Still no break-up. 2x 5F1's.

[Jazz P Bass]

Would any voltage or current tests be of any use?

They sure would.

Set your meter to read Volts dc.
Ground the Black Lead & use the Red lead for measurements.

Leave the tubes installed in there sockets, including the Rectifier.

No signal as yet.

V1: Pin 1 & 3.
V1: Pin 6 & 8
V2: Pin 3 & 8
V2: Pin 2 & 7 (Heaters:* Set meter to read Volts ac: go directly across the pins with the Red & Black meter leads)

[Sea Chief]

Ok JazzP-

will do later tnite once I extract amp (a royal pita/ baffle out 1st, amp goes in from cab front on fat side rails).

Thanks, Sea Chief.

[eschertron]

While you have the chassis out, maybe you could sketch out the schematic for the amp?

[Sea Chief]

While you have the chassis out, maybe you could sketch out the schematic for the amp?

escherton- not sure I understand 'sketch' : its a plane jane 5F1/ the usual monkey here..

Davidson Amplifier Repair, Nashville, TN : Schematics: Fender: Champ Amp 5F1 Schematic

What this means Ive not understanding either "If it still won't get loud enough, it's probably broken". If referring to the "2w OT" (which its spec shows it is).. in fact rewired then into my 8ohm 112 cabinet it sounded way louder than my 4Ohm 8" (a 5w radio spkr): OT rewired back with this as a combo [pic^] as the 112's bass was very ott with the gibson. SC

[eschertron]

What this means Ive not understanding either "If it still won't get loud enough, it's probably broken".

Just my sig line, not directed at you.

escherton- not sure I understand 'sketch' : its a plane jane 5F1/ the usual monkey here..

No disrespect, but IIRC that's what you said about Amp1, too. It was a 5F1, with a tone control, and with a MV. Those additions make it not a 5F1. Not. Close. Just hoping we can all get on the same page and find a solution for your quandary.

[Wes]

Man, this thread is crazy town.

Eschertron is on to something, in my opinion, concerning the "tone stack." I understand that you're saying this amp is not a Champ 600 reissue,
but is housed in one. Schematics or gut shots need to be posted.

If you have components acting as a tone stack in between V1A and V1B- playing with, or bypassing, these will make a world of difference with how
that thing breaks up.

I bypassed my champ 600 reissue's tone (sucking) stack and it is very dramatic. In fact, I tried a couple different things and was able to get it to snarl
at 2. It was too much breakup and I subsequently found a happy halfway point.

Mine breaks up at nearly the same point with a tele with singles and an sg with humbuckers.

[Sea Chief]

Man, this thread is crazy town.

Eschertron is on to something, in my opinion, concerning the "tone stack." I understand that you're saying this amp is not a Champ 600 reissue,
but is housed in one. Schematics or gut shots need to be posted.

If you have components acting as a tone stack in between V1A and V1B- playing with, or bypassing, these will make a world of difference with how
that thing breaks up.

I bypassed my champ 600 reissue's tone (sucking) stack and it is very dramatic. In fact, I tried a couple different things and was able to get it to snarl
at 2. It was too much breakup and I subsequently found a happy halfway point.

Mine breaks up at nearly the same point with a tele with singles and an sg with humbuckers.

Break up at 2?! for crying out loud/ this is a big joke on me with these amps.

Ok please do just disregard amp1 for here; the thread was intended to be re the 2nd am (from which I was going to pillage) specifically why this one doesn't break up you see: I only mentioned amp1 in passing (as I dont precisely remember what it is, as I said/ so its not so easy to establish reasons for that one) to outline it as a "5f1" in inverted commas/ of sorts.

Finding solutions to both amps on the thread I didn't have in mind. Amp2 V checks later/ post results.

Thanks, Sea Chief.

[Sea Chief]

[eschertron]

Nice shots, thank you.

While you are reading voltages, compare component values to the schematic (if you haven't already done so). I see some components (cathode bypass cap on stage 1, treble bleed cap on the volume) that are not on the schematic. be sure to note those, so we can fill in our blanks.

[Sea Chief]

Hi eschertRon-

I will do another check of cap values. I did also note the 1st cap on the RHS too as being different to the fender 5F1.

Also I just an hr ago added the treble cap myself (120pf/ actually a good difference, I thought it unlikely it'd interfere with the growl query/ overall point in Q).

Good to know these spotted! they should be the only two anomalies at all. What's the point of the cathode bypass cap anyway?

[loudthud]

Is that a 1/2 Watt 470 ohm resistor on the cathode of the 6V6 (pin 8)? Most people use a two to five watt part in that position. Measure it's resistance (power off) and measure the voltage at pin 8 with the power on.

[eschertron]

What's the point of the cathode bypass cap anyway?

More gain! The cap keeps the cathode voltage from wiggling around under the force of the grid (signal) voltage. Theoretically, the output voltage can be double with, versus without the cathode bypass cap.

[Sea Chief]

Figures:

V1: Pin 1 & 3. (190v, 1.6v)
V1: Pin 6 & 8 (207v seemed to slide down to 197v, 1.6v)
V2: Pin 3 & 8 (392v, 22.5v)
V2: Pin 2 & 7 (6.3 vac) Heaters:* Set meter to read Volts ac: go directly across the pins with the Red & Black meter leads.

[Fwiw rectifier V3 across pins 2,7 reads 4.9v VAC].

I did forgot to plug spkr in doing VAC and V1 readings- assuming makes no difference tho. Thx Chief.

[guitician]

I would parallel a known good cap across the cathode resistor with some clip leads just to eliminate those as possible bad parts. As those loosing their capacitance can do just what you are describing.

[Justin Thomas]

Not even 5V across th 6V6 heaters? Is the 12AX7 also low? Should be around 6-7V on all the heaters. 4.9V is about 20% low, well outside recommended tolerance...

Justin