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trace and pad damage to Zenkit 1 circuit board (Read 270 times)
goso64
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trace and pad damage to Zenkit 1 circuit board
01/07/23 at 01:33:28
 
As you can see in the pic below, 2 bad things happened when I tried to remove the volume control leads.

1. One of the traces became separated from the board (see pic). The red arrow points to the end of the trace (some metal still there.

2. The pads came off all 6 holes (see pic).

Before I expend the energy to try to patch this back together, is this worth trying to save or is a new board in order?

If so, any suggestions regarding getting the trace re-attached to the board? †

Also, is it possible to prepare the pads?

I'm disappointed - maybe this board is now junk.

Thank you all for your feedback.

[img][/img]

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4krow
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Re: trace and pad damage to Zenkit 1 circuit board
Reply #1 - 01/07/23 at 04:32:09
 
 It might depend on how far along you are with the build. Less than 1/4 of the way, I might get a new board. The good news is that the trace is simply a wire stuck to a board, meaning that you can abandone it on both ends and run a wire from where it was supposed to go. Make sure that both ends are cut.
Just as importantly, it is possible that you are using too much heat with the soldering. How many watts does your solder iron have? Is it adjustable? What tip are you using? These are important questions trust me. I did some horrible work before I bought a good soldering station. Since you are removing pads and traces are coming loose that is important to consider.
 I won't say that the board is defective, but it is possible. When you were getting the pot out, what did you use? A solder sucker? Solder wick? Sorry for all the questions. Yup been there done that. It all matters.
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goso64
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Re: trace and pad damage to Zenkit 1 circuit board
Reply #2 - 01/07/23 at 17:19:03
 
@4krow - many thanks for all these questions, as they lead me to research my soldering techniques.  Now I am a little more informed.  Here are the answers to your questions.

Any comments regarding restoration of the 6 pads that are gone?

1. I may be using too much heat.  My iron was set to 775 deg.  I did some research and seems I should be using 600-650 deg for tin/lead solder.  
2. Iím using a 60 watt Weller soldering station.
3. I was using conical tip - after some research, I should probably be using a bevel tip for this board.
4. When pulling out the pot, I applied heat only.  My solder sucker broke last week and I didnít think to use solder wick.
5. The trace in question makes several turns and goes all the way across the board, to the 1k resistor which is connected to the input tube so it's a difficult repair to say the least.
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4krow
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Re: trace and pad damage to Zenkit 1 circuit board
Reply #3 - 01/14/23 at 01:21:10
 
Sorry for the late reply. The information that you have supplied tells me a few things:

1) 775 F of heat is way too hot unless you can get in get out fast. I run my iron at 650 and that is considered pretty hot too. The melting point of a lot of solders is between 380-450 degrees, so try experimenting with a much lower temp to see what happens.

2) The right tip will ensure the best heat transfer. I typically use a 2-3 mm chisel tip so the heat transfers more evenly. It works for most applications.

3) Solder wick is your friend when extracting solder from multiple connections. The solder must be removed from each connection as in the case of a volume control. Then bit by bit it may wiggle out as you apply more heat to the pins.
Fwiw, there is a product that is called Chip quik. It is actually an alloy made mostly of Cadmium. The melting point is low at about 200 F. So then you apply it to the original solder on the pads and it mixes with it. Now you can melt the 'new ' bunch of solder at a much lower temp, and it will stay molten much longer, giving you extra working time and ease with the solder wick to pick it up.

3) It's not likely that the traces can be repaired easily, but don't worry. A jumper wire can run straight across the circuit board where it ends up at the far connection. Make the wire long enough so it doesn't get in the way of anything or pick noise from nearby circuits.

You will be fine.
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goso64
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Re: trace and pad damage to Zenkit 1 circuit board
Reply #4 - 01/14/23 at 01:34:30
 
Thanks for your reply. †I'll take your comments on the soldering to heart.

Agree - tried to repair the traces but it's not feasible. †I can try the jumpers but I already decided to get a new board last night. †I found that both traces from volume to the RCA inputs were lifted. I was concerned running 2 wires all the way across the board, over the components and to the inputs would result in noise so I bailed for the easier solution. †I'll let you know how it goes.

When I get the new board, I will mount the POT to the board and move the standoffs close to the edge of the enclosure so I don't have to run wires from the board to the POT. †

A secondary reason for me to restart is I need to redo the enclosure - it has so many holes it looks like Swiss cheese It's the first time I build an amp with an enclosure and I'm still learning so I chalk up the cost as training cost. †I've learned a lot and am enjoying it.

Cheers
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goso64
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Re: trace and pad damage to Zenkit 1 circuit board
Reply #5 - 01/14/23 at 03:38:11
 
UPDATE: †I tried running a jumper from the POT to each RCA input and also to each 1K resistor to the input pins of the tube. †I lifted the pads on every interface that I jumpered and pulled the trace of a bit and snipped it. (see pic)

Couldn't get it to work. †One channel was non-responsive and the other was always on, regardless of the position of the pot. †

It was worth a try - had nothing to lose. †

thank you again for your advice and encouragement. †Will redo once the new boards come in.

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Mannytheseacow
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Re: trace and pad damage to Zenkit 1 circuit board
Reply #6 - 01/14/23 at 03:53:45
 
Bummer! If itís not too late maybe just build a point to point amp and forget the board?  Youíve got all the components.
Though, you probably need a new volume pot if you got it that hot.
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goso64
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Re: trace and pad damage to Zenkit 1 circuit board
Reply #7 - 01/14/23 at 04:11:28
 
Interestingly, I was thinking the same thing about point-to-point!  That will be my next amp.  Thanks again.  Cheers
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4krow
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Re: trace and pad damage to Zenkit 1 circuit board
Reply #8 - 01/14/23 at 04:45:38
 
Play it as is and see what you think. It's fine that you have a new board coming. Also, if you decide to go the point to point way, you are going to have to buy what are called turret strips to connect the wires to. Mostly it will work, but you may have to lengthen leads and other stuff to get everything to reach. Just something to consider.
Let us know the outcome no matter which way it goes. I think that you have done the right thing for now. Who hasn't burned a trace or broken something or lost something? You wouldn't want to see my short comings in the shop, BUT I will gladly show off my successes!
And yes, I know what it is like to have a few too many holes in a chassis as well.
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