Forums :: Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives
Support This Site: Contributors :: Advertise


It is currently Jun Sat 06, 2020 7:08 pm


All times are UTC [ DST ]





Post New Topic Post Reply  [ 26 posts ]  Go to page 1, 2  Next
Author Message
 Post subject: How does a guy fix this?
PostPosted: May Wed 13, 2020 1:25 am 
Member
User avatar

Joined: Dec Wed 23, 2015 3:03 am
Posts: 1027
Location: Northwest Indiana 46350
Picked up an old Sansui receiver, had aux input working but not am and fm. Thought that was odd and started to trace the power supply. Found the daggum selector switch was cracked across some of the traces. The knob must have took a hard hit and cracked, the shaft it slightly bent. I plan to sand off the trace coating and solder the broken traces but I want to reinforce the board. Gonna use pieces of a junk board the split but will glue stick well to these boards? Gonna glue it on the other side opposite of the traces with maybe contact cement cuz that seems to really be sticky?

Attachment:
IMG_1141.JPG
IMG_1141.JPG [ 210.34 KiB | Viewed 828 times ]


Attachment:
IMG_1144.JPG
IMG_1144.JPG [ 214.96 KiB | Viewed 828 times ]

_________________
"It's amazing what you can accomplish when you throw safety out the window", Brent Butt


Top
 Profile  
 
 Post subject: Re: How does a guy fix this?
PostPosted: May Wed 13, 2020 1:31 am 
Member

Joined: Feb Wed 07, 2018 6:52 pm
Posts: 727
Location: Stone Mountain, GA
Scrape off the solder mask across the break. Then use some solid wire and solder it across the trace.

Solder will fatigue when flexed so the wire is needed.

Epoxy should work to glue on a stiffener.

_________________
Scott.
Powered by infinite improbability drive.


Top
 Profile  
 
 Post subject: Re: How does a guy fix this?
PostPosted: May Wed 13, 2020 1:40 am 
Member

Joined: Jan Tue 16, 2007 7:02 am
Posts: 3623
Location: Lexington, KY USA
After the traces are bridged, clean the board with lacquer thinner or acetone. Then use epoxy. Probably just glue will work, but you might glue on a bit of phenolic or FR4 PCB material. You can put the epoxy on both sides, including over the patched traces.

Ted


Top
 Profile  
 
 Post subject: Re: How does a guy fix this?
PostPosted: May Wed 13, 2020 1:52 am 
Member

Joined: Oct Sun 18, 2015 2:49 am
Posts: 302
Location: San Angelo, TX
I would use regular JB Weld, not the 5 minute stuff and use a backup piece of something on the back side. There needs to be some thing across the crack for additional support just as the guys already said about a wire across the land pattern crack. Denis


Top
 Profile  
 
 Post subject: Re: How does a guy fix this?
PostPosted: May Wed 13, 2020 1:56 am 
Moderator

Joined: Jan Thu 01, 1970 1:00 am
Posts: 26019
Location: Detroit, MI USA
DenisN wrote:
I would use regular JB Weld, not the 5 minute stuff and use a backup piece of something on the back side. There needs to be some thing across the crack for additional support just as the guys already said about a wire across the land pattern crack. Denis


This, exactly. I have done it multiple times and it works just fine. I typically roughen up the back side of the switch wafer and the backup material a bit with the Dremel tool so the JB Weld has something to bite into. It's not coming apart if you do that.

_________________
Dennis

Experience is what you gain when the results aren't what you were expecting.


Top
 Profile  
 
 Post subject: Re: How does a guy fix this?
PostPosted: May Wed 13, 2020 2:40 am 
Member

Joined: Nov Tue 14, 2017 5:09 am
Posts: 2613
Location: Austin, Texas
Greg,
Why do you hate PC boards?

Jay


Top
 Profile  
 
 Post subject: Re: How does a guy fix this?
PostPosted: May Wed 13, 2020 2:44 am 
Member

Joined: Nov Tue 14, 2017 5:09 am
Posts: 2613
Location: Austin, Texas
I just repaired one of those last week.

Along with the broken traces, you will need to carefully scrape the tarnish off of the contacts and rivets and solder them to the copper traces. It only takes a tiny amount of solder. You will be removing the switch again because of intermittent operation if you don't solder down the contacts.

