....and others wot know about Roland keyboards/power supply boards again.

Here's some piccies... http://photobucket.com/gytha_ogg

Anything there identifiable as a potential reset-causer?

Si

Mungo "Two Sheds" Toadfoot wrote:
...and others wot know about Roland keyboards/power supply boards
again.
Here's some piccies... http://photobucket.com/gytha_ogg

Anything there identifiable as a potential reset-causer?


Oh, in picture 2 there's what I assume to be a cap that's covered in some
kind of plastic. I'm also assuming it's covered because it's next to the
transformer and might get hot? If so I suppose it's fairly likely it could
have failed, but how to tell?

Si

"Mungo "Two Sheds" Toadfoot" wrote in message
...
...and others wot know about Roland keyboards/power supply boards again.

Here's some piccies... http://photobucket.com/gytha_ogg

Anything there identifiable as a potential reset-causer?

Si



Post some close ups of the solder side so dry joints can be spotted.

"Mungo "Two Sheds" Toadfoot" wrote in message
...
Mungo "Two Sheds" Toadfoot wrote:
...and others wot know about Roland keyboards/power supply boards
again.
Here's some piccies... http://photobucket.com/gytha_ogg

Anything there identifiable as a potential reset-causer?


Oh, in picture 2 there's what I assume to be a cap that's covered in some
kind of plastic. I'm also assuming it's covered because it's next to the
transformer and might get hot? If so I suppose it's fairly likely it could
have failed, but how to tell?

The one next to R17? in pic 4 looks more interesting.
There doesn't appear to be a need to put resin on them but there looks like
there may be some.

In article ,
"Mungo \"Two Sheds\" Toadfoot" writes:
...and others wot know about Roland keyboards/power supply boards again.

Here's some piccies... http://photobucket.com/gytha_ogg

Anything there identifiable as a potential reset-causer?

In picture 2, at the back, there's a component lead just
visible with some charring of the circuit board. In
picture 3, it looks like a 180ohm resistor, but the leads
and board aren't visible. That could be a thermal/dry joint
candidate.

Need to see the underside of the board for any charring
and quality of the soldering.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

In article ,
(Andrew Gabriel) writes:
In article ,
"Mungo \"Two Sheds\" Toadfoot" writes:
...and others wot know about Roland keyboards/power supply boards again.

Here's some piccies... http://photobucket.com/gytha_ogg

Anything there identifiable as a potential reset-causer?

In picture 2, at the back, there's a component lead just
visible with some charring of the circuit board. In
picture 3, it looks like a 180ohm resistor, but the leads
and board aren't visible. That could be a thermal/dry joint
candidate.

I missed picture 9 first time - It's R14, and it does look
like the board might be charred around it or the transistor
on the heatsink next to it (BD ?43B).

Need to see the underside of the board for any charring
and quality of the soldering.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

dennis@home wrote:
"Mungo "Two Sheds" Toadfoot" wrote in
message ...
Mungo "Two Sheds" Toadfoot wrote:
...and others wot know about Roland keyboards/power supply boards
again.
Here's some piccies... http://photobucket.com/gytha_ogg

Anything there identifiable as a potential reset-causer?


Oh, in picture 2 there's what I assume to be a cap that's covered in
some kind of plastic. I'm also assuming it's covered because it's
next to the transformer and might get hot? If so I suppose it's
fairly likely it could have failed, but how to tell?

The one next to R17? in pic 4 looks more interesting.
There doesn't appear to be a need to put resin on them but there
looks like there may be some.

This squidgy-looking black thing here, next to the brown cap.

http://s478.photobucket.com/albums/rr149/gytha_ogg/?action=view&current=Project2.jpg

Si

Andrew Gabriel wrote:
In article ,
"Mungo \"Two Sheds\" Toadfoot" writes:
...and others wot know about Roland keyboards/power supply boards
again.

Here's some piccies... http://photobucket.com/gytha_ogg

Anything there identifiable as a potential reset-causer?

In picture 2, at the back, there's a component lead just
visible with some charring of the circuit board. In
picture 3, it looks like a 180ohm resistor, but the leads
and board aren't visible. That could be a thermal/dry joint
candidate.

