Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: kill_surf_city on December 26, 2019, 01:51:24 PM
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Both tubes light up completely and one LED lights up (A8).
Here’s my readings:
1. 94.5
2. 183.3
3. 0.0
4. -00.1
5. -00.1
6. Starts at 95 then gradually drops
7. 144.7
8. 0.0
9. 67.7
10. 93 then gradually drops
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Terminals 2 and 4 are wired together with a jumper wire. I would guess that yours is missing or not well soldered.
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Terminals 2 and 4 are wired together with a jumper wire. I would guess that yours is missing or not well soldered.
Thank you, Paul. I’ll check it out.
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Terminals 2 and 4 are wired together with a jumper wire. I would guess that yours is missing or not well soldered.
Yep, turns out I had missed that step completely. Just put it in and rechecked the voltage. Only terminals that are out of range are 6 and 10. Both should be zero but 6 floats around 100 then gradually starts to drop. 10 starts at 101 then floats between 99.3-99.4. Any idea what the problem is here?
Edit: google search came up with my headphone jack being miswired. Fixed it but now my voltages are all too low.
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Edit: google search came up with my headphone jack being miswired. Fixed it but now my voltages are all too low.
What was miswired? What did you change?
"Too low" is not a number and doesn't tell me much about what's going on.
Please post build photos at your earliest convenience.
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What was miswired? What did you change?
"Too low" is not a number and doesn't tell me much about what's going on.
Please post build photos at your earliest convenience.
The black wire that goes from 3L to the headphone jack wasn’t wired all the way up, so I removed the wire and replaced it correctly. Now the one LED that was turning on, turns on initially then goes out. Here’s my readings now.
1. 45
2. 72.6
3. 0
4. 73.4
5. 17.1
6. 0
7. 49.9
8. 0
9. 14.3
10. 0
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Not sure if this is related to the problems you're having, but you have some leads that need trimming, particularly the one circled in the attached. It looks like it might be creating a short to chassis ground.
cheers, Derek
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Not sure if this is related to the problems you're having, but you have some leads that need trimming, particularly the one circled in the attached. It looks like it might be creating a short to chassis ground.
cheers, Derek
Thanks. Also just realized the right blue capacitor is getting warm but the left one is not. Hmmm.
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A blue cap that gets hot could be in backwards, but I can't see that from your photos.
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A blue cap that gets hot could be in backwards, but I can't see that from your photos.
Oh shit you’re right! I feel so dumb. Thanks Paul. I’ll turn it around and report back soon
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From the photo it looks like the top of the cap is already bulging. PB can tell you if it's still usable.
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Ok I got both the caps in the right orientation now. Here’s my new readings. Neither LEDs are turning on.
1. 134.2
2. 169.2
3. 0
4. 169
5. 124
6. 0
7. 140.7
8. 0
9. 135.2
10. 0
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From the photo it looks like the top of the cap is already bulging. PB can tell you if it's still usable.
I think the cap is blown. I re-did the voltage checks and the numbers are all in range except for terminals 5 and 7 which I’m pretty sure is the left channel. So I thought what the hell, and decided to plug it in and see how it sounds. Right channel is absolutely silent and when I played music it sounds incredible - like absolutely perfect. The left channel however, barely any music came through if any at all and it’s mainly a loud hiss with some crackles here and there. Does that sound like the cap needs replaced? If so how do I go about ordering a new one?
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You really ought not try to listen to the amp with the voltages out of spec.
Mouser will carry those capacitors, as will digikey
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You really ought not try to listen to the amp with the voltages out of spec.
Mouser will carry those capacitors, as will digikey
Thank you. Does what I’m describing sound like a blown capacitor?
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A blue cap that gets hot could be in backwards, but I can't see that from your photos.
Caps are now put in properly.
Final readings before I do anything else
1. 84.6
2. 174.3
3. 0
4. 174.3
5. 116.8 *
6. 0
7. 107.6
8. 0
9. 130.3 *
10. 0
5 and 9 are out of range. Neither LED lights up.
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I think you should wait for PB's input before powering the amp again.