Jay


Top
 Profile  
 
 Post subject: Re: How does a guy fix this?
PostPosted: May Wed 13, 2020 11:45 am 
Moderator
User avatar

Joined: Feb Sun 01, 2009 2:56 pm
Posts: 11126
Location: Victoria, Australia
It is often possible to put reinforcing strips on its back & bolt it (2mm) to stop it bending: Glue if you wish. You can in addition drill either side of the crack into the track & make a copper wire pin like a staple that folds over on the back & that will also stop separation. That does not have to be done to every track if it can short.

Annoying rather than an irretrievable disaster.

On the comment above: The great unwashed I have some cattle stuff here that will get rid of any fauna in the hair.

Marc


Top
 Profile  
 
 Post subject: Re: How does a guy fix this?
PostPosted: May Wed 13, 2020 11:55 am 
Member
User avatar

Joined: Jul Mon 26, 2010 8:30 pm
Posts: 28221
Location: Annapolis, MD
JnTX wrote:
Greg,
Why do you hate PC boards?

Jay


Greg's sense of humor is sometimes unique......

Be nice to him---he knows how to find service information when noone else can.

_________________
-Mark
"Even if you don't understand Ohm's Law, you are still required to obey it."


Top
 Profile  
 
 Post subject: Re: How does a guy fix this?
PostPosted: May Wed 13, 2020 3:08 pm 
Member

Joined: Sep Tue 30, 2014 6:08 am
Posts: 5554
Location: Norfolk, VA
SHenion wrote:
Scrape off the solder mask across the break. Then use some solid wire and solder it across the trace.

Solder will fatigue when flexed so the wire is needed.

Epoxy should work to glue on a stiffener.


^^^^^ This. ^^^^

Same as taught in our Micro-Miniature repair course, save for good ol' DoD using a piece of pure copper foil, Wire= copper in round form, and much easier to use. :mrgreen:

_________________
Brian
"Capacitor Cosmetologist since 1979"
USN Retired 1984-2006 (Avionics/Cal)


Top
 Profile  
 
 Post subject: Re: How does a guy fix this?
PostPosted: May Wed 13, 2020 4:07 pm 
Member

Joined: Jan Mon 27, 2020 3:46 pm
Posts: 50
Location: Wilderville, Oregon 97543
DenisN wrote:
I would use regular JB Weld, not the 5 minute stuff and use a backup piece of something on the back side. There needs to be some thing across the crack for additional support just as the guys already said about a wire across the land pattern crack. Denis


JB Weld is great but somewhat conductive. Use a non-conductive epoxy.


Top
 Profile  
 
 Post subject: Re: How does a guy fix this?
PostPosted: May Wed 13, 2020 4:40 pm 
Member

Joined: Nov Tue 14, 2017 5:09 am
Posts: 2613
Location: Austin, Texas
Marcc wrote:
You can in addition drill either side of the crack into the track & make a copper wire pin like a staple that folds over on the back & that will also stop separation.

Marc


Is that what Greg was suggesting with the staple gun?
He just forgot to mention drilling the holes before shooting the staples.

Jay


Top
 Profile  
 
 Post subject: Re: How does a guy fix this?
PostPosted: May Wed 13, 2020 5:19 pm 
Member

Joined: Nov Tue 14, 2017 5:09 am
Posts: 2613
Location: Austin, Texas
This Sansui got a set of new 100W amps. Lots easier than repairing the originals that had about 100 parts per channel.
Attachment:
Sansui_R-50_New_Amps.JPG
Sansui_R-50_New_Amps.JPG [ 464.01 KiB | Viewed 594 times ]

Jay


Top
 Profile  
 
 Post subject: Re: How does a guy fix this?
PostPosted: May Wed 13, 2020 5:44 pm 
Member

Joined: Sep Tue 30, 2014 6:08 am
Posts: 5554
Location: Norfolk, VA
JnTX wrote:
This Sansui got a set of new 100W amps. Lots easier than repairing the originals that had about 100 parts per channel.

Jay


Smart move, given the number of counterfeit 2SA1102/2SA1104/2SA1106 and their complements out there. Sanken really missed out by not extending the production of those outputs. Gone by 1994.....

