Patches and discussion for Ensoniq VFX family

...sorry to add yet another post on this problem, but I could use 
some advice from VFX veterans. I recently picked up a VFX with the 
calibration error thinking I could fix it, but it's a bit more tricky 
than I thought.

It looks as though the hard-wired repair has been attempted in the 
past, but not very well. It seemed to me that the original connector 
looked as if it had 12 wires going across, but only 11 new 
connections had been made. It looked as if only a single join had 
been made across the top two; as if the top connection points on each 
side were linked, if you see what I mean. A large blob of solder on 
each side joined them together.

I cleaned the solder off to investigate, but it appeared to me that 
these points were indeed originally joined on the circuit board, so I 
thought maybe they knew what they were doing after all. 

But looking at the help sheet in the Files sections, it seems that 
you do indeed have to make 12 connections. It's not very clear from 
the picture exactly where they are though. Can someone confirm that 
there are twelve individual separate points on each side that have to 
be bridged...? Or is there a single point on one side going to two 
points on the other side at the top of the board, or what...? 

(Apologies if this is unclear - I'm a soldering newbie so I don't 
know the technical terms.)

Thanks!

Ben

b_j_glover wrote:

> the picture exactly where they are though. Can someone confirm that 
> there are twelve individual separate points on each side that have to 
> be bridged...? Or is there a single point on one side going to two 
> points on the other side at the top of the board, or what...? 

With multi-layer boards, whenever you've got a hole through the board, 
all the layers are interconnected.  This used to be done by pressing a 
copper rivet into place but is now more commonly done by plating the 
inside of the hole.

If the board has been badly overheated when the original connector was 
removed, it's possible that the through-hole plating has been ripped 
out.  This is Not A Good Thing.  Fortunately the boards in the VFX are 
(as far as I can tell) only double-sided - some more complex boards have 
copper tracks sandwiched inside the fibreglass, which is built up in 
layers - so it's easy to repair.

With a suitable soldering iron (a little 15W pointy one, not some 
whacking great thing that you use to solder the battery terminals on 
your car) and a solder sucker, carefully clean up all the pads.  Then 
cut little wire links to join the board halves.  Trim the insulation 
back about 6mm (1/4") from the ends, twist it up and tin it - this is 
very important if you want the joint to be mechanically good as well as 
electrically good!  Now feed the tinned end of the wire through the 
hole, leaving a little bare bit on the top side of the PCB.  Solder the 
wire to both sides of the PCB, just in case the through-hole plating is 
gone.

If you find that one of the pads has been ripped off, you'll probably 
see where the trace leads back from the edge of the board to whatever 
it's supposed to connect.  If that happens, run a wire from the nearest 
pad along that trace that's still good, to the next board.

Once you're done, check *very* carefully to make sure that all the 
joints are good, and that there are no stray wires or blobs of solder 
shorting out any pins.  It's worth checking the whole board over, just 
to be sure.

I recommend that you get some scrap PCB to practice soldering and 
desoldering on, and be prepared to burn your fingers and ruin some 
components while you're learning!  If you're not comfortable with the 
fine work needed to do this (it's not *that* bad but if the smallest 
thing you've soldered is a 1/4" jack then it's pretty tiny) then I 
suggest you get someone with more soldering experience to help you. 
There are lots of articles on the Internet that will show you how to 
solder, and what constitutes a good or bad solder joint.  Keep 
practicing and before long it will be as easy as writing your name.

Gordon

Thanks for the advice. What I'm planning to do is create the 12 
connections across the back of the board, as shown in the "VFX Cal 
Error Repair" document in the files section:

http://f1.grp.yahoofs.com/v1/MIkqSdiPWBaEZD0ruTF8BSM6fG-
NDq96QzI2CPFPmNjmoM7_5ojS1QhYq-IYq4Ry-dPLXTHKfRoY4VR111bNUpKoT3QL--
Y/Tools%20and%20service/Poly%20board%20separation%20fix/VFX%20Cal%
20Error%20Repair.pdf

But my problem is that I can't tell from the illustration what's 
going on at the top of the picture. On my VFX, it looks as though the 
connection points on at least one side (left or right) are joined 
together on the PCB itself at the top. The top two on each side are 
certainly joined by a blob of solder at the moment, and I'm wondering 
if they do indeed need to be separated. (I'm only talking about one 
surface here.)

