Technique to replace SMD cap with thru-hole? - diyAudio
Go Back   Home > Forums > Source & Line > Digital Source

Digital Source Digital Players and Recorders: CD , SACD , Tape, Memory Card, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 22nd April 2011, 06:27 PM   #1
goody75 is offline goody75  United States
diyAudio Member
 
Join Date: Apr 2010
Location: Motown (area)
Default Technique to replace SMD cap with thru-hole?

I am modifying a Sony SCD-CE595 but have a general question about smd cap replacement. I am a relative newbie and would appreciate any suggestions or help that anyone could provide.

I have already replaced the larger electrolytic caps with Elna Silmic II's and Nichicon KG's. I replaced the front channel op amp with LME49720. I also placed a pair of 0.47 X-rated caps in parallel across the transformer for high frequency filtering. Nice improvement so far with op amp & caps still burning in.

My next plan is to replace the output/coupling caps with 1.0uF AudioCap Theta's bypassed with 0.1uF FT-3 teflon - not much space for them but it's possible. I removed the smd output/coupling caps (both the 47uF & 0.1uF bypass) and was pleasantly surprised to find some posts that I could use to attach the new thru-hole caps. It seemed like the most practical way to work with the limited space was use a wire with small insulated alligator clips at the end to connect to the old smd posts.
I also used a rubber band to hold all 4 caps together (for stability).

At first it worked fine but after a the player was moved a few times, one of the channels cut out and, with further inspection, I discovered that one of the old smd posts had broken off.

I am trying to decide (again) the best way to attach the new thru-hole caps to the smd spots on the board. Any suggestions will be much appreciated.

goody75
  Reply With Quote
Old 24th April 2011, 12:24 AM   #2
erin is offline erin  Australia
diyAudio Member
 
Join Date: Nov 2006
Location: http://www.makeitpossible.com/
In this case you would find the point where the cap connects to the op-amp output leg and solder one leg there ( to the leg of the op-amp) , and the other end of the cap you should solder to the RCA jack.
my 2c.
  Reply With Quote
Old 26th April 2011, 07:30 AM   #3
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Another idea if there is enough space on the PCB is to drill it to suit the new leadouts.

Also if the output is at zero volts DC (circuit side of caps) then you may not need them at all and they could be shorted out. Does the equipment this player feeds have input caps any ?
__________________
-------------------------------------------------------
A simulation free zone. Design it, build it, test it.
  Reply With Quote
Old 26th April 2011, 07:52 AM   #4
diyAudio Member
 
sofaspud's Avatar
 
Join Date: Nov 2005
Location: San Antonio
I think the soldering part is fairly straightforward. Bend a small end L in each of the cap leads parallel with the PCB, trim to fit the pads, and solder them down. The important part is now providing stability for the capacitor body. Of course that should be thought out before soldering. Hot glue or silicone is perhaps best for general-purpose duty.
__________________
It is error only, and not truth, that shrinks from enquiry. - Thomas Paine
  Reply With Quote
Old 26th April 2011, 08:47 AM   #5
diyAudio Member
 
Join Date: Jun 2010
Location: Germany and www.aca-vogel.de
You can also solder a SMD capacitor with small value (some pf) and then the THT one with bended legs. Then you have the stability of the end connector caps of the SMD part and the SMD pads are fixed. Be carefull with soldering THT parts on SMD-pads. Often, the SMD pads are removed from board by mechanical stress !
__________________
Designing audio electronics isn't a job, it's a mission
  Reply With Quote
Old 1st May 2011, 01:54 AM   #6
goody75 is offline goody75  United States
diyAudio Member
 
Join Date: Apr 2010
Location: Motown (area)
First, thanks for your feedback. Second, the Sony SCD-CE595 is probably not a good player for modding - too many smd components and the pcb is cheaply made. There are some warnings in this thread that I found but I did not heed them. If you do mod it, the Swenson Mod is probably the way to go since it is the least invasive and reversable - but very difficult on this machine.

Things have worsened since my last post. There are multiple problems now and I'm very frustrated. There is a fine line between being persistent and being stubborn. I lean towards the latter - like a mule. Although I am tempted to quit, I'm not sure I can but I also don't really know what to do at this point so any suggestions/comments are welcome. Here we go.

Since my last post, I replaced the old, brittle smd posts with new ones I made from the left-over leads from the AudioCap Thetas (thick & sturdy copper). My plan was to attach the two pairs of Theta/FT3 output caps to some perfboard with a rubber band (pretty ghetto) and simply rest it on top of the PCB until it was ready for a more permanent fixture. The posts that connect to the smd pads were to be fed thru the perfboard and then attached to the caps with a wire & alligator clips (until ready for soldering). I figured this solution would provide good stability for everything.

Problem 1 - Lifted Pads
As I was guiding some of the new posts thru the perfboard, one of them broke off, taking the trace pad with it.

