Ts808 Help!

[Phried_Bananas]

Hi everyone! I'm new to this forum, as well as pedal building in general and have a question about a ts808 BYOC kit that I am working on. Sorry if this isn't on the right board, or if I didn't give enough info, like I said I'm a noob. Anyways, I looked at the debugging thread and here's what I've come up with:


1. When activated, LED lights up but no noise except for faint crackling. Works fine in bypass mode.
2. TS808
3. http://byocelectronics.com/classicodinstructions.pdf (schematics are at the end)
4. no modifications
5. Built to exact original specs, including 511k resistors instead of the pcb suggested 510k as specified in the instructions.
6. circuit is a negative ground
7. I have been testing using a wall wart, which has been confirmed as recently as today to work fine with 5 other pedals.


Voltages:

Q1
C=9.32
B=2.14
E=1.61

Q2
C=9.32
B=??? (couldn't get at it, if it's crucial i can take some stuff apart and get the reading)
E=1.63

IC1
P1=0.763
P2=1.76
P3=1.037
P4=9.32
P5=0.580
P6=0.485
P7=0.767
P8=2.1 mV

Sorry, I'm a noob and couldn't figure out which diode is which. There are only 2, they are right next to each other, and I am sure that they are facing the right direction.

D1
A=0.585
K=0.490

D2
A=0.490
K=0.585


Thanks so much for taking the time to read, any help or advice would be greatly appreciated!

Have a good day!

[ashcat_lt]

Either you're counting the pins on the opamp wrong, or it's installed incorrectly, or your power supply is reversed, but that last would probably let the smoke out before you were able to read those voltages, so...

[Ice-9]

Have you checked that the IC is in the correct way around. Pin 4 should be ground but your readings show 9v. Pin 8 should be +v

[Phried_Bananas]

I had thought this might be the problem originally (reversed IC), but the circular indentation on top of the chip is on the same side as the notch in the socket. I tried it the other way around earlier, and it still didn't work. I suppose it is also possible I was counting the pins wrong, I started with 1 right next to the indentation in the bottom right and went around the chip counter clockwise. At this point I think i soldered the socket in facing the wrong way, would this be a possibility? Thanks for the help guys.

[ashcat_lt]

It sounds like you've counted them correctly.  The orientation of the socket doesn't really matter.  If it was soldered in wrong, and you turned the opamp around (so that it was now wrong compared to the socket), then the opamp itself would be correct with board, and it should work.  The square pad on the PCB should be under pin 1.

Course, if you had it reversed at any point, you may well have fried the opamp.  If you then orient it the right way, it probably still won't work.  Take the opamp out and measure the socket or PCB pads directly, starting with the square pad as 1 and going around counter clockwise.

[MrStab]

if the opamp was always in the right orientation, then with 9V at pin 4, which should be ground, and nearly 0V at pin 8, i'd imagine the chip is fried either way. so you might wanna look elsewhere.

hang on a second - i've just noticed something. D1 & D2 share the same voltages as pins 5 & 6, which is definitely wrong, because not only does the BYOC PDF suggest the diodes are connected to the other half of the chip, but even if that weren't the case, pin 5 should not be connected to either diode (as it's the input).

i could be misreading the data, but something's definitely not right with the opamp or how you counted it the pins.

[mcknib]

Just in case, IC / Op Amp pins are numbered like this



and +1 to Ashcat It - taking the readings on the socket with the op amp removed will let you know if the op amp's goosed i.e correct voltage readings with it removed from the socket tell's you the circuits ok and the op amp's the problem if the readings are still iffy then it's a problem somewhere in the circuit, cold solder joint, wrong orientation, incorrect value etc.

Upload some images of the board both sides and off board wiring that way we can have a look to see if we notice anything amiss.

[ashcat_lt]

Honestly, I don't see anything even close to proper bias voltage on any of the opamp pins.  The second stage seems to get its bias from the first, so if nothing's getting through there, it would explain that side, but there should be approx half the supply voltage on at least one of the pins.  Then again, idk for sure what happens when you put an opamp in backwards or broken...

BTW mcknib - my name ends in LT for Lorenzo's Tractor, but the lowercase l and uppercase I look a lot alike.

[mcknib]

It may be worth checking to see if you've bent any op amp or socket pins out of position it's easy enough to do and would give strange readings I bent a socket pin recently doing a repair and got weird op amp readings just prise the op amp out carefully and check the pins and visually check the socket and underside of the board of to make sure all the pins are through the pads

[karbomusic]

BTW mcknib - my name ends in LT for Lorenzo's Tractor, but the lowercase l and uppercase I look a lot alike.

Well that clears that up. I always thought you were an IT admin.

[Phried_Bananas]

Just in case, IC / Op Amp pins are numbered like this



and +1 to Ashcat It - taking the readings on the socket with the op amp removed will let you know if the op amp's goosed i.e correct voltage readings with it removed from the socket tell's you the circuits ok and the op amp's the problem if the readings are still iffy then it's a problem somewhere in the circuit, cold solder joint, wrong orientation, incorrect value etc.

Upload some images of the board both sides and off board wiring that way we can have a look to see if we notice anything amiss.

OK. here's the voltages with the op amp removed, starting with where pin 1 should be (square solder pad).