But there is one thing I would suggest doing in the interim . See circled area in the attached pic: the black wire has too much exposed wire and looks like it might be touching (or might end up touching) the lead of the diode below it. If that happens, I think you'll have a short circuit every half cycle that will draw a ton more current than the transformer and diodes are meant to handle. I suggest reheating the joint and pulling the black wire further into the solder lug so that the bare wire and the diode lead no longer overlap.
I've also indicated with arrows what look to me like signs that the first 270 ohm resistor has been overheated - this is really just to bring it to PB's attention. I'm not sure if has been overheated, or even if it has, whether this is a problem. PB will let you know.
cheers, Derek
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I think you should wait for PB's input before powering the amp again.
But there is one thing I would suggest doing in the interim . See circled area in the attached pic: the black wire has too much exposed wire and looks like it might be touching (or might end up touching) the lead of the diode below it. If that happens, I think you'll have a short circuit every half cycle that will draw a ton more current than the transformer and diodes are meant to handle. I suggest reheating the joint and pulling the black wire further into the solder lug so that the bare wire and the diode lead no longer overlap.
I've also indicated with arrows what look to me like signs that the first 270 ohm resistor has been overheated - this is really just to bring it to PB's attention. I'm not sure if has been overheated, or even if it has, whether this is a problem. PB will let you know.
cheers, Derek
Got it. Thanks!
Edit: there was actually a pretty good amount of space between the wire and the diode but I pulled the black shielding further over anyway.
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Do both halves of the 12AU7 still glow? Your voltages tell me that one half is not conducting.
Do not listen to an amp that hasn't passed its voltage checks. Those tell you whether or not the amp is working properly, and an amp that isn't working properly can destroy headphones. (In fact having the 100uF cap in backwards will melt one headphone driver if you tried to listen to the amp like that, if you put a bulged cap back in and attempted to listen to the amp, you may have already caused some damage)
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Do both halves of the 12AU7 still glow? Your voltages tell me that one half is not conducting.
Do not listen to an amp that hasn't passed its voltage checks. Those tell you whether or not the amp is working properly, and an amp that isn't working properly can destroy headphones. (In fact having the 100uF cap in backwards will melt one headphone driver if you tried to listen to the amp like that, if you put a bulged cap back in and attempted to listen to the amp, you may have already caused some damage)
Yep. Both sides of the 12AU7 glow.
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Do both halves of the 12AU7 still glow? Your voltages tell me that one half is not conducting.
Do not listen to an amp that hasn't passed its voltage checks. Those tell you whether or not the amp is working properly, and an amp that isn't working properly can destroy headphones. (In fact having the 100uF cap in backwards will melt one headphone driver if you tried to listen to the amp like that, if you put a bulged cap back in and attempted to listen to the amp, you may have already caused some damage)
Do you think the cap needs replacing? That’s what I’m thinking since I seem to be having the voltage problem with the left side (Terminals 5 and 9). Also I only listened to it after I had put the bulged cap in properly. I’ve listened to my headphones since with my other amp and there doesn’t appear to be any damage.
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You could post more pictures of the cap and the rest of the build. If you don’t have a way to test its capacitance you could just buy a new one since they’re not super expensive.
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You could post more pictures of the cap and the rest of the build. If you don’t have a way to test its capacitance you could just buy a new one since they’re not super expensive.
Here’s some pics
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I’m not an expert at this at all, so maybe PB disagrees, but I’d replace that cap before I ran electricity through the amp again.
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I’m not an expert at this at all, so maybe PB disagrees, but I’d replace that cap before I ran electricity through the amp again.
That’s what I was thinking. Ordered a couple new ones last night from Mouser. Thanks!
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Yes, that cap is damaged.
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You can run the amp with no 100uF cap to continue debugging the issue you're having up front with those DC voltages that aren't correct. Do both the LEDs on the 9 pin socket illuminate still? At least one must be lit, but perhaps not both?
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You can run the amp with no 100uF cap to continue debugging the issue you're having up front with those DC voltages that aren't correct. Do both the LEDs on the 9 pin socket illuminate still? At least one must be lit, but perhaps not both?
I have both the caps in right now. I’m gonna remove the bad one. But as of right now, neither LED comes on. I think one comes on initially then fades out. But I’ll have to let you know for sure.
