SOLVED Viceroy very low gain

[Fama]

Built up the Viceroy, and it passes signal and sounds somewhat like it should if I dime level, gain and juice and toggle juice to be enabled. Toggle juice to disabled, and it's more of a mid gain thing. Lower either level or gain and it gets way too thin. In short, I don't have as much signal as I should.

First off, I've got some substitutions. Main one being MMBF4393LT1G's for Q1, Q2 and Q3. Second, a 2N5088 for Q4. All of these seem to be lower gain than the normal ones, but my impression was that it shouldn't be a very drastic difference.

At first I had something like 1.3V for Q1, so I desoldered and socketed R6 and R4. Switching out R6 to a 3.3k resistor I now get 5.37V at the drain and 1.63V at the source of Q1 (0V at the gate). Audio probing it it sounds like it amplifies the signal decently, and it's a big improvement over the original with 1.3V.

Q2 is 5.12V and 1.13V for drain and source (gate again at 0). Q3 is 8.36, 5.12V and 2.8V for D/S/G.

I've checked all the caps (except for C2 since I can't see the markings on it - but I don't think it should make a huge difference here?) and I think all the resistors now too, and they match (except for the aforementioned R6). Resoldered all the component joints, didn't see any problems with any of those.

Now, I know Q1 looks horrible because I switched it out for another one thinking it might just be a bum JFET, but it seems to be soldered fine right now from what I can see. The others might look bad due to the flux, but the soldering is ok with those too. Similarly some wires seem like they're not soldered - they are, just from the "wrong" side of the PCB. All of them are firm to tugging with pliers, and there doesn't seem to be grounding or power issues.

I put in a socket for Q1 in preparation for getting a 2N5457 in the mail sometime in the future, which I might try subbing out, but I've only ever had the SMD parts in it, the socket has been empty the whole time. From what I can see, the pinout should match between the MMBF4393's and the PF5102's (https://datasheet.lcsc.com/lcsc/2304140030_onsemi-MMBF4393LT1G_C152291.pdf, I ordered them from LCSC).

Audio probing the whole way, it sounds like I get decent amplification from Q1, then lose a lot of signal to the bass and treble controls, and then get a lot of amplification from Q2 again - which seems more or less like it should go. I can try to measure dB values if that's helpful, but it's probably not going to be very accurate - I would have to use the audio probe and audio interface for that.

Edit: Handy links:

https://docs.pedalpcb.com/project/Viceroy-PedalPCB.pdf

PF5102 datasheet https://www.mouser.com/datasheet/2/149/pf5102-99964.pdf

 

[Fama]

I put in PF5102's that I ordered from Retroamplis which just now arrived, and even though they were pretty expensive since I didn't need anything else, I can happily say I now consider this pedal fixed.

It still feels a bit weird with the level and gain controls, at least compared to most other pedals, but I can now get around unity with level at 12'o clock and gain around half or maybe a bit higher. Lower gain than that gets a bit weird, but it's fine. I can now get a dirty clean (or even just a beefier clean I guess) that moves into a medium overdrive with the Juice switch, or a low gain overdrive sound that goes into a massive distortion with the Juice switch, so it's very much usable without having to keep level dimed all of the time.

Edit: I did keep whatever values I used for R4 and R5 while testing, which I think add more gain than the original, but it works fine like this so I think I'll just leave it. Maybe solder in the socketed resistors and now the transistors too to avoid any contact issues.