Troubleshooting a TS808

[inefficiency]

Hi guys.

I just finished building a TS808 and the light comes on, but there is absolutely no sound.

Just before I start going over things, I've realised that the current layout on this site is different to the one I have printed. The one I have printed has a long jumper cable down the right hand side and there are a lot of differences in the layout.

Anyone know if there was something wrong with this layout or something I should bear in mind?

I should note that I didn't connect the LED+ wire on the left hand side of the layout. I figured this must be power to the LED and I've connected it differently. Will this stop the circuit from working?

Thanks for any advice or solutions before I go through the nightmare of pulling this thing apart!

EDIT: I believe the layout on the right is the one I used;

[Vince]

The difference is just between the 808 and one on the left is a Ts9. Leaving the LED connection out wont effect it as I've done it that way. I've built a few of the 808's using that layout (on the right) so it's correct. Have you tried different OpAmps? I've had a few dead JRC's. Also the same goes for the transistor, and making sure it's the correct way around depending on which one you're using. Apart from that, scratch between the copper tracks to make sure there are no solder bridges.

[inefficiency]

Thanks for your reply.

I understand the differences between the two on this page, I just used that picture because it was the only one I could find of the layout I followed. Do you know what the difference is between this layout and the one on this site? Is it simply more compact or something?

After doing some testing and playing around last night, I found that something is probably seriously wrong with the way I've built it.

When plugged into my power supply, it causes my other pedals to go turn off. I'm thinking this is perhaps my power supply's was of making sure they don't explode, haha. Luckily, after unplugging it, everything still worked fine.

I have some spare opamps, so I can try another one, but I'll hold off until I can find out if this thing is going to fry anything.

EDIT: Turns out I had a couple of capacitors swapped around. I had confused the 1u ones and the 220n ones and had them the wrong way round.... I've switched them back now, but am still apprehensive about plugging it in. Could this have been the problem? Would the above be symptoms of this?

[IvIark]

Yes I've done slight mods to a few layouts on the site, that one was because I really hated the red supply link and so I wanted to add a normal link to perform that function.  The original worked fine though.

Plug it in and see what happens

[inefficiency]

Hey, sorry to revive this fairly old thread on an issue that I should have fixed, but I put this project off for a while.

I had to order some more caps because I couldn't fit the board in the enclosure with the massive Mylar ones you get in the kit from bitsbox. I had to replace them with polyboxes, which I'm assuming must be fine?

Anyway; I've done a lot to try and troubleshoot this board and today I noticed something a bit worrying when I plugged it in.

I plugged it on, tested the clean bypassed sound - clear as day. I switched on the effect and it was silent.

I flipped it over to look at the board and touched the board by accident and felt a bit of heat coming from it. After poking around I noticed that the IC was pretty warm/hot.

So I guess I might have found the problem. Could it be a faulty IC or is too much current making it's way there somehow?

Could I have the orientation wrong? When looking at the layout, I have the little dent in the IC towards the bottom of the board.

EDIT: Just to add. I used a socket for the IC, so I haven't damaged it whilst soldering.

[IvIark]

I'd say if it's getting hot it's likely to be a short somewhere.  Follow the Fault Find guide on the top menu on the main blog, and if that doesn't sort it out then post your voltages as described in that post.  Without those voltages it's all guesswork.

[dexxyy]

the dent in the ic should be facing the top of the board

[inefficiency]

Could the dent in the top of the IC facing the wrong way cause it to get hot like that?

Also, as soon as I noticed it wasn't working I switched it off immediately and it wasn't scorching hot, just quite noticeably warm. Will I need to bin the IC? I have spares, but I don't want to waste it and likewise I don't want to do more damage by not replacing it.

I'll get the knife out and make sure there aren't any bridges. There shouldn't be, but it wouldn't hurt to try.

Also,  I'll get some readings.

[inefficiency]

Oh jesus. I just flipped round the IC the other way and the pedal works instantly!

Amateur mistake here guys!

Thanks for all the help and fast responses.

Any ideas on how I can avoid making this mistake again?

[IvIark]

ICs have either an indented circle next to pin 1, or a half moon between pins 1 and 8.  That's the way the positions are always identified.

[inefficiency]

So, is pin 1 always at the top for the layouts on this site, or is the IC sometimes the other way round?

If they're always the same, then I guess I don't need to know any more for now!

[tjdracz]

Most of the time, yes, but just look at the layouts. ICs always got that faint notch on the layouts where the top is. See? I definitely remember seeing layout with reverse orientation, can't remember v what it was though!

[IvIark]

99% of the time pin 1 is top left, but occasionally I will rotate some 180 degrees.  With the charge pump circuits for a +/- 9V supply I will sometimes mount the charge pump IC rotated because pin 5 provides the -9V and if that is required to be linked to pin 4 of the main opamp then they are at opposite sides of the board.  So if I mount it upside down it means I can take links from the charge pump to the main opamp for both the 9V and -9V side, and they will be on the correct side of the board so I can keep them both underneath the ICs to save space for components.  If I don't do it it means I have to offset both ICs to accommodate the links which can complicate things and get in the way in some more complicated layouts.

And now I will always mount any quad opamp upside down if they are used in a circuit which also contains a dual opamp (like for instance the recent gyrator EQ layouts).  Some bright spark decided to put the supply and ground wires on opposite sides of the IC for quads to what is used with singles and doubles, which is a real pain when doing the power links for all the ICs.  But with the quads, if you mount them rotated 180 degrees the pin positions for all the +in, -in and outputs remain in exactly the same position, and so you don't have to compensate at all for the rotation when doing the layout.  No matter what the orientation, each side of the ICs will always be:

Output
In -
In +
[power connection]
In +
In -
Output

So I don't even have to think about the rotation once placed.  Whereas if I rotated the 8 pin dual opamp the pins would be all over the place and I'd screw up somewhere

[inefficiency]

Hahaha, "some bright spark" indeed!

That's great Mark, thanks a lot for all the help. Great site you've got here that has made it possible for people like me to get involved with DIY.

[IvIark]

To be fair that bright spark is no doubt considerably brighter than me and I'm sure they have a perfectly valid reason for doing it remembering that with PCBs things like this really don't matter so much.  But with vero they do, so he should still be sacked, the nob!