Boss SD-1 veroboard build - problems with 4558 chip

[Yazoo]

I've just built a version of the BOSS SD-1 on veroboard. I was going to try and get one on eBay and mod it until I saw what prices they were going for.

I found Torchy's veroboard layout for a Tubescreamer and just rejigged it for the SD-1 as they are very similar anyway. I also added the metal film capacitor mod and metal film resistor mods, changing the values accordingly. For the input and output buffer I used 2N5088 transistors, as I didn't have the 2SC2240s. I used a DPDT switch for true bypass, rather than the FET switching bypass on the original pedal.

When I fired everything up, I found I only got very distorted stabs of sound when I hit the strings hard. I went through the layout and rechecked it, looking for any short circuits. Looking on the bulletin boards, I found a post which said the voltages on the 4558 amp sections should be at vb @ 4.5 volts. I was getting readings of just under 9v on almost all of them. After clearing what I thought might be a short between pins 7 and 8 on the 4558, I did briefly get 4.5 volts on the other pins, but when I put everything back together again, this reverted to 9 volts. I swapped out the chip and tried 2 others, but I was still getting around 9 volts on the pins.

Finally, I tried a TL072 chip I had spare, and lo and behold, the pedal started to work. If I measure the voltage on the TL072, the first time I touch a pin, I get around 5v, but if I remove the probe and try again, it reads about 1.7 volts.

If you have come across this, or have any advice I'd be grateful. I thought I might have had a faulty 4558, but thought it unlikely all three could be faulty. The other weird thing I came across when I was at the "try anything" stage was to reverse the transistors, putting C where E should be, and the pedal did actually work with the 4558 in, though I couldn't say it sounded exactly right.

[Eric H]

Sounds like a bad solder joint, or a problem with the socket itself.

-Eric

[petemoore]

  Sounds like it's working or not.
  Check out some of the other help/please/not working threads which appear as though the posters are avoiding reading and following the DEBUGGING thread.
  Otherwise it could be anything that visual inspections may or may not find more slowly.