1st time DIYer - tales of my build - questions in 1st post

[Jim R.]

Dave,

It's actually good that you questioned your abilities when you thought about having BH build it.  You'll soon see how easy and straightforward it is to troubleshoot and repair these things and as a result your confidence willl double and your ultimate satisfaction in a job well done will just feel all that much better.

There is value in making mistakes, finding them and fixing them yourself -- don't be discouraged.

-- Jim

[wullymc]

Thanks guys for your encouragement and help!

Grainger!

You were absolutely right.  It was a bad ground connection.  I worked my way through each ground starting with 3.  I ended up resoldering 2 locations - 12L and the inside volume control......and it worked!!

Thank you so much.

Rather than start testing with the voltages I think I am going to take a break tonight and bask in the success of the resistance test!

Thanks again to everyone for there help.  This is a great board and I truly appreciate it!

[wullymc]

Sorry guys, I have another question!

I am going to be testing the voltages and don't totally understand this:

1.-Attach the negative lead of a volt-ohm meter to ground.  A good spot to do so is at terminal 12.  Use of a clip lead to connect the black test lead to the ground will free one hand, making testing much easier and safer.

2.-   Turn the chassis over and reconnect the negative lead of the volt-ohm meter to the ground buss. 


I understand #1 and I know to flip it over so that I can turn on the amp but I don't understand to reconnect the negative lead to the ground buss.  Is the ground buss still Terminal 12?  Shouldn't it still be attached?

Please say a prayer for me.  Don't really want to stop my heart with measuring voltages!!...plus I want to hear the amp before I go!


Thanks everyone!

[Grainger49]

It sure sounds like you are doing the test lead twice.  

Just be certain that you attach to a good ground, you have several now, I like T3 the best, and use one hand to make measurements.  Don't touch the chassis or any other ground with your free hand while making measurements.

I've been shocked several times.  It may have hastened my needing a pacemaker.  The Pacemaker was going to happen because of A/V problems but it may have hastened it.

[Noskipallwd]

Dave, T12 was where I connected my meter to ground. When I took voltage readings I installed the tubes and put the amp in its base upside down, ran the power cord under the base and after connecting my meter to ground reached under the base and turned the amp on, worked well for me anyway.

Cheers,
Shawn

[wullymc]

Thanks guys,

Excellent idea Shawn.  I will flip the chassis and put it in the wood base.

I just powered up the amp.  The 6080 lit up fine, however the 12au7 did not exhibit any light.  My thoughts are that I will check the A* terminals for any what looks like bad connection. It would be the red wires for power right?

Would it be bad to go ahead with the voltage check for all terminals and report back?

The fuse seems to have worked fine!

Thanks!

[Laudanum]

Not for sure here but I think the EH 12AU7, because of the filaments, may not exhibit much visible glow but still may be working fine.  Go by your voltages, not the tube glow.

[Grainger49]

For the 12AT7 check voltage from either tube pin 4 or 5 to pin 9.  There should be 6.3V AC between these points.  It is low voltage and should be safe.  Just don't short pin to pin.

[wullymc]

Thanks guys,

Tonight the plan is to do the voltage checks.   I will report back.

hope everyone is having a great weekend!

Dave

[wullymc]

Hey guys,

I did the voltage checks.  My dmm is a cheap one with no auto-range.

So for my DCV I have the settings 200m, 2000m, 20, 200, 1000.

For the voltage test I used the setting of 1000.

Also, both LEDs did not light up and like I stated in a previous post the 6080 lit up but it doesn't seem that the 12AU7 lit up.

Warning: below might hurt your eyes! 

Terminal                     Voltage                 S/B Manual
1                                 228                        90
2                                 233                        170
3                                  233                       0
4                                 228                        170
5                                 233                        90
6                                 233                        0
7                                 233                        100
8                                 233                        0
9                                 233                        100
10                               233                         0
11                               233                         0
12                                 0                          0
13                               233                         170
14                                  0                           0
15                               233                         185
20                                  0                            0
21                               234                          206

A1                              288                         90
A2                               234                         0
A3                              233                          1.5
A4                                  0                           0
A5                                  0                           0
A6                               228                          90
A7                               234                           0
A8                               234                          1.5
A9                                   0                           0

B1                              229                          90
B2                              234                         170
B3                              234                         100
B4                              229                           90
B5                              234                          170
B6                                  0                          100
B7                                  0                             0
B8                                  0                             0

I tried taking the voltages by grounding first at Terminal 12 and then took the readings again grounded at Terminal 3.

good news:  I didn't see any smoke.  A lot of numbers seem to be the same.  ie. 234, 233, hopefully this indicates an easy enough problem....hopefully.

