New to Forum..... Echo Delay Kit no output.

[tony311]

Hello, I didn't realize a forum such as this existed untill I read about it elsewhere. Sure is a bonus. Sadly my brother in law, who was an electronics engineer, passed a few years ago. He taught me the very little I know.

I have been building kits since back in the 80s when ETI and EA were king. 98% of 100 kits have all worked well. Recently decided to build some pedals. Out of 4, one works? I'm sure it is me doing somthing stupid as I know others have these successfully working.

My current kit is a Landtone Echo kit purchased from AliExpress  Of course you get no circuit, however in my reaseach there has been mention that it is similar, if not the same, as the Deep Blue Echo. From the little I know of reading circuits, it certainly looks the same, so I include that.

My issue is, I have no output at all. With my audio probe, I have verified that I have audio every where except the output however, from the circuit or kit, I cannot figure out where the output signal is meant to come from? The audio does not come from the switch to the output, if it is meant to, I have no idea. There is a 1uf Cap and a 1k resistor near the output that I have no signal at but again I have no idea if this is relevant. Unfortuantly my knowledge of circuits and using the probe is limited. I have verified all voltages and outputs on the PT2399 and TL074 are present and correct. I am stuck on what I think is a simple issue. Especially compared to my issue with my other two that dont work. But those kits are for another time....

I would greatly appreciate any guidance, advice on where to start looking prior to the output, ie: which components on the board are related to the output and why there is no signal there.

I have attached what I have and think I have covered most of the information.. Thank you.

[ElectricDruid]

Welcome Tony!

The output comes from the wiper connection of the mix pot. I'd guess that's the one with white wires on your PCB because it's nearest to the output jack, but I might be wrong.

You're dead sure you've got 9V across the op-amp? Which op-amp did they use? Is it a single amp?

And then you need to be sure about the 5V supply too, on pin 1 of the PT2399. If that isn't working, no echoes. You can check with the audio probe on pin 15 of the PT2399 (input filter) and pin 14 (output filter). But if you had audio at both of these places, the pedal would be working, so I'm not expecting much.

Have you got clean signal when the footswitch is switched to bypass? Have you got clean signal when the footswitch is switched to the effect? "no echoes" is one thing, but "no audio" is something quite different.

Sorry to bombard you with so many questions straight away, but don't worry, we'll get it sorted!

HTH,
Tom

[duck_arse]

also welcome.

yer board has a dual opamp fitted, both halves apparently in use, but only one half is showing on the circuit dia, so it only qualifies as a bit like this circuit. also, I think you've missed the ground lug connection on your purple/black jack. it won't matter too much if you don't use stereo plugs, but probably better to correct it. the sleeve lug is the one on the slant side.

there's also a ground track runs to the footswitch on one side, it gets fatter between the lugs. could you make sure there is no shorts between that track and those pins, please?

[antonis]

Hmmm.. PT2399 relevant thread..   

Just WELCOME..!!!

P.S.
I'm pretty sure it's a simple ouput grounding issue..
Just go backwards with audio probe (mix pot wiper, lugs 3 & 1, 1μF caps negative legs, etc..)
Of couse, first of all, verify OUT jack Sleeve  grounding..

[tony311]

Welcome Tony!

The output comes from the wiper connection of the mix pot. I'd guess that's the one with white wires on your PCB because it's nearest to the output jack, but I might be wrong.

You're dead sure you've got 9V across the op-amp? Which op-amp did they use? Is it a single amp?

And then you need to be sure about the 5V supply too, on pin 1 of the PT2399. If that isn't working, no echoes. You can check with the audio probe on pin 15 of the PT2399 (input filter) and pin 14 (output filter). But if you had audio at both of these places, the pedal would be working, so I'm not expecting much.

Have you got clean signal when the footswitch is switched to bypass? Have you got clean signal when the footswitch is switched to the effect? "no echoes" is one thing, but "no audio" is something quite different.

