SL+: pcb layout and jcm800 mod are the same

[SacredGroove]

Are the sl+ modules shipped with the jcm800 mod values now? If so, what are the old values?

Scott

 

[turbolx5oh]

Old values are 56K and .0022uf I believe.

 

[SacredGroove]

Right on! Thanks for the help!

Scott

 

[bmf5150]

anyone have a schematic to the sl+
stan

 

[turbolx5oh]

Well, according to the schematic, it says its a 250pf so now, I'm confused. Anyone know for sure?

 

[SacredGroove]

Well, according to the schematic, it says its a 250pf so now, I'm confused. Anyone know for sure?

Wouldn't 250pf=.0002uf?

Scott

 

[turbolx5oh]

Well, according to the schematic, it says its a 250pf so now, I'm confused. Anyone know for sure?

Wouldn't 250pf=.0002uf?

Scott

Yes it would but the part on my board reads 222K which is .0022.

 

[strato62]

Still want a schematic ?

Someone posted a link for the SL+ a while ago. Take a look to this thread:

http://mtsforum.grailtone.com/viewtopic.php?t=1685&highlight=

Claude

 

[SacredGroove]

Well, according to the schematic, it says its a 250pf so now, I'm confused. Anyone know for sure?

Wouldn't 250pf=.0002uf?

Scott

Yes it would but the part on my board reads 222K which is .0022.

222k=.00022uf. I actually just learned this lesson yesterday. I had a question about a cap (471k) and it turns out that it's .00047uf, (basically .0005).

Scott

 

[turbolx5oh]

Well, according to the schematic, it says its a 250pf so now, I'm confused. Anyone know for sure?

Wouldn't 250pf=.0002uf?

Scott

Yes it would but the part on my board reads 222K which is .0022.

222k=.00022uf. I actually just learned this lesson yesterday. I had a question about a cap (471k) and it turns out that it's .00047uf, (basically .0005).

Scott

222K is 2200 microfarads which is 0022uf. And you're right 471K is 470 microfarads or .00047uf or 470pf.

 

[rjmmusic]

Almost correct... 'uF' and 'microfarads' are exactly the same. On the other hand, 1uF (microfarad) = 1000000pF (picofarad).

The '222K' type of notation works as follows: the first two digits are the value in picofarads, and the third digit is the power of ten exponent.

So, 222K is 22pF times 10 to the 2nd power = 22pF x 100 = 2200pF = 0.0022uF

471K is 47pF times 10 to the 1st power = 47pF x 10 = 470pF = 0.00047uF

Hope that makes sense... :shock:

 

[Shinozoku]

That's all well and good, but that doesn't answer the initial question of the post. Are the new SL+ modules shipped with the JCM800 values? I have a newer S+ and did the JCM800 mod to it, but I'm not sure if the difference was actually made (I do believe I hear some more midrange and clarity), or if I'm just imagining it (there was a week between the times it was stock and modded).

 

[SacredGroove]

I originally asked this question because my SL+ came with the JCM800 components, but I bought it used. The weird thing was, is that it didn't look modified, so I needed to find the stock values and that was answered in this thread and later found that the SL+ and Plexi have the same tone stack components. So, all is good now.

 

[nikki-k]

One of the Randall guys said that SL+ from '07 on up had the JCM mod from the factory. C3 is different, along with another cap and resistor. On mine (a 2008), R31 is marked as a resistor close to the right edge, mid to front area-ish (R34 on old ones/"correct" ones?). In an old mod pic, R31 is up behind the mid pot I believe.. would need to look again.

So, for my SL+, layout/markings have differences, plus the modded parts on the old "SL+ mod to JCM values" are JCM already.

This thread shows an old one, and I think mine has R34 marked as R31.. not sure if mine is a mistake/ooops one or not. The resistors on mine are different as well.. mostly gray ones, a few tan ones (metal film I assume?) versus strictly tan (as in the pic in that thread; except the brown R31, which looks to be a carbon comp?)

 

[Shinozoku]

Ahhh, okay. That explains why I couldn't tell much difference. Do you think Going from a 500v cap to a 1kv cap in C14 would have changed anything? Cuz I'm just ever so slightly noticing a midrange difference. Once again though, that could simply be my mind THINKING I made a difference

 

[okstrat]

Ahhh, okay. That explains why I couldn't tell much difference. Do you think Going from a 500v cap to a 1kv cap in C14 would have changed anything? Cuz I'm just ever so slightly noticing a midrange difference. Once again though, that could simply be my mind THINKING I made a difference

Voltage handling won't make a difference on your caps, at least one you should be able to hear. What might be making a difference is value of cap - some are 20% tolerance, which means a 500pf cap could be anywhere from 400 to 600pf and still be considered a good part. Even if it's a 10% tolerance, that's still 450 to 550pf. Also, is it the same type of cap (both silver mica or both ceramic, etc?) that makes a difference too.

Pete

 

[Shinozoku]

Ahhh, okay. That explains why I couldn't tell much difference. Do you think Going from a 500v cap to a 1kv cap in C14 would have changed anything? Cuz I'm just ever so slightly noticing a midrange difference. Once again though, that could simply be my mind THINKING I made a difference

Voltage handling won't make a difference on your caps, at least one you should be able to hear. What might be making a difference is value of cap - some are 20% tolerance, which means a 500pf cap could be anywhere from 400 to 600pf and still be considered a good part. Even if it's a 10% tolerance, that's still 450 to 550pf. Also, is it the same type of cap (both silver mica or both ceramic, etc?) that makes a difference too.

Pete

Thanks for that info, Pete
The one I put in is 470pF, 1kV ceramic disk cap. Only visible difference is that the original one was yellow and slightly smaller, and this one is kindof a brownish red (like a clay pot).