Desoldering problem with vintage pioneer recap project - diyAudio
Go Back   Home > Forums > Source & Line > Analogue Source

Analogue Source Turntables, Tonearms, Cartridges, Phono Stages, Tuners, Tape Recorders, 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 2nd July 2012, 08:25 PM   #1
diyAudio Member
 
Join Date: Dec 2005
Location: California
Default Desoldering problem with vintage pioneer recap project

I am recapping a Pioneer turntable circa 1974-1977. I am having a dickens of a time melting and removing the old solder from the board to remove the original capacitors. I have attached a picture of the bottom of the PSU board that I started on. The motor board has everything closer together so I would like to get my technique down before starting that one.

I first tried using the desolder braid, I tried the M.G Chemicals brand (no clean and then the regular) and then the Radio Shack brand with no luck. I set the iron to 600 degrees, then 650, and finally 700 (I was reluctant go any higher than that). The solder would not melt with the braid between the solder and the iron tip. What temperature should I be using?

Removing the braid and applying the tip directly to the joint, at 700 degrees the solder melted. I used one of those spring operated one handed vacuum pumps to remove a few capacitors, but this operation is not as clean as I think I should be able to do with the braid.

I tried applying a bit of new solder to the joint, I tried putting extra flux on the braid (but I was using an old flux pen that may or may not have actually applied any additional flux). Does anyone have any suggestions? I do not know why it is so hard to melt the old solder. Is that typical? Should I increase the heat? or maybe buy a bottle of flux and try putting more on the braid?

Thanks for any help on this.
Attached Images
File Type: jpg Bottom of PSU board before cap change.jpg (746.9 KB, 141 views)
  Reply With Quote
Old 2nd July 2012, 08:37 PM   #2
diyAudio Member
 
sofaspud's Avatar
 
Join Date: Nov 2005
Location: San Antonio
I would use just the iron to melt the solder and pull out the cap. Then use sucker, braid, and/or a thump on the table to clear away the solder for the reinstall. To me, tip temp isn't so important if contact time is adjusted accordingly.
__________________
It is error only, and not truth, that shrinks from enquiry. - Thomas Paine
  Reply With Quote
Old 3rd July 2012, 12:39 AM   #3
Simon B is offline Simon B  United Kingdom
diyAudio Member
 
Join Date: Dec 2011
Location: North-East England
Stripped scrap flexible wire rather than braid, the end dipped in rosin flux. Solder flows better through this and it's available in a variety of sizes.

A little rosin flux to the joint to be de-soldered, with a cocktail stick.

Dry tissue and moist (not sodden) sponge in the wells of the iron stand, for a clean tip, and an appropriate width bit on the iron.

Good initial thermal contact is key to desoldering, start off with just the bit to the joint. Fresh flux helps this. As the old solder melts, roll the bit sideways to make room, insert the braid/wire then roll the tip back on to maximise heat transfer. As the solder flows move the braid/wire along to speed the soaking up, then disengage. Trim the braid/wire as needed, it's an unnecessary heatsink otherwise.

Do this to all the leads of a component, then extract it with a touch of the iron where needed. Save the vacuum pump for clearing through holes where necessary.
__________________
Engineer: One who can do for 10 shillings what any fool can do for 10 pounds.
  Reply With Quote
Old 3rd July 2012, 05:38 AM   #4
dangus is offline dangus  Canada
diyAudio Member
 
Join Date: May 2004
Location: Vancouver Island
When I'm desoldering something, I nearly always apply some fresh fluxcore solder.

Then the classic Edsyn DS017 Soldapullt to remove most of the solder. Braid if I need to get the pads really clean, but with braid you have to keep cutting off chunks as it becomes saturated. Also, I think the brand and type of braid is important: finer strands may wick better.

Last edited by dangus; 3rd July 2012 at 05:40 AM.
  Reply With Quote
Old 3rd July 2012, 04:12 PM   #5
diyAudio Member
 
Join Date: Dec 2005
Location: California
Thank you all for the help. I plan to try again this weekend.
  Reply With Quote
Old 3rd July 2012, 06:19 PM   #6
macboy is offline macboy  Canada
diyAudio Member
 
Join Date: Oct 2003
Location: Ottawa, Canada
When I have problems melting old solder joints, I add more fresh rosin core solder (60/40 or 63/37). Not a little, but a lot of it. This always helps. I think that the hard-to-melt solder might be some alloy that melts at a higher temp. Mixing it with the low temp stuff (63/37 is the lowest common solder alloy IIRC) makes it easier to melt. The side effects of extra flux and the removal of surface oxidation also help a lot. I will often use the sucker to remove the initial big blob, then follow up with braid, otherwise you'll go through lots of braid.
  Reply With Quote
Old 4th July 2012, 01:45 PM   #7
diyAudio Member
 
indianajo's Avatar
 
Join Date: Jan 2010
Location: Jeffersonville, Indiana USA
I have a lot of irons that heat but the tip does not. Sometimes this can be repaired by removing the tip and dropping solder down in the hole to improve heat flow, but not always.
I've got a Weller WP25 iron that works pretty well now, but if there are more than 4 20 gauge wires on a joint (old tube equipment) the iron doesn't have enough wattage. Oh, the WP25 is modified with a 7/32" inch flat end screwdriver tip. The pointy tip sold with the iron is only useful for tiny microelectronics.
I've got an 80 watt weller from Home D**** with a big wedge tip that won't melt solder at all. And various R**** S**** irons that melted solder only the first month.
To save money I use the scrap stranded wire dipped in flux to soak up old solder, but an iron with good heat flow will melt solder through the commercial braid. I don't like solder suckers, they mostly burn up the tip when I used them. If the end of the part lead is bent over, it helps to save the PCB by removing the solder before trying to bend the lead up.
__________________
Dynakit ST70, ST120, PAS2,Hammond H182(2 ea),H112,A100,10-82TC,Peavey CS800S,1.3K, SP2-XT's, T-300 HF Proj's, Steinway console, Herald RA88a mixer, Wurlitzer 4500, 4300

Last edited by indianajo; 4th July 2012 at 01:50 PM.
  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
pioneer a-88x recap,what else could be done paul.42 Solid State 1 17th July 2012 12:08 AM
Vintage Pioneer Equipment Perry Babin Car Audio 11 14th September 2011 01:36 AM
Vintage Pioneer SA-6200 sound problem coming from power amplifier assy! SeMu Solid State 8 4th September 2011 10:01 AM
Pioneer HPM100 Recap & Modifiction triodes4ever Multi-Way 2 27th February 2011 05:18 AM
Recap Problem 65blkbkgt Car Audio 0 14th August 2007 10:04 PM


New To Site? Need Help?

All times are GMT. The time now is 05:15 AM.


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