G'day
I made up a PCB for the Marshall Mosfet 3310, 5213, 5215 amplifier, I used KiCad to make it but I have no idea if the transistors I substituted will work right.
The Mosfets in the circuit might not be available any more neither, but you can just run wires to whatever you want to use after they are mounted on a heatsink
The original Mosfets were TO-3 type connected with wires running back to the PCB.
I have no idea what the choke or inductor value should be, or the resistor it is wound around, I asked the Marshall tech support and they had no clue either.
The footprint for the choke and the resistor  it is wound around are on top of each other.
Will it work ?  I guess I will find out when I build one, I have 5 PCB's on the way from JLCPCB
I am a complete beginner when it comes to making up PCB's so anything can happen. I have built amps and stuff a long time ago,and then I became a sparky for 40 years.
Anyhow, here are some  pics and files.
Cheers....Mick

G'day
I made this PCB up for myself using KiCad so I can make up some Marshall SS amps, and the Marshall Artist SS pre and valve main amp.
This is not tested and but I have ordered 5 PCB's for myself and they are on the way.( Use at your own risk )
I used the footprints for the Tayda A-5079 PCB mount Jack Sockets and Alpha (Taiwan) pots.
The 2.2uF Electrolytic caps footprint will also fit MKS caps 7.2mm x 7.2mm 5mm Pitch, thats why they look strange on the pics.
IGNORE VALUES IN SCHEMATIC......use the ones in the component list, the schematic is mixed up with values from the various versions.
The 5213 Mosfet also has a clean channel and this is on the PCB as well, only first 3 pots and 2 inputs are on the PCB and the rest of the pots are wired up from plugs on the PCB.
I made up the spacing between pots and sockets etc. myself and it does not correspond to an actual Marshall amp (I think)
I made it to fit into a rack-mount case or whatever I can get cheap.
If I have any problems when I build one I will leave a message, anyone can use the files anyway they want.
I leave the Gerber files I sent to JLCPCB to order my PCB's.
Also the Kicad files if you can open them (might need my modified footprints ? I don't know how to save them yet.)
Cheers.....Mick

After thinking about it for a long while, I finally decided to create a Sun Beta PCB for myself and order some.
I was trying to work out the correct dimensions between the pots but it was really hard, until Fishheadjoe posted some pics for me of his head on the TalkBass forum.
The spacing is most likely not spot on but it is as close as I can get unless I have a original PCB to work from.
I made the PCB up in Kicad, and I added some of my own mods because I like them.
All the 2.2uF NP Electro capacitors ( originally 2uF ) can be used or there is space for WIMA MKS type at 5mm pitch and up to 7.2mm x 7.2mm body in the same place.
I made it for both Bass and Lead, just remove the pots you don't need, Lead - remove the Bass Level pots and Bass Master pot, Bass  - remove the reverb pots and Lead Level and Master.
I bet some who look at the pics will think it has some funny spider pot on there instead of either a Lead Reverb or Bass Level in the same place.
I also added a different power supply plug where the power goes through a 7815 and 7915 regulator in case it is needed to make +-15V
Just delete C1 D1 U1 C2 D2 U2 and the 18-35V supply plug if you already have a +-15V supply handy.
I also made a different footprint for the supply caps C156, C157, C1, C2,  originally C156 and C157 was 10uF 25V, the footprint will fit caps up to 10mm with 2.5mm or 5mm pitch so you can go for a higher value if you want.
The foot Switch circuit is one I got from DiscoVlad on the FSB forum, he used it and said it works fine. Original chips used by Sunn are too hard to find.
This PCB is not tested to see if it works so use at your own risk
I have ordered 5 PCB's from JLCPCB and am waiting for them to arrive, I will post if I have any trouble with them, Its my Xmas present for myself.
I am going to stick it in a 2U or 3U ( front send / return jacks ) rack mount case for myself and my daughter, Lead for me and Lead and Bass for my daughter.
I made all the connectors Molex KK396 type as Tayda carries them and I get most of my components from them when its for me or my daughter, I might just solder wires straight to the PCB though instead of using connectors.

Sound great, now we just have to get the schematic for it.

Do you have the serial number ?
The circuit is different after a certain serial number.
A photo of the back of the Jack socket for headphones might help.

Thanks for all that info Phatt.
I definitely live in Tassie, where the Devils roam free. ( I have had them under the bedroom, makes you jump when they scream at night. )
I was born in Sweden but moved to Australia when I was 12, I still remember climbing on Viking rune-stones as a kid, they were all around the area where I lived.
I went back to Sweden in 1976 when I was 16 for a holiday, but it was still too bloody cold, stayed down under since then.

I am interested in solid state guitar amps off all kinds, I am going to order PCB's for Marshall Mosfet 3310 and Sunn Beta very soon and I just wanted another type of preamp for the order.
I order my PCB's from JLCPCB and find it better if I have a lot of different boards in one order, postage is the killer, but does not increase too much for more boards.

I like to stick circuits into KiCad and making circuit boards up for myself, I find it relaxing, I will have to learn the simulation bit soon in KiCad or some other software.
I don't have much experience in audio circuits, but been a sparky since 1980, mainly industrial maintenance repairing DC and AC drives and any other electronic boards that needed it to keep machinery running. My only tube experience was with high voltage spark testers checking insulation in cable manufacturing.