1: 4.65
2: 4.62
3: 4.65
4: 0
5: 4.65
6: 4.65
7: 4.65
8: 9.35


Edit: plugged the op amp back in (facing the right way this time...ugh) and here's the voltages from each of the legs:

1: 8.63
2: 8.59
3: 5.89
4: 0
5: 8.39
6: 8.73
7: 8.75
8: 9.35

[mcknib]

Out of socket readings look good so the op amp must be duff

[mcknib]

No probs ashcat I thought it was IT for Italia I'm taking it its a band I'll check it out cheers

[ashcat_lt]

With the opamp in, it looks like the feedback loop is either open or shorted to actual ground.  If the other end of the cap went to ground, I'd say check that, but it goes to Vref, so that can't be the problem.  I don't have time to look at it further right now.  What happens if you jumper pin 1-2 temporarily with straight wire?

[Phried_Bananas]

With the opamp in, it looks like the feedback loop is either open or shorted to actual ground.  If the other end of the cap went to ground, I'd say check that, but it goes to Vref, so that can't be the problem.  I don't have time to look at it further right now.  What happens if you jumper pin 1-2 temporarily with straight wire?

How exactly should I go about doing this? Sorry if this seems like a stupid question but it looks like I already have to order another op amp so I'm not trying to @#$% up anything else lol.

edit: should i also go ahead and order a new chip? If so should I just snag any old 4558D JRC off ebay for $1 or does it make a difference?

[mcknib]

OK. here's the voltages with the op amp removed, starting with where pin 1 should be (square solder pad).

1: 4.65
2: 4.62
3: 4.65
4: 0
5: 4.65
6: 4.65
7: 4.65
8: 9.35


Edit: plugged the op amp back in (facing the right way this time...ugh) and here's the voltages from each of the legs:

1: 8.63
2: 8.59
3: 5.89
4: 0
5: 8.39
6: 8.73
7: 8.75
8: 9.35

If these readings are correct then I'd try another op amp your readings with it out of socket are ok with it in the socket they're not and would indicate the internal workings of the 4558 are fried probably with you inserting it incorrectly and applying power

Any dual op amp should work e.g TL072, TL082, NE5532, LM358N etc some may be noisier but should still make the circuit function so replacing it with a JRC or RC4558 is your best bet obviously check the feedback of the seller or use a good supplier like http://smallbear-electronics.mybigcommerce.com/ic-jrc4558d/ hopefully this will be your only problem if not post pictures as suggested earlier

[Phried_Bananas]

OK. here's the voltages with the op amp removed, starting with where pin 1 should be (square solder pad).

1: 4.65
2: 4.62
3: 4.65
4: 0
5: 4.65
6: 4.65
7: 4.65
8: 9.35


Edit: plugged the op amp back in (facing the right way this time...ugh) and here's the voltages from each of the legs:

1: 8.63
2: 8.59
3: 5.89
4: 0
5: 8.39
6: 8.73
7: 8.75
8: 9.35

If these readings are correct then I'd try another op amp your readings with it out of socket are ok with it in the socket they're not and would indicate the internal workings of the 4558 are fried probably with you inserting it incorrectly and applying power

Any dual op amp should work e.g TL072, TL082, NE5532, LM358N etc some may be noisier but should still make the circuit function so replacing it with a JRC or RC4558 is your best bet obviously check the feedback of the seller or use a good supplier like http://smallbear-electronics.mybigcommerce.com/ic-jrc4558d/ hopefully this will be your only problem if not post pictures as suggested earlier

Ok cool, I ordered an RC4558P chip from small bear last night. Here's some pictures of the build in case anyone wants to take a look and make sure I haven't messed anything else up. Thanks for your help!

http://i.imgur.com/5WiaE6n.jpg

http://i.imgur.com/MhrYj9U.jpg

[bloxstompboxes]

It looks like you definitely have some issues with your stompswitch wiring. Looks like you have some frayed ends touching other switch terminals. Better snip the extra off. Also, the pots, particularly the middle one, might be touching the back of the board and causing a short. Hard to tell from that picture.

[Phried_Bananas]

It looks like you definitely have some issues with your stompswitch wiring. Looks like you have some frayed ends touching other switch terminals. Better snip the extra off. Also, the pots, particularly the middle one, might be touching the back of the board and causing a short. Hard to tell from that picture.

Thanks, but none of the wires on the switch are touching. I can definitely see why you might think so from the picture, but what looks like a frayed end is the jumper wire from 5 to 9. The pot also has a good quarter inch of clearance above the back of the board. Thanks tho, good lookin out!

[Ice-9]

It looks like you definitely have some issues with your stompswitch wiring. Looks like you have some frayed ends touching other switch terminals. Better snip the extra off. Also, the pots, particularly the middle one, might be touching the back of the board and causing a short. Hard to tell from that picture.

Thanks, but none of the wires on the switch are touching. I can definitely see why you might think so from the picture, but what looks like a frayed end is the jumper wire from 5 to 9. The pot also has a good quarter inch of clearance above the back of the board. Thanks tho, good lookin out!

Both items mentioned look like valid points to me, I would re-wire the switch and check the underside of the pot isn't shorting on the PCB. From the voltage readings I would expect a bad op amp as well.