The mystery of the snobish chorus

[alfonso_bundis]

Hello everyone,

So, I built a box with three effects, a tremolo, a phase 45 clone, and a little angel chorus. The all share the same DC jack. To power the pedal I use a one spot power source connected to a white power strip with a red switch. The pedal seems to be working OK but if I power it using a daisy chain connected to the same one spot/power strip setup the chorus stops working, when engaged it only delivers clean signal. The other effects work normally.
To make the chorus work again I must connect the pedal to to the one spot, without the daisy chain, and turn on and off the switch of the power strip.
Any idea why is this happening? I would appreciate any tips or advice.
In case it helps here is the schematic of the chorus:

http://diy.musikding.de/wp-content/uploads/2013/12/angelschalt.pdf

Thank in advance.

[mth5044]

What else is the daisy chain connected to?

[alfonso_bundis]

I've tried it connecting also a Big muff and nothing at all, in both cases the results is the same.

[anotherjim]

sometimes a Big Muff isn't any help at all 

I don't know why the power supply/combination could be an issue, but many PT2399 chips are likely to "lock up" with low resistor values on pin6. They still handle clean audio via the built in op-amps but nothing comes through the delay. It seems to have something to do with the quality of recent chips.
100R is low - although it is the original design value.

For you, it might simply be the restart from switching the power supply connections giving you working -  or not working; and nothing to do with changing combined pedal arrangement.

They can be made to work reliably if the pin6 resistance is gradually reduced my a timer circuit such as this version...


You can prove it by replacing the 100R on pin6 with a 1k - if you can then reliably hear the effect (but with a built in slap-back delay due to a longer delay time), you need to consider the start up mod.

[MrStab]

+1. my gut-reaction is PT2399 latch-up, too. iirc there are some counterfeit chips that are prone to this, so if Jim's suggestion doesn't work, you might wanna try a different batch from a different source.

[alfonso_bundis]

sometimes a Big Muff isn't any help at all 

I don't know why the power supply/combination could be an issue, but many PT2399 chips are likely to "lock up" with low resistor values on pin6. They still handle clean audio via the built in op-amps but nothing comes through the delay. It seems to have something to do with the quality of recent chips.
100R is low - although it is the original design value.

For you, it might simply be the restart from switching the power supply connections giving you working -  or not working; and nothing to do with changing combined pedal arrangement.

They can be made to work reliably if the pin6 resistance is gradually reduced my a timer circuit such as this version...


You can prove it by replacing the 100R on pin6 with a 1k - if you can then reliably hear the effect (but with a built in slap-back delay due to a longer delay time), you need to consider the start up mod.

Thanks a lot for the tips guys, I will tri to make the mod to see if it helps.
+1. my gut-reaction is PT2399 latch-up, too. iirc there are some counterfeit chips that are prone to this, so if Jim's suggestion doesn't work, you might wanna try a different batch from a different source.

[peterg]

Does the LM78L05 get hot? If so try an LM7805 in it's place. It can take more heat and may reduce latching.

[mth5044]

It shouldn't get tooo hot if connected correctly. The PT2399 draws something like 22mA, well below the 100mA spec of the regulator, but still worth checking for sure.

[alfonso_bundis]

Hi everyone,

First I gotta apologize for my belated reply, some unforeseen personal circumstances got on the way and I could not focus on this project for a while. I finally managed to get back to it, I tried getting new PT2399 form other supplier and to add the startup delay. Neither of this solutions has worked so far, as soon as I connect the pedal with a daisy chain the chorus stops working. Is there anything else I could try?
Thank you for your help

[duck_arse]

from your original post:

The all share the same DC jack. To power the pedal I use a one spot power source connected to a white power strip with a red switch.
Thank in advance.

something RG said recently leads me to ask: can we see a photo of your/this one spot, please?

[ElectricDruid]

Is the rest of the daisy chain connected to anything? Could there be a partial short or bit of muck stuck in one of the other plugs?

Perhaps if the voltage were getting dragged down for some reason, the chorus might be the most sensitive pedal and the first to pack up.

You could test the actual supplied voltage with the power supply going direct and then going via the daisy chain. If they're different, you're getting warmer.

HTH,
Tom

[alfonso_bundis]

Does the LM78L05 get hot? If so try an LM7805 in it's place. It can take more heat and may reduce latching.

Nope it does not get hot at all.

from your original post:

The all share the same DC jack. To power the pedal I use a one spot power source connected to a white power strip with a red switch.
Thank in advance.

something RG said recently leads me to ask: can we see a photo of your/this one spot, please?

Sure, here it is

Is the rest of the daisy chain connected to anything? Could there be a partial short or bit of muck stuck in one of the other plugs?

Perhaps if the voltage were getting dragged down for some reason, the chorus might be the most sensitive pedal and the first to pack up.

You could test the actual supplied voltage with the power supply going direct and then going via the daisy chain. If they're different, you're getting warmer.

HTH,
Tom

Thanks for the tip, the problem occurs just by connecting the daisy chain, even without other pedals connected to it.

[bluebunny]

Thanks for the tip, the problem occurs just by connecting the daisy chain, even without other pedals connected to it.

So the chorus pedal is OK with the 1Spot connected directly, but not with the (empty) daisy chain attachment?

[deadastronaut]

pic of the chorus dc socket?...

is the dc socket the same as the others?...e.g.

[duck_arse]

ahh, yes, thanks for the picture. but what I was wanting was a shot of the label on the wall wart, saying "this is a gen u wine one spot ac adaptor, made by the one spot manuf corp.". words to that effect.

the point RG was making is that people refer to warts as one spots, because they only take one-spot on a power strip, rather than them actually being made by one spot.