simple se c1 capacitor blew

[kerux]

I powered up my simple se for the first time today. After the pop noise and the smoke cleared. I turned it upside down and saw the c1 capacitor blew.

I did the inverted assembly method. I disassembled and I see that it was correctly installed. I attached a picture too and it matches tubelab's capacitor page that has the pictures.

Any help is appreciated before I try again.

Andy

 

[korneluk]

The picture is too fuzzy to be able to read the polarity on the capacitors, but the negative terminals should be facing each other. Was the capacitor the correct voltage rating?

It also looks like you have a choke installed across the L1 connectors. What does the rest of the power supply look like. Did you make any changes?

 

[Ty_Bower]

Yes. the picture is a bit fuzzy. Use a macro setting on your camera if it has one. There is usually a little icon which looks like a flower.

The polarity on the caps look correct. The top of the cap seems to be the metal type with the X shaped rupture notch stamped in. My C1 cap has a plastic disc on top. I wonder if you got the correct voltage rating on C1.

I can see you did not install the FREDs. That is good. Installing them backwards will cause blown supply caps.

What is your power transformer? Did you have the power tubes (EL34, 6L6, 6550, KT88, etc.) installed when C1 popped? The B+ voltages are much higher when no power tubes are installed. I seem to recall that if I run mine with no power tubes, my Hammond 374BX will develop voltages in excess of the capacitors rated continuous working voltage (over 500 VDC). The caps should be able to handle some additional surge voltage for a short time (see the mfg's datasheets for details).

Here's a pic of the bottom of my Simple SE board. I also opted for the under chassis mount.

 

[kerux]

I have a hammond 374bx with KT88 tubes installed when I powered up.

The capacitor was a 47uf 500v capacitor. That I got off the part list.

After doing some checking, I realize I forgot to put the fuse into the IEC fuseholder. I have a digital multimeter so I will try to test for shorts as I have seen in other posts.

Thanks for your help.

 

[Ty_Bower]

After doing some checking, I realize I forgot to put the fuse into the IEC fuseholder.

You have a serious wiring error, which may result in damage to the amp, fire, or death.


If there is no fuse in the fuse holder, there should be no possible way for power to get into the primary of the power transformer. Nothing should be energized with no fuse.

 

[HEADinaJAR]

I have an IEC in which the fuse leads are touching each other, on a spring. It can be used without a fuse. When you insert the fuse it separates the leads to each end of the fuse. But be absolutely sure this is the case in your amp.

 

[cddeluca]

Wiring Error

Perhaps you fused the neutral?

 

[kerux]

"Perhaps you fused the neutral?"

I think this is part of the problem. I spoke to my dad and explained some of the wiring I did and he said it is not correct for the switch. I realize how to fix part of the switch wiring.

After more discussion with dad, I don't understand all of the necessary wiring so I will try to get someone professional to help out.

I have looked at tubelab's diagrams multiple times but am not understanding how the neutral wiring is done.

Thanks everybody for their help.

 

[nic6paul]

This diagram shows how it should be wired.

An externally hosted image should be here but it was not working when we last tested it.

 

[kerux]

Thank you nic6paul for the picture. I have seen that picture and I see the problem now.

http://www.magnequest.com/2a3_diy/Seth_2A3_s240_Manual_v1.pdf

This document is for a different amp but shows wiring up a hammond 374bx which I have and shows how to wire up the 2 primaries wires and the neutral wiring.

Thanks

 

[kerux]

Thank you nic6paul.

My simple se is now working and sounds great!!!!

 

[lineup]

Can not be un-usual that people get caps blown into pieces
when we think of the voltages used in tube amps.

I am sure most tuube builders have been there?
At least once or twice?

Even me, have experieced this. Using only moderat 'transistor-voltages'.

 

[BudP]

Kerux,

Completely off topic, your earthlink dot net email address bounces when I try to return your contact about Electron Pools. Please send me a new one or call me at 425 823 2279.

Bud

 

[chrish]

Yes, those 500V caps are running very close to their rated power with a 374BX transformer. I would suggest stick with a tube rectifier, do not use the standby switch option (an indirectly heated rectifier like the 5AR4 will give slow turn on) and use an inrush current limiter on the centre tap (just solder one leg of the current limiter to the centre tap wire and put the other leg in to the phoenix connector on the board).

Enjoy the new amp!

Chris