Sea Urchin problem..

[ckim715]

So I have an odd issue. My Sea Urchin works for about 10 minutes, then loses all delay, and won't work anymore. I initially thought it was an LM7805 issue, so I changed it out, as well as changing out the PT2399, but no dice. Any ideas?

[sgmezei]

Hmmmmm any pictures? And have you double checked all of the values on your board?

I know I had a sunking that would work for 2 mins then go caput because of some wrong values.

[ckim715]

[sgmezei]

Well first, I would add a PT2399 chip..........

I am on the road this weekend so I can't offer any more advice on this layout. Is this the one from Josh?

[madbean]

Why are you using an LM3508?

[ckim715]

I don't know where I got htat number from. It's an LM7805.

[madbean]

Have you checked to make sure it's putting out 5v? Also, try powering it up and check it continuously for about 2-3 minutes with your DMM to see if the voltage is draining somehow.

[gtr2]

Where did you get you pt2399's from.  I had a lock up problem with a batch off ebay.

Josh

[madbean]

Where did you get you pt2399's from.  I had a lock up problem with a batch off ebay.

Josh

It would seem that's not the case here since it's not locking up when powered on. Or, did you have a similar experience with the bad batch?

[gtr2]

Oops I didn't see the 10 min part.  Mine were locking up on power up.

Josh

[madbean]

Oops I didn't see the 10 min part.  Mine were locking up on power up.

Josh

You can actually design something around that if you use an LM317 instead of the regular 7805. The datasheet has a little circuit for a slow warm up....I think that might take care of the lockup problem. I've tested it out, but not on a PT2399. It's really similar to the anti-lockup circuit from the Little Angel, except in that case it doesn't control the regulator but the VCO pin of the PT2399. Obviously, that way works really well, too!

[ckim715]

I checked the voltages with the DMM, and I'm getting 5.1 VDC into pin 1 of the 2399. Just to make sure, when I check the voltages, I can ground out the ground lead anywhere, i.e. on the case, right?

[ckim715]

Also, my LM7805 is getting warm to the touch. Is that normal?

Here's the pin readings for the 2399.

1: 5.1
2. 2.54
3. 0
4. 0.17
5. 3.02
6. 2.55
7. 4.4
8. 0
9. 2.55
10. 2.55
11. 2.54
12. 2.55
13. 2.53
14. 2.53
15. 2.54
16. 2.55

TL072
1. 3.26
2. 3.26
3. 3.26
4. 0
5. 3.26
6. 3.26
7. 3.26
8. 6.52

[ckim715]

Where did you get you pt2399's from.  I had a lock up problem with a batch off ebay.

Josh

I got them from Tayda. I've used 3 separate PT2399s all with the same symptom..

[madbean]

The TL072 is problematic. Your supply voltage on pin8 is only 6v. It should be 9v.