Moodring weird issue

[jkokura]

So, I'm working on a Moodring, and I have the most bizarre issue. I'm hoping some of you have some idea where I should start. I rarely can't find a solution on my own, so it's a major puzzler for me. I did spend about 3 hours on this issue so far.

Anyway... my Moodring PCB is exhibiting the following behaviour:

1. With power and all chips in, the 9V power rail drops down to about 5V.
2. VB drops down to about 2.5V
3. The Reg is putting out about 4V

The weird thing is that when I remove the 5V Regulator, everything goes like this:

1. The Power rail is up to about 9.3V
2. VB is up to 4.65V
3. Obviously theres no REG in so I don't get any regulator readings.

I've resoldered, triple checked every thing, and I'm pretty confident in my ability to see these sorts of things. I just need someone to give me some idea on what it could be.

Jacob

[madbean]

Try these two things: remove D2 and/or jumper out R33. See if either of those fixes your issue. If not, possibly another regulator.

[midwayfair]

What are you powering it with? Check the value of R33 to make sure it's 10R. However, it looks correct when you've got the regulator out, so I suspect that's correct.

If you pull JUST he PT2399 and leave in the regulator, does it help, or raise the voltage at all? It's not exactly practical to pull the brick ...

PUll D2 as well [woops, Brian beat me to it ...]

I'd also try replacing the regulator. I had some bad ones from Tayda a while back, so they do exist.

[madbean]

If D2 is bad that could certainly mess up things. It's not really necessary---just added protection for the regulator. But, a bit of overkill too.

[jkokura]

I just verified that my Regulator(s... I've tried several) are working properly on a breadboard. I lifted one side of the D2, and it's not in circuit any more.

Neither seems to be the issue.

What perplexes me is that the issue only shows up with the power applied. It's strange, because without the Regulator in, the issue goes away. With all the chips out, there's no issue. But as soon as I put the regulator in it goes weird.

I've tried three different Reverb blocks. I've tried 3 different regulators. The ICs don't seem to be the issue, but I'll try swapping the PT2399, because I don't think I've switched that.

Jacob

[madbean]

What about with the regulator in and just the belton brick but not other ICs? What do your voltages look like then? That's the one with the highest current draw, obviously.

[jkokura]

What about with the regulator in and just the belton brick but not other ICs? What do your voltages look like then? That's the one with the highest current draw, obviously.

Regulator and brick in, drops to 5.6V

[jkokura]

I get continuity between the in and out of the reg when it's in and powered. No power or reg, everything checks normally.

Jacob

[blearyeyes]

Ever hear of any bad bricks?

[madbean]

Kinda stumped on this. Do you happen to have an LM7805 instead of the L05?

[midwayfair]

If you're powering it with a regulated 9V supply all the time, you can drop the voltage with some LEDs and diodes instead of using the regulator.

[danwelsh]

If you're powering it with a regulated 9V supply all the time, you can drop the voltage with some LEDs and diodes instead of using the regulator.

Wish I would have known this when I fried my one and only regulator I had a while back (instead of waiting 3 weeks for some to come in)......awesome thinking man

[madbean]

Possibly if C17, 18, 29, 30 or 37 were bad (the decoupling caps on 5v) it could cause the voltage to leak.

[jkokura]

Possibly if C17, 18, 29, 30 or 37 were bad (the decoupling caps on 5v) it could cause the voltage to leak.

I'll try replacing them.

Jacob