RedBox repair

[Ken1]

Hi all!

I've just signed up in the forum and it really has alots of info.
I hope I don't violate any rules by asking this, and I am not sure this topic
fits in here .. but here goes:

I couple of years ago I had this "incident" while jammin´ something went up in smoke
hehehe ... I dove in behind my rack and found a "steamy" H&K RedBox MKII ...nedless
to say I pulled it out of the mixerboard and ran to the garden door and "threw an homerun" with it





*grin* I didn't even know something like that could happend with something that only ran on a battery
(yep.. you have probably figured it out, I don't know much about electronics and such .. but I can
toy around with my soldering iron and fix stuff if I only know which part goes were)

Well when I've calmed down and the thing stopped smoking, I took it apart and I could see which part
that burned out. At that time I just gave up ... but now the other day I found it, and I would really like to repair it
and make it work again.

I cannot identify components on my own, cause all those numbers and dohickies doesn't mean jack to me,
and the little thing that went up in smoke has just 2 small "legs standing up from the board ..heheheh"
but there is another that may be the same thing besides it.

Sorry about the long description:
I was thinking if I took real good pictures of the board, is there anyone that could be kind enough
to try to help me to identify the piece that is broken, and maybe hint me to what I might want to buy
extra in case there are other particulary fragile components in the proximity.

I've searched for a board layout for it, and found something but the problem is that I don't understand which
is what .. just numbers and frightening lines .. hehehe

you all have a good one and thanks for taking the time to read this post

//Ken1

[zpyder]

Ken-

Take a pic of the board and post it and someone here should be able to point you in the right direction.  If the thing is burnt to a crisp no one may be able to read the numbers off of it, but that may or may not be a big deal... depends on what it is.  Probably a capacitor I'd guess, since those guys are known for burning up.  But capacitors generally only pop if they recieve the wrong direction of voltage, so if it's a burnt cap it's possible that some other part of your circuit failed - maybe a diode - and caused the cap to pop.

post a pic

zpyder

[Peter Snowberg]

Welcome to the forum, Ken.

If you can post a picture of the board, there's a good chance someone here can come up with an answer. If you don't have a site to host the image(s) on, I would suggest http://www.photobucket.com/

Best of luck with the debug.

[Ken1]

Thanks Guys!!

I really appreciate it ..

will post the pictures asap ..

have a good one
//Ken1

[Gilles C]

Here is the schematic:



I have pictures of the pcb somewhere.

Gilles

[Gilles C]

Agrrr... I hate it when it let me modify a post, and then says I can't because of the elapsed time. 


Ok, here are a couple of the underside of the pcb:





I don't have a picture of the components side, but these should help you to figure it out.

Gilles

[Ken1]

Thanks for helping me, I wasn't aware of the last post so I have prepared some pictures.

5 pictures showing the circuit board and the damage and have some description on it as well

http://www.kh-interworks.com/redbox/redbox1.jpg
http://www.kh-interworks.com/redbox/redbox2.jpg
http://www.kh-interworks.com/redbox/redbox3.jpg
http://www.kh-interworks.com/redbox/redbox4.jpg
http://www.kh-interworks.com/redbox/redbox5.jpg

thanks for checking this out

//Ken1

[aron]

Agrrr... I hate it when it let me modify a post, and then says I can't because of the elapsed time.

How much time is reasonable? How about 30 minutes?

[aron]

pic 3 and 5 really show it.

I wonder if it was a tantalum capacitor that went up in smoke?

I think it's a 22uF tantalum. Also check junction of R17 and R18 for 4.5V. D1 might be no good as well.

[slacker]

I'd agree with that, it looks like the component was connected between pins 4 and 11 of the opamp which would be +9 and ground, so I'd guess it was the 22uF cap. Don't know how it blew though, the other tant looks like it'is rated at 16 volts so the battery couldn't have overvolted it. I suppose it could of shorted out on something.

[zpyder]

Without having traced the circuit myself, but looking at the carnage and looking at the schematic, I would certainly think that the 22uF caps are likely suspects.  Either C13 or C14... My guess as to why it blew would be, as aron said, that D1 shorted.  It doesn't make much sense to me, however, that this would happen unless you were using an adapter rather than a battery and you said you were using a battery... So...

Ken1-
What was powering this thing when it blew?

zpyder

[Gilles C]

Agrrr... I hate it when it let me modify