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Thunderbird Club

#235,321
Stealth57 said:
Thoughts?
I did a continuity test from the back of the pot to well up the braid and it gives a solid signal. I then tested from the exposed wire to the flat part coming off the second lead on the pot. Same result. I measured 9.17 kOhms across the pickup leads.

So, not sure why the output of the pickup is near zero. Clearly, I didn’t vibrate the wires loose.
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If you measured about 9k ohms across the bridge pickup (mesh outer wrap to insulated center wire) it’s working correctly. The next step I’d take is to remove all connections on the bridge pot and measure the resistance across the lugs fully open and fully closed. It should measure about 500K (give or take about 10%) when turned all the way one direction and zero when turned all the way the other direction.

If it does not do that, then you’ve probably overheated the pot when soldering the wire mesh ground to it and may have damaged the rotor or sweep. If so, no big deal. Just buy a new pot for about $5 and replace the old one.

If the bridge volume pot measures ok (and the pup measures ok) then you probably had the hot pickup wire accidentally touching some part of the pot housing other than (or in addition to) the center lug and grounding out, or the mesh ground wire was possibly in contact with the hot wire or you didn’t have the mesh or other ground wires properly soldered to the pot housing or lug, i.e. a cold solder joint.
 
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#235,322
bobyoung53 said:
1955




th
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Now that’s a Tbird!
 
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#235,323
GBassNorth said:
If you measured about 9k ohms across the bridge pickup (mesh outer wrap to insulated center wire) it’s working correctly. The next step I’d take is to remove all connections on the bridge pot and measure the resistance across the lugs fully open and fully closed. It should measure about 500K (give or take about 10%) when turned all the way one direction and zero when turned all the way the other direction.

If it does not do that, then you’ve probably overheated the pot when soldering the wire mesh ground to it and may have damaged the rotor or sweep. If so, no big deal. Just buy a new pot for about $5 and replace the old one.

If the bridge volume pot measures ok (and the pup measures ok) then you probably had the hot pickup wire accidentally touching some part of the pot housing other than (or in addition to) the center lug and grounding out, or the mesh ground wire was possibly in contact with the hot wire or you didn’t have the mesh or other ground wires properly soldered to the pot housing or lug, i.e. a cold solder joint.
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Measure across which lugs? Second and third - Meaning not the one that is grounded out to the case?

EDIT: Just saw a previous post saying outer legs.
 
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#235,325
Stealth57 said:
Measure across which lugs? Second and third - Meaning not the one that is grounded out to the case?

EDIT: Just saw a previous post saying outer legs.
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With all wires disconnected from the bridge volume pot - connect one of the leads from your multi meter to the pot center lug and the other lead to either one of the side lugs. Read the resistance, then turn the volume knob to see if that resistance changes. As you turn the knob the resistance should change from 0 to about 500K or from about 500k to zero depending on which outside lug your meter lead is on.
 
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#235,326
JIO said:
If that wiring diagram is followed - it will result in a predictable result. Anything aside from that will need trouble-shooting.
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I took that straight off the VP. So, it is wired correctly but there is clearly something messed up. Bad pot, not seeing a short that is really there...next step will be to measure the pot.
 
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#235,327
GBassNorth said:
With all wires disconnected from the bridge volume pot - connect one of the leads from your multi meter to the pot center lug and the other lead to either one of the side lugs. Read the resistance, then turn the volume knob to see if that resistance changes. As you turn the knob the resistance should change from 0 to about 500K or from about 500k to zero depending on which outside lug your meter lead is on.
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Thanks
 
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#235,328
Stealth57 said:
Thanks
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No problem. Playing a bass isn’t much fun when it doesn’t work like it’s supposed to.

On the outside chance that the pup checks out ok with the multi meter and the pot checks out ok with the multi meter and the neck pup is sending a clear signal to the output jack and the tone knob is functioning you will have narrowed the issue down to wiring. The wiring diagram you posted is correct. So follow each wire in the bass and make sure it matches the diagram and you should be good.

If still no luck it could possibly be one if a couple of oddball situations - maybe a broken wire hidden inside the insulation. I had that happen with an instrument wire not too long ago. It took a bit of head scratching to figure out because sometimes it read perfect continuity and other times not, depending on which direction the wire was bent. About the only other oddball situation would be from over heating the mesh ground wire when soldering, to the point it degraded the insulation between it and the hot wire thus shorting out the signal from the pup, but maybe only when the wire is bent or wiggled in a certain direction. The odds of either of those things happening in your case is slim to none.
 
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#235,330
Good gig. That SWR sounded really good, but I only used its power amp section since I used my 800RB pre into its FX Return. I'm sure it would've sounded good on its own for me, but was able to hit the ground running with my own preamp. Interesting the SWR had a level knob for the FX loop. Took a minute to realize that when I wasn't hearing anything. And the EHX Steel Leather was a hit. Everyone liked the tone I was getting from it, and I was able to hear myself clearly. Quite a gem that thing.
 
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#235,331
bobyoung53 said:
Check this one out, it's pretty clear, 1979 Thunderbird, on this one the third lugs of both vols go to the middle lug of the tone, the green wires, and the black goes to the hot. The problem is with yours it's so tight in there I can't see all the wires. The yellow is ground. This one is not stock although I think it's wired right.

The 1st lug is grounded to the case on them all, the signal from the pickup (central wire) goes into the middle lug and comes out the third lug on all and out to the jack. The tone is backwards I think on this.


76-T-Bird-control-cavity2.jpg
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Has it been changed to a parallel wiring? The stock '79 has the series wiring like '76 and '77 T-Birds had too.
 
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#235,332
Also interesting how what you hear and experience from stage is often quite different in the audience. There were lots of technical difficulties (none of them mine) and I thought we must've sounded terrible, but everyone in the audience thought we sounded great. A good friend of mine said it's the best we've sounded. Amazing the perspective.
 
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#235,334
bobyoung53 said:
Check this one out, it's pretty clear, 1979 Thunderbird, on this one the third lugs of both vols go to the middle lug of the tone, the green wires, and the black goes to the hot. The problem is with yours it's so tight in there I can't see all the wires. The yellow is ground. This one is not stock although I think it's wired right.

The 1st lug is grounded to the case on them all, the signal from the pickup (central wire) goes into the middle lug and comes out the third lug on all and out to the jack. The tone is backwards I think on this.


76-T-Bird-control-cavity2.jpg
Click to expand...

My II has two .02 / 50w caps - original from the Gibson factory in 1964.

upload_2023-1-21_23-38-49.jpeg
 
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#235,337
DJ Bebop said:
So this Thunderbird talk has me thinking of dipping my toe in the water.

Any opinion on these joints? ...

View attachment 4943577

Thanks
:)
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My advice Deej, find a nice used Vintage Pro Tbird. No sense messing around. If you don’t care for it (some think it feels too big), you won’t have a hard time flipping it, especially if it’s white. Then you can try a bolt on before moving to a Gibson which is no doubt in your future. Waiting to hear how your new cab works out.
 
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