Building Fender Frontman 212R

[pacific112j]

I decide to build my own amp.
Is there anyone who can help me?
send me a schematics, pictures of finished amp and board with elements..

[Diablo]

Why build it? It's a solid state amp, which typically sell for dirt cheap when used.

[pacific112j]

If I want to graduate in my school I need to build something by myself.. I decide to build amplifier because I play guitar and need a little better amplifier than I have..
I have Laney HCM30R..

[Enzo]

There seems to be some discussion whenther there is a difference between the FM212R and the Frontman 212R. On the Fender service disc, they call the file Frontman 212R, while the schematics are titled FM212R. In either case whichever one you look at is a complete and functional amp circuit.

The FM212R is an entry level model, Fender has it on the replace only warranty list. There is little support documentation, such as board layouts, and the only parts list is about a dozen items like speaker, footswitch, etc.

I would say this is rather a large circuit to build for a school class.

[Diablo]

You could build a Tweed Bassman, and it sure would be a lot easier, and probably sound a heck of a lot better. Tube circuits are a lot easier for me to understand anyway. Here are the original Fender schematics and layouts, along with the easier to read Ted Weber schematic and layout. Weber can supply all the parts or a kit for you to build......no instructions.

http://www.schematicheaven.com/fende...5f6a_schem.pdf

https://taweber.powweb.com/store/5f6a_schem.jpg

https://taweber.powweb.com/store/5f6a_layout.jpg

[pacific112j]

Originally Posted by Enzo

There seems to be some discussion whenther there is a difference between the FM212R and the Frontman 212R. On the Fender service disc, they call the file Frontman 212R, while the schematics are titled FM212R. In either case whichever one you look at is a complete and functional amp circuit.

The FM212R is an entry level model, Fender has it on the replace only warranty list. There is little support documentation, such as board layouts, and the only parts list is about a dozen items like speaker, footswitch, etc.

I would say this is rather a large circuit to build for a school class.

Thank you a lot.
Is that schematics completed? I looked at it and I saw there is missing resistors between R145 an R201. Also missing capacitors between C89 and 201. Is that sort of numbering or really missing some parts?
Do you have page 2 on schematics? Where I can get it?

[Steve Conner]

Often the first digit of the part number denotes a subassembly. You'll probably find that the component numbers 201 and up are on a different board and R146-200 don't actually exist.

I agree with the other comments, this is probably not a good choice of project. The fact that it has multiple PCBs and more than 46 resistors sets alarm bells ringing for me. A simple tube amp like the 5E3 or Champ would probably be better, unless your school require you to use solid-state, in which case you could do worse than check out the projects at ssguitar.com

[Enzo]

Even if they are on the same circuit board, schematic drawers will also often group numbers for sub sections of the schematic. SO all the preamp parts would be in the 100s, the powr amp in the 200s, the power supply in the 300s, and the channel switching controls in the 400s. I made up that example, but that is why your parts numbers are "missing."

Seriously, the circuit boards for that amp are about the size of my computer keyboard.

If you want to make a non-tube circuit for a project, an effect pedal might be a more reasonable size project.

The schematics I posted are what Fender sends me as a service center. It looks complete to me. I don;t offhand see R201 or C201 on there anyway.

[pacific112j]

Originally Posted by Enzo

Even if they are on the same circuit board, schematic drawers will also often group numbers for sub sections of the schematic. SO all the preamp parts would be in the 100s, the powr amp in the 200s, the power supply in the 300s, and the channel switching controls in the 400s. I made up that example, but that is why your parts numbers are "missing."

Seriously, the circuit boards for that amp are about the size of my computer keyboard.

If you want to make a non-tube circuit for a project, an effect pedal might be a more reasonable size project.

The schematics I posted are what Fender sends me as a service center. It looks complete to me. I don;t offhand see R201 or C201 on there anyway.

Do you have any pictures of circuit board or something else of FM212r?

[Enzo]

I have no images other than what has been posted.

[pacific112j]

Originally Posted by Enzo

I have no images other than what has been posted.

In schematic of FM212R where connect "to pot brackets" and "ground" in D8 sector?

[olddawg]

When I got my AS Degree in electronics way back in the day, I also had to design and build a project. Your choice IMHO is WAY too ambitious, will be WAY too expensive, WAY too time consuming, and you will have an inferior, problematic amp when you are done. What I ended up doing is making an expandable 4 channel mixer using opamps and butterworth filters. I did this because my band needed a mixer at the time and mixers were much more expensive than they are now and opamps were the big new thing at the time. I never used it and never fully completed it. I got an A because it worked and I demonstrated that it did. I did however scavange it and use what I had learned to build active crossovers for our PA eventually that year. Enzo's recommendation to build a pedal is probably right on the mark. If you insists on building an SS amp there are lots of simple preamps (or even a pedal) that you can meld with a simple monolithic output IC of your choice. Keep in mind your skill level, project complexity, and time constraints. You are flurting with disaster. There is much more to it than understanding the schematics. You probably want something you can build up on a perf board that you can put in a standard enclosure off the shelf.

[Enzo]

Fender - and many other brands - often uses pots with added support brackets. The brackets are soldered to the board for extra strength.


Fender runs a grounding trace from bracket to bracket. On some models, this actually carries the ground to portions of the circuit.

SO that reference means that the row of control brackets are connnected to that point, which grounds them to chassis with the 10 ohm resistor.

Note the R1 ground symbol is different from the others. That means R1 is grounded to chassis, while the other grounds are gathered together, then sent to chassis through that resistor.

If you build an amp like this just following the schematic, it might work, but there is a lot of layout nuance and details such as grounding patterns that is not discussed on the drawing. You may wind up with hum and noise problems that can be baffling.

[black_labb]

i had that amp, there is no reason you would want to build it. the circuit board is very complex without sounding very good.

do a pedal or something simpler.

[cminor9]

OMG, look at the schematic! You could build the entire line of narrow panel tweeds for about the same part count as one amp that sounds like an electrified turd!

[Steve Conner]

That's harsh! (But probably true LOL)

[Phostenix]

Originally Posted by Enzo

Note the R1 ground symbol is different from the others. That means R1 is grounded to chassis, while the other grounds are gathered together, then sent to chassis through that resistor.

What is the purpose of raising the ground with R1?

[Enzo]

I call them insurance resistors myself. Not sure what the official term might be. PV often uses as many as sox grounds, and then some of them are tied together through 47 ohm resistors. But since the ground points at the jacks are also in contact with the chassis, those 47 ohmers are usually shorted across. but if the jack nut ever falls off, the resistor insures a ground reference.

Same here, that 10 ohm goes to a chassis connection, but so do the jack grounds in many cases. In some amps like a lot of recent marshalls, the whole thing is raised by a 10 ohm resistor from chassis in an attempt to beat ground loops.

[lemu22]

Somebody can help me to find a bill of materials from FM212r I have broken pots and i need de serial number of bill materials. please help me

[TD_Madden]

Just out of curiosity, why did you choose that amp to build?