Solution 1a - Repair Output Cap Pads (FAILED)
I investigated repairing copper pads. The best option seems like a silver conductive epoxy but it was difficult to rationalize the $130 per kit. I ended up purchasing a silver conductive pen (MG Chemicals) thinking I could redraw a pad (~$20). The pen didn't work that well but 1) I may not have used the correct technique and 2) The contents of the pen were difficult to get out and clumped somewhat which is not good for drawing around small smd traces (is there a shelf life for this product?). Bottom line is that some of the original output cap pads are now non-functional and I gave up on repairing them.


Solution 1b - Find new location to tap signal (post opamp & pre output cap)
Since there are so many tiny smd components, the only place I could find to tap the signal was @ the opamp output pins (thanks, erin). I soldered one end of my new FT3/AudioCap Theta wires to pin 1. At some point during the process of soldering & moving the board & components around, I not only lifted the pad for pin 1 of the opamp, I actually broke the pin off. D'OH!

The opamp I installed is the cheap but excellent LME49720 so I could replace it for a couple bucks. And since the output caps were going to get the signal from the output pins anyway, I don't need to worry about repairing the pad. I like this idea and think it's far less difficult than the next solution but I need to figure out how to attach the wire in a stable way. FYI, the opamps are on the bottom of the PCB.

Solution 1c - Swenson Mod (not yet attempted)
This may be the best solution but at this point, I'm not sure if I can solder a connection to the output pins of the DAC because they are so tiny. I do have a pretty good soldering iron with a fine tip and have some pretty fine (skinny) solder but I definitely need some finer gauge wire (size recommendations & sources welcome).


Problem 2 - Mysterious Laser/Transport Problem
At some point, after disconnecting and reconnecting the player innards multiple times, the player started behaving strangely. When I power up the machine and try to play a cd, the tray slowly opens and/or rotates back and forth then it either stops responding to commands or simply spins without being able to read the disc. Sometimes I even get an error message that says "REMOVE". On the bright side, It seems like if I play with the 11 pin flat cable that sends the signal from the laser to the PCB, it will start working properly for a minute. This cable has gotten a lot of action lately since it must be removed/plugged in every time I do work on the player. And now that I think about it, it was difficult to unplug the 1st time. Maybe it was glued in? Either way, I suspect that it is damaged and causing this mysterious behavior.

The most frustrating, depressing and hilarious part of this whole thing is that I bought a couple more players and all of them are now exhibiting this strange behavior and are not functioning. Could this fixing this issue be as simple as replacing the 11 pin flat cable? If yes, can I just buy a generic one somewhere like digikey?

Once again, any feedback is welcome and encouraged.
  Reply With Quote
Old 1st May 2011, 04:50 AM   #7
erin is offline erin  Australia
diyAudio Member
 
Join Date: Nov 2006
Location: http://www.makeitpossible.com/
Try re-soldering (reflow) the solder on the bottom of the 11 pin cable as you may have some hairline cracks in the old solder. Or cut the connector off and solder the wires directly to the PCB. Also try Deoxit contact cleaner on all connectors.
  Reply With Quote
Old 8th May 2011, 04:21 PM   #8
goody75 is offline goody75  United States
diyAudio Member
 
Join Date: Apr 2010
Location: Motown (area)
Quote:
Originally Posted by erin View Post
Try re-soldering (reflow) the solder on the bottom of the 11 pin cable as you may have some hairline cracks in the old solder. Or cut the connector off and solder the wires directly to the PCB. Also try Deoxit contact cleaner on all connectors.
  Reply With Quote
Old 8th May 2011, 04:40 PM   #9
goody75 is offline goody75  United States
diyAudio Member
 
Join Date: Apr 2010
Location: Motown (area)
Thanks, Erin.
I did try Deoxit on one of the cables. It helped but did not fix the problem. I will try re-soldering and update you with the results.

Regarding the repair of the analog stage (either the op amp pads or the Swenson mod)... I was pretty clueless about technique when I posted the longer post above and was NOT scraping off the green protective layer from the circuit path. This is an important thing to do when restoring a lifted/missing pad. It ensures a good connection and since solder doesn't want to adhere to plastic, it adds some stability. In addition to tools found in basic soldering tools kits, I found an abrasive brush pen at Radioshack that is helpful as well.

Out of frustration last week, I switched to another project so it may take a little time before I resume salvaging these Sony changers. I will post an update when that happens.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Finding SMD equivalents of through hole transistors Brannigan Solid State 17 18th October 2012 02:39 PM
Polar electro with bypass cap to replace nonpolar as coupling cap? at77 Parts 0 12th January 2010 02:05 AM
Hole in Dust Cap Affect Sound Quality ?? excetara2 Multi-Way 20 4th September 2009 10:30 PM
How to replace SMD-microphone. SE Mobile silversweden Everything Else 1 14th November 2008 11:20 PM
SMD ceramic cap. Which one? antomas Parts 3 12th September 2006 12:05 PM


New To Site? Need Help?

All times are GMT. The time now is 03:00 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2