aion gladiator

[keithhicks]

hi guys. new to the group. I have a gladiator here that's giving me some trouble that i have'nt seen before. The TS side will pass signal through the pedal with the switch engaged and no effect. The volume and tone seem to work but no gain. I have signal to the gain pot and through the diodes. The only place it seems to die is at the eq toggle. I have replaced that toggle and still no change. Thanks in advance....

[duck_arse]

hello, and welcome.

more info, please. links to build docs, circuit diagram, and post photos of what you have built, on board and off board parts. then voltage measures on IC's, transistors, supply and bias, where used.

[keithhicks]

Voltage is pin out in numerical order-3.6v,3.6v,3.6v,0.0v,1.4v,3.6v,8.93v. I use an OP amp tester and it test good. https://aionfx.com/app/files/docs/gladiator_documentation.pdf

[duck_arse]

voltages - for each pin of each IC - that is the only way we can make sense of them.

a few observations of your build - R7 seems to have 6 colour bands. is this correct, and what resistance does your meter read on it?

I can't fathom the value of your fitted R5, but I don't think it is 20k as specced. please meter and report.

C21 you have 15nF fitted instead of 10nF. matters not a jot of difference - but in a build that calls for 9k53 and 28k7, anything is possible.

but the main point - at C19 you have fitted 4n7 instead of the specced 4u7, a difference of 1000x. and this will choke all your lows from the output, no matter how well the rest the circuit is working.

over to you.

[keithhicks]

R7 is 220ohm.R5 reads 19.72k.you are correct on the 4n7 cap. PIN1=4.85V. PIN2=4.86V. PIN3=4.85V. PIN4=0.0V. PIN5=1.37V. PIN6=7.2V.PIN7=4.87V. PIN8=8.93V. I don't think the OP amp is the problem. I have an OP amp tester and according to it,it's functioning as it should and ive changed just to be sure.

[ElectricDruid]

There are two op-amp chips in the circuit, and you haven't told us clearly which one you're measuring. Are these numbers for IC1 or IC2?

The voltages don't look *too* bad, but pin 5 and 6 are slightly concerning. But I need to know which one I'm looking at to be sure. Also these numbers are quite different from the first set you posted, so what changed between the two readings?

[keithhicks]

Side A is the only side not working. I thought I mentioned that. My apologizes,so it would be IC1. As far as what has changed. The only thing ive done different is change the banana clips on my tester leads to gold plated connectors. It had gotten to where i had to twist and turn the leads in my tester to get my meter to work. I get that i totally missed the 4.7u cap. I was doing 3 of these at the same time and just missed it and I missed it on all three,but this one is the only one with that has no effect on the signal as far as boost and gain on Side A. Thanks.

[duck_arse]

https://www.diystompboxes.com/smfforum/index.php?topic=29816.0

[r080]

I could be misunderstanding your problem, but it looks a bit like an issue I once had with a broken trace in the feedback. Does it work if you bridge a 1M resistor across pins 6 and 7?

[ElectricDruid]

I think I agree with Rob above - it sounds like something might be wrong with the feedback. Check the soldering on C3 and C4. If there was no effective connection down to Vb, then there's no feedback and the thing becomes a unity gain buffer basically.

The pin 5 voltage is very low (it should be Vb) but that probably means you have a meter with a low impedance which is loading it right down. Check the VB somewhere (middle pin of that EQ switch?) to make sure it's where it should be; about 4.5V.

From the top side your soldering looks nice. The gold-plated through-holes help, since everything sticks nicely and they "suck" the solder through and make a solid connection. Can we have a look at the bottom too, please?

[keithhicks]

Thanks for some useful advice. I will try these suggestions and check back. Thanks again.

[keithhicks]

1M resistor between pin 6 and pin 7 made no difference

[keithhicks]

Soldering for C3and C4.

[PRR]

>> PIN5=1.37V. .....PIN7=4.87V. ....PIN8=8.93V

> The pin 5 voltage is very low (it should be Vb) but that probably means you have a meter with a low impedance which is loading it right down. Check the VB somewhere (middle pin of that EQ switch?) to make sure it's where it should be; about 4.5V.

The pin 7 voltage is the true pin 5 voltage buffered by the opamp. Pin7 is very nearly half of Pin8 V+ so at a first guess I think all is really well.

The "low" voltage on Pin6 is same except we do not know the setting on the 1Meg potentiometer. Assuming it is "kinda part-way", 7.2V is not wrong. Again the 4.87V at pin 7 says no problem.

1.37V is 4.87V through 1Meg. This suggests (if I did math right) 390k meter input. Not a common value (I like 1Meg, 10Meg, 11Meg) but recent meters are all over the place.

[keithhicks]

4.7v to center lug of the toggle and a pic of the meter in question

[ElectricDruid]

OK, good. So we're all agreed that the voltages look ok, right?

In which case, "no gain" must be caused somewhere else. I wondered about no connection to Vb. The soldering on those two caps C3 and C4 looks fine though, and *both* would have to have faults for there to be no gain.
Another possibility would be a short from pin 6 to pin 7 on the op-amp, reducing it to a unity-gain buffer. There are quite a few places that could happen: on the IC itself, across D2, across C2, etc - I'm sure there are more, but it'll depend on how the tracks are routed.

Also I'm assuming you fixed the C19 problem that Duck raised. It's not directly relevant to the fault-finding here since it's on the other op-amp, but it'll make a big difference to the overall sound of the thing, so it matters.

[duck_arse]

another observation - C2 is specced as 47pF. I can see your fitted cap marked as "470". this means 470pF, not 47 x no multiplier. the difference could well eat a lot of gain.

[antonis]

another observation - C2 is specced as 47pF. I can see your fitted cap marked as "470". this means 470pF, not 47 x no multiplier. the difference could well eat a lot of gain.

That's for sure for a LPF of 338 Hz cut-off frequency..

[keithhicks]

Here is C2 measured with a capacitor tester. I see 48.5 pF. Also a pic of the changed out C19 to 4.7u

[antonis]

C2 is specced as 47pF. I can see your fitted cap marked as "470". this means 470pF, not 47 x no multiplier.

471 stands for 470pF
470    //      //   47pF