Equinox: Easy PT2399 Reverb

[gtangas]

So i build this baby  yesterday since my pt2399 arrived from ebay!

But i dosent work! for start the led dont light up.

I checked for bridges... i can see none!

check the parts e all seems nice

I have on both pt 5v on pin 1


help please!

[garcho]

start here.

[gtangas]

So I checked again the components and all are ok. The trans U4 (78L05) is F**** hot!!

The U1 that I have is different. I have an TL082 and not the TL072 indicated on the boom….

Voltages:
U1
Pin 1: 16,10mV   Pin 8: 2,06v
Pin 2: 12,50mv   Pin 7: 8,6mv
Pin 3: 0v      Pin 6: 9,6mv
Pin 4: 0v      Pin 5: 0v

U2
Pin 1: 4,20V      Pin 16: 2,06v
Pin 2: 2v              Pin 15: 2,06v
Pin 3: 01.1 mv           Pin 14: 2,06v
Pin 4: 1,47v      Pin 13: 2,06v
Pin 5: 4,17v      Pin 12: 2,05v
Pin 6: 1,99v      Pin 11:2,05v
Pin 7: 0,12v      Pin 10: 0,73v
Pin 8: 3,90v      Pin 9: 4,06v

U3
Pin 1: 4,72V      Pin 16: 2,11v
Pin 2: 2,22v      Pin 15: 2,11v
Pin 3: 01.2 mv           Pin 14: 2,11v
Pin 4: 1,65v      Pin 13: 2,11v
Pin 5: 4,40v      Pin 12: 2,11v
Pin 6: 2,11v      Pin 11:2,11v
Pin 7: 0,15v      Pin 10: 0,77v
Pin 8: 4,07v      Pin 9: 4,20v

There are several pins that when I was probing start decreasing is values but I suppose that is the caps…

[gtangas]

some pics

[Govmnt_Lacky]

Those U1 voltages look WAYYYYYYY bad!

Check around there for problems

[garcho]

Those U1 voltages look WAYYYYYYY bad!

Check around there for problems

+1

Pin 8: 2,06v
Pin 5: 0v

pin 8 should = power supply voltage, i.e. +9V

pin 5 should = power supply voltage divided in half, i.e. +4.5V

[gtangas]

so i´m going to check everything! 

i will start for the soldering and then to components! OMG!!!

[gtangas]

ok so i have check the solder and all the components. No bridges, no wrong components, no wrong caps orientation!

Any sugestion?

[garcho]

Follow the trace from D1 to pin 8 of U1 with your multimeter. How could the voltage be +9V at the regulator (which is giving you +5V) and only +2V at pin 8?

[gtangas]

Follow the trace from D1 to pin 8 of U1 with your multimeter. How could the voltage be +9V at the regulator (which is giving you +5V) and only +2V at pin 8?

look what i have found!!!!!!
this are the readings from point to point



I dont understand!!!!!!

[garcho]

So, is pin 8 U1 at +2V or 0V?

[gtangas]

So, is pin 8 U1 at +2V or 0V?

I was getting the 2v. Yesterday I redone some soldering, cables new pots... After that 0v

[merlinb]

I was getting the 2v. Yesterday I redone some soldering, cables new pots... After that 0v

How come your 9V input actually says 6.91V?

Remove both PT2399s and try to get U1 to working before anything else.

[gtangas]

I was getting the 2v. Yesterday I redone some soldering, cables new pots... After that 0v

How come your 9V input actually says 6.91V?

Remove both PT2399s and try to get U1 to working before anything else.

The battery is not new... maybe that explains the +/-7V

the strange thing is why i have voltage to the left side of the diode exit (green line) and no voltage to the right side (red line)!!

The trans U4 is very hot... if i take out the PT it doesn't get hot at all!!!

[Govmnt_Lacky]

If I were you, I would start by re-flowing ALL of the solder joints on ALL of your power rails. Some of those solder joints (especially the power input joints) look very suspect.

Also, trace along the ENTIRE power rail (9V AND 5V) with a magnifying glass and an xacto knife to ensure there are no bridges.

[gtangas]

why the ****** the voltage don't flows to both sides?!?!

this pcb was the first etching  i did! so the job isn't good... at all!!

after this one i made a few more and the results are getting much better! I´m using magazine paper

All-ready finished a rangemaster, a blue delay and now i want to finish my most wanted!

I sold my old crate vintage club amp and bought a tubemeister 18 head... so no reverb on it!  And i love the sound of this equibox reverb!

I´m having a great fun with this lunch box amp BTW!

Honestly i´m pointing the problem to the pcb it self!  Perhaps etching a new pcb for this baby solves the problem!

[Govmnt_Lacky]

why the ****** the voltage don't flows to both sides?!?!

Check for continuity between Pin 8 of the dual op amp and the diode's cathode. You probably have a break in the trace somewhere.

[merlinb]

why the ****** the voltage don't flows to both sides?!?!

Are you sure it is not simply dirt/toner transfer on the copper, stopping your meter probe from making contact with the copper?

[gtangas]

why the ****** the voltage don't flows to both sides?!?!

Are you sure it is not simply dirt/toner transfer on the copper, stopping your meter probe from making contact with the copper?

PROBLEM SOLVED!!!!   YESSSSSSSSSSSSSSSSSSSSSSSSSSSSSS

The problem was the PCB... as i showed on the photo there was no voltage going neither to pin 8 or any other pin! So i remove the solder on that spot and found that when i drill the pcb i cut the copper line or almost cut it because the first time i had some V measures on some of the pins.

fixed that spot; put a fresh battery and test it. The led was on but.... just bypass signal!

I bought a pack of 5 PT so i changed the pt and... "Houston we have Reverb"

I haven't box it so i´m having some static/interference noise but i believe that will disappear after i box it

Do you think i fried the PT´s??? is there a way to check it?

I dont notice a big change on tone using the switch. I think i read that you made some mods... any tips?

Resuming... I´m learning... and making mistakes it´s the best way!!  BS.... Is much better to finish the build... fire it up and play! hehehehe

Thx for the help.

Merlin nice reverb!!!

[merlinb]

Do you think i fried the PT´s??? is there a way to check it?

I wouldn't expect them to be damaged, since they received nothing more than 5V. But some PTs are just bad. Plug 'em in, and if they don't work, well, then they're kaput.

I dont notice a big change on tone using the switch. I think i read that you made some mods... any tips?

Yes, I reduced C33 to 10nF I think. You could try even smaller.