Beiträge von syntesys

  • [Solved] The Screamer Kit problems

    Hi and thank you all,

    The problem was chip+board fault. In the feedback circuit of the gain amplifier there was an open circuit between gain pot and 51k resistor; making a little bridge and changing the chip, I resolved all the problems. I found the problem checking the resistor between pin 1 and 2: in my case I found that there was an open circuit; then, tested continuity point to point from pin 1 to pin 2.

    Problem resolved, thank you all!

  • [Solved] The Screamer Kit problems

    Yesterday I was a lot tired, sorry:

    • On pins 1-3-5-7 I have 4.5V;
    • On pins 2-6 I have 4.0V;
    • With the phrase "the pedal doesn't sound", I meant that even if the voltages are pretty good, the sound arrives to the pin 3 of the RC4558 and then gets lost, there is no sound in the output pin 1;
    • Another thing I noticed is that when I touch the volume pot I can hear a hum going to the amp.

    Launch of a scream or launch of the scream? This is the problem :D

  • [Solved] The Screamer Kit problems

    Hi Loetbert and thank you.
    Ok, I thought that for R5, good.
    Then, I measured without the chip and the resistance is 20 ohm (also in the pins of the second amp) so the problem is not R5. Installing a new rc4558, I found that all the pins and the VBias is more or less 4.5, so now the bias is correct... But the pedal does not sound.

  • [Solved] The Screamer Kit problems

    Hi!

    there are no problems on R15-R16 (TS9-TS808), I desoldered the cables and put in the resistors without changing the result. Also, removing the IC and jumpering pin3-pin7 in the socket, the sound goes flawlessy from in to out.

    Zitat von Loetbert

    Sure the 4558 has not been upside down?

    Yep, it's installed correctly.

    Zitat von Loetbert

    Did you insulate the pots toward the PCB?

    Yes, I put the black bumpers arrived with the kit and no one part it's touching the pot.

    Zitat von Loetbert

    Is the R5 still doing it's job?

    I measured it and seems working; with the audio probe i checked in the pin 3 of the IC and it works. What's the job of R5?

    Zitat von Loetbert

    Helpfull would be a measurement of the voltages (just DC) at all pins of the 4558

    I measured it, I expected 4.5V on 1-2-3-5-6-7 pins but the measures on 1-2-5-6 are in the order of 40mV, OV on GND and 9.06V in Vcc. In pin 3 I have 2.4V.

    This evening I'll go to a shop to buy a new RC4558, just to see if the problem is chip-related.

    Thank you!

  • [Solved] The Screamer Kit problems

    Hi,
    I bought and built The Screamer kit but it doesnt work.

    Using an audio probe, I noticed that the problem is related to the RC4558: thesound arrives correctly to the pin 3, but no sound comes out from the pin 1 or pin 2. Ialso noticed that the VBias without the RC4558 is 4.5 V, but only 2.3 V withthe chip installed.

    I tried also with tl072cn (with this, Vb is correct but sound very distort with no mode to regulate gain and pot not working), tl072cp and tl471 but the problempersists. And no, I don't have an replacement for rc4558.
    I desoldered every single resistance, diode (received 1n4007 and changed with 1n4001) and every cap to check it. I built it two times desoldering and soldering the pieces, but nothing.

    Here attached the images.


    What could be the problem?