I checked the fuse and it is okay.

I might try to borrow another dmm but this one worked for the resistance checks.

I kindof stuck again.  Thanks...Dave

[Laudanum]

According to your numbers,  you have voltage on T3 which is a ground.  Im assuming you listed that voltage from clipping the ground on T12 and measuring at T3.   Obviously there are other terminals where you list high voltages where there should be none.  But just looking at that alone ... I would double check your wiring.   If it were an autoranging meter, I would think maybe you were reading millivolts but you stated that it isnt.  Someone smarter with this stuff will chime in and narrow it down but seems that to have voltage on a ground when measuring from what should be a ground termial to ground terminal,  something is either wired wrong or you have leads touching between two terminals or something.    Also, make sure your transformer is labeled correctly.  I dont know if that would cause all the measurment anomalies but worth a check.  The stickers have been placed on upside down/reversed in atleast one instance.  You can check by looking for the terminal numbers on the white terminal insulators and comparing to the label/sticker.

[Grainger49]

Your tubes are not turning on.  You should see an AC voltage, 6.3V AC, from the 12AU7 tube pins 4 or 5 to tube pin 9 that is the heater.  You would have gotten an odd reading there to ground set on DC.

For all your measurements you can choose 200V after the problems are cleared. All voltages should be under 200V.  But for now, 1000V is fine.

If none of the LEDs light then check to see if they are in with the silver band toward terminal 3.  

As Desmond above says, you shouldn't get voltage from a "ground" lug to another "ground" lug.  This indicated that your grounding scheme is off.

Terminals 3, 8, 11, 16, 17 and 22 are all grounded.  The list of signal grounded points is in my previous post.  Before turning it on again verify that they all measure zero (one ohm on your meter) to each other.   233V on T3 and others means that there is still a problem in the grounding scheme.  

[wullymc]

Thanks Desmond, Grainger,

I went back and checked the ground connections.  It looked like my terminal 12 was not working.  I resoldered it but it didn't make a difference.  I then went and looked at the black wires coming from it and going to it and noticed that my connection to the headphone jack had come loose.  Resoldered and everything checked out okay for resistence.

Next:  I fired it up and tested the voltage.....I did it!!!!1  I am sooooo happy.

My new numbers are:


Terminal                     Voltage                 S/B Manual
1                                 81                        90
2                                 169                        170
3                                  0                          0
4                                 169                        170
5                                  83                        90
6                                 0                           0
7                                 103                        100
8                                 0                           0
9                                 104                        100
10                               0                           0
11                               0                           0
12                               0                          0
13                               170                       170
14                               0                           0
15                              191                        185
20                              0                            0
21                             212                         206

A1                              82                          90
A2                              0                            0
A3                              1                          1.5
A4                              0                           0
A5                              0                           0
A6                              81                          90
A7                              0                           0
A8                              1                           1.5
A9                              0                           0

B1                              81                          90
B2                              170                         170
B3                              104                         100
B4                              82                           90
B5                              170                         170
B6                              105                         100
B7                              0                             0
B8                              0                             0


....and both LEDs lit up!!!

And for the headphone TRS jack the readings I got when I turned it on were:

Tip - very quickly goes to 12.1 but then quickly down to 0 within I would say 2 sec
Ring - fast 16 then down to 0 in 2 seconds.

I am thinking about trying headphones now do you think I should be fine.  I guess that if it reaches 0 your headphone will be fine?  Is that right?

I have read not to start the amp with headphones plugged in but to wait a little while and then insert the tip into the headphone jack with the volume at 0.

Thanks for all your help.  I am feeling realllllly good!

Take care.....Dave

[kgoss]

Congratulations!

This community is AWESOME isn't it!

[fullheadofnothing]

Congrats Dave!

Your next post will be your most important: how the thing sounds! It is a known fact that a piece of gear you build yourself always sounds better than anything else.

You're right on with those safety precautions for protecting your cans.

Pick out a good track you love and prepare to be blown away!