Trouble with Fender Champ 5F1 clone.

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Travis
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Joined: Sat Aug 09, 2008 2:13 pm

Trouble with Fender Champ 5F1 clone.

Post by Travis »

This is my first tube amp build so I expect to make mistakes on this one. I purchased the required parts from Antique Electronic Supply(tubesandmore.com) for the Fender Champ 5F1. I went strictly by the original layout and finally turned in on to see the rectifier glowing only. If anyone would guide me through this I will owe them big time.

I have voltages for this amp:
5y3 tube:
pin2= 482 vdc
pin3=349 vac
pin6=349 vac
pin8=482 vdc

6v6 tube:
pin 1=0
pin2=0
pin3=482vdc
pin4=481vdc
pin5=.5 to .6 vdc
pin7=0
pin8=.4 to .6 vdc

12ax7 tube:
pin1=470vdc
pin2=0
pin3=0
pin4=0
pin5=0
pin6=472vdc
pin7=.03vdc
pin8=.5vdc
pin9=0
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Sonny ReVerb
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Re: Trouble with Fender Champ 5F1 clone.

Post by Sonny ReVerb »

You don't have any heater voltage. I'd start with that. Check your grounds. Does your power lamp light up? Check the bulb. Check the voltage between the two green wires coming from the PT. You should see ~6.3V AC or slightly higher.
Travis
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Re: Trouble with Fender Champ 5F1 clone.

Post by Travis »

The pilot light is on but I'm still not getting the heaters going. I'll check out the grounds again.
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Phil_S
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Re: Trouble with Fender Champ 5F1 clone.

Post by Phil_S »

It appears that your 6.3v supply has a center tap. You have grounded the CT and one outer leg at the same ground point. This is shorting half the filament winding.

Leave the CT grounded. Rework the filament supply so that one leg of the 6.3v supply goes to pin 2 and the other to pin 7 of the 6V6. Then jumper the filament supply to the 12AX7, feeding one leg to pin 9 and the other to pins 4&5 (4&5 need to be jumpered.) Please post results.
Travis
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Re: Trouble with Fender Champ 5F1 clone.

Post by Travis »

I disconnected the 2 green heater wires and measured them separately and together. Im getting .22 volts each which is fluctuating, together I'm getting 0 volts. I bought this PT new, its a Hammond 290AX. Am I overlooking anything?
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Travis
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Re: Trouble with Fender Champ 5F1 clone.

Post by Travis »

Phil_S wrote:It appears that your 6.3v supply has a center tap. You have grounded the CT and one outer leg at the same ground point. This is shorting half the filament winding.

Leave the CT grounded. Rework the filament supply so that one leg of the 6.3v supply goes to pin 2 and the other to pin 7 of the 6V6. Then jumper the filament supply to the 12AX7, feeding one leg to pin 9 and the other to pins 4&5 (4&5 need to be jumpered.) Please post results.
Here are the stupid questions as follows:

My PT has: 2 red wire2 650vct, 1 red/yel, 2 green heater wires and 2 yellow wires.

Are you saying that I need to remove one of the grounds? Right now I'm grounding with the red/yel, and one green wire. Where do I go from there?
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Travis
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Re: Trouble with Fender Champ 5F1 clone.

Post by Travis »

Also, what is a CT?
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Travis
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Re: Trouble with Fender Champ 5F1 clone.

Post by Travis »

Which wire is my CT?
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Travis
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Re: Trouble with Fender Champ 5F1 clone.

Post by Travis »

I have new voltages for this amp with rewire:
5y3 tube:
pin2= 484 vdc
pin3=352 vac
pin6=352 vac
pin8=484 vdc

6v6 tube:
pin 1=.4
pin2=32vdc
pin3=486vdc
pin4=470vdc
pin5=398 vdc
pin7=35vdc
pin8=467 vdc

12ax7 tube:
pin1=283vdc
pin2=0
pin3=2.22vdc
pin4=45
pin5=45
pin6=472vdc
pin7=.09vdc
pin8=466 vdc
pin9=45vdc

What do you think im doing wrong now? I have every tube heater working now but the voltage is too high.
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sliberty
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Re: Trouble with Fender Champ 5F1 clone.

Post by sliberty »

Something still seems very wrong with your heater voltages - now they are VERY high. Please post another photo showing the inside of the amp, since you have rewired some things, the old photos don't help anymore. Also, pull the 6V6 and 12AX7 tubes out, and don't turn it on with these tubes installed again until we get the basic voltage were they need to be. Just leave the 5Y3 in place for now.
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Cygnus X1
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Location: Midlands South Carolina

Re: Trouble with Fender Champ 5F1 clone.

Post by Cygnus X1 »

Helpful Tip of the Day:

Use different colored wires for different functions.
Like green for heater, red for plate, blue for grid, etc.

Your CT for the heater is normally a green/yellow wire off the PT.
In your picture it appears you ran one leg of the heater straight to chassis ground. No need to ground one leg if there is a CT on the heaters.

So run one green PT wire to pins 1&2 of your 6v6, then to pin 9 on the 12ax7. The other heater lead looks ok. Then ground the CT.
I think you got your voltages all wonky by mixing up the B+ CT and the heater CT. Or the wires are touching somewhere in one of the sockets.
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Cygnus X1
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Re: Trouble with Fender Champ 5F1 clone.

Post by Cygnus X1 »

I just saw your PT wiring post.
Forget everything I said about a green/yellow heater CT.

Do run the other heater wire as stated, though.
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Richie
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Re: Trouble with Fender Champ 5F1 clone.

Post by Richie »

since your new to building.. be sure you are using the meter correctly.
When measuring the DC.. have the meter set to DC.. clip the meter ground to the chassis,and measure with the pos-red probe,

When measuring the AC..you would set the meter to AC..and measure across both AC heater wires.. one probe on one side of the heaters, and the other probe on the other side. You would not have the neg probe clipped to the ground when measureing this way. And if you had the meter set to AC, it could give almost double [high] readings ,if you were measuring the DC voltage..and meter set to AC..
Travis
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Re: Trouble with Fender Champ 5F1 clone.

Post by Travis »

Richie wrote:since your new to building.. be sure you are using the meter correctly.
When measuring the DC.. have the meter set to DC.. clip the meter ground to the chassis,and measure with the pos-red probe,

When measuring the AC..you would set the meter to AC..and measure across both AC heater wires.. one probe on one side of the heaters, and the other probe on the other side. You would not have the neg probe clipped to the ground when measuring this way. And if you had the meter set to AC, it could give almost double [high] readings ,if you were measuring the DC voltage..and meter set to AC..
I'm new to building but not that dull, however you had me on this one with the AC heater that I thought was DC!! I work in the Automotive field with electrical as a specialty. This is a new project to learn the idiosyncrasies to it. Thanks for looking out though.
Last edited by Travis on Sun Aug 31, 2008 3:20 pm, edited 2 times in total.
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Travis
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Re: Trouble with Fender Champ 5F1 clone.

Post by Travis »

Here is a new pic of the board.
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