Need to see the underside of the board for any charring
and quality of the soldering.

It must be very difficult diagnosing faults from photos

No, there's no charring on the board at all, despite appearances from my
not-good photos. I've re-soldered everything which looks even slightly
suspect underneath, even though there was nothing at all which made me think
"That's the problem". I sucked all the old solder off the joints and re-made
them at the correct temperature, i.e. the new solder flowed properly.

Thing is, I've seen dodgy joints, burnt boards and damaged components in the
past so I do have an *idea* of what to look out for, but I've no clue how
circuit boards work so I'm unable to look at a component and know that it
could cause the problem. They're Italian boards too. Great.

I'll take some underside pics soon, just in case I've missed something.

Si

In article ,
"Mungo \"Two Sheds\" Toadfoot" writes:
dennis@home wrote:
"Mungo "Two Sheds" Toadfoot" wrote in
message ...
Mungo "Two Sheds" Toadfoot wrote:
...and others wot know about Roland keyboards/power supply boards
again.
Here's some piccies... http://photobucket.com/gytha_ogg

Anything there identifiable as a potential reset-causer?


Oh, in picture 2 there's what I assume to be a cap that's covered in
some kind of plastic. I'm also assuming it's covered because it's
next to the transformer and might get hot? If so I suppose it's
fairly likely it could have failed, but how to tell?

The one next to R17? in pic 4 looks more interesting.
There doesn't appear to be a need to put resin on them but there
looks like there may be some.

This squidgy-looking black thing here, next to the brown cap.

http://s478.photobucket.com/albums/rr149/gytha_ogg/?action=view&current=Project2.jpg

Looks like a shrink wrapped component, probably an inductor
where the shrink wrap would be keeping it wound.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

"Mungo "Two Sheds" Toadfoot" wrote in message
...
dennis@home wrote:
"Mungo "Two Sheds" Toadfoot" wrote in
message ...
Mungo "Two Sheds" Toadfoot wrote:
...and others wot know about Roland keyboards/power supply boards
again.
Here's some piccies... http://photobucket.com/gytha_ogg

Anything there identifiable as a potential reset-causer?


Oh, in picture 2 there's what I assume to be a cap that's covered in
some kind of plastic. I'm also assuming it's covered because it's
next to the transformer and might get hot? If so I suppose it's
fairly likely it could have failed, but how to tell?

The one next to R17? in pic 4 looks more interesting.
There doesn't appear to be a need to put resin on them but there
looks like there may be some.

This squidgy-looking black thing here, next to the brown cap.

http://s478.photobucket.com/albums/rr149/gytha_ogg/?action=view&current=Project2.jpg

Si

Nope.
Its bottom center of
http://s478.photobucket.com/albums/r...t=Project4.jpg

In front of the two electrolytics.

It may just be something that has dripped on the components but its hard to
see.

dennis@home wrote:

Nope.
Its bottom center of
http://s478.photobucket.com/albums/r...t=Project4.jpg

In front of the two electrolytics.

It may just be something that has dripped on the components but its
hard to see.

Ah right. No, that just looks like some kind of varnish. They're not as
"lumpy" as they look.

Si

In message , "Mungo \"Two
Sheds\" Toadfoot" writes
...and others wot know about Roland keyboards/power supply boards again.

Here's some piccies... http://photobucket.com/gytha_ogg

Anything there identifiable as a potential reset-causer?

Si


Yes. In project3.jpg I'd suspect the leftmost brown capacitor inside the
aluminium heatsink but if I suspected on I'd change them all. They're
cheap enough that I'd consider the time taken to remove and test them
all more expensive than the cost of the parts. Basically, that heatsink
is an oven for cooking capacitors.

In project2.jpg the heat-shrink covered part to the left of the obvious
capacitor is also likely to be an electrolytic capacitor as well but
check the board designation.

In project9.jpg be very wary of everything to the left of the yellow
covered transformer, that's the non isolated side and it will bite you
if there's charge left or it's plugged in.

