Trouble Shooting an F1

[Donovad]

Well, my DIY F1 seems to measure as it should but the output is very weak. With my 24v Aikido preamp i can barely get any sound out of my C&C Abbys. 3/4 on the volume and just barely anything. Full volume and distortion sets in but it doesnt get any louder. Zero bass, but nice soundstage would be the best way to describe it. I've measured just about everything i know of and the values are as follows...and were taken after 1 hour warm-up...


Source Drain Gate

L Q1 3.77 13.77 8.15
R Q1 3.75 13.77 8.13

L Q2 3.78 13.82 8.15
R Q2 3.76 13.81 8.15

L Q3 21.85 13.82 17.30
R Q3 21.91 13.82 17.30

L Q4 21.84 13.91 17.20
R Q4 21.90 13.89 17.30

L Q7 .094 2.82 5.00
R Q7 .087 2.82 5.01

Voltage across R27-R30

L R27= .577, L R28= .577, L R29=.573, L R30=.576
R R27= .571, R R28= .572, R R29=.572, R R30=.570

The differential DC offset measured across the speaker terminals

Left 45mV (with load) 60mV (NO Load)
Right 25mV (with load) 35mV (NO Load)


I've attached some pictures for reference , maybe you folks can see something I'm missing ...?

Thanks in advance for any help.

Regards, Daniel.

[Netlist]

I didn't check your voltages but they seem consistent.
Do you have a scope to trace a signal?

[Donovad]

Thanks for stopping by Netlist. No scope unfortunately, just a Fluke 179 multimeter. The boards are from DIY member Suds, but I'm not sure there are any other documented builds with this version of boards.

Regards, Daniel.

[Gyuri]

I'm not sure that a good insight, but if the reverse polarity protection zener would be present.
Not on the board in relation to drawing, but the original wiring diagrams for comparison.
Maybe.

Gyuri

PS:

Of course, it would be better if the bottom could be seen.

[Zen Mod]

I can bet that you feed it with unbalanced signal , and that you forgot to ground minus leg input

[Netlist]

Bad solderings could be a cause of your problem.
Apart from that, a signal tracer can be made with very simple tools.
If you have a signal generator, you can inject a 1kHz into the input and follow the signal path with your multimeter in AC mode.
Else, internet or a kind fellow member can provide you with a simple sine wave, playable from your PC.

[Gyuri]

I think it was not a bad idea, but I found this photograph, this is not the problem.
I'm sorry.
Perhaps there is someone better idea.
Papa Pass help us!
And besides, your name included in our daily prayers.

F1 Amplifier + PSU PCB's for Free

Wacky Gyuri

PS:

And those diodes really zener diodes?

[flg]

Originally Posted by Donovad

.... No scope unfortunately, just a Fluke 179 multimeter....
Regards, Daniel.

Does that Multimeter do AC volts. You can use that to trace the signal

[flg]

From what I've read so far, maybe you should measure the values of the Rs around the input. R1, 13, 7, 5 and the other side

[Zen Mod]

Originally Posted by Zen Mod

I can bet that you feed it with unbalanced signal , and that you forgot to ground minus leg input

.