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PIMETA: troubleshoot request, problem with walwart.

post #1 of 15
Thread Starter 
Hi all,
My Pimeta was working great on battery, but the power don't last too long on 2x9v, so I wanted hooked it up with Elpac WM080-1950 (output:+24V;0.33A) with closed circuit CD jack which cuts off the power from the battery when the walwart power jack is connected.

The voltage that came in to the pimeta was 24V ( via walwart) and 14.4V ( via batteries), so there shouldn't be a problem with the wiring.
but whenever I connected the walwart and turned on the power, the LED barely lit up, sound came out from the earphone jack but soon dissapeared. It seemed that the current only trickled from the walwart. The LED was fully lid for a split second when I plugged in the jack, but soon dissipated to very dim light.

First I thought the diode impeded the current, so I removed it (this soon lead to disaster), but it didnt' help. I plugin and unpluged the jack several times and everytime the led barely lid. and at the very last moment the LED was fully lit before it immediately-completely dead, I smelled a foul odor. Dear god I think I burned something. it doesn't even turn on with battery now.

It is very frustrating!
what might have been damaged? I swapped opamp powered it on battery and it still wasn't working. What should I do?

What might be problem with running on the walwart? I want to have it fixed as soon as possible. please assist me.

regards,
-ADi-

Here's the detail:
Biased to class A.

Ground Channel
R1G = 4.32K
R3G= open
R4G=4.32K
R11=220
C6=10pf 50WDC

Left and Right Channel:
R1 = 4.32K
R2 = 1M
R3 = 1K
R4 = 10K
R5 = 3.32K
R6 = 1M
R8 = jumper
R10 = 1K
R11 = jumper

Powesupply:
4x 420uF 25V (C2/C3)
2X 6.8uF WIMA
2X 0.22uF 63V
Rled=4.7K
Diode = 1A 30V
post #2 of 15
I'm guessing that you have a metal case. The ground connection of your input or output jacks are tied to the case, and the DC input jack is also tied to the case. You are effectively tying V- to vground. You must isolate either the signal jacks or the DC input jack. The DC jack is the better choice.
post #3 of 15
edit


Get something like this....
post #4 of 15
adi,

tangent is absolutely correct about the insulated jacks. I put my second Pimeta in a Hammond metal case and had problems also. But, then I bought an insulated DC input jack and everything was working fine.

I was getting all kinds of distortion and noise, plus my rail splitter(TLE) was getting hot also. The insulated DC jack definitely did the trick, and all is well.
post #5 of 15
Thread Starter 
Quote:
Originally posted by Magic77
... plus my rail splitter(TLE) was getting hot also. The insulated DC jack definitely did the trick, and all is well.
Thank you Tangent, Magic77, and Jasonhanjk,
you're right, the amp is in a metal case.

any idea what damage might have been done?
what component might have been damaged? the TLE?
Where can I get the insulated jack? Mouser maybe? and if you have the part number on hand please tell me.

Thank you so much,
-ADi-
post #6 of 15
Quote:
Originally posted by adi
Thank you Tangent, Magic77, and Jasonhanjk,
you're right, the amp is in a metal case.

any idea what damage might have been done?
what component might have been damaged? the TLE?
Where can I get the insulated jack? Mouser maybe? and if you have the part number on hand please tell me.

Thank you so much,
-ADi-
The Part Number is: 163-1100, from Mouser. Actually I was lucky and none of my parts were damaged, not even the TLE.

As soon as I heard the distortion, I would turn the power off very quickly. So, I guess the TLE was able to withstand the short duration of heat.

But anyway; you may not have damaged any parts either. After you install the insulated DC jack, you will know. It may not be a bad idea to order another TLE just in case.
post #7 of 15
You don't have to use an insulated jack. You may have some insulating washers from RCA jacks that will fit. Or, you can lash something up with thin strips of electrical tape or similar. Or isolate the I/O jacks instead and let the case be V-. Certainly the insulated jack is the cleanest solution, however.

Quote:
what component might have been damaged?
Probably nothing. You've just been overworking your TLE. Since you didn't let it run for a long time that way, it's probably fine.
post #8 of 15
Thread Starter 
Thank you Magic77 and Tangent.
I connected the amp on batteries and the TLE got so hot that it burned my finger. What does it mean? I can't have it on with out the TLE getting hot now.

-Adi-
post #9 of 15
You still have the same problem. The batteries are connected through that jack, so you get the same problem as with the wall wart. The jack is the problem, not the wall wart. Fix the jack.
post #10 of 15
Thread Starter 
Quote:
Originally posted by tangent
You still have the same problem. The batteries are connected through that jack, so you get the same problem as with the wall wart. The jack is the problem, not the wall wart. Fix the jack.
Thank you Tangent,
I isolated the input and output jacks with electrical tape, and the case being the DC ground, (the input & output jacks are grounded to virtual ground, and the DC jack is grounded to the case).


So now I manage to run the amp both on batteries and on walwart, the sound is great, no noise. But with the walwart it gets VERY hot with in a second. Even with the batteries, the TLE was still getting hot in about 4 seconds, although it never got as hot as with the walwart.

Then I removed the DC jack so the amp is connected straight to the batteries, and ran it, the TLE was still getting hot. I guess it's always been getting hot when I use it all this time, but I didn't notice how hot it gets untill I hooked it up with the walwart.


I am going to get the insulated CD jacks, and I hope it will solve the problem, but do I need to put a heat sink on the TLE? or something else is happening?

Thanks,

-ADi-
post #11 of 15
Thread Starter 
Forget my previous post that the batteries doesn't cause the TLE to be too hot. I ran it again on batteries just now, and the TLE was smokin hot, I mean literaly smoking. I immediately turned it off. the amp is still working however. This never happened before on battery power.

I dont' understand. everything is the same as before I messed around with the walwart (except that I put a new diode), but now the TLE is getting cranky. what might be happening?

-ADi-
post #12 of 15
I guess you killed it.
post #13 of 15
Thread Starter 
Quote:
Originally posted by tangent
I guess you killed it.
ah that's not such a bad news, I hope that's the only one I might have involuntarily murdered. Thanks so much Tangent.

-ADi-
post #14 of 15
adi,

Glad you found the problem. It's good that you will get the insulated jacks to be on the safe side.

I had the same exact problem you had. My TLE was getting very hot and it would have burnt my finger also.

But, like I said before; I'm using an insulated DC jack now and I also insulated the RCA input jacks with plastic washers.

Hope everything works out for you.
post #15 of 15
Thread Starter 
Quote:
Originally posted by Magic77
adi,

Glad you found the problem. It's good that you will get the insulated jacks to be on the safe side.

I had the same exact problem you had. My TLE was getting very hot and it would have burnt my finger also.

But, like I said before; I'm using an insulated DC jack now and I also insulated the RCA input jacks with plastic washers.

Hope everything works out for you.
Thank you Magic77,
what would I do with out everyones help here?

-ADi-
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