Sorry to bombard you with so many questions straight away, but don't worry, we'll get it sorted!

HTH,
Tom

Thanks for your prompt reply.. The op amp is dual, circuit is only showing one side? Voltage definatley there on the op amp and correct. Same on PT2399. When on, No sound at all just some static noise. There is a signal at the wiper of the pot which is the white wires, (Repeat Pot). In bypass there is no signal either. just a slight buzz.
Now not being too sure on using the probe, for example, should I be getting a sound on all obvious components? I have found that there is a section of resistors and caps that do not sound (I would guess that means no signal) at all on either side of the compents. I have highlighted those components on the attached image.

[tony311]

also welcome.

yer board has a dual opamp fitted, both halves apparently in use, but only one half is showing on the circuit dia, so it only qualifies as a bit like this circuit. also, I think you've missed the ground lug connection on your purple/black jack. it won't matter too much if you don't use stereo plugs, but probably better to correct it. the sleeve lug is the one on the slant side.

there's also a ground track runs to the footswitch on one side, it gets fatter between the lugs. could you make sure there is no shorts between that track and those pins, please?

I have double checked that switch. It is not shorted at that lug.

[ElectricDruid]

The op amp is dual, circuit is only showing one side?

Ok. This is important to know.

Voltage definatley there on the op amp and correct. Same on PT2399.

Ok, good start!

When on, No sound at all just some static noise.
In bypass there is no signal either. just a slight buzz.

This means there's something seriously wrong somewhere!

Did you get a wiring diagram with this kit? Have you checked the in/out jack wiring? If there's no sound even in bypass, then the problem is most likely in the offboard wiring, since if the signal made it to the PCB, the bypass should at least work. The exception would be if the footswitch was dead somehow.

Check that ground wire connection on the output jack like Duck suggested. No ground on the output would explain it (as Antonis suggested).

[tony311]

The op amp is dual, circuit is only showing one side?

Ok. This is important to know.

Voltage definatley there on the op amp and correct. Same on PT2399.

Ok, good start!

When on, No sound at all just some static noise.
In bypass there is no signal either. just a slight buzz.

This means there's something seriously wrong somewhere!

Did you get a wiring diagram with this kit? Have you checked the in/out jack wiring? If there's no sound even in bypass, then the problem is most likely in the offboard wiring, since if the signal made it to the PCB, the bypass should at least work. The exception would be if the footswitch was dead somehow.

Check that ground wire connection on the output jack like Duck suggested. No ground on the output would explain it (as Antonis suggested).

Thank you. I will go through it carefully in the morning. I'm in Australia so when I am up and working on the problem, most of you would be in bed and visa versa. So midnight here now and just checking forum prior to going to bed... thank you. I will post back. Hopefully with more positive news.

[Phend]

Like others said, when in bypass do a continuity (or other) check of the input and output jacks tips and barrels. In bypass the signal should go straight thru both.

[tony311]

 >:(I"VE FOUND THE PROBLEM... Thanks to all you on the forum, I tracked down the issue. Whilst doing a continuity test, I checked the tip and ring on the sockets. They were DEAD SHORT..  I thought, well I know thats not right and explains why it doesn't do anything more than turn on.

So remember what you all have mentioned, I spend an hour just going over the back of the board. On the board I had, the switch centre track on one side was connected to the outside track. I realized that the centre track is usually the common but I thought well there must be some reason or another they have made the track that way. Still believing that isn't right, after a bit of searching I found an image of a Landtone Delay board. Sure enough, comparing the switch tracks, the others were not shorted. Somehow, mine must have missed their quality control, if there is any. I cut the track and everything worked like it should.

Really frustrating and realiving when you find it wasn't something you have done wrong.

I have inclued the images.
I THANK YOU all for your assistance and guidance as I would not have found it otherwise. I would have just put it in a pile of failures.... Great to have found this forum. Hopefully I can be of assistance to someone as well or at least I can vist the forum for information and new things..

Thanks again.