Nitefly RF722 bridge pickup issue

[Sor]

Hi everyone. I have a Nitefly RF722 (I believe) that I bought new in 2013.

Recently I’ve noticed that the Seymour bridge pickup has a hard time “engaging”. I’ve inspected all of the connections, everything seems impeccable, it has been well cared for and lightly used. I checked the DC resistance on the bridge out of circuit and it reads normally, about 9k to center tap and 18k across both coils.

It doesn’t pop in and out, it usually doesn’t come on at all, and when it occasionally does it “fades” in for a few minutes and eventually out.

I have tried several batteries. The switches all seem solid and clean. Solder points look great and wiring is quite clean. Measured the resistance through the switches in various settings and all seems good (push pull to center tap the humbucker gives good resistance reading, blending with neck pickup gives good reading).

I am suspecting maybe the buffer on the piezo circuit doesn’t like the high output bridge. I have no evidence of this other than the fading nature of the issue rather than one that sounds like a loose connection or an open circuit. Also the middle position that blends the two humbuckers sounds good and normal to my ears.

The interesting thing is that the piezo circuit looks like a Fishman power chip (with the pot soldered to the board), even though the catalog claims it should be a Graphtec ghost.

Is it possible this had a Fishman for some reason, despite the catalog, and is this issue something heard of?

Should I just replace the power chip? Maybe with the ghost? I was also considering trying a lower output bridge pickup under the theory that the high output pickup doesn’t work well with the buffer - maybe too much resistance to turn it on?

[mmmguitar]

Welcome, @Sor. Despite the ad copy, if your guitar came from the factory with chrome saddles, it has the Fishman Powerchip preamp; and contacting Fishman may get you to the bottom of what is causing the issue fastest. In the meantime:

Thanks for mentioning that you checked all the connections and swapped in new batteries. Are you saying that the guitar's magnetic and piezo circuits work perfectly when selecting, say, the neck pickup with the 3 way switch - but that there is no sound when selecting the bridge pickup, other than it occasionally fading in and then out? If so, that's at least indicative of a faulty pickup selector switch (it's a common, Gibson-style SPDT on-on-on switch with leaf contacts which are susceptible to failure). The quality of the generic 250k pots and SPDT switches used for Parkers from 2003-onwards seems to have been exceptionally lousy; with high rates of mechanical failure (my '11 Supreme with all the same components as your RF722 came from the factory with a volume pot which bled signal through at 0, a push-pull tone pot shaft which fell out of the guitar with the knob attached, a pickup selector switch which would not consistently switch in any position, and a mag/mix/piezo version of the same switch modified to be on-off-on which let the piezo signal through in all switch positions - My first order of business was to replace all of them).

The guitar's magnetic pickup signal path is pickups > selector switch > volume and tone pots in parallel > Powerchip input > output to T/R/S barrel jack in parallel with SPDT on-off-on mag/mix/piezo selector switch.

The signal gradually fading in and out only in the case of selecting the bridge pickup is an odd one: If, for example, this was symptomatic of a
more common fault in the preamp powering on, it would result in the "signal gradually fading in and then out" symptom regardless of switching further up in the signal chain; and wouldn't necessarily be indicative of such a specific impedance issue between the bridge pickup and preamp as you're hypothesizing (though I can see how such an usual symptom would lead one to consider it).

Because the guitar is eleven years old and can't receive warranty work, Fishman will likely end up recommending replacement of the Powerchip at your own expense. However, the simplest way to troubleshoot this would be to bypass the preamp by taking the output wire running from the center lug of the magnetic pickup volume pot to the input solder pad on the Powerchip preamp and clipping or unsoldering it, then running it to the "tip" terminal of the output jack after unsoldering or clipping the preamp output wire connected there. This results in the magnetic pickup signal path being entirely passive. If the guitar then works perfectly with the preamp out of the signal path, the odd symptom can be narrowed down to the preamp circuit. If not, then you have a selector switch to replace before reincorporating the preamp to confirm whether there were faults specific to each of the two circuits. Disclaimer: This is all obviously hypothesized without having the guitar in front of me.

[Sor]

Looks like it was the switch after all. I rerouted, bypassing the Powerchip as you suggested and the issue remained. So I took off the mag selector switch and bent the two inner leaves outward slightly for better contact. That seems to have completely resolved the issue (for now). I suppose I'll try to find a higher quality switch and have it on hand for later.

As a side note, bypassing the Powerchip makes me appreciate its ability to balance the output of the pickups. I do like using it without a battery though, maybe I'll research the mod that allows the option.

Thanks for the insight and clear troubleshooting instructions.

[mmmguitar]

Thanks for the insight and clear troubleshooting instructions.

Happy to help where I can. The common preamp bypass mod using a 4PDT on-on-on switch still draws current from the battery so that there isn't an audible pop or other power-on artifact in the signal when moving between switch positions. You can additionally re-rout the battery negative wire connected to the output jack for preamp power switching to a secondary push-pull pot or other switch if you want a "preamp bypass, no battery usage" option.