Pilot 240 motorboating
- Thread starter James Cox
- Start date
So i think the schenatic ive been using is for that later version with the bias test jacks on the back intead of the center channel. My version is the earlier one with the center channel instead. I can really make out the resistor value on the other schematic. What size resistor should be parallel with the 150mmf cap? For now should i just remove that all together and see what happens?
are they connected to different taps? 10k with 150pf on the 16 ohm tap would give near enough to the same feedback level as 4.7k and 250pf on the 4 ohm. Voltage at the 16 ohm tap is double what it is at the 4 ohm, so the resistor is double the size. The caps scale in the opposite way, so double the resistor, half the cap.
and just to toss a wrench in there, 6.8k is about right for a connection on the 8 ohm tap, cap would be about 180 pf, but it could be some either way depending on the specific HF properties of the tap but thats how you'd calculate a starting point.
and just to toss a wrench in there, 6.8k is about right for a connection on the 8 ohm tap, cap would be about 180 pf, but it could be some either way depending on the specific HF properties of the tap but thats how you'd calculate a starting point.
^^ agree on this, if the parts appear original, they are likely the correct value. If replacements need to be made because they are off value, I'd replace the parts with new ones of the same marked value as the originals. Schematics can be from multiple sources and covering multiple variations over the production run so sometimes they just are not a dead-on match.
Resistor and cap in parallel tied to the speaker selector switch.
So the 10k/150mmf is coming from the 8ohm tap. The 4.7k/ 250mmf cap is connected to the 16ohm tap. Honestly when i forst got the amp it seemed to be all orignal but i notice that most of the solder points have been marked with red marker prior to any of the rebuild work we've done but the 4.7k/250mmf has no red mark and looks to be connected in a slightly different way which leads me to think it may not be original. But then again it very well could be
Uh oh! As soon i sent the last reply i found a black wire coming from the 8ohm tap on channel B that was broken but still touch the connection. That would explain why it would come and go and why movimg the anp aroumd would make the noise either start or stop! I just soldered it back where it goes and im about to hook it back up for testing. Cross you fingers guys!
