I believe another reason you want it at the end of the chain, is that's where it used to be when there was a FET there, if you put the 150k earlier in the chain voltages across the amp will differ, and therefore not be the same as the original, it will drop them wherever you put it in the chain by some amount. You want it doing the same thing as dropping for the FET only at that point in the chain.
pompeiisneaks wrote: ↑Tue Sep 18, 2018 3:51 pm
I believe another reason you want it at the end of the chain, is that's where it used to be when there was a FET there, if you put the 150k earlier in the chain voltages across the amp will differ, and therefore not be the same as the original, it will drop them wherever you put it in the chain by some amount. You want it doing the same thing as dropping for the FET only at that point in the chain.
~Phil
Hi Phil, I think electronically the junction of the two 100K plates, the end of the 2.2K dropping resistor and the end of the 150K plate of the FET are the same point. What I was thinking is the 150K on the board like the attached below (yellow circle - red lines), instead of adding it by the 2.2K at the Sprague Supply Cap
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pompeiisneaks wrote: ↑Tue Sep 18, 2018 6:21 pm
Yes those are all the same logical point in the circuit, sorry misunderstood the explanation earlier. That should be perfect.
~Phil
+1 - Two Rock did that on their Jet........
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pompeiisneaks wrote: ↑Tue Sep 18, 2018 6:21 pm
Yes those are all the same logical point in the circuit, sorry misunderstood the explanation earlier. That should be perfect.
~Phil
+1 - Two Rock did that on their Jet........
That looks ugly to me. Putting it on the power board mages more sense to me from an ergonomic point of view.
Martin, any electrical engineering reason why it's better the way Two rock did it?
pompeiisneaks wrote: ↑Tue Sep 18, 2018 6:21 pm
Yes those are all the same logical point in the circuit, sorry misunderstood the explanation earlier. That should be perfect.
~Phil
+1 - Two Rock did that on their Jet........
That looks ugly to me. Putting it on the power board mages more sense to me from an ergonomic point of view.
Martin, any electrical engineering reason why it's better the way Two rock did it?
M
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I agree Marcus. It looks like a band aid repair - not what HAD would do, I bet.
Bombacaototal wrote: ↑Tue Sep 18, 2018 7:50 pm
No worries Phil and thanks for helping out!
Thanks for sharing guitarman. They went for 2W as well. Any reason not to use a 1/2W like the FET plate would?
Raphael,
it's NOT a plate resistor it's a dropping string resistor hence it neds to be a 2W, if you look at the electrolytic cap and the 150k resistor mounted in the right hand chassis of #102/124 ODS they're part of the power section it's just that on earlier Dumble's there wasn't room on the power board. As the caps are now smaller and we have a great board layout by Martin, all those caps and resistors are now on one board, so putting the FET dropping string resistor on the end of the dropping string makes sense if you know you're not using a FET.
that's why that two rock looks poor to me, it's a bodge.
Bombacaototal wrote: ↑Tue Sep 18, 2018 7:50 pm
No worries Phil and thanks for helping out!
Thanks for sharing guitarman. They went for 2W as well. Any reason not to use a 1/2W like the FET plate would?
Raphael,
it's NOT a plate resistor it's a dropping string resistor hence it neds to be a 2W, if you look at the electrolytic cap and the 150k resistor mounted in the right hand chassis of #102/124 ODS they're part of the power section it's just that on earlier Dumble's there wasn't room on the power board. As the caps are now smaller and we have a great board layout by Martin, all those caps and resistors are now on one board, so putting the FET dropping string resistor on the end of the dropping string makes sense if you know you're not using a FET.
that's why that two rock looks poor to me, it's a bodge.
M
Thanks Marcus, I will follow your advice as far as placement of the 150K and noted with thanks regarding it being a dropping
sluckey wrote: ↑Sun Sep 16, 2018 3:45 pm
I like to use a standoff turret to support grid stoppers. This one has a base with 4-40 threads. Simply screws onto the socket screw.
Sluckey, I want to give it a go at your suggestion and I was wondering if you by any chance have handy the part of the turret standoff. I am struggling to find it in mouser. Many thanks!
as long as the thread works with your screws any standoff will work I'd just replace the screw and use a regular standoff you use for mounting boards here in the UK as it will be a metric thread, getting/using US threads is a PIA here. Computer motherboards use standoffs too so are easy to find.
