Help with fender champ 5f1 with low volume/noise

[Etr300]

Hello
My friend bought a few years ago a kit of clone fender champ 5F1. I decided to help him, and I assembly this kit. Initially I had hum noise and pop noise, but after I reweld the circuit I reduced this noise.
If I connect a microphone(not amplified)to input with low impedance I listen a weak sound with pot. at maximum.
I disconnected microphone and I measured the voltage on input without audio source. I read a 2 V.
I don't know how to procede to solve the problems?
The amp works with 220V at 50Hz, and I changed the original pot which has switch to power on/off with simply pot(10k log).
Do you have advice to procede?
My friend play guitar, but he would like to use with harmonic, because he plays jazz and blues music.

Thanks

[shooter]

I read a 2 V.

AC or DC volts?
did it come with the schematic?  you posted a layout?

[HotBluePlates]

... I measured the voltage on input without audio source. I read a 2 V. ...

Your layout shows 2,3v DC at the 68kΩ resistors and at Pin 2 of the input tube.  These should be 0v DC.

If you amp is wired exactly as the layout shows, the problem is the jack labeled "Jack 2" does not have the ground connection it should have, which is instead at "Jack 3."

Unsolder the Green ground wire from Jack 3, and move it to Jack 2 so that your jacks match the image below:
(Your layout's "Jack 2" is the image's "1 High"
Your layout's "Jack 3" is the image's "2 Low")

[Etr300]

Hello
I change the input jack like figure, but I read voltage but it didn't change.
I verify output jack and I have a doubt.

Could you confirm what is the correct schematic?

Because I weld 22k together one pole of transformer to T connector, another pole I connect to G. The connector is screwed directly to chassis.

In the second schematic G of jack is connected to ground.
Do I need to isolated the output jack?

I have transformer with 0 4 8, but I would connect only speakers with 8 Ohm

[Platefire]

I think you need to show full schematic that you built the amp from. That would be complete circuit from input jack to speaker jack and everything in between. There can be a lot of variations of the 5F1

[Etr300]

There are a difference between components that I received in the kit and the component in the layout/schematic.
For example in the layout there are a different type of connector of input/output and there isn't a selector for 4-8-16 ohm. The output transformer has only 4 and 8 ohm.
In the kit there was a wrong value of resistor. I had bought the correct resistor.
My friend hasn't interest to have more output impedance. He bought a speaker of 8 ohm of Jensen.

[shooter]

whoever drafted that schematic should be taken out back, duck-taped to a tree, then forced to sharpen 2,718 Ticonderoga #2 pencils, while saying "I will learn to properly draw a schematic" for every pencil they sharpen.


to the smart kids;
is the cathode R going to the secondary of the OT at the 4ohm tap a mistake?, some sort of funky NFB?
edit R8 22k

[SEL49]

That's just the standard NFB on a standard 5F1.

[shooter]

thanks, found it on a 5F2 schematic, also figured out there's no "tie" at the cathode/volume pot NON-junction
woulda been a good place for DC to get on the input jack.


too much fun in the sun working the park to switch between tech, landscaper, tech.....

[Etr300]

Sorry, If I understand, I connect OT to 8 ohm and leave 4 ohm, exactly?
If yes I had connected to label of OT 0 and 8.
Do you have another idea about DC voltage on input?

[mresistor]

Can you post good pictures of the actual ampifier's circuit inside the chassis that you have built.  We have no idea what it looks like or if the wiring is good.


Yes  use ground and 8 ohm tap if your speaker load is going to be 8 ohm.  That is fine.
heat shrink to insulate the non used 4 ohm tap and tuck it away .

[SEL49]

Yes  use ground and 8 ohm tap if your speaker load is going to be 8 ohm.  That is fine.
heat shrink to insulate the non used 4 ohm tap and tuck it away .

I would connect the 4Ω tap to R8 on the board just to keep the NFB at the same level as the original.

[SEL49]

I measured the voltage on input without audio source. I read a 2 V.

You should read zero volts! Which brand and model number is your voltmeter and are the batteries fresh? I'm asking because there are so many unbelievable voltage numbers on that layout. Did you write those numbers on the layout?

I changed the original pot which has switch to power on/off with simply pot(10k log).

Why? I can understand if you want a separate power switch. But you cannot replace a 1M pot with a 10K pot. The schematic and layout specify a 1Meg pot. Using a 10K pot is unacceptable.

In the second schematic G of jack is connected to ground.
Do I need to isolated the output jack?

The sleeve (ground lug) must be connected to ground.

[mresistor]

Yes  use ground and 8 ohm tap if your speaker load is going to be 8 ohm.  That is fine.
heat shrink to insulate the non used 4 ohm tap and tuck it away .

I would connect the 4Ω tap to R8 on the board just to keep the NFB at the same level as the original.

It's whatever sound he likes   it's not that critical 8 ohm or 4 ohm   but original is always good.

[Etr300]

for SEL49:

You should read zero volts! Which brand and model number is your voltmeter and are the batteries fresh? I'm asking because there are so many unbelievable voltage numbers on that layout. Did you write those numbers on the layout?

I used a Fluke 175. I bought new a few years ago. The battery is ok.

Why? I can understand if you want a separate power switch. But you cannot replace a 1M pot with a 10K pot. The schematic and layout specify a 1Meg pot. Using a 10K pot is unacceptable

I wrote 10k but I wrong to write. I used 1M, excuse me for a mistake.

The sleeve (ground lug) must be connected to ground.

Ok

It's whatever sound he likes   it's not that critical 8 ohm or 4 ohm   but original is always good.

I would connect the 4Ω tap to R8 on the board just to keep the NFB at the same level as the original.

If I connect to 4ohm the speaker of 8 ohm, Is there a loss of power? Is it better to connect at the same impendance?(I think change how to sound amp, but I can't play musical instruments and therefore I don't know)

[Etr300]

These are the picture of amp. There are some welds which I'm not happy how I did, but I think that these weld are accetable(I don't know).
I disconnected the input and output connectors, but I did the measures connected to chassis.

[SEL49]

I would connect the 4Ω tap to R8 on the board just to keep the NFB at the same level as the original.

If I connect to 4ohm the speaker of 8 ohm, Is there a loss of power? Is it better to connect at the same impendance?(I think change how to sound amp, but I can't play musical instruments and therefore I don't know)

Let me be clear... connect the 4Ω tap to R8 on the board. And connect the 8Ω tap to your 8Ω speaker.

[Etr300]

Other photos

[Etr300]

Let me be clear... connect the 4Ω tap to R8 on the board. And connect the 8Ω tap to your 8Ω speaker

I didn't know that it is possible to realize this connection. Ok, I will do. Thanks

[Etr300]

I tried to modify to connect speaker to 8ohm and R8 to 4ohm, but I have DC voltage on input. Is there the possibility to test ECC83 tube?

[Willabe]

I tried to modify to connect speaker to 8ohm and R8 to 4ohm, but I have DC voltage on input.

DC voltage on the input of what? 

[Etr300]

Input jack, on high and low impendance.

[Willabe]

Input jack, on high and low impendance.

I think you mean hi/low input?

[Etr300]

Yes