Warm capacitors.

globalweb · 20th May 2007, 07:56 PM

When powering up my Aleph-x at about 5V (normal is 24 V) two electrolytes are getting warmer then six of the rest. About 29 C instead of 24 C. Is this something to worry about?

Zen Mod · 20th May 2007, 07:59 PM

are this two in same position in circuit as rest of them?

Netlist · 20th May 2007, 08:00 PM

Yes, maybe.
If the ambient temperature is 24°, and the rail voltage is only 5V, I would presume something is wrong. Is the amp newly build or not?

/Hugo

globalweb · 20th May 2007, 08:08 PM

Zen Mod

Yes they are.

Netlist

Yes it is. This is the first test. Slowly, slowly I’m raising the voltage.

Netlist · 20th May 2007, 08:17 PM

Don't raise the voltage.
5V is plenty and don't leave it on too long if the caps get warm.
Measure if your polarity is correct; confirm you got a positive voltage on the positive side of the cap and negative on the negative side.
That would of course be DC. Tell us if you measure AC voltage over the caps as well and how much.
In any case: don't raise that voltage for now.

/Hugo

globalweb · 20th May 2007, 08:20 PM

Netlist
That will I certainly do, tomorrow.

Powering it up again. Now it has disappeared. Strange. I’ll be back tomorrow with further reports.

Netlist
Do you measure this with or without connecting it to the power mains? (Maybe a stupid question but I'm asking it anyway to be sure).

Netlist · 21st May 2007, 06:20 AM

When you told us about the 5V, I assume there was mains voltage true a variac. I also assume the 5V was the rail voltage you measured somewhere after the rectifier. It is obviuos that you can not measure voltage without applying the mains.

Try to be specific as to what and where you measure voltages. Can you post a schematic of the power supply you used?

/Hugo

globalweb · 21st May 2007, 08:13 AM

Netlist

Yes I’m using a variac. 5V was measured after the capacitors. between + and
ground and - and ground. Using two multimeters.
Here’s the schematic:

http://www.kk-pcb.com/power-x.html

Netlist · 21st May 2007, 08:34 AM

Well, keep the multimeters in place, slowly rise the voltage and keep an eye on the caps for heat.
It would be best to disconnect the power supply from the amp until you are sure both + and - voltages are fine.

/Hugo

globalweb · 21st May 2007, 07:42 PM

Netlist

Using the Vac scale on the multimeter I couldn’t find any AC.

But another thing happens. When turning down the variac after measuring voltage. The voltage quickly goes down to 0V. I don't think that is ok.

20th May 2007, 07:56 PM	#1
globalweb diyAudio Member Join Date: Sep 2006	Warm capacitors. When powering up my Aleph-x at about 5V (normal is 24 V) two electrolytes are getting warmer then six of the rest. About 29 C instead of 24 C. Is this something to worry about?

20th May 2007, 07:59 PM	#2
Zen Mod diyAudio Member Join Date: Jan 2003 Location: ancient Batsch , behind Iron Curtain	are this two in same position in circuit as rest of them? __________________ my Papa is smarter than your Nelson ! tnx to clean thread ; Cook Book ; PSM LS Cook Book ; Baby Diyaudio FORUM ; BAF Forum & Gallery;I'm dumb

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20th May 2007, 08:00 PM	#3
Netlist diyAudio Moderator Join Date: Jan 2003	Yes, maybe. If the ambient temperature is 24°, and the rail voltage is only 5V, I would presume something is wrong. Is the amp newly build or not? /Hugo

20th May 2007, 08:08 PM	#4
globalweb diyAudio Member Join Date: Sep 2006	Zen Mod Yes they are. Netlist Yes it is. This is the first test. Slowly, slowly I’m raising the voltage.

20th May 2007, 08:17 PM	#5
Netlist diyAudio Moderator Join Date: Jan 2003	Don't raise the voltage. 5V is plenty and don't leave it on too long if the caps get warm. Measure if your polarity is correct; confirm you got a positive voltage on the positive side of the cap and negative on the negative side. That would of course be DC. Tell us if you measure AC voltage over the caps as well and how much. In any case: don't raise that voltage for now. /Hugo

20th May 2007, 08:20 PM	#6
globalweb diyAudio Member Join Date: Sep 2006	Netlist That will I certainly do, tomorrow. Powering it up again. Now it has disappeared. Strange. I’ll be back tomorrow with further reports. Netlist Do you measure this with or without connecting it to the power mains? (Maybe a stupid question but I'm asking it anyway to be sure).

21st May 2007, 06:20 AM	#7
Netlist diyAudio Moderator Join Date: Jan 2003	When you told us about the 5V, I assume there was mains voltage true a variac. I also assume the 5V was the rail voltage you measured somewhere after the rectifier. It is obviuos that you can not measure voltage without applying the mains. Try to be specific as to what and where you measure voltages. Can you post a schematic of the power supply you used? /Hugo

21st May 2007, 08:13 AM	#8
globalweb diyAudio Member Join Date: Sep 2006	Netlist Yes I’m using a variac. 5V was measured after the capacitors. between + and ground and - and ground. Using two multimeters. Here’s the schematic: http://www.kk-pcb.com/power-x.html

21st May 2007, 08:34 AM	#9
Netlist diyAudio Moderator Join Date: Jan 2003	Well, keep the multimeters in place, slowly rise the voltage and keep an eye on the caps for heat. It would be best to disconnect the power supply from the amp until you are sure both + and - voltages are fine. /Hugo

21st May 2007, 07:42 PM	#10
globalweb diyAudio Member Join Date: Sep 2006	Netlist Using the Vac scale on the multimeter I couldn’t find any AC. But another thing happens. When turning down the variac after measuring voltage. The voltage quickly goes down to 0V. I don't think that is ok.

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