C4S Upgrade Blown LED

[JosephDuffy]

Hi,

I've just finished installing the C4S upgrade, and when I turned it on on of the LED blew (D1). It literally broke in half and part of the plastic went flying off. I've done all my visual checks and I can't see any issues, so I'm not too sure what to check. I guess my 2 questions are:
How do I get another LED?
How do I check what I've messed up?

 

[galyons]

For a replacement LED just call BH HQ tomorrow or send an email to replacementparts@bottlehead.com .  Before you install the new LED,  inspect the orientation of the LED's and transistors. Make sure your leads are going to the correct terminals.  Post pics!!

Cheers,
Geary

 

[mcandmar]

Flying electronic components is usually a sign of too many volts, it should only see a few volts. Assuming the amp worked fine before installing the C4s i would read through the manual again from the start and double check every component is installed the correct way.

 

[Paul Joppa]

The resistor R2 is what limits the current in D1 and D2. If it's the wrong value, or shorted out by a solder blob, that is another possible cause of the symptom. Good idea to make sure D2 is good - personally, I'd ask for two and replace both. But check all the things already mentioned before you try to blow them up again!  :^)

 

[JosephDuffy]

Thanks for all the replies guys. I'm about to send them an email. I've uploaded a couple of photos to Imgur, and double checked against the instructions and I still can't see anything that's wrong. I can't see anything that's shorted and everything oriented correctly. I will note that I originally put the blue resistors in the holes closer to the edge (as show, they're still soldered), but I fixed this before turning it on.

I have also checked the connections that the wires coming off make and the joints look fine and are in the correct position. One thing that threw me off about those was the "Attach and solder the white wire to 11U. Touch up the solder joint at 11L if needed" on page 13, which confused because it talked about both 11U and 11L, but I checked against the photos and the white wires are in 11U and 23U.

Thanks for all the replies guys. Are there any tests I can do now/next time with the multimeter without turning it on?

Quick Edit: Since I'm in the UK it might be quicker for me to just order some LEDs myself. These have the same name and look the same so I might as well just order these, for the sake of a few quid?

 

[mcandmar]

Thanks for all the replies guys. I'm about to send them an email. I've uploaded a couple of photos to Imgur, and double checked against the instructions and I still can't see anything that's wrong. I can't see anything that's shorted and everything oriented correctly. I will note that I originally put the blue resistors in the holes closer to the edge (as show, they're still soldered), but I fixed this before turning it on.

I have also checked the connections that the wires coming off make and the joints look fine and are in the correct position. One thing that threw me off about those was the "Attach and solder the white wire to 11U. Touch up the solder joint at 11L if needed" on page 13, which confused because it talked about both 11U and 11L, but I checked against the photos and the white wires are in 11U and 23U.

Thanks for all the replies guys. Are there any tests I can do now/next time with the multimeter without turning it on?

Quick Edit: Since I'm in the UK it might be quicker for me to just order some LEDs myself. These have the same name and look the same so I might as well just order these, for the sake of a few quid?

Imgur link?

The reference to 11L/21L is just to double check the joints in case they came undone while unsoldering the resistor from the upper positions 11U/21U and soldering the C4S wires to them. They are joined together so its possible the heat could transfer and unsolder them.

I'm not 100% on the circuit, unfortunately they didn't put it into the manual but if you measure resistance from each white wire to the LED's you should see some sensible resistance, i'm going to guess ~150k assuming those resistors are there to drop the voltage supply to the LED's.  Basically use the good side as your reference and look for differences.

LED's you linked look like the correct ones, "pcarena-bristol" generally have a quick turn around in my experience.

 

[JosephDuffy]

Thanks for all the replies guys. I'm about to send them an email. I've uploaded a couple of photos to Imgur, and double checked against the instructions and I still can't see anything that's wrong. I can't see anything that's shorted and everything oriented correctly. I will note that I originally put the blue resistors in the holes closer to the edge (as show, they're still soldered), but I fixed this before turning it on.

I have also checked the connections that the wires coming off make and the joints look fine and are in the correct position. One thing that threw me off about those was the "Attach and solder the white wire to 11U. Touch up the solder joint at 11L if needed" on page 13, which confused because it talked about both 11U and 11L, but I checked against the photos and the white wires are in 11U and 23U.

Thanks for all the replies guys. Are there any tests I can do now/next time with the multimeter without turning it on?

Quick Edit: Since I'm in the UK it might be quicker for me to just order some LEDs myself. These have the same name and look the same so I might as well just order these, for the sake of a few quid?

Imgur link?

The reference to 11L/21L is just to double check the joints in case they came undone while unsoldering the resistor from the upper positions 11U/21U and soldering the C4S wires to them. They are joined together so its possible the heat could transfer and unsolder them.

I'm not 100% on the circuit, unfortunately they didn't put it into the manual but if you measure resistance from each white wire to the LED's you should see some sensible resistance, i'm going to guess ~150k assuming those resistors are there to drop the voltage supply to the LED's.  Basically use the good side as your reference and look for differences.

LED's you linked look like the correct ones, "pcarena-bristol" generally have a quick turn around in my experience.

