Frontman 212R schematic needed

[bob_amos]

I am trying to locate a Fender Frontman 212R schematic. I have the FM 212R but it isn't the same. Can anyone help out?

[Enzo]

Hi Bob, welcome to the forum.

I posted to you over in the SS Guitar forum on this.

As far as I knew the FM and Frontman were the same thing. WHat is different between your amp and the FM212R schematic?

[bob_amos]

Enzo, I got your post over there. Thanks for responding. Ya know, you asked me what the difference was from the FM diagram and my Frontman. The last time I tried using the FM diagram to work on a Frontman was a number of months ago. I just remember that some of the circuits didn't match the amp I was working on. I just got this new one to work on a problem with the gain. Instead of ripping it appart and not have the schematic I figured that I'd try to get my paws on the correct one before starting. I may have no choice but to try and use the FM diagram. I would imagine that they are close. I'd really like having the correct one though. I do recall that the assembly of the two are as diffent as night and day. The FM doesn't have the quality of assembly that the Frontman does. Not that the Frontman is all that great. But it is leaps and bounds better than the FM. I've had both and prefer the Frontman.

[Enzo]

Well, if they are different, I stand corrected.

Call Fender and ask them for it.

[bob_amos]

Not at all, you may be right. I'm just going on memory and at my age it may be a bit hazy. I'll post the schematic if I find it. Thanks for the input. It's always a pleasure sharing information.

[bob_amos]

Enzo, You asked me where I found the difference on the FM 212R schematic and the Frontman 212R amp and I couldn't quite remember. I've taken your advise and used the FM schematic and did run across the point that I was trying to recall. Now it may just be me missing something in understanding the solid state wiring schematic. (Remember, I am an automotive electrical tech and there are differences) Well, what I ran across last time as well as now is the ICs. On the diagram it calls for U6a, U6b and U6c. My Frontman only has a single U6. Please correct my thinking if I am misunderstanding the diagram. (Which I probably am.) Anyway, I have a low distorted volume on both channels and inserting the signal at the power amp input did not change it. Moving on in my checks I find that I seem to be lacking the 33mA readings at the U6 pin 1 as called for in the diagram and this discrepancy in the diagram has me lost. Perhaps if I understood what I was reading a little better I could proceed.

[Enzo]

On the FM212R, U6 is a TL072 dual op amp IC. That means it has two sections. U6A and U6B refer to the two halves of the same U6 IC chip. Since the schematic also shows pins 1,2,3 on one, and 5,6,7 on the other, the A and B are not really needed. So not all schematic drawers will add the A and B, hence plain old U6. You have one IC on th board marked U6, and the schematic shows its two section where they are in the circuit.

Are the power amp transistors labelled with the same part numbers on your amp as on the FM schematic? If so, even if the board is laid out different, I'd bet the circuit was the same.

At pin 1 (and at pin 7 for that matter) that is 33mV not 33ma. That is millivolts of signal, provided you applied the specified test signal to the amp input.

I would apply a nice strong signal to the power amp in jack, then trace it into the power amp. Does the signal appear on pin 7 of U6? If not, try a new TL072 there. Those ICs are darn cheap, so if it isn;t the problem, no big loss.

[bob_amos]

Well, that would explain things. I figured that I might be reading it wrong. (And I was.) The "ma"...Opps, that was a typo. I meant "mv". In my business we deal with "ma" draws all the time and a brain fart caused me to type an a instead of the v. Thanks for setting me straight.

I put the amp away for now in place of another project. I will drag it out this week end and try as you say. Think I'll drop by the electronics parts supplier and pick up that IC and have it on hand. Thanks for the input.

[Enzo]

The TL072 is a very common general purpose dual op amp. And not expensive. But if you have any 4558, 4560, 4580, 5532, or a number of other dual op amps, they will work too. Those are common types.

[pacific112j]

I am trying to locate a Fender Frontman 212R schematic. I have the FM 212R but it isn't the same. Can anyone help out?

Can you send me schematics for FM 212R ?
Or post me a link to download?

I download it from fender.com but I think in that schematic missing some parts and elements..