fender princeton 5D2.. DONE!

[elementx]

http://schematicheaven.com/fenderamp..._5d2_schem.pdf

I'm all done, finally. Take a look at my voltages, they're a bit off but acceptable, no? Unfortunately I don't have my guitars with me so I can't even try it out... grrrr. The wiring got a little crazy as time went on too...

[Makofoed-6sn7]

Hi,

Great job!

About your voltage mesurment,
they seem's to high. You have 453v on a 450v rated cap. That is too much! Also, 6V6 can't handle that high voltage, even the orignal amplifier used to high anode voltage so yours are way to high! I guess you used a mains transformer with too high secondary voltage? A quick fix is to wire a resistor between the rectifier valve and first filter cap. If the rectifier tube can handle the secondary voltage from your transformer. Also, since you have so high voltage, arn't the 20k resistor between the second cap and last filter cap running very hot?

[Trout]

Is that the transformer set that Triode Electroics sells on eBay? If so, They should have been closer on the voltages than your showing.

Basically that model princeton is about the same as several other models including the champ.

Nice job for a first attempt!!
My first champ is still in my garage hanging on the wall as a reminder to think out my layout first. I had at least 30% more wire!!

The Amp I just built this week is evidence of my persistance to shoe horning to much junk into a small chassis.

Here is a 5E3 deluxe stuffed into a 13.5 X 5 X 2 Hammond chassis.




I noticed that the voltage reading on your 4th ref point ( L-R ) is rather low, You may need to adjust that bias resistor. I seem to recall mine needing to be much higher.

I'll look up my notes and post them later.
Trout

[elementx]

The transformer is supposed to be 650ct according to the datasheet below. I'm using the RED/YELLOW CT, maybe this is the problem? Should I use the Red/Black, that gives me 300-0-400.



As it is now, (with RED/YELLOW)
I'm measuring off the secondaries:
353-0-353
the original amp calls for, I believe:
325-0-325

I saw that the 5Y3-GT RMSin is 350-0-350, so does that mean the secondaries are acceptable operating range for the tube? I mean, I'm not gonna shorten its life? As for the rectified voltage...

What value resistor do you recommend before the first filter cap to drop the rectified voltage?

I understand it's running a little high, so I've only turned it on for a few secs, as to not damage anything (famous last words)

[elementx]

hey trout, that's a beautiful layout, very nice 'n neat. I always start out with good intentions as to keep it clean... but it never ends up that way!

This was the first tube amp I built, and I find it a LOT more fun than the chipamps... it's fun building an amp where a bench grinder, hole saw, miter saw, and brad nailer are required tools!

...And yeah, that's the TRIODE brand transfomer(s). I wonder if they just aren't to spec, or (more likely) I did something wrong... but really the only thing I could change when you're just looking at the transformer is the darn center tap, and that don't seem to help... (stumped)

[tubelab.com]

The red-yel wire is the one that you should be using. The red-blk is for bias voltage on fixed bias amps.

[Trout]

As it is now, (with RED/YELLOW)
I'm measuring off the secondaries:
353-0-353
the original amp calls for, I believe:
325-0-325


Thats plenty close enough, But, Heres my thought, Look at the champ power supply. The First resistor on your layout is only 470ohm.
I am guessing but I think the champ values will get you much closer. the 5F1 specifically uses a 10K in that location. Thats a huge difference.

When they listed those transformers, The used general names like Princeton or Champ but there were many models of those amps. Not all of the transformers were the same.

The set includes our 5F2 Power transformer, Choke, and TF-103 Output transformer. The TF-103 has the added flexiblity of ultra-linear taps if you wish to use them. The Power transformer also adds a center tap to the filament and a 60V bias tap if you wish to convert to fixed bias. This bundle is great for replacing blown or upgrading the worn out trannys in your fender, also works great for DIY projects. Strip out that lame solid state amp and build this one inside. Output transformer has 4 and 8 ohm taps.

The 5F2

5F2 Schematic

That 8.6V reading should be closer to 19V which I beleive will load the voltages down somewhat.

Are you using the choke on the 5D2 circuit? I ask because the original did not have one.
Trout

[elementx]

Ok, well I added a 940ohm resistor before the filter cap, my voltages are now as follows...



A lot closer! What about that 11v measurement, it's way too high... should I add another resistor or ignore it? Thanks guys!

[tubelab.com]

The 11 volt measurement is the cathode voltage on the 6V6. 1.5 volts is wrong. I would expect 15 volts. If the cathode resistor is 470 ohms, 11 volts is only 23 mA of current. It should be around 30 to 40 mA. If you have another 6V6 try it and see if the readings change.

If you like the sound, it is probably OK.

If you want to raise the current, try lowering the value of the 20K resistor in your 5D2 schematic. Note the screen grid connection is different in the 5E3 schematic. This will increase the tube current a bunch, which will lower the B+ voltage.

[poobah]

Trout,

That is some damn fine lookin' work! Can I even post on your threads any more???

elementx,

Congrats! and don't let Trout's amp show you up! (I still have pictures of his first... we never could find the problem)