New 700b WOPL build... blowing fuse 2 on left backplane

WOPL Sniffer

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#21
Hi @George S. - Thanks for the suggestions. Bias transistors are clear of the P-straps, nothing touching there. Boards were cleaned, leads on the back planes trimmed nice and close to ensure no shorts. Top side high-res pics attached of those to start:

Is it just a trick of the light or ??? On the pic showing both backplanes in the same shot, it looks like there is no wire in the UF_B- pad (In between the 2 fuses).
 

Gepetto

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#23
The wires going to the Bias EBC on each back plane , the insulation should not be touching the pads on the component or solder side of the board.
And all wires in general, I see many spots where you may be suffering a solder joint problem to the actual wire.

You should be able to see a joint to the actual wire strands on the top and bottom side of the boards. Also ensure you have enough strip length to avoid an insulation only connection on the Phoenix contact connectors.
 

WOPL Sniffer

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#25
you MUST.... Take your time and get the wires stripped all to the correct length and flowed with enough heat to make a clean and shiny joint. Looking at the wires going into the control board connectors, they have stripped wire which is not tucked in to the connector leaving room for shorts. Stripping the wire a little long gives you the opportunity to get all the lengths correct so no stripped tinned wire hangs out when connected. wiring and solder connections and solder balls are questions you need to address.
 

dtafil

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#26
Is it just a trick of the light or ??? On the pic showing both backplanes in the same shot, it looks like there is no wire in the UF_B- pad (In between the 2 fuses).
Hi Perry! Yep, trick of light. There's a black lead to each of those connections.
 

dtafil

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#28
you MUST.... Take your time and get the wires stripped all to the correct length and flowed with enough heat to make a clean and shiny joint. Looking at the wires going into the control board connectors, they have stripped wire which is not tucked in to the connector leaving room for shorts. Stripping the wire a little long gives you the opportunity to get all the lengths correct so no stripped tinned wire hangs out when connected. wiring and solder connections and solder balls are questions you need to address.
Will go back and redo, thank you!
 

George S.

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#30
I cheat and solder bottom first, then go to other side with a long thin tip and add a little more. Wires are stripped and placed to facilitate this. Usually do entire bottom first, flip, touch up the top.
 

Gepetto

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#31
Will go back and redo, thank you!
Not your current problem Dave but you want to achieve the best performance. Note how the black (hot AC) and white (neutral AC) wires are tightly coupled together to create field cancellation. The hot wire is routed to the front AC switch between the 2 backplane boards and again are coupled tightly together to provide field cancellation (current flowing one way in wire 1, and the reverse direction in wire 2).
 

dtafil

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#32
I do appreciate the feedback and examples! I like Joe's tagline "Always working on making it better..." Ditto. Will pull backplanes are redo wiring. Thanks guys.
 

Skratch

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#33
It looks like you have no heatsink on Q1 and not Q50, that isn't your problem but down the road Q1 may overheat
 

George S.

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#35
Let me elaborate. I use the same screwdriver or chisel tip for the large wires on the top as I use to solder every thing on the bottom, with the exception of the bias transistor. For the bias transistor and those tiny delicate traces I use a long thin tip.
For everything else on top other than the larger wires, I use a long thin tip. A long thin tip allows me to get to the target area without touching components, and has low thermal mass at the tip so nothing will get overheated.
Quite often there is solder there, it just need a little flux to flow. I touch solder to it, I can see the flux flow, and add a little solder if needed for the nice meniscus as Joe calls it, or fillet as I call it. I call it a fillet because I used to bronze weld or fillet braze bicycle frames long ago.
You want that nice shiny, sloping solder shape on both sides of the board. Then take your flush cutters and cut most of it off on the bottom side!!!
Double sided, through plated boards are great, especially the heavy quality boards Joe provides in the kits. But I'll never rely on a through plated hole soldered on one side only to carry the load. I want a wire or component lead through that hole and a shiny meniscus on both sides. Have fun!
 

dtafil

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#40
It's an older Hakko FX-888 (before they went digital)... ~399 degrees Celcius/750 degrees F. I may have used the smaller tip for the wires that I used for the components (T18-D12) which would be 1.2 mm... too small for the wires perhaps?
So, one mystery solved. New Hakko FX888D digital station on the way. The temp I had my old station set to is off enough that it's time to relegate it to back up duties or the scrap heap. Looks to be off ~ 50 degrees, at least according to my Fluke IR probe. Sheesh. Getting much better results with the temp turned up to compensate on the wire work. It is about 10 years old.

IMG_3014.jpeg
 
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