Oops, I had the URL copied, but forgot to put it in. Here's the link, and I also edited the original for anyone reading that.

I'll take a look at the resistance, but I've feeling that because of the broken LED it won't be a full circuit anyway, so it might not be any good? I should be able to check the resistance across the resistors, which would confirm that they're working I guess.

I assume that that's what they were referencing to with the 11/21/U/L, which I did check, but I thought I'd double check, thanks

 

[JosephDuffy]

Thanks for all the replies guys. I'm about to send them an email. I've uploaded a couple of photos to Imgur, and double checked against the instructions and I still can't see anything that's wrong. I can't see anything that's shorted and everything oriented correctly. I will note that I originally put the blue resistors in the holes closer to the edge (as show, they're still soldered), but I fixed this before turning it on.

I have also checked the connections that the wires coming off make and the joints look fine and are in the correct position. One thing that threw me off about those was the "Attach and solder the white wire to 11U. Touch up the solder joint at 11L if needed" on page 13, which confused because it talked about both 11U and 11L, but I checked against the photos and the white wires are in 11U and 23U.

Thanks for all the replies guys. Are there any tests I can do now/next time with the multimeter without turning it on?

Quick Edit: Since I'm in the UK it might be quicker for me to just order some LEDs myself. These have the same name and look the same so I might as well just order these, for the sake of a few quid?

 

[mcandmar]

I dont see anything obvious, but double check the three pins on the small round transistor on the B side in case they are shorting out.

Doesn't look like the resistor measurement i mentioned above will work, circuit is very different than i thought.

 

[JosephDuffy]

I dont see anything obvious, but double check the three pins on the small round transistor on the B side in case they are shorting out.

Doesn't look like the resistor measurement i mentioned above will work, circuit is very different than i thought.

This is something I checked a few times since the gap is so small and I remember messing that up when I did soldering in school. I can't see anything that's a possible cause of a short, so I've pretty much ruled that out.

 

[Paul Birkeland]

It looks like you have a solder blob shorting the 2N2907 on the "B" side.

 

[JosephDuffy]

It looks like you have a solder blob shorting the 2N2907 on the "B" side.

Admittedly, that does look like it's got a bridge across 2 connectors, but I can assure you that it's not. I've tried to take a better photo but I've not got good light right now (it's night time now) and I can't get it to focus.

 

[JosephDuffy]

Hi guys.

I got my LEDs today, and I've now re-soldered it on. I've uploaded a couple of pictures to Imgur:
http://imgur.com/svHUCbc
http://imgur.com/rzWei5f
Can anyone let me know of any resistance etc. checks I can do before I switch this on which could let me know if this is going to pop again?

 

[Paul Birkeland]

I think you have a little soldering work left to do.  When you heat a joint on a PC board, you want to see the solder actually suck into the hole. 

I would also guess that you either have a chilly iron (less than 40 Watts), or that you are using lead free solder (copper or silver bearing).  This tends to make the work more difficult. 

-PB

 

[JosephDuffy]

I think you have a little soldering work left to do.  When you heat a joint on a PC board, you want to see the solder actually suck into the hole. 

I would also guess that you either have a chilly iron (less than 40 Watts), or that you are using lead free solder (copper or silver bearing).  This tends to make the work more difficult. 

-PB

Thanks for the reply, I now see that a couple of joints hadn't "sucked through" (though some just had too much solder).
After your comments I've gone through and made sure that I could see solder on both sides of the board:
http://imgur.com/xjymLXT
http://imgur.com/V8WQZca
I'm using a 40W (maybe more, not sure) soldering station and turned it up to 400

 

[kgoss]

If the solder joints look good on the two wires behind the transistor on the left you should trim those wires just to be certain there is no chance of a short.
The joints themselves are hidden by the transistor so just make sure they are soldered properly.  And before you turn the amp on again you should go through the resistance checks again.

 

[JosephDuffy]

If the solder joints look good on the two wires behind the transistor on the left you should trim those wires just to be certain there is no chance of a short.
The joints themselves are hidden by the transistor so just make sure they are soldered properly.  And before you turn the amp on again you should go through the resistance checks again.

I have clipped the ends as much as I can, and checked underneath that the joints are good (sorry, I didn't realise that they were covered on the photo!)

I've just done the resistance checks and A5 isn't showing as anything. B5 is showing as 185kΩ. Neither B5 nor the red wire on the circuit board look to be bad joints, but I'll reflow them for the sake of it. Are then any other s I should look at reflowing to try and solve this problem, or any other areas I can look at?

Edit: I've reflowed A5 and the red connector on the board and I'm still seeing nothing on A5

 

[Paul Birkeland]

That is looking much better, nicely done!

 

[JosephDuffy]

That is looking much better, nicely done!

I'm still no soldering-guru, but I think I've learnt a lot from the S.E.X. kit Looking back at it, I shouldn't have been soldering on the day I completed the C4S upgrade; I was a bit too ill to be doing something like that, so I'm sure that didn't help.

 

[Grainger49]

Watch the solder liquify with the iron against both the PCB trace and the component.  After it liquifies hold it for 3s (it is a mental count).  This gives me good solder joints every time.