I take it from your e-mail address that you're not in the north-west?
--
Clint Sharp

Clint Sharp wrote:
In message , "Mungo \"Two
Sheds\" Toadfoot" writes
...and others wot know about Roland keyboards/power supply boards
again. Here's some piccies... http://photobucket.com/gytha_ogg

Anything there identifiable as a potential reset-causer?

Si


Yes. In project3.jpg I'd suspect the leftmost brown capacitor inside
the aluminium heatsink but if I suspected on I'd change them all.
They're cheap enough that I'd consider the time taken to remove and
test them all more expensive than the cost of the parts. Basically,
that heatsink is an oven for cooking capacitors.

In project2.jpg the heat-shrink covered part to the left of the
obvious capacitor is also likely to be an electrolytic capacitor as
well but check the board designation.

In project9.jpg be very wary of everything to the left of the yellow
covered transformer, that's the non isolated side and it will bite you
if there's charge left or it's plugged in.

Thanks, Clint. I'll see about making another list of capacitors and then
find out what Maplins has to offer. There used to be a good components shop
in Ramsgate but he went yonks ago. As I recall it was the big 'uns that I
had trouble finding.


I take it from your e-mail address that you're not in the north-west?

Heh. About as far from the North-East as you can get without drowning.

Thanks again for your help.

Si

Mungo "Two Sheds" Toadfoot wrote:

Heh. About as far from the North-East as you can get without drowning.


....And the NW too, obviously.

*Slaps head*

Si

In message , "Mungo \"Two
Sheds\" Toadfoot" writes
Thanks, Clint. I'll see about making another list of capacitors and then
find out what Maplins has to offer. There used to be a good components shop
in Ramsgate but he went yonks ago. As I recall it was the big 'uns that I
had trouble finding.
Forget Maplin, use either Farnell or RS, both will deal with private
individuals. Farnell have a minimum order which may make them too
expensive unless you can find other stuff to buy, if you have a local RS
trade counter go and open an account (it's a paperwork exercise if
you're going to pay with cash or a card) and they'll post on anything
they don't have in stock for free.

www.farnell.co.uk
rswww.com

Make up a list of the caps and I'll translate into part numbers if you
like. The dimensions of the larger capacitors would be useful.



I take it from your e-mail address that you're not in the north-west?

Heh. About as far from the North-East as you can get without drowning.


Thanks again for your help.

Si



--
Clint Sharp

Clint Sharp wrote:

Make up a list of the caps and I'll translate into part numbers if you
like. The dimensions of the larger capacitors would be useful.


I've ordered them all from a nice chap (hopefully) on ebay now. The
resistors are being a bit of a nuisance though. I thought I'd replace the
bigger ones, just in case, and they are whoppers. One's [finds resistor
calculator because forgotten value] 220 ohms but about an inch long. Seems
there's lots of 1/4w ones about. No idea what wattage this one is! How do
you tell?

Si

In message , "Mungo \"Two
Sheds\" Toadfoot" writes
I thought I'd replace the
bigger ones, just in case, and they are whoppers.
Probably no need to replace the resistors if the PSU is working, a
simple multimeter check will tell you if a resistor's faulty or not in
almost every case.

One's [finds resistor
calculator because forgotten value] 220 ohms but about an inch long. Seems
there's lots of
1/4w ones about. No idea what wattage this one is! How do
you tell?
Experience generally although you can (simplistically) calculate the
wattage required by measuring the voltage across it then dividing
voltage squared by resistance. Round up to the nearest standard wattage.
I suspect that the 220R one you mean isn't original though if it's the
one near the heatsink. Looks 'wrong' to me.

Si



--
Clint Sharp

Clint Sharp wrote:
In message , "Mungo \"Two
Sheds\" Toadfoot" writes
I thought I'd replace the
bigger ones, just in case, and they are whoppers.
Probably no need to replace the resistors if the PSU is working, a
simple multimeter check will tell you if a resistor's faulty or not in
almost every case.


Well, it's working so they can stay then. The caps though, are going.
They're old anyway so I'm thinking that years of heat cycling can't have
been good for their general health. The metal of the keyboard frame under
the PSU is quite discoloured through, I'm assuming, heat. I wonder if it
would like a little fan in there?

Si