TS808 Clone doesn't work

[Amitay3333]

I thought to dessert my week of stomp building with a clone of the vintage TS808... It's true bypass and works well when it's off but when Its on- only when I'm strumming hard I get this weird farting sound like hard fuzz.
I have chaked the switch and connection between components and as so bridges, everything seems ok.
Needed to mention that after a close look at the schematic I spot a couple of "mistakes" on the schematic that lead me to change:

C11 from 1UF to 47UF
R18 from 100k to 10k
R6 goes to 4.5V not to GND

Still got farts

This is the voltage reading:

Pin   Drive   Volume   Tone   IC1
1   8.02   5.666   8.033   8.269
2   8.268   5.617   8.035   8.029
3   8.269   5.616   8.034   0.003
4                                    0
5                                     8.034
6                                     8.036
7                                     8.036
8                                     9

Pin   Q1          Q2      
E   4.265   4.272      
B   4.629   4.692      
C   9           9      


I did also audio probe and I got sound until I touched Q1 base so I swaped for 2n5088 transistors and have chaked theorientation and still got nothing... maybe someone  can help me here.

*C2 ,C7 are NP
C5, C6 are Tantalum

Don't know why but I can't upload the pictures from my phone Can someone send them instead of me pls?

[idy]

So the IC getting correct supply voltage
but the opamps are not getting "biased"
except for pins 4 and 8, all should be at "mid voltage."
instead they are some scary high number.

The schematic? where? link?

On vero? on a pcb?

do you know the part of the schematic that creates that VB or bias voltage?
Two 10K R and two big caps....

PS: gated sound, among most common causes: mis-bias.

[antonis]

Schematic..??

P.S.
Q1 Emitter is biased correctly.. If you don't have signal after Q1 Base it means Q1 Emitter is AC grounded..
3mV at first amp non-inverting input (pin 3) calls either for abscence of Vref bias resistor or GND instead of Vref..
Second amp saturation is normal taking into account direct coupling to first amp out..

[antonis]

On behalf of OP..

[antonis]

R5 should go to Vref (+4.5V) and NOT to GND..!!!

(R6 could go to either Vref or GND..)

[duck_arse]

one of those jacks has only a single wire - you will need two wires to pass signal properly, if at all.

[Amitay3333]

On behalf of OP..

Thanks for helping me with the pictures man!

R5 should go to Vref (+4.5V) and NOT to GND..!!!

(R6 could go to either Vref or GND..)

Thanks Mann! seems like my eyes are tierd from building this...
I'll check next time if that was the problem(probably is), this week I'm not home(:
I figure it out by the farting/fuzz tone that it's something regards the voltage bias and stuff...
I wandering if connecting R6 and Level pin 1 to GND changing the tone?

one of those jacks has only a single wire - you will need two wires to pass signal properly, if at all.

That's actually works well since the connection to GND happend trough the chassis, but when I use it without the enclosure I use alligator clips...

[antonis]

I wandering if connecting R6 and Level pin 1 to GND changing the tone?

No, as far as +4.5V point is consedered AC grouns (via C11, which could be bigger for more effective grounding..)

Also, your schematic needs some corrections, like R17 & R18 values ratio (the have to be of the same value), C1 value (make it 22nF) and some improvements like increasing R5 and R10 values..
Also, R15 could be ommited or replaced by a 1k Base series resistor (like R2)..
(it's there for Q2 Emitter follower oscilation prevention in case of OUTPUT coupled on load exhibiting "unknown" capacitance..)

But let them be for the time being and focus on initial issue troubleshooting..

[Amitay3333]

I wandering if connecting R6 and Level pin 1 to GND changing the tone?

No, as far as +4.5V point is consedered AC grouns (via C11, which could be bigger for more effective grounding..)

Also, your schematic needs some corrections, like R17 & R18 values ratio (the have to be of the same value), C1 value (make it 22nF) and some improvements like increasing R5 and R10 values..
Also, R15 could be ommited or replaced by a 1k Base series resistor (like R2)..
(it's there for Q2 Emitter follower oscilation prevention in case of OUTPUT coupled on load exhibiting "unknown" capacitance..)

But let them be for the time being and focus on initial issue troubleshooting..

Ok thanks man!
Yhe I went fast with that schematic but as I told I have changed C11 and R17 & R18(:
Maybe I'll try later the improvements(:  thanks for the tips!



Regards
Amitay Kehaty.

[PRR]

My eyes, or does this look wrong to anybody else?

Smells like 8V from here.

[antonis]

OP stated the below changes in his 1st post:

C11 from 1UF to 47UF
R18 from 100k to 10k
R6 goes to 4.5V not to GND

[Amitay3333]

R5 should go to Vref (+4.5V) and NOT to GND..!!!

(R6 could go to either Vref or GND..)

Problem fixed😁 Thanks!