Trouble with amp 6V6

Tachyon · 10th October 2008, 01:32 PM

A tube (6V6) was inserted the wrong way in its socket, the middle guide pin was missing.
Now one channel is dead

What components can possibly have been broken?

Two output tubes 6V6 in triode mode, one 6NIP and one 5Y3. The amp is homemade, not by me, and I dont have a schematic for it and sadly no way to aquire it.
The man who built the amp is no longer with us.

I would really appreciate help with troubleshooting.

Tom Bavis · 10th October 2008, 02:42 PM

Measure the voltages on the two 6V6 sockets and post them here.

Tachyon · 10th October 2008, 04:02 PM

Both channels same values +/- 1V

BTW. the tube is still ok , tested on the other channel and it works fine..

Tom Bavis · 10th October 2008, 04:54 PM

Are these voltages with tubes removed? If so, measure from bottom with tubes in place. Screen or cathode resistors could have gotten zapped, which may not not show when it's unloaded.

azazello · 10th October 2008, 05:11 PM

Is there smell from output transformer ?

Tachyon · 10th October 2008, 05:47 PM

Previous measurement was without tubes.
With tubes voltage is now 231-234V

The resistor 1k shown in photo was bad, I don't know if it's screen or cathode resistor, changed to new but still no sound..

Please advice on which pins to measure and settings on multimeter.

azazello -> No burned smell from output transformer.

Thanks for your guiding me!

kstagger · 10th October 2008, 07:02 PM

if you have a working channel and a non-working channel, then you have to start making measurements comparing the two. You can even sketch out the basic schematic to get a feel for whats going on.

Check plate and cathode voltages with the tubes in it. Is it fixed or self bias?

You can also measure and compare transformer resistances between the two channels as a method for shorts or open circuit.

As always, be careful when working with high voltages.
Safety Practices, General and Ultra-High Voltage

Tachyon · 10th October 2008, 08:24 PM

Thanks for your concern, I read the Safety Practices sticky before I started to probe.

Both channels measure very similar, 6.6V on both,
234V-236V on the other chanel.

I belive that the 6.6V AC is filament and the 234V DC is plate. Could cathode be -12V?

The 234V and 231V is connected togheter with a 1K ohm resistor.

Dont know if its fixed or self bias, there is a bunch of big resistors in series, 174ohm.

Please elaborate how to measure the output transformers.

This is where I soak up info..this is all new to me..

http://www.radiomuseum.org/tubes/tube_6v6g.html
http://boozhoundlabs.com/howto/

azazello · 10th October 2008, 10:57 PM

Tachyon,
Mesure is there connection between cathod and ground. It must be
0-1 ohm /for fixed bias/ or more 240 ohm /for self bias/.
Burned 1 kom is for triod mode 6V6.
Can You change 6N1P ? Or put 6N2P, 6N23P, ECC85 ?
Is there capacitor between 6N1P and 6V6 ?
How You wrong put 6V6 ? To clockwise, or contre clockwise ?

Tachyon · 10th October 2008, 11:34 PM

azazello

Between cathode and ground its 174ohm,
five resistors in series.

I belive the tube was rotated 3 pins clockwise.

At the moment I dont have any 6N1P. I ordered new tubes today, all of them just to be safe

I have some ECC82 that are from my old tube pre-amp, could that temporarily replace 6N1P?

I measured the output transformers, between the two primaries its 0.27ohm and between the two secondaries (speaker) its 0.5ohm. That is measured with amp off, as a newbie to this I'm not sure if that the correct way..

10th October 2008, 01:32 PM	#1
Tachyon diyAudio Member Join Date: Feb 2005 Location: Sweden	Trouble with amp 6V6 A tube (6V6) was inserted the wrong way in its socket, the middle guide pin was missing. Now one channel is dead What components can possibly have been broken? Two output tubes 6V6 in triode mode, one 6NIP and one 5Y3. The amp is homemade, not by me, and I dont have a schematic for it and sadly no way to aquire it. The man who built the amp is no longer with us. I would really appreciate help with troubleshooting.

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10th October 2008, 02:42 PM	#2
Tom Bavis diyAudio Member Join Date: Jun 2002 Location: Macedon NY	Measure the voltages on the two 6V6 sockets and post them here.

10th October 2008, 04:54 PM	#4
Tom Bavis diyAudio Member Join Date: Jun 2002 Location: Macedon NY	Are these voltages with tubes removed? If so, measure from bottom with tubes in place. Screen or cathode resistors could have gotten zapped, which may not not show when it's unloaded.

10th October 2008, 05:11 PM	#5
azazello diyAudio Member Join Date: Aug 2008 Location: Bulgaria	Is there smell from output transformer ?

10th October 2008, 07:02 PM	#7
kstagger diyAudio Member Join Date: Dec 2003 Location: Grand Rapids	if you have a working channel and a non-working channel, then you have to start making measurements comparing the two. You can even sketch out the basic schematic to get a feel for whats going on. Check plate and cathode voltages with the tubes in it. Is it fixed or self bias? You can also measure and compare transformer resistances between the two channels as a method for shorts or open circuit. As always, be careful when working with high voltages. Safety Practices, General and Ultra-High Voltage

10th October 2008, 08:24 PM	#8
Tachyon diyAudio Member Join Date: Feb 2005 Location: Sweden	Thanks for your concern, I read the Safety Practices sticky before I started to probe. Both channels measure very similar, 6.6V on both, 234V-236V on the other chanel. I belive that the 6.6V AC is filament and the 234V DC is plate. Could cathode be -12V? The 234V and 231V is connected togheter with a 1K ohm resistor. Dont know if its fixed or self bias, there is a bunch of big resistors in series, 174ohm. Please elaborate how to measure the output transformers. This is where I soak up info..this is all new to me.. http://www.radiomuseum.org/tubes/tube_6v6g.html http://boozhoundlabs.com/howto/

10th October 2008, 10:57 PM	#9
azazello diyAudio Member Join Date: Aug 2008 Location: Bulgaria	Tachyon, Mesure is there connection between cathod and ground. It must be 0-1 ohm /for fixed bias/ or more 240 ohm /for self bias/. Burned 1 kom is for triod mode 6V6. Can You change 6N1P ? Or put 6N2P, 6N23P, ECC85 ? Is there capacitor between 6N1P and 6V6 ? How You wrong put 6V6 ? To clockwise, or contre clockwise ?

10th October 2008, 11:34 PM	#10
Tachyon diyAudio Member Join Date: Feb 2005 Location: Sweden	azazello Between cathode and ground its 174ohm, five resistors in series. I belive the tube was rotated 3 pins clockwise. At the moment I dont have any 6N1P. I ordered new tubes today, all of them just to be safe I have some ECC82 that are from my old tube pre-amp, could that temporarily replace 6N1P? I measured the output transformers, between the two primaries its 0.27ohm and between the two secondaries (speaker) its 0.5ohm. That is measured with amp off, as a newbie to this I'm not sure if that the correct way..

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