PT2399 flaws?

Pedro Freitas · February 25, 2009, 02:14:56 PM

Hello!
I finnished a Rebote Delay and can't get the thing to work properly, the delay signal is distorted.
I've checked everything a zillion times and can't find a bad trace, solder bridge, misplaced component,
faulty battery,... nothing

Straight signal goes through to the output jack clean and also goes up to pin15 of PT2399 clean.
At pin 12 I got the delayed signal but distorted.
Is there any known PT2399 defect that does this? I got 10 from Ebay and they all do this

Or should I continue probing 'till my eyes fall out of their sockets?

Regards,
Pedro

cloudscapes · February 25, 2009, 06:12:59 PM

some clips would help us determine if it's the natural dirty "quality" of the chip or something else wrong

does it get cleaner as you lower the delay time?

Pedro Freitas · February 25, 2009, 08:16:13 PM

Quote from: cloudscapes on February 25, 2009, 06:12:59 PM
some clips would help us determine if it's the natural dirty "quality" of the chip or something else wrong

does it get cleaner as you lower the delay time?

Ok, I've built a few other PT2399 effects and know how it's supposed to distort.
It doesn't get much cleaner with lower delay times. Sounds like it's internal preamps are clipping the signal or something.
Feedback resistors for the internal preamps are correct. Lowering the guitar signal doesn't reveal anything.
I'm about to shoot at it

WLS · February 25, 2009, 08:40:24 PM

What was the name of the outfit selling the bad chips???

MikeH · February 26, 2009, 12:11:25 AM

Sounds like you've got a problem somewhere- I had a rebote do something similar because I had a solder bridge. The delay worked, but it was a distorted and noisy. Once I fixed it it worked fine.

smallbearelec · February 26, 2009, 03:52:06 AM

Quote from: Pedro Freitas on February 25, 2009, 02:14:56 PM
Is there any known PT2399 defect that does this? I got 10 from Ebay and they all do this

Bad lots of PT2399 are a known issue! I had bought 5,000, and 80% turned out to be defective in various ways. I was fortunate, because the seller was a company I had been doing business with for many years, and they made good. The replacement lots cost me double, but it is worth it; they are known to be from the Princeton factory, and I have had no complaints.

Regards
SD

alex frias · February 26, 2009, 06:04:06 AM

Did you try to replace th IC for another PT2399?

German · February 26, 2009, 12:41:35 PM

Is the voltage right? Do you have a correct 5 volts on VCC?

Pedro Freitas · February 26, 2009, 05:33:20 PM

Quote from: German on February 26, 2009, 12:41:35 PM
Is the voltage right? Do you have a correct 5 volts on VCC?

My batch of 10 are marked PTC, I guess that makes them Princeton's?
I bought them from Allpartspipe, on Ebay.
And yep, the 5VDC are correct.

Thanks for the input!
Pedro

German · February 26, 2009, 06:01:56 PM

Could you please place a LED on 12-11 pin and 10-9 - directly on filter caps.
That will help a bit with clipping and also will indicate an input distortion.

News:

PT2399 flaws?