Thanks

Ben


--- In Ensoniq-VFX-SD@yahoogroups.com, Gordon JC Pearce MM3YEQ 
<gordon@...> wrote:
>
> b_j_glover wrote:
> 
> > the picture exactly where they are though. Can someone confirm 
that 
> > there are twelve individual separate points on each side that 
have to 
> > be bridged...? Or is there a single point on one side going to 
two 
> > points on the other side at the top of the board, or what...? 
> 
> With multi-layer boards, whenever you've got a hole through the 
board, 
> all the layers are interconnected.  This used to be done by 
pressing a 
> copper rivet into place but is now more commonly done by plating 
the 
> inside of the hole.
> 
> If the board has been badly overheated when the original connector 
was 
> removed, it's possible that the through-hole plating has been 
ripped 
> out.  This is Not A Good Thing.  Fortunately the boards in the VFX 
are 
> (as far as I can tell) only double-sided - some more complex boards 
have 
> copper tracks sandwiched inside the fibreglass, which is built up 
in 
> layers - so it's easy to repair.
> 
> With a suitable soldering iron (a little 15W pointy one, not some 
> whacking great thing that you use to solder the battery terminals 
on 
> your car) and a solder sucker, carefully clean up all the pads.  
Then 
> cut little wire links to join the board halves.  Trim the 
insulation 
> back about 6mm (1/4") from the ends, twist it up and tin it - this 
is 
> very important if you want the joint to be mechanically good as 
well as 
> electrically good!  Now feed the tinned end of the wire through the 
> hole, leaving a little bare bit on the top side of the PCB.  Solder 
the 
> wire to both sides of the PCB, just in case the through-hole 
plating is 
> gone.
> 
> If you find that one of the pads has been ripped off, you'll 
probably 
> see where the trace leads back from the edge of the board to 
whatever 
> it's supposed to connect.  If that happens, run a wire from the 
nearest 
> pad along that trace that's still good, to the next board.
> 
> Once you're done, check *very* carefully to make sure that all the 
> joints are good, and that there are no stray wires or blobs of 
solder 
> shorting out any pins.  It's worth checking the whole board over, 
just 
> to be sure.
> 
> I recommend that you get some scrap PCB to practice soldering and 
> desoldering on, and be prepared to burn your fingers and ruin some 
> components while you're learning!  If you're not comfortable with 
the 
> fine work needed to do this (it's not *that* bad but if the 
smallest 
> thing you've soldered is a 1/4" jack then it's pretty tiny) then I 
> suggest you get someone with more soldering experience to help you. 
> There are lots of articles on the Internet that will show you how 
to 

> solder, and what constitutes a good or bad solder joint.  Keep 
> practicing and before long it will be as easy as writing your name.
> 
> Gordon
>

b_j_glover wrote:
> Thanks for the advice. What I'm planning to do is create the 12 
> connections across the back of the board, as shown in the "VFX Cal 
> Error Repair" document in the files section:
> 
> http://f1.grp.yahoofs.com/v1/MIkqSdiPWBaEZD0ruTF8BSM6fG-
> NDq96QzI2CPFPmNjmoM7_5ojS1QhYq-IYq4Ry-dPLXTHKfRoY4VR111bNUpKoT3QL--
> Y/Tools%20and%20service/Poly%20board%20separation%20fix/VFX%20Cal%
> 20Error%20Repair.pdf
> 
> But my problem is that I can't tell from the illustration what's 
> going on at the top of the picture. On my VFX, it looks as though the 
> connection points on at least one side (left or right) are joined 
> together on the PCB itself at the top. The top two on each side are 
> certainly joined by a blob of solder at the moment, and I'm wondering 
> if they do indeed need to be separated. (I'm only talking about one 
> surface here.)
>

I can only count 11 wires on that diagram.  I can't get at my VFX to 
take it apart at the moment, but perhaps someone else can wade in here. 
  When I checked my old VFX-SD the job had already been done so I closed 
it up without thinking any more about it, and that was around eight 
years ago.

Gordon

...yep, that's partly why I was confused, because the text 
says: "Solder in 12 wire connections" but it's hard to see more than 
11. It looked like maybe there might be a couple of wires attached to a 
single point at the top-right. And the original connector seems to have 
12 struts. Curse those JPEG artifacts...!

Ben


> I can only count 11 wires on that diagram.

b_j_glover wrote:
> ...yep, that's partly why I was confused, because the text 
> says: "Solder in 12 wire connections" but it's hard to see more than 
> 11. It looked like maybe there might be a couple of wires attached to a 
> single point at the top-right. And the original connector seems to have 
> 12 struts. Curse those JPEG artifacts...!
> 

It's possible that it's a ground or power connector, so two have been 
used for a higher current capacity.

Can you get a good high-res photo of your boards?

Gordon

Aha! Many thanks Hans. If you saw the state of my VFX you'd realise why 
I was in a muddle...;)

Thankss--- In Ensoniq-VFX-SD@yahoogroups.com, "Hans Artmann" <hans-
artmann@...> wrote:

>
> I apologize for the poor jpeg quality and for the mistake I made.
> It's indeed only 11 wire connections.
>  
> Hans
>