I have never seen a Sunn SL160 or SL260 in my life, but I might just have the preamp made by Xmas. (Just for fun)
I do love Rod's circuits and have looked at nearly all of them, I have read up on the reverb circuits on his page, but I will stick to what was original on the Sunn SL260 circuit.

Again, thank you for your help, I' gonna start reading up on what you mentioned now.
Michael

I just looked at the TDA2003 spec sheet, it looks like you would get 4 watts at 12 volts, not enough for bass in my opinion, but I am not an expert.
If you have the kit, build it and run your send/line out/ to effects output of your amp into it, and run the output to a separate cab and see what it sounds like.
Or get the signal from your stereo/phone/MP3 player and try it, see how loud the music sounds.
If its not enough the just get another amp module, like I mentioned before, the TPA3116D2 has 15 watts at 12v on the spec sheet at 4 ohm speaker.
You will not us a lot of extra power with a TPA3116D2 if you keep the volume down.
Class D power amps are very efficient and only use a bit more then what you use, if you use a 100w class D amp and only turn it up to 10Watt you will only use about 12-13 watts of power, at least that's my understanding.
Check the spec sheets of the power amp you are thinking off using and find the power rating for the voltage you intend to use, that's what I would do.
Class D amps don't need big heatsinks as well which saves money and weight.

If you are busking I imagine you might be doing it mainly during the day, have you considered a small solar cell ?
You can get a 20 watt panel that would be smaller then the top of a small amp with a 10" speaker in it.
The solar panel would continuously top up the battery as you are using it, you might possibly be able to use a smaller battery.
The solar panel does not need to supply enough power for continuous use, just enough to prolong the use, ie. using 2 amps playing and putting 1 amp back in at the same time. And the solar panel keeps working while you have a break.
Just a crazy thought that popped into my mind.

Another small amp module I think might be good is the TPA3116D2, very cheap on Ebay ($8 up).
In stereo at 12 volts it can go up to 15 watts per channel into 4 ohm speakers.
If you needed more power you could use 2 x 12 volts batteries for 24 volts, then you can get 60 watts per channel into 4 ohm speakers
If you do go with a stereo amp module you could run one channel Bass amp and one for voice / guitar, 2 different speakers.
The TPA3116 can run on 4.5 volts to 26 volts.
I have 2 100 watt mono  modules I bought ages ago, they are small enough to fit into a 1590B stomp box, I was thinking of using one with a laptop power supply for a small pedal amp.
I think that would go nicely with the Sunn Beta preamp pedal I made.

Thank you LoudThud for that information.
I don't suppose you would know the Dual Pot orientation in the variable frequency circuit for the Mid control, If I can't find out I could just leave the viper (leg2) disconnected, and then short it to the correct leg after i build it. The viper (leg2) has to be shorted to leg 1 or 3 of the pot.
Even better if someone could identify what kind of circuit it is so I can do some research on it, it has to be some kind of active notch filter I presume.
Again, thanks LoudThud for your help.
Michael

G'day
I am drawing up the Sunn SL260 into KiCad so I can make the preamp PCB for myself.
I have hit a roadblock as I cant work out the orientation of the Pots in the tone section
can someone please check and advice me how they should be mounted, ie, pin 1 on pots.
That's the Bass, Mid, Mid frequency, Treble pots.
I have also made some mods to the original circuit, power supply and foot switch circuit for reverb, do they look ok ?
Thank you for any help.
Michael

There are plenty of circuits out there to find, just google busking amp circuit, then try them out.
It sounds like a small mixer desk might be worth a look, I know people have used the old Sunn Alpha powered mixer for guitars in the past.
I'm not suggesting that the Sunn Alpha would suit you, but looking at the circuit might give you some ideas.
You can easily incorporate some stomp box circuits into it as well, like reverb, chorus etc.
Do you have a battery operated drill ? Or any other portable power tools ? Nice portable battery packs.
You can get adapters to fit portable drill battery packs so you can use the batteries for other things.
Good luck with your project, please keep the post going if you proceed.

I have never heard of this amp, but I'm just beginning to make stomp boxes so am not too familiar with the gear.
What sort of amp is it ? How big etc. How many knobs on front ? Reverb ?
If I got an old amp chassis I would replace it with something like a stompbox preamp board.
If the power amp still works you would just need a basic one like a Sunn Beta preamp, quite a few of those around to choose from.
Lots of other PCB's or complete preamp kits for stompboxes out there, you could include a few different effect pedals inside the amp box.
Tube screamer or Rat for distortion, Reverb pedal board (BTDR based)  chorus, etc.
Just run wires from the PCB's to the pots mounted on the front panel,
If the power amp is dead then for a quick fix get a 3886 amp module from Ebay.
It all depends on if you are talking about a small practice amp or a big amp with a 12" speaker in the cabinet.
Sunn Beta (Sunbeam)  https://effectslayouts.com/product-category/pcb/overdrive/page/2/
Other Preamps:  https://aionfx.com/projects/
lots out there made for stomboxes but will work just as well in a full amp in a cab.
post a pic of the cab you are dealing with and you might get better information, what do you want from it ? Clean, crunch, rock, soul, metal.
That's my inexperienced 5 cents worth.

First thing to do is to find out which model MosFet you got, they made more then one model as far as I know.
Then i would find the correct circuit for it.
Try DrTubes website for the circuit to start with.
https://drtube.com/en/library/schematics/69-marshall-schemas
Once we know what you have we can make better guesses