[tommy87]

ok, so while we left pickups passive, there is no problem with scratchy blend pot. but this annoying noise is there in both cases, even with everything grounded, what i've tried. when the trebble pot is lowered to minimum, the noise is gone too. so the last thing that comes to my mind is to make the guitar, for this purpose, passive, so bypass whole electronics and battery circuit. i'm pretty courious if it will be humming even with this diagram too. if yes, then it's pickups where is the problem, if not, the electronics is noisy, so change will be the best way..

edit: yesterday i tried to bypass the electronics and my bass remained deadly quiet after that. So the verdict sounds that we've got s shity electronics in there. im gonna order some new parts and completely rebuild my t-bird to passive, i didnt like so much trebble and bass after some time anyway. what i want is to make 1x volume pot, 1x balance pot and 2x tone pot, for each pickup separatelly. there is option to buy one push/pull pot and make it switchable between power supplied and non-power supplied pickups. so this is my next job as soon as my next sallary will come

[Fitzie]

Quiet!!! Finally!!!

Disconnecting the ground from the blend did NOT work. But I noticed that the red signal wire and the brown power wire were wrapped together!?! Anyone should know that you always keep signal and power separate! I separated them and moved the power around away from the signal wire and my hum is completely gone!

So what I have at the moment:

I have put everything back to the way it was when I bought it
The red pickup wires are not connected to anything.
There are no new ground wires run anywhere.
I separated the brown and red preamp wires (just cut the black wrap) and moved them away from eachother.

Hum GONE!!!

To those others who have solved this issue by re-soldering and fiddling around, did you separate those wires as well?

[baaz11]

I own a Thunderbird PRO-V (NO) aswell and found the hum unbearable. Even though I didn't try any of the mentioned methods, I found the solution by accident when I touched the potentiometers without the caps on, and found out that only when touching specific ones (volume and treble) the hum goes away, then I tried connecting those with a metal object (without me touching the object ofc.) and voila the hum was still gone. Then I just attached a new wire inside.

I soldered a new wire on the housing of the treble potentiometer (GND) and the other end to the housing of the volume pot. (GND) Eliminated the HUM entirely, and theres no cracking or whatsoever!!!

Just wanted to share my discovery with all you dissatisfied Thunderbird players in hope it works for you too.
here's the proof

[SigiZ58]

Hi together,

at first thank you for the work you already put in this thread. it helped me very much to investigate the hum-problem.

and now - maybe surprise for some of you
the T-Pro Pickups are definitely not active! if you make some measurements, you find out very fast that the resistance of the pickup from white wire to screen wire is around 7k, and from white to red 3.5k resp. red to screen around 3.5k.

This shows we have a primitive mode selection available (coils in series or parallel). The parallel mode works when you short the white wire and the screen wire as + and use the red wire as - .

This also solves the "mystery" with the scratching blend potentiometer. When you connect the red wire to battery, you bring a DC in the circuit. Each potentiometer scratches when you control a signal and also DC is flowing through it. When you ground the red, then you use the pickup in single coil mode, because you short the second coil of the humbucker.

I came to this because I started with the hum problem like most here. Some days of investigation brought a clearer sight to principles. Nevertheless, without this thread I wouldn't have had a good starting point.

The last two posts show that there a several problems with shielding. None of them worked for me. BTW, it doesn't matter when you have a battery + near a signal line. You have problems when you have AC cable near signal. So I think, both solutions helped by accident.

When all is cleaned up with electronics , nevertheless the circuit is still a bit noisy, but not much more then other ones. If you open the highs, you have a pretty shhhh....

also the pickups are hmmm - even they are humbuckers.

What I did finally: I made them passive, using 2x 500k for volume and 250k for tone combined with .047 C.
Now I have a hole - I guess I will put a switch in it, either to switch the pickups from serial/parallel or the classic way for pickup selection.

The sound in passive mode is much more dynamic from my point of view. Direction goes a bit to precision / rickenbacker but darker.

To be honest - the bass is a complte shielding problem. I cut the connection between bridge and ground, because I hate when i touch the strings to be shield. This has a simple reason. When you play, you sometimes touch it and sometimes not. When you are in studio, you get this difference and it is more noticeable then a soft but constant hum.

I guess, the finish is somehow static. when I rub the back of the neck or the plastic of the pickguard, I get noises.

Nevertheless - I like the sound of the bass - even more passive - and every single coil bass is worse relating hum

Sorry for my English....

[SigiZ58]

Hello,

it is me again with some additional news. After the last change I got relative fast that even with the correct 5-string pickups (NOT the known-as-faulty-ones, at first I had a model with those)) the B-String and also the G-String were thinner as expected. Not very strong, but for me nevertheless a noticeable difference. So I asked me why.
What Pickups are build in ? If you compare to standard five string pickups from Seymour Duncan or EMG with soap bars, you see the 4-string types are 3,5" (89mm) while the 5-string types are 4"(102mm). But our 5-string Thunderbird has 3,5" pickups. Those 3.5 pickups are given with a max string space of around 68mm. That fits - but what does this mean ? The G- and the B-String are at the ends of the bar then. With a 5-string pickup you get a magnetic field of nearly 80mm, that means also the outer strings are lying pretty in the magnetic field, not on the edges.
The question for me is, why uses epiphone such a strange measure for the t-bird pro V string ? The older t-birds have wider pickups, around 96 mm. This could also fit for a five string. But in the newest generation the pickups became smaller instead....... very bad idea.
The other thing is, it seems my pickups are microphonic. The hum is noticable, even in passive mode and too much for humbuckers.

Finally I decided to throw them away. The bass itself really has a nice tone. I ordered a set of Seymour Duncan passive 5-String soapbars SSB-5.
At work I have a friend who did the necessary routing for me. It is very very narrow, but it fits. The wood still has 2mm reserve on each side now

The sound now is complete different of course - even with the old bad original strings the B now is really fat, also the G is not thinner anymore. That is the V-String T-Bird Pro as it should have been from the beginning. Really a pity to make such a weird construction (electronic, pickups) , as the base idea of the t-Bird pro was really great.
Of course no hum anymore. I guess I will try the old active electronics later, but for now I am complete happy with the Seymours in passive mode (2x500k A, 1x250k A, 1x0.047 uF).

Best regards

Sigi

[tommy87]

Did somebody try to connect original pickups in parallel mode(shielding and white wire together and red wire as the signal one)? How does it sound? Since the impedance of single stock pickup is 7k, then impedance in this way should be 1/3,5k+1/3,5k)=1/?.....1,75k. Isnt this value too low and signal too weak?