Low voltage on finished Crack (repost)

[tsuid1]

Hi all, I posted about this before, but for some reason, the website is giving me a hard time replying and updating, so I decided to post again with more details.



Like the title says, just finished building the crack. I checked the resistance this morning and the numbers all matched the manual's.

Last night I was performing the voltage test with tubes installed. The 12u7 tube glows with no issue but the 6080 doesn't glow at all. The LED's were on for five minutes, but then they turned off and hasn't turned back on since.

The voltage also seems to be pretty low compared to what the manual says. Also worth noting that I checked the orientation of the 8 pin socket and it's pointing towards the vent holes as instructed. As for the L+N voltage test, my meter measured 121v, so I followed the instructions on page 25

1- 2.30v
2- 2.30v
3- 0v
4-2.3v
5-2.3v

6-0v
7-0v
8-0v
9-0v
10-0v

Also added photos below.

Thanks

[oguinn]

You might need to check the file size of the pictures since there’s an attachment limit.

[tsuid1]

Just added. Thanks!

[Paul Birkeland]

Can you perform the checks on page 29 of the manual?

[tsuid1]

Sure. For the first part, I got 6.5v, and 177v on the second part. Looks like the numbers are in range

[Paul Birkeland]

Are the tubes glowing?

20U and 21U do not look to be all that well soldered. 

[tsuid1]

The 12u7 tube glows but not the 6080. I'll try to add more solder.

[Paul Birkeland]

B7/B8 make the 6080 glow.  Can you post some photos of your 6080?

[EricS]

The 12u7 tube glows but not the 6080. I'll try to add more solder.

In addition to a bit more solder, it may be necessary to add a bit more heat to the junction so the solder flows nicely leaving a clean and shiny joint behind.  Higher heat for a shorter period of time is often an effective approach if you have the ability to adjust the temperature of your soldering iron.

[tsuid1]

Here are some pictures of the 6080, 8 socket and 20u and 21u.

Does this mean I have to reheat the solders at 20u and 21u? How long should I reheat them for? I just checked them and they were both filled before I resoldered anything.

[EricS]

Just a few seconds should do it, usually not more than 4-5s depending on the overall mass of what you are trying to heat.  It you watch carefully with a bright light, you'll see the solder melt when you apply the iron and you'll also see the melting spread across the solder joint as you heat it.  If you need to add more solder, this is the time.  Then, just remove the iron and let it cool on its own and you should be good to go. 

If you have any doubts, there are TONS of youtube videos about forming proper solder joints.  If you are new to soldering, it sometimes takes a little bit of practice, but you'll get it!

[tsuid1]

Ok, before I had a chance to solder, my dad who is an electrician checked on the wiring. Everything seemed fine, but we found that the 5w 270ohm resistor by terminal 13 and 14 is open. Could this explain why the amp isn't working properly aside from soldering those two joints?

[Deke609]

... we found that the 5w 270ohm resistor by terminal 13 and 14 is open. Could this explain why the amp isn't working properly aside from soldering those two joints?

Yup. With an open 270R resistor, you'll have no high voltage power supply. You'll want to replace that resistor.

cheers, Derek

[Paul Birkeland]

Definitely replace that resistor.  Any 200-300 ohm 5W resistor will do.

Also do post photos of the 6080 you have in the meantime.

[tsuid1]

Sure no problem. Images are below.
Just contacted the replacement service. Hopefully will have it by Saturday. I'll probably try to look for it in a local hardware store. How much does it usually cost?