Beginner attempt at building pedal from scratch (Tascam 246 Input Assembly)

[antonis]

You may delete everything after the PAN pot (downstream) with no issue..

Your audio out should be OK..
(you might need a Volume/Level pot the way PAN pot is wired and get OUT from its wiper..)

Connect overload light OV(D) right on Power supply GND (as close as physically possible)

IMHO, they don't have to be non-flamable, as long as their wattage (power rating) is ample..
(can't figure out how the JFET differential pair could draw large current, but I can't be inside the designer's mind..)
After all, they're just part of particular circuit supply LPFs (together with C103 & C104)..

P.S.
I'd feel more comfortable if you ignore my last suggestion and proceed to non-flamable resistors..

[PRR]

N.F. resistors are near the +/-12v ins. These are just non flammable resistors?

Here, "NF" is Negative Feedback, not Non-Flammable.   I am WRONG!

Yes, the power rail decoupling resistors are noted as Non-Flammable. Because worry-warts say the 47uFd caps might go short, and put 1.44 Watts in the 100r resistors, which might burn with a tiny flame, and panic a large crowd. If you are subject to safety-regulator scrutiny, you better consider. Don't do as I would do (let it burn).

[antonis]

Do we have to pay special attention on those Negative Feedback points..??
(can't figure out the purpose of excalmation mark inside equilateral triangle sign..)

Maybe it worns for some unknown danger (K-25)

[PRR]

can't figure out the purpose of excalmation mark inside equilateral triangle sign..

Used in much service literature to say "IMPORTANT", possibly life-critical safety.

I don't have a legible example at hand, but if you squint these you can imagine a "!" in the triangle.

[ElectricDruid]

Jeez, it's only a tape player!! It doesn't have to be intrinsically safe for use in a flammable atmosphere!

(Unless you want to do four-track recording in a mine, or at a petrol station, say... )

[PRR]

(can't figure out the purpose of excalmation mark inside equilateral triangle sign..)

Ah, I found the treasure-trove of triangled "!" marks: IBM/Lenovo documentation.

[antonis]

OK we're making fun till now but, IMHO, it should be considered "tragic" for a circuit designer to warn instead of making their own prevention.. 

[meldrop]

Okay still trying to locate all the parts for the test build. Still having some trouble finding suitable parts. Wanted to check in with everyone to see if there were any known replacements.

D101 D102 - 5224015020 -DIDOE, 1SS133T-77 --> (1N4148 is acceptable replacement?)

Q103-5230780920-SI.TR. 2SC2603F
Q101 Q102 - 5145103000 &  - FET, 2SK-68A-M --> People seems to be really fussy over the use cases of these two parts. I really havent been able to find anything on google but I will keep looking.

These two I am having trouble with currently, but will continue looking and update yall.

[meldrop]

Another post quotes the following

"For 2SA1115 / 2SC2603, in most cases you shouldn't use the KSC1845 pair you listed (Ic=50mA vs. 200mA). These parts are occasionally used where they shouldn't be to begin with, so I'd aim for equal or greater on Vceo / Ic / Pc unless you are sure the circuit allows lower values.

If there's a big increase in Vceo, Ic or Pc on your substitute, there's often a compromise elsewhere.
As elnaldo said you just need to search the forum, you'll find subs and reasoning."

So i am taking this as the KSC1845 is not a good replacement part for reason stated above that are beyond my understanding at this point. What would be a reasonable replacement in this case?

[meldrop]

I also assume the IC,NJM4560DX can just be replaced with a standard NJM4560? I couldn't find much about the DX suffix on this part?

[ElectricDruid]

So i am taking this as the KSC1845 is not a good replacement part for reason stated above that are beyond my understanding at this point. What would be a reasonable replacement in this case?

My usual rule of thumb is "Use a 2N3904 unless there's a damn good reason not to". Other people here have similar rules for other jellybean parts, like the 2N5088 or BC549.
The unit was built in Japan so all the parts are stuff they had easily available, not something that was selected specifically out of all the transistors in the world for that particular job.

I would try something simple and see how it goes.

[antonis]

Λ What Tom said..!!

Q103 Collector current is about 5mA (when ON) with a V_CE of about 3.2V, so ANY general purpose low power n-p-n BJT (TO-92) should be fine..

P.S.
Gain suffixes like A,B,C or 16,25,40 should leave you indifferent..