New crack - No sound from right channel [resolved]

[calmiswar]

Hello All,

Just finished my crack build and the resistance and voltage test (almost) checked out. But, when I play music, there is sound only in my left ear. Swapping cables still gives me sound only in the left ear.
When I remove the left channel and keep only the right channel, I can very faintly hear the song playing, again in the left ear. Have reflowed all joints to no avail.

Here are my voltage readings:

1 - 152  (*)
2 - 171
3 - 0
4 - 171
5 - 74.5
6 - 0
7 - 151  (*)
8 - 0
9 - 102
10 - 0

(*) Had doubts about these.

I ended up burning the RCA jacks and had to buy some cheap replacements. The resistances check out for both the RCA jack channels..


Will upload some pictures shortly.

Thanks.

 

[calmiswar]

Here are some pics

 

[calmiswar]

Some more

 

[calmiswar]

Some more

 

[calmiswar]

Pics

 

[calmiswar]

Anyone?
Any help would we appreciated.

Thanks.

 

[calmiswar]

Checking properly, my A8 LED is actually not lighting.

When I test continuity on the other LED, it lights up. But this one(A8) doesn't. Is the LED dead?

And stupid me has fried my HD700s. Be careful guys, don't be an idiot like me.

 

[calmiswar]

Some more voltage readings:

A1 - 73.4
A2 - 0
A3 - 1.5
A4 - 0
A5 - 0
A6 - 144
A7 - 0
A8 - 12.3
A9 - 0
Centre - 0


B1 - 144
B2 - 160.2
B3 - 142.2
B4 - 72.6
B5 - 162.8
B6 - 98.2
B7 - 0
B8 - 0

I tried replacing the LED (took one from the speedball package) and it was lighting up when I tried a diode test from my DMM. connected it, didnt glow and now it wont glow when I test with my DMM.

Someone please help me before I hurt myself tinkering with this.

Thanks.

 

[Paul Birkeland]

First things first. Your amp didn't pass its voltage check. When it failed the voltage check, plugging in headphones risks damage to your headphones, head, and amplifier.

With that out of the way, an LED that doesn't light up can have several causes, only one of which is the LED itself being a problem.

When you have the amp powered up, do you see little glowing dots on both plate structures in the 12AU7?

 

[calmiswar]

First things first. Your amp didn't pass its voltage check. When it failed the voltage check, plugging in headphones risks damage to your headphones, head, and amplifier.

With that out of the way, an LED that doesn't light up can have several causes, only one of which is the LED itself being a problem.

When you have the amp powered up, do you see little glowing dots on both plate structures in the 12AU7?

Thnks a lot for the reply PB.

Yes, when I power up the amp, I can see little glowing dots on top of (and below) both the plates.

Thanks.

 

[Paul Birkeland]

I see you have 12V at A8.  This is indeed indicative of a cooked LED.

The good news is that you can install a wire jumper between A3 and A8 and you should be back in business.

 

[calmiswar]

Thanks! Will try that and get back to you.

 

[calmiswar]

Hello,

Just realized that I was connecting the A8 LED to A9. Fixed that (2 burned LEDs later).

Now, when I do the voltage check, it looks like a complete disaster.

1 - 93
2 - 230
3 - 0
4 - 230
5 - 93
6 to 10 - 0.

I must sound like a complete retard right now but please help me!

 

[Paul Birkeland]

The 12AU7 is now working properly.  How are the voltages on terminals 6-10?

 

[calmiswar]

Terminals 2 & 4 are 230 V, is that fine?

And terminals 6-10 are 0 V now.

 

[calmiswar]

To add to this, the terminals 6-10 were working properly before. The (bigger) tube doesn't seem to light up now. I also see that it has gotten cloudy white at the top of the tube.
Did I do something to mess it up or was it faulty?

 

[Paul Birkeland]

If the 6080 is cloudy white at the top, it's lost its vacuum and it needs to be replaced.

The front end (12AU7) is working properly, and with a working 6080 installed in the amplifier, you should get good voltage checks.

 

[calmiswar]

Here are my voltage readings now:

1 - 93
2 - 230
3 - 0
4 - 230
5 - 93
6 - 0
7 - 93
8 - 0
9- 93
10 - 0

Is this fine? Could you please tell me how 230v at 2 & 4 terminals are normal? Does it depend on the input tube?

Also, do you think I can claim a replacement for the driver tube?

Thanks a lot for you help.

 

[calmiswar]

And last question.. can I use the amp now??

 

[calmiswar]

Very sorry to bombard you with questions, but should I check the voltage/current at the headphone jack too or should we be good?

I ask because I'm scared I'll fry more headphones. :-[

Thanks!