[aeriyn]

Well, this is not encouraging.

I had a working, brand-new functional TLE in my PIMETA, and it smoked again. I checked for solder joints and there are none. Everything looks fine.

Also, my 7815 regulator was getting very hot.

I noticed something that's definitely not supposed to happen here; I saw a spark when I plugged the DC jack in the second time, and the LED flickered (with the power switch on this time, the times before I had it off and I couldn't tell).

So... I'm guessing I need to isolate that power jack (metal case) because that's what keeps frying TLEs.

Does this sound right?

 

[drewd]

Definitely. If you have a metal power jack in a metal case, that puts the case at V-. If your headphone jack or your input jack is not isolated, then ground is at V-. The TLE is trying to hold ground at V+/2, but the case is trying to pull it to V-. The TLE is effectively trying to source enough current to drive a short circuit to V+/2 - it can't do that!

Try this DC jack from Mouser. It's plastic, totally isolated and inexpensive.

Also, when you've isolated your power jack, make sure that your headphone jack is isolated, too. The input and output grounds must be isolated from each other on the Pimeta.

-Drew

 

[aeriyn]

The headphone jack IS isolated. It's one of the switchcraft isolating models (not the Neutrik "isolatable" one). It has plastic mounting threads.

But the inputs aren't isolated...

Would I have to isolate the pot as well? (ALPS RK27)

 

[Edwood]

Jeez, that sucks.

I had so many problems with my CMoy's non-insulated DC jack, I use insulated ones now.

Plus the recommended one (CM6, I think) from Digikey sucks. Not a solid connection at all.

-Ed

 

[Okkler]

I have avoided the isolating issue altogether by only using plastic or other insulating cases on my amps. It makes case work and parts selection so much easier.

 

[aeriyn]

Quote:

Originally Posted by Edwood Plus the recommended one (CM6, I think) from Digikey sucks. Not a solid connection at all.

Problem is, I can't get 2.5mm jacks locally. o.O I'll have to cut the plug off of my wall wart and put a 2.1mm one on it if I want to do it that way.

Meh, it's a good thing I ordered 3 more TLEs from digikey, having the feeling this would happen.

 

[drewd]

Quote:

Originally Posted by aeriyn The headphone jack IS isolated. It's one of the switchcraft isolating models (not the Neutrik "isolatable" one). It has plastic mounting threads. But the inputs aren't isolated... Would I have to isolate the pot as well? (ALPS RK27)

As long as the headphone jack is isolated from the input ground, you're fine. You don't need to isolate the pot because it shares the input ground - just be sure that it's properly grounded.

-Drew

 

[aeriyn]

Well, since I'm broke and bored, any suggestions on a way to isolate my current power jack, which is the digikey CP-6 jack that Edwood (and I) don't really like.

 

[dsavitsk]

To be sure I get this all correct -- I am casing up a Pimeta as we speak -- with battery power (2x9v), I should isolate the headphone ground from the input/pot ground, but other than that I m okay?

-d

 

[dsavitsk]

Quote:

Originally Posted by aeriyn Well, since I'm broke and bored, any suggestions on a way to isolate my current power jack, which is the digikey CP-6 jack that Edwood (and I) don't really like.

Purchase a large nylon washer with a small hole, mount the dc jack in the washer, and drill a case hole larger than the dc jack but smaller than the washer. Epoxy the washer to the case.

-d

 

[Edwood]

Quote:

Originally Posted by aeriyn Well, since I'm broke and bored, any suggestions on a way to isolate my current power jack, which is the digikey CP-6 jack that Edwood (and I) don't really like.

Well, you could do what I did with my CMoy. Insulate part of the threaded part of the DC socket with a small bit of heatshrink, use plastic washer on the inside of the case (put plastic washer on before putting socket in hole). You can make your own plastic washer by drilling the correct hole size in a thin piece of plastic (those "free credit cards" in the mail are a good source), then trimming around that hole to make a washer.

-Ed

 

[__redruM]

Quote:

Originally Posted by aeriyn Well, since I'm broke and bored, any suggestions on a way to isolate my current power jack, which is the digikey CP-6 jack that Edwood (and I) don't really like.

The easiest setup is to drop the RCA inputs and buy another isolated headphone jack like you used for output. You're using a ipod as source anyway. But I suppose you've already cut the holes in the case. Isolating the power jack is tough. Ed's method works great. You could also cut the hole much bigger than the jack, mount a flat piece of plastic in the hole with screws or glue, and cut a hole of the right size in the plastic.
Last option depends on how your cut your case. But it is relitivly easy to isolate parts of a hammond case.

Lastly, the ALPS is isolated, unless you purposely connected it to IG with a piece of wire.

Next time, before connecting the wall wart, use you ohm meter to check continuity between V- and IG. If you have ~0-Ohm resistance, then you've still got to isolate.

 

[aeriyn]

Actually, my Cambridge Audio CDP is my source for the pimeta. It is not set up as a portable amp. RCA jacks are the only ones that make sense.

I'll follow Ed's suggestion as it is the simplest. I can easily get more isolating washers, and heatshrinking up the power jack's threads is no big deal.

 

[Edwood]

Quote:

Originally Posted by __redruM Lastly, the ALPS is isolated, unless you purposely connected it to IG with a piece of wire.

Yes, if you don't get a hum or buzz when you touch the shaft of the ALPS, then there is no need to ground it's case.

-Ed

 

[Edwood]

Quote:

Originally Posted by aeriyn I'll follow Ed's suggestion as it is the simplest. I can easily get more isolating washers, and heatshrinking up the power jack's threads is no big deal.

Don't forget to drill a slightly larger hole for the DC Jack to account for the added thickness by the heatshrink.

-Ed