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You can run the amp with no 100uF cap to continue debugging the issue you're having up front with those DC voltages that aren't correct. Do both the LEDs on the 9 pin socket illuminate still? At least one must be lit, but perhaps not both?
Okay, so as it stands with the cap damaged cap still in, the LED connected to A8 initially turns on when I plug it in then fades out. The other LED stays off. What should I look for?
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The LED should not turn on when you power up the amp.
Does this also happen with no tubes in the amp at all?
Can you post a fresh photo of just the 9 pin socket wiring?
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The LED should not turn on when you power up the amp.
Does this also happen with no tubes in the amp at all?
Can you post a fresh photo of just the 9 pin socket wiring?
When I take the tubes out the LED doesn't turn on at all. Here’s pics of the sockets as well. I’m about to take out the bad capacitor.
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On the 9 pin socket, it looks like maybe the end of the LED going to A8 is touching the wire at A7.
On the 8 pin socket, it looks like some of the ends of the green wires need to be trimmed that are sticking out.
Do both halves of the 12AU7 still glow when the amp is running?
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On the 9 pin socket, it looks like maybe the end of the LED going to A8 is touching the wire at A7.
On the 8 pin socket, it looks like some of the ends of the green wires need to be trimmed that are sticking out.
Do both halves of the 12AU7 still glow when the amp is running?
I’ll get to trimming! Also, yes both halves the the 12AU7 still glow. I have removed the bad cap.
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Can you also carefully measure the voltages at A3 and A8?
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Can you also carefully measure the voltages at A3 and A8?
A3 - 02.7
A8 - 01.9
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Can you also carefully measure the voltages at A3 and A8?
Also after doing the trimming I’ve gotten terminal 9 to come down to 115-116 and terminal 5 down to 92.1
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A3 - 02.7
A8 - 01.9
And they aren't glowing?!
I suspect that you have many cold solder joints. If I had this amp on the bench for repair, I would reheat each one and let the solder flow out again.
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And they aren't glowing?!
I suspect that you have many cold solder joints. If I had this amp on the bench for repair, I would reheat each one and let the solder flow out again.
The tube is glowing on both sides yes. But neither LED is lighting up. So are you saying i should re-solder the joints where the LEDs are connected?
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And they aren't glowing?!
I suspect that you have many cold solder joints. If I had this amp on the bench for repair, I would reheat each one and let the solder flow out again.
Ok I resoldered the joint on the LEDs and got A8 to light up but broke A3 in the process. Something tells me that the A3 LED wasn’t in there very well to begin with. So I’ll have to order a new LED for that joint unless there’s some kind of work around for that. Thanks Paul!
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You can install a wire jumper between A3 and A8.
I would resolder all of the joints in the amp, not just the ones where the LEDs connect.
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You can install a wire jumper between A3 and A8.
I would resolder all of the joints in the amp, not just the ones where the LEDs connect.
Okay. How long should the jumper be? I’ll install that later tonight and then do a recheck of the voltages and post them here.
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Okay. How long should the jumper be?
Long enough to reach between A3 and A8 and not touch anything else.
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Long enough to reach between A3 and A8 and not touch anything else.
Okay, put the jumper cable in, the remaining LED is strongly lit, and I put in the replacement cap. The one I got is 160v 100uf but it’s a bit smaller looking. Either way, here’s my voltages. Should I be safe to try it out? 2,4,7, and 9 are on the high end but within 10% of the goal.
1. 94.8
2. 176.1
3. 0
4. 176.3
5. 93.6
6. 0
7. 115.0
8. 0
9. 117.1
10. 0
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Those are functional voltages.
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Those are functional voltages.
Works and sounds incredible! Thanks a lot for you help Paul and everyone else here!! Im sure I’ll be back when the times comes to install the Speedball
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Those are functional voltages.
Hey Paul, just a quick question - I replaced just the cap that was bulging so the caps, while the same voltage and uf, are mismatched. Is this a problem?
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If it's something that bothers you, you can certainly replace them both.
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If it's something that bothers you, you can certainly replace them both.
Oh no I don’t kind I just wasn’t sure if it’s something that might cause problems down the road.