I got it used I was doing a recap and looking at problem areas - like the relay pull in, beefier trans in the power supply...1438 is VAS here? since I am in there is an 1845 good insurance or would you not waste the solder?

Yes, 2sc1438 at GWH-101 q4 and q5 IS VAS (Voltage Amplifier Stage). I would put in the ksc1845.
The 2383 would be for current drive which is not needed here and is a slightly lower gain device.

I have seen instances of apparently working signal amplifing transistors being replaced with new KSC1845's and sound "improvements" being noted - which I note, is a restoration of former performance as opposed to being confused as "better than factory new"...

 

[quaddriver]

thanks guys. work resumes after my real job tonight...I wanna wrap this up and get to the 2 sx3700's in the wings!

 

[rcs16]

For a VAS bjt, best choice is one with very low collector base capacitance (Cob) such as ksc3503 and ksc1845, ksc3503 has a higher ft than a ksc1845

 

[quaddriver]

for posterity:

as of sept 2018 the KSC2383 is a righteous sub for all the C1647's and is listed at least twice as the sub for Q9 on GWR-101 (C945 from the factory) VAS got KSC1845F's

Also, I got it together and was testing (she works) and when flipping inputs I noticed a barely audible hum on phono (more on that below)

2 questions: are there vastly different revs of this machine? I have only worked on 3 lifetime, this being the 3rd. In another post, another thread, the phono eq amp was recommended to have KSC1845s used - BUT! this uses a SIP style IC for phono amp, 1 per side also another post mentioned 2SA723/725s or something like that on the amp board - none were in attendance.

I used all the uprated voltage subs from another thread for the GWR101 board (2 steps in most cases, i.e. 16->35v, not 25, or similar)

on the phono hum: she had all the metal off and waving my hand produced various levels of hum when on phono, volume way way up, nothing connected.

I found 4 2.2uf-25v tants in there. I had some 2.2uf-50v nichions I have inserted in marantzes and they fixed it. I am sure the hum would have been less with the metal on and my hands not in there but I am not a big fan of old tants.

 

[zebulon1]

Several of the Pioneers SX models share a very similar EQ and they utilize the Tants. The 2.2's and or the .22's. Get rid of them.