Debugging a Timmy+ MG clone

[suryabeep]

Hi everyone, I built a MG into Timmy clone (2 in 1) and neither side is working. I'm using this layout for the timmy : http://tagboardeffects.blogspot.com/2012/03/paul-cochrane-timmy.html and this layout for the MG: http://tagboardeffects.blogspot.com/2013/05/jhs-morning-glory.html

The voltages on the Timmy are:
Pin 1: 6.76
2: 6.76
3: 3.52
4: 0
5: 0
6: 3.70
7: 6.22V
8: 6.76
Pin 8 looks low, but my supply voltage is 9.53 V.
far side of the 1n5817 shows 9.24 V, and the far side of the 100R resistor shows 6.24 V?
Sound dies on the bottom of the 510K resistor when audio probing.

On the MG:
1: 4.00
2: 4.00
3: 3.64
4: 0
5:3.79
6: 0
7: 0
8: 9.24
On the MG, I get correct sound up to the south side of the 10nf cap thats second from the bottom left (4 right, 3 up from the bottom left). Sound dies on the north side of the cap.

There are no shorts as far as I know, I've gone over all cuts and spaces in between rows with an exacto knife.
What could be the problem?

[thermionix]

Schematics are way easier to follow than vero layouts.  Starting with the timmy, check that your 100r isn't something higher like 10k or 100k.  Did you miss the cut between pins 4 and 5?

[suryabeep]

Yes, the 100r is 100r (brown, 3 black, brown)
You're right, the cut between 4 and 5 wasn't solid so I fixed it just now. Now pin 5 is at 5.41, but so is pin 8. The far side of the 100r now shows 5.41 V. I'm really confused [emoji28]

[iainpunk]

Id love to help but i can't read striped boards (my concentration is lacking), do you have a schematic diagram with the same component names of the "vero board" layout? Id love to help.

[suryabeep]

[suryabeep]

On the timmy: Put in a TL072, voltages are now
1: 6.66    8: 6.66
2: 6.26    7: 6.15
3: 3.46    6: 3.46
4: 0.00    5: 6.66
I was missing the 100pf cap but putting it in doesn't change any voltages.

[thermionix]

Looks like you have some opamp pins shorting to each other somehow.  Can you post pics, front and back, of your board(s)?

[suryabeep]

You're right! Pin 8 and pin 1 were shorting out. I fixed the cut.
However now the power supply that has provided 9.58 Volts for as long as I have had it is supplying 12.99 Volts.
Pin 8 is getting 8.22 Volts,
Pin 1: 0.19
Pin 2: 1.06
Pin 3: 4.09
Pin 5: 0.77
Pin 6: 4.31
Pin 7: 7.13

[highwater]

You're right! Pin 8 and pin 1 were shorting out. I fixed the cut.
However now the power supply that has provided 9.58 Volts for as long as I have had it is supplying 12.99 Volts.

Is it a regulated supply?

An unregulated supply will definitely go up in voltage after a short is removed.

I'm not sure whether a short between pin 1 (output A) and pin 8 (V+) would be enough to pull *that* much current as-to pull 13v down to 9.6v...

...but it doesn't really matter right now, because fixing that short didn't fix the pedal, that means there are other problems.

I'm at a loss for what to do, as those pictures are too gigantic for me to look at. Let me fix that for you (and anyone else who only has time for a quick glance):

Pin 8 is getting 8.22 Volts,
Pin 1: 0.19
Pin 2: 1.06
Pin 3: 4.09
Pin 5: 0.77
Pin 6: 4.31
Pin 7: 7.13

If you add "width=400" between "[IMG" and "]", the image will show as 400 pixels wide. The image will still be full resolution, though, so someone can still see the high-resolution version if that's useful.

I chose 400 pixels to keep the height down; 600 would be a better choice for pictures that are wider than they are tall.

[antonis]

Sorry Surya but your board is full or solder/flux residuals..

Not to mention wire hairs hanging around on item side..

[Les Turnbull]

My timmy has a 4559 op amp .Just looked up the specs and same pinout as 4558 , slew rate and gain bandwidth differ .

[patrick398]

Quite a few joints which look cold to me too. I'd reflow a lot of them joints and solder suck-er the joints where you have solder blobs building up, then resolder them being careful not to use too much and making sure the joint looks clean and shiny.

Also double check you don't have continuity on either side of all of your trace cuts. Some look a bit suspect. I use a 2 or 3mm drill bit very slowly on a low power drill (or sometimes by hand) to make trace cuts, then use a scalpel (exacto-knife) to make sure there are no small copper hairs which could create shorts.

[suryabeep]

Guys you were right! I resoldered the timmy board and went over all trace cuts and checked continuity and now that board works (I think).
Another problem has come up: in bypass mode, there is an awful hum. The i/o jacks are right above two pots which I've insulated with electrical tape (the usual Tayda pot covers are too fat). There is continuity from the in jack to the out jack, but not from the in jack tip to ground. Everything that should be grounded is showing continuity to a main ground bus (a little 5 hole strip of Vero). I'm also using a similar strip of Vero for a 9v bus. Could this be the reason for the hum?
Also, the MG board shows the right voltages and continuity/non-continuity as expected, but still doesn't work after cleaning and resoldering. I may be wrong on this though, because I only gave it a precursory test - I have to test it again this evening

[suryabeep]

I'm not sure why, but the edit feature seems to have disappeared. Anyway...
The Timmy controls work as expected, but clips way too early. There's heavy fuzz even at minimum gain. Audio probing pin 5 gives good signal, pin 6 is heavily distorted but faint signal, pin 7 is just insane volume and insane distortion. All voltages seem normal (4.5V on 1,2,3,5,6) except for pin 7 (6 V) and pin 8 (8.5V)
The humming from earlier was just me being dumb and wiring jacks the wrong way around.
Strange thing: when audio probing both the Timmy and the MG, signal dies after passing through a 10nf Tayda box film cap. It's fine up until the first lead and then nothing on the second lead.
Is this a thing now? Faulty caps? My DMM is a $15 pos so its capacitance function is garbage and doesn't work at all (reminder to self: I need to upgrade soon)

[PRR]

> the edit feature seems to have disappeared.

You only have a short time after posting in which you can edit. An Hour? 20 minutes? This is selectable by forum manager. 

> Tayda box film cap. ... Is this a thing now? Faulty caps? My DMM is a $15 pos .... garbage....

Maybe don't buy "bargains"?

[idy]

Usually when I find the signal dies after a cap or resistor it's because there a short there.