What are the amp chips? One day, I'll fix an old Realistic I've got with some of the LM3886 samples I got back in college.

_________________
Brian
"Capacitor Cosmetologist since 1979"
USN Retired 1984-2006 (Avionics/Cal)


Top
 Profile  
 
 Post subject: Re: How does a guy fix this?
PostPosted: May Wed 13, 2020 7:02 pm 
Member

Joined: Nov Tue 14, 2017 5:09 am
Posts: 2613
Location: Austin, Texas
Findm-Keepm wrote:
What are the amp chips? One day, I'll fix an old Realistic I've got with some of the LM3886 samples I got back in college.


These boards use a TDA7293. It's one of the few chips designed for high voltage and will take up to +/-60V power. The board has 50V caps so best to use with supplies in the 30 to 45V range. The Sansui has +/-45V supplies so the boards are a good match. The boards can take AC or DC input.

Here's one supplier. Two boards for $15.
https://www.ebay.com/itm/TDA7293-85W-Au ... 3464647535

The 33V max is AC voltage input. That produces a DC level of about 45 volts on the board.

Jay


Top
 Profile  
 
 Post subject: Re: How does a guy fix this?
PostPosted: May Wed 13, 2020 10:19 pm 
Member
User avatar

Joined: Dec Wed 23, 2015 3:03 am
Posts: 1027
Location: Northwest Indiana 46350
Here is the repair. :D

Attachment:
IMG_1145.JPG
IMG_1145.JPG [ 167.89 KiB | Viewed 521 times ]


Attachment:
IMG_1146.JPG
IMG_1146.JPG [ 232.74 KiB | Viewed 521 times ]


Attachment:
IMG_1147.JPG
IMG_1147.JPG [ 240.26 KiB | Viewed 521 times ]


Attachment:
IMG_1148.JPG
IMG_1148.JPG [ 172.03 KiB | Viewed 521 times ]

_________________
"It's amazing what you can accomplish when you throw safety out the window", Brent Butt


Top
 Profile  
 
 Post subject: Re: How does a guy fix this?
PostPosted: May Wed 13, 2020 10:40 pm 
Member

Joined: Nov Tue 14, 2017 5:09 am
Posts: 2613
Location: Austin, Texas
Looks good. Don't forget to solder those switch contacts to the copper on the board. The ones that use the rivets to connect through the board are the most likely to have intermittent connection.

Jay


Top
 Profile  
 
 Post subject: Re: How does a guy fix this?
PostPosted: May Wed 13, 2020 11:02 pm 
Member
User avatar

Joined: Jul Tue 15, 2008 6:13 pm
Posts: 7738
Location: Gretna, Nebraska
Good job, T.
Looks like you are ready to roll.

_________________
http://www.vintagerestorationservices.com
Paul
...... how hard can it be?


Top
 Profile  
 
 Post subject: Re: How does a guy fix this?
PostPosted: May Thu 14, 2020 12:55 am 
Moderator
User avatar

Joined: Feb Sun 01, 2009 2:56 pm
Posts: 11126
Location: Victoria, Australia
Basically what I had in mind; so good job. The idea of the bolt was so as it was not just reliant on the glue. Don't know what the black stuff is, but keeping solvent away from the new Epoxy resin, I would at a minimum, clean it off the rivets, even considering a small wire brush: Before soldering those rivets.

Marc


Top
 Profile  
 
 Post subject: Re: How does a guy fix this?
PostPosted: May Thu 14, 2020 1:24 am 
Member
User avatar

Joined: Jan Tue 31, 2012 1:55 am
Posts: 12768
Location: Mountains of Mourne. Ireland.
Well I never... :shock:

I guess whoever removed my posting of the stapler has never made a clinched-staple repair of a broken conductor.

Image


Maybe someone complained. lol
Greg.


Top
 Profile  
 
Post New Topic Post Reply  [ 26 posts ]  Moderators: Marcc, Norm Leal Go to page 1, 2  Next

All times are UTC [ DST ]


Who is online

Users browsing this forum: AJJ, Googergeiger, Tom Albrecht, Torino351 and 12 guests



Search for:
Jump to:  


































-->


Privacy Policy :: Powered by phpBB