Help with TS808 buildq

[Halp!]

Hi all, I've come here seeking help!

I've been putting together a tubescreamer however it's not working..the pass through works but the pots aren't working at all.

Everything is soldered on and I've checked the transistors with a multimeter, not really sure where to go from here. I've double checked the schematic and resistors and everything is as it should be.

Also I'm picking up radio on the volume pot...help!

[Kipper4]

Welcome Halp

Go here


http://www.diystompboxes.com/smfforum/index.php?topic=29816.msg202738#msg202738

follow the instructions and report back please.
Include the schematic you used or a link to it.
Take some picture of your pcb and host them on an image hosting site (Imgur, etc Others are available.)
Post pictures as well all of which will help us to help you.

[Halp!]

Thank you! I shall do that!

[GibsonGM]

Welcome Halp...one other thing - did it work BEFORE you soldered up all the output stuff, like the stomp switch?

FYI for the future, I like to connect the PCB with jumpers and alligator clips, just the input and output, to my amp.  And power wires to the PCB, of course.   Then I know if the effect works.

Then I will add the stomp switch, jacks, and put it in the enclosure...so if something goes wrong, I have an idea about what may be causing it!  If the board isn't tested before the complicated switch wiring, there are  many unknown things you must go thru to find the problem.

Fill out the 'debugging' as best you can, and we will try to help you!! 

[GiovannyS10]

We can find some versions of TubeScreamer on web, can you share your schematic and your board for we take a look? 

[Halp!]

At the minute I have it soldered directly to jacks without the switch- the pots have no effect though I'm getting a signal through. I haven't got the exact schematic as it is a PCB kit from here:

http://www.jedspeds.co.uk/_p/prd1/1378180811/product/ts808-pcb-kit

There are a couple of switch mods on the board but I haven't wired any of them in yet.
This is the instruction for the kit: https://drive.google.com/open?id=0B_S3N6QGaBlCY3dIdkM0ZDNaVTQ

I've begun the process of testing the circuit and there are no obvious problems with continuity and there is power getting to the IC. I haven't written down all the voltages ..yet!

I'll post pics in a mo.


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[Halp!]

Please don't judge my hacky soldering [emoji15]

[Halp!]

And direct links for the pics if you're using a web browser..sorry [emoji847]

https://drive.google.com/open?id=0B_S3N6QGaBlCbUVTaHRSc3pVTG8

https://drive.google.com/open?id=0B_S3N6QGaBlCaWNWeHVGSU94d28




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[Kipper4]

Your IC and BJT voltages would help.
Did you ask the vendor which schematic this is built from?
Rich

[GibsonGM]

When using a meter to measure IC voltages...black probe connected to the battery "minus" terminal, of course, and be VERY careful that your red probe does not connect more than one IC leg at a time!  If this happens, it could short out the chip.

[Halp!]

Thanks for the tip, I have been very careful!

I emailed the vendor about the schematic, I've put the voltage readings here:

https://drive.google.com/open?id=0B_S3N6QGaBlCT2xrWk5kaGpNTWc

Q1 and Q2 are the transistors...I'm thinking that zero reading isn't good!


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[Kipper4]

Yer 0v ain't good at the base of Q1 if it's anything like this

http://www.electrosmash.com/tube-screamer-analysis

Discounting the jfet bypass switch I'm guessing.



I'd have a closer look at Q1. Magnifier will help.

Also Google Audio probe. A device for signal tracing. Which should you choose to carry n making pedals will prove invaluable and cost pence.

[Halp!]

Cheers I'll procure a magnifying glass! Is it possible the transistor is bad or damaged?


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[GiovannyS10]

One time i had problem like this, trust me or not i was solded the transistor inverted 

[pappasmurfsharem]

What is that NAMELESS IC?

[Halp!]

4558 ETC according to the instructions


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[Halp!]

[Keeb]

Q2's base should be at about 4.5V, as others have pointed out.

This is sort of a shot in the dark but...

Looking at the pictures and trying to trace the layout is difficult but the 470K resistor closest to Q2 should be the one to bias the base of Q2, I think. (On the schematic linked above it's R12 a 510K resistor going to Q3.)

Do you have a cold joint here?
http://imgur.com/a/shV2N

[J0K3RX]

Your IC in backwards?

Nevermind.. looks like it's in the right way

[Halp!]

I checked the joint and am now getting 4v on that previous 0 measurement, thanks! I've had little poke of all the joints however the board still isn't working.

No schematic yet either, sorry!


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