Fender Frontman 25 schematic doubts.

[praneet.mervin]

Hey folks,
I'm wanting to build a fender frontman amp, so i downloaded the schematic and layout from the fender website . . This is my 1st time so i got a few question. I'm not totally new to electronics as i've studied control engineering at college.
1. there's a label on both the schematic and the layout called "tp< number> " like tp5 tp6 etc . . what does it mean?

2. do i have to devlop my own PCB layout using something like orCAD? or better to hand wire the components?

thats all for now i guess . .

[loudthud]

Is the Frontman 25 a tube amp? All I could find was a Frontman 15. Usually a PCB is too expensive to get made if you are only building one amp. There are services that will make PCBs pretty cheap but I've never used them. If it's solid state, it's easier to build on a prototype board with holes on a 0.100 inch grid. Some even have plated thru holes.

TP5, TP6 usually refer to test points within a circuit. Many times there will be a turret on the circuit board that makes it easy to attach a test probe, DVM etc.

[Enzo]

No, it is a basic solid state amp. The Frontline series are entry level SS amps.

Loudthud is correct, as usual, TP on the schematic refers to "test point." On a Fender like this there will rarely be an actual test point. In this case test point just refers to a point in the circuit. The end of a resistor, the leg of a transistor, etc. Usually there will be a voltage in the TP box. And the shape of the TP box tells you if it is a DC voltage or AC voltage they are looking for. There will be some note as to what signal was applied at the input for the signal voltages throughout to occur.

[praneet.mervin]

thank you

thanks a lot loudthud and enzo i'll buy a grid board in that case and start off with my first amp . . and about the debugging . . will it be good if i individually test the gain/reverb/power etc etc circuits or is there a better way of doing it?

[praneet.mervin]

oh actually i could check all the tp's for correspondence :P

[loudthud]

Novice builders will usually make several mistakes wiring an amp and it can be tricky finding them all. As a minimum you will need a DVM. Wire up the power supply and get it making the + and - 15V. Start at the input jack and wire up the first IC up to the Effects loop jack. It would be smart to install IC sockets for all the ICs. Now if you have another amp, connect the effects loop jack to the input of your other amp and verify that you can play through the amp and the Level and EQ controls work. If you can't get a signal through, check that you have close to zero volts at pins 1 and 7 of U1 and pin 1 of U2.

Wire up the rest of the amp but don't install U4. I'm not exactly sure what U4 does. It's either some type of protection circuit or some kind of distortion or compression feature. Power up the amp with the speaker disconnected. Verify that pin 5 of U5 is near zero volts before you connect a speaker.

For a power transformer you will need something like 36 volts center tapped at between 1 and 2 amps. Hammond 186E36 should work. U5 will require a heat sink with an insulating washer.

[praneet.mervin]

sounds wonderful . . . thanks a lot again