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Vintage Synth Repair

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Desoldering / Resolderin IC's with no access to underside

Desoldering / Resolderin IC's with no access to underside

2009-03-07 by mrjdevries

I'm in the process of fixing up my semi working Delta Labs DL-4 delay, and making good progress.. I've fixed one fault (dying Tantalum)
and pretty much diagnosed another fault (Faulty 4011 CMOS).

My question is, with one of the PCB's, It's a total arse to get out etc.. too many jumpers etc.

This raised a small thought, if I cut out the old IC, and removed the remaining pins etc, and wanted to solder in an IC mount, do you think it would be possible to do it all with no access to the underside of the PCB?

I was thinking about getting one of those long wire wrap IC holders, cutting the legs a bit, and solder it with it's base a fraction above the PCB, and use the solder to 'wick' to the underside of the PCB.

Has anyone done this before? Any thoughts?

Regards
Mike

Desoldering / Resoldering IC's with no access to underside

2009-03-07 by Alan Probandt

Yes, soldering the leg of a wire-wrap IC socket should work.  Usually the through-holes of a PCB are plated in the area of the hole itself if the board has traces on both sides.  The new solder will alloy between the socket pin and the plating metal on the side of the hole.

  If the PCB is single-sided then this might not work. If the socket pin fills the hole then the melted solder will not flow around the socket pin and contact with the trace pad on the other side of the hole.  Applying too much heat with the soldering iron tip may cause the pad to lift from the fiberglass surface of the PCB.


--- On Sat, 3/7/09, mrjdevries <mrjdevries@...> wrote:
Show quoted textHide quoted text
> From: mrjdevries <mrjdevries@...>
> Subject: [vintagesynthrepair] Desoldering / Resolderin IC's with no access to underside
> To: vintagesynthrepair@yahoogroups.com
> Date: Saturday, March 7, 2009, 1:10 AM
> I'm in the process of fixing up my semi working Delta
> Labs DL-4 delay, and making good progress.. I've fixed
> one fault (dying Tantalum)
> and pretty much diagnosed another fault (Faulty 4011 CMOS).
> 
> My question is, with one of the PCB's, It's a total
> arse to get out etc.. too many jumpers etc.
> 
> This raised a small thought, if I cut out the old IC, and
> removed the remaining pins etc, and wanted to solder in an
> IC mount, do you think it would be possible to do it all
> with no access to the underside of the PCB?
> 
> I was thinking about getting one of those long wire wrap IC
> holders, cutting the legs a bit, and solder it with it's
> base a fraction above the PCB, and use the solder to
> 'wick' to the underside of the PCB.
> 
> Has anyone done this before? Any thoughts?
> 
> Regards
> Mike
> 
> 
> 
> ------------------------------------
> 
> Yahoo! Groups Links
> 
> 
>

Re: [vintagesynthrepair] Desoldering / Resolderin IC's with no access to underside

2009-03-07 by Philip

A bodge I've seen on many boards over the years is that you cut the old IC out leaving the legs there. Then solder the new IC's legs to the old IC's legs.
Phil.

--- On Sat, 7/3/09, mrjdevries wrote:
Show quoted textHide quoted text
From: mrjdevries
Subject: [vintagesynthrepair] Desoldering / Resolderin IC's with no access to underside
To: vintagesynthrepair@yahoogroups.com
Date: Saturday, 7 March, 2009, 9:10 AM

I'm in the process of fixing up my semi working Delta Labs DL-4 delay, and making good progress.. I've fixed one fault (dying Tantalum)
and pretty much diagnosed another fault (Faulty 4011 CMOS).

My question is, with one of the PCB's, It's a total arse to get out etc.. too many jumpers etc.

This raised a small thought, if I cut out the old IC, and removed the remaining pins etc, and wanted to solder in an IC mount, do you think it would be possible to do it all with no access to the underside of the PCB?

I was thinking about getting one of those long wire wrap IC holders, cutting the legs a bit, and solder it with it's base a fraction above the PCB, and use the solder to 'wick' to the underside of the PCB.

Has anyone done this before? Any thoughts?

Regards
Mike


Re: [vintagesynthrepair] Desoldering / Resolderin IC's with no access to underside

2009-03-07 by Mike de Vries

Yea, I'm thinking of doing this...
Also, the circuit board is double sided.
Thanks for your input!
Regards
Mike

--- On Sun, 8/3/09, Philip wrote:
Show quoted textHide quoted text

From: Philip
Subject: Re: [vintagesynthrepair] Desoldering / Resolderin IC's with no access to underside
To: vintagesynthrepair@yahoogroups.com
Received: Sunday, 8 March, 2009, 1:02 AM

A bodge I've seen on many boards over the years is that you cut the old IC out leaving the legs there. Then solder the new IC's legs to the old IC's legs.
Phil.

--- On Sat, 7/3/09, mrjdevries wrote:
From: mrjdevries
Subject: [vintagesynthrepair ] Desoldering / Resolderin IC's with no access to underside
To: vintagesynthrepair@ yahoogroups. com
Date: Saturday, 7 March, 2009, 9:10 AM

I'm in the process of fixing up my semi working Delta Labs DL-4 delay, and making good progress.. I've fixed one fault (dying Tantalum)
and pretty much diagnosed another fault (Faulty 4011 CMOS).

My question is, with one of the PCB's, It's a total arse to get out etc.. too many jumpers etc.

This raised a small thought, if I cut out the old IC, and removed the remaining pins etc, and wanted to solder in an IC mount, do you think it would be possible to do it all with no access to the underside of the PCB?

I was thinking about getting one of those long wire wrap IC holders, cutting the legs a bit, and solder it with it's base a fraction above the PCB, and use the solder to 'wick' to the underside of the PCB.

Has anyone done this before? Any thoughts?

Regards
Mike



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Help with keys not sounding

2009-03-08 by Don Sealer

I'm looking for some help, advice, or direction on what could be wrong with and how to fix, my Korg SGproX. Last night at a gig none of the G or C# keys sounded off. All the other keys worked fine.
Any suggestion or advice?
Thanks,
Don...........

Re: Help with keys not sounding

2009-03-08 by Scott

--- In vintagesynthrepair@yahoogroups.com, "Don Sealer" <vze2t273@...> wrote:
>
> I'm looking for some help, advice, or direction on what could be wrong with and how to fix, my Korg SGproX.  Last night at a gig none of the G or C# keys sounded off.  All the other keys worked fine.
> Any suggestion or advice?
> Thanks,
> Don...........
>
If thou wouldst dare to open the unit I wouldst check any cables ( flat or otherwise) coming from the keyboard assembly to the circuit boards. Disconnect any that you can and re-seat them.It could be just some oxide buildup in the contacts

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