500k tone pot in my TA classic ?

[spitalny]

Hi,
I got a new TA pick guard for my TA classic and it seemed like things sounded kinda brite no matter what pickups I loaded into it. So, I measured across the tone pot and it is ~500k ohm. Is this right? I though it should be 250 k? Wouldn't a 500k pot make things a bit on the brite side?

* I measured the tone pot impedance between the two terminals on the tone pot that the capacitor is connected to.

[spitalny]

There is some other stuff in there I don't understand. There are two resistors across the volume pot. I have never seen that before in an "S" guitar guitar.

I could sure use a complete TA classic (with pull add bridge, VA boost) wiring diagram that shows passive compeonents (R's and C's, Pots) and their values.

Tom - would this be possible?

Thanks!
P.

[Mister T]

The wiring spec on TA's is different from other makers.

[spitalny]

there is some other stuff that surprises me too. If I measure the output impedance (at 1/4 output jack) of the guitar, it is not 6k/3k/6k/3k/6k (N, N/M, M, M/B, B) as I would expect....it is closer to 1.4k, unless the VA booster is turned-on, in which case I see the expected impedances. Is my VA booster wired-up correctly? If I disconnect it (i.e., the VA booster) and measure from volume pot center tap I see 6k, 3k, 6k, etc. But, when the VA booster is connected the impedances don't look right at the same point (vol pot center tap) when VA booster is off. But, I thought the VA booster was hard bypassed? In which case the booster should not affect the output at all when it is switched off. Very puzzling.. it is if the booster is acting as a parallel load on the pickups even when the booster is off.

P.

[tom]

we use 500k pots and have a loading resister (the one either attached to the side of the pot or switched on with the 5 way or splitter, ) to simulate what a 250k pot does. that way we can get the best of singles and humbuckers.

[spitalny]

Hi Tom,
Ah thanks! That makes sense to me.

My other question is more puzzling...Is it possible a kickback switch was given to me instead of the VA booster. Reason I ask is that when the switch is in the up (towards the player) position the guitars output impedance doesn't seem right..unless the switch is down, in which case the impedances are closer to what you'd expect. But, the guitar is louder in that position, the positionin which the impedances seem about right. To me, that seems to more like the kickback switch (that functions when it is in the up postion). Does this make sense?

Update: I measured the output impedance of my TA cobra (3 M's, with kickback). It behaves similarly to the VA boost in my new pick guard. That is, when Kickback is off the output impedance of the guiar ranges (roughly) between 6K (neck, middle, or bridge) to roughly 3K (neck/middle and middle/bridge. When kickback is on, the outputimpedance goes down to 2k or so.

This further makes me wonder whether there is a VA boost in my pickguard or maybe it's a kickback circuit?

[tom]

your kickback readings sound about right. i'll have to check on va boost reading at the shop tomorrow. did we install the booster? they do look very similar, so it is possible you have the wrong part. i will look at the contacts on both tomorrow too.

[spitalny]

Hi Tom,
Yes, the pickguard was wired-up by you guys. I could be wrong, but I have a hunch that I may have a kickback circuit instead of VA booster..just a hunch

[tom]

wired as a replacement pg? or on a new guitar? i'll check for how many terminals it should have. can you see the top of the module from the coverplate cavity?

[spitalny]

Hi Tom,
It's a replacement pick guard I bought from you guys. It came wired-up and only needed pickups to be wired-in (which I did). The booster looks like a rectangle, with blobs on top that the wires are soldered to. One end has rounded corners, the other has corners that are more square. There are (what looks like) six possible connection points.

My thinking is that with the booster off (less volume, switch is up) the output imepdance of the guitar should be (roughly) 6k or 3k depending on whether the 5-way is in an in-between position or not. Then, you'd expect the output jack impedance to possibly be different when the boost switch is down (on). That is, when not boosted the boost circuit should not be affecting the signal.

Thanks Tom,
Paul

[tom]

6 terminals does make it a boost not a kickback. did the hot from the jack get connected to the empty terminal on the boost? you will get low readings even when it's off, but we have listened with the normal bypass and hard wired bypass and there is no dif. you are reading some bleed form the boost.

[spitalny]

Hi Tom,
Thanks for looking into this. If a std pickup is roughly 6k and the output impedance is near 2k or so (due to boost leak) , then, isn't quite a bit of the pickups output signal being lost due to loading by the boost?

Thanks

Paul


P.S. The mini-switch looks like it has three sets of connections, Could I use the other two unused connections to create a true bypass. That is, disconnect the booster completely when it is off? Would that cause a pop or a click when turning the boost off/on?

[tom]

just because an ohm meter is reading it does not mean you can hear it. a 2k load would be severe, easily hearable. that's not happening. like i've already said, we did a hard bypass and could not tell the difference. you are welcome to do that if you want to go through the exercise.