Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: bucketofguts on March 05, 2022, 01:05:09 PM
-
With the the volume at 0 on power on i get a loud hum. Turn the volume up a little the hum goes dead quiet. This is repeatable for about 30 seconds then all is right in the universe. I am going to roll some valves to check. Wonder if the powers that bee have seen this issue. So many thanks in advance.
b~
-
How are the voltages in the kit? I would recommend posting some build photos if possible, as during power-on there's nothing conducting in the circuit, so you shouldn't hear any noises.
-
I can not find my downloaded instructions for checking the voltages. thank you for getting back.
b~
-
I guess now i need to find out how to get the instructions sent to me. Mine will be fun to test. I used tape and numbered it for each terminal. Then removed the tape when everything was working. I guess I thought I was Joe cool. Changing to several 6080 valves the issue is gone. It returns with my two 5998. I will try to post some pics tonight. I looked with my glass and flashlight, tugged with my tweezers nothing jumped out at me.
-
If the noise is only there with the 5998, then the easy option is to simply use the 6080. You can e-mail replacementparts(at)bottlehead(dot)com to ask for an additional download link. Be sure to provide your name and pertinent information about your order so we can look you up.
-PB
-
Thank you Paul. I am enjoying the 6080 WA from France in the giant white box. I sent a email to you guys about the download.
-
I have the download. Thank you Team Bottlehead!
-
Voltage Speedball board DC- VOLTS 200 scale
OA 38.5
1A 62.8
B/AB 96.8
1B 62.7
OB 31.6
Speedball board w/ heat sinks 0A 98.6 OB 98.7 G 100.0 B+ 87.2.
-
That's not a working amp. Seeing B+ at 87V on the big board but OA/OB higher than that makes me think you have a loose black wire in the amp. The most common spot for that is where the two black wires meet on the headphone jack, though flaky solder joints elsewhere can cause nonsensical voltage readings like this.
-
Thank you! back to work.......................
-
Thank you Paul. I am enjoying the 6080 WA from France in the giant white box. I sent a email to you guys about the download.
Be sure to test voltages you post here with another tube.
I would recommend using a tube that you know to function perfectly in the amp.
I'd have that Thomson tube tested before use.
Especially if you've bought it via Ebay from eastern Europe.
-
Will do, thank you .Pulling my hair out. The two leds on the big board will not light, Could this narrow it down some. going to put is another 6080.
-
new valve lit the 4 leds on the big board
-
If you got the 6080WA off eBay and it's labeled Thomson, those have been a tube with persistent problems for many who have used them.
-
I have read that. Stock 6080 big board voltages. all leds lit both boards and socket. AO 5.7 OB 10.7 G 97 B+ 63
-
Thompson 6080 .... worst vacuum tubes I ever owned .... not worth the headache .....
-
Those voltages are still really wrong, are you measuring AC or DC volts with your meter? Are you able to measure a 9V battery?
-
DC and I will look for a nine volt battery.
-
I can measure a surfire 3 volt cr123 3 volt battery new at 3,4 volts....
-
With no tubes in your Crack, what voltage do you get at B+ on the big PC board?
-
94.3
-
I have been working this issue all day. Thank you for the help!
-
Please post build photos.
-
Will get some up tomorrow. Thanks for all the help today.
b~
-
Here are the requested photos.
-
What are the voltages at 13 and 15?
-
#13 63.5V
#15 80V
Power on.
(Valves in)
-
Are you using terminal 12 as your ground reference?
-
yes
-
BTW, thank you for your kind replies.
-
What voltage do you see at terminal 22?
-
97.6V
Power on
Valves in
Thank you. You are a gentleman and a scholar.
-
Can you perform the AC voltage checks for the power transformer again?
I would also suggest reheating and adding some solder to all the solder joints with UF4007 diodes, especially if the transformer AC voltage checks are correct (which I suspect they are).
-
Thank you. Will do.
is there a resistance value across those diodes that I should be looking for? Could one or both be faulty? (I see four)
Where are the ac terminals on the transformer? help.....
-
Page 29 in the manual provides the test for the power transformer.
When diodes like those fail, they tend to explode, so I don't believe that's worth looking at just yet.
-
I measured 6.24 V AC as shown on page 29. (I have the exact same multi meter)
-
How about for the high voltage winding?
-
174.9
-
What's the DC voltage between 20 and 21?
-
Thank you ! That will have to wait. It is not my fault.
b~
-
97.5 on both. thank you!
b~
-
Terminal 20 is grounded. If terminal 20 has 97.5V on it, it's not grounded, and one of your black wires is loose (there are only two black wires between this terminal and terminal 12).
-
I will replace both with new wire, test and get back. Thank you kind sir. Lots to do today, out the door "in the rain". Will post as soon as I can. Probably this evening EST.
b ~
-
The wires are probably OK; it's more likely to be a solder joint issue.
-
(there are only two black wires between this terminal and terminal 12). I know that sounds easy but what two black wires. I have sucked, chem-wik, and soldered and still no joy. I am sorry to have ask.
b~
-
One black wire connects to terminal 20, the other black wire connects to that black wire.
-
I could not make finer mechanical connections. Solder joints shine like the finest silver. I still have the same values.
-
I could not make finer mechanical connections. Solder joints shine like the finest silver. I still have the same values.
But you can't. If you have ~90V DC across a piece of wire, the wire will heat up until it melts and falls apart. One of these wires has to be broken or loose.
-
I will keep working. Thank you Paul.