#1
I am performing a cap job on my Maestro M201 amp. It's a 10", 4watt, 1960-something Gibson variant. My electronics skills/knowledge is still only basic, and I've begun attempting simple mods and maintenance jobs to build it up.

So i've purchased some Sprague branded Orange drop capacitors (716 series) to replace the original electrolytics. The filter cap is a JJ electronics piece, and its replacement was very straitforward. However, the tone caps are another story. The original caps have a ring on one end, denoting polarity. The new orange drops have no id whatsoever. Now, i made the assumption that current flows through them in the direction that the label was printed (left to right). But i have no idea how valid of an assumption that is? These caps are polar, right? How do I identify which lead is in or out?

thanks in advance
#2
Orange drops aren't electrolytic. You don't need to replace them; they can't be used to replace electrolytics.
Only replace the electrolytic capacitors.

The tone caps don't need to be replaced...
Orange drops aren't polar...
Wait for me to get home from school and I'll help you out with this. You seem quite confused.
I'm not very active here on UG currently.
I'm a retired Supermod off to the greener pastures of the real world.
#3
For clarification:

The large cap, originally a sprague 3x20 @ 300v, is now a jj electronics 3x20 @500. This was straitforward. It's the filter cap, right?

I am adding a tone circuit to this amp. It originally had just a .022 cap between v1 and the volume control, which i removed and replaced with bass and treble knobs, using component values taken from a fender champ schematic. The orange drops were intended for use here. There is also a 250 pf silver mica cap that isn't marked polarity either. These is where my issue lies. Are you telling me that orange drops were the incorrect choice? And, obviously, does it matter in which direction they are installed?

The .022 taken out was a sprague black beauty. Do these drift over time?

Small electrolytics (there were two of 20 @ 35) were replaced with new electrolytics from radio shack; that was straitforward as well.
#4
Non electrolytic caps can leak a bit of DC, but usually they're fine. you don't need to change them.

I see what you're doing now. It sounds like you have all the filter caps fixed up along with the cathode bypass caps. Good job.

I'm not totally clear what you're doing with the tone control. Could you draw a schem?

I thought you meant you wanted to replace the filter caps etc. with Orange Drops You have the right idea.

Most caps are nonpolar, ODs included.
I'm not very active here on UG currently.
I'm a retired Supermod off to the greener pastures of the real world.
#5
I think I understand what you're doing.. You're just putting a basic FMV tonestack in place of a simple variable low-pass filter? That should work, although you might find there's a little less gain on tap (the FMV stack will cut an extra extra few decibels but it should still sound great.)

ODs will work, the reason you don't see a "polarity" is that they're not made in the same way as some older "foil in oil" sort of caps which have a definite "inner" and "outer" foil which need to be connected in the right way to prevent oscillations (however in some cases you can get away with just chucking them in there.) ODs don't really have an inner or outer foil (per se) and can be connected in either polarity.. If you are being EXTREMELY anal about it you will find one polarity picks of RF EVER SO SLIGHTLY more than the other, however I've never managed to actually "hear" much of a difference between each polarity. If you feel like being really picky (I tend to do it just because it puts me at peace of mind.. I'm a bit OCD with these things. ) you can find out which lead "acts" like an outer foil by hooking up a sig. generator to the the capacitor and also an oscilloscope. If you then touch the edge of the capaictor you should see the amplitude of the scope change, if you cahnge the polarity of the sig. gen and repeat there should be a different change in amplitude.. When you've found the direction where there's a bigger change in amplitude, the outer foil is connected to the +ve on sig. gen. and the inner is connected to the 0V. (Obviously you need a sig. generator with a ground!)

But as I say that's being extremely anal about things..
For sale: Early 1985 Ibanez AH10 (Allan Holdsworth signature model) PM for details
#6
Also, the Silver Mica cap you found isnt polarized. Silver Mica caps in amps are usually used in Tone controls or Tone Stacks. They have low values in the pico Farads (pF).

power freak- your no mod anymore
...
#7
Quote by call1800ksmyazz
power freak- your no mod anymore
...

Unfortunately not.. I just don't have the time anymore (thanks to exams and university applications) so thought it's best I leave. I'll still be around now and again though.


For sale: Early 1985 Ibanez AH10 (Allan Holdsworth signature model) PM for details
#8
Quote by call1800ksmyazz
power freak- your no mod anymore
...




Quote by power freak
Unfortunately not.. I just don't have the time anymore (thanks to exams and university applications) so thought it's best I leave. I'll still be around now and again though.


Ah, you're doing the same as I am (exams that is, I'm leaving the university applications to next year. Gap year FTW!).
Last edited by mr_hankey at Jan 6, 2007,
#9
Quote by power freak
Unfortunately not.. I just don't have the time anymore (thanks to exams and university applications) so thought it's best I leave. I'll still be around now and again though.




Too bad. I havent seen you posting in a few months too (probably just in the forums I look it). But yea, I still have a year or 2 before I have to do college apps.

GuitarRock04- Is that JJ cap a Can Capacitor? If it is, it should have 3 lugs on it. This is basically 2 electrolyte capacitors in one each sharing the middle lug. I have one of these JJ ones in my 18watt Plexi.