Batch of bad PT2399s?

[Slade]

Hi,
I've had some troubles with the last batch of PT2399s that I've bought from my local dealer, who buys them to a chinese dealer.

1 out of 10 works ok, to say something, and the other 9 work "randomly", working ok 1 time of say... 20 times that I connect the pedal, and the rest of the time they're not doing anything.

On a voltage measurement to the "random working" PTs I only noted that the pins 9 and 10 give strange voltages of 4.8v and 0.7v. And suddenly they start working just fine with the common 2.4v - 2.5v from pin 9 to 16.

I'm pretty sure that the ICs come from a secure dealer, they ARE authentic, and I'm also sure that it's got nothing to do with the circuit, as it works perfectly with the "good" PTs with no faults or strange behaviours.

I'm saying this after building 3 different delays this last 2 weeks.

Here's a photo of the PTs I'm talking about:



Maybe it has happen to anyone else? Maybe I'm coursed?

Fernando.-

[deadastronaut]

hi fernando,  i recently bought 10 cheapo's from ebay/china on a 'risk'  but luckily they are all fine!..i tried em all out on breadboard.

[Skruffyhound]

This has been going on for a while. I remember asking Rick about this several years ago when we both bought PT2399's from Tayda. I definitely had some that were acting up, but Rick's five were fine. I like Tayda so no disrespect to them. In the end I sort of went with the idea that maybe they were coming out from the factory like this, as if there were different quality control levels, the €7-8 chips from Banzai were better vetted than the 50 cent Tayda bargain bin chips.
This is all speculation on my part.
If you search the forum you will see that this issue pops up from time to time.
Good Luck

[Slade]

Sadly Tayda doesn't ship to Chile anymore.
I'm really pissed about this... it's just like matching fets, I have to buy a lot to see if some of them work.
Does anyone know about another confident and not very expensive PT2399s seller on ebay?

[wavley]

Sadly Tayda doesn't ship to Chile anymore.
I'm really pissed about this... it's just like matching fets, I have to buy a lot to see if some of them work.
Does anyone know about another confident and not very expensive PT2399s seller on ebay?

Apparently Tayda doesn't ship to Virginia either, I paid extra for 7 day shipping three weeks ago.  I kinda had an emergency repair for a friend, maybe not my best decision to place my first order with them when time was an issue.  I ordered a bunch of PT2399s, I'll let you guys know how they turn out when I finally get them.

[richardk]

i got a bunch of pt2399s from china last year, paid them a ridiculous price and none of them worked: i spent about two weeks fighting with a rebote 2.5 delay not understanding what was wrong...in the end i bought one pt2399 from an italian dealer, paid it 6 euros and magically the delay worked fine! i think in these cases often you get what you pay for...

[Slade]

I think I discovered something here:

The problem with the PTs was the use of the chip's digital ground instead of the common circuit ground to control Time.

My dealer tried the last PTs that I bought from him on a Rebote Delay, and he told me they worked perfectly fine. Then I tried them in my circuit and I had this problem with almost all of them. So today I just checked the differences between my circuit and the Rebote Delay and I saw that the only important change was that I was using the digital ground to control time instead of the common circuit ground. I changed to try and voilá, all the PTs worked perfectly okay.

I'm not gonna use the digital ground again, as I see now that it works only with some PTs, although I never had this problem before...
Anyway, that was it.

[IvIark]

Yes some pedals seem to have pin 3 and 4 grounded, like the Deep Blue Delay.  Some people had issues with my layout until I amended that, and afterwards they worked fine.

[cloudscapes]

russian roulette in my experience. only smallbear has been consistant in ones that work well.

[bluebunny]

If it's of any help, Dr Tweek in the UK has genuine PTC PT2399 parts, which Steve tests before sending them out.  Ships internationally too.

[Chugs]

I had the exact same problem with multiple PT-2399's working intermittently and, as Slade suggested, connecting time control to common ground instead of digital ground fixed the problem.

[Slade]

I had the exact same problem with multiple PT-2399's working intermittently and, as Slade suggested, connecting time control to common ground instead of digital ground fixed the problem.

So, that's it!

[Skruffyhound]

Great! Maybe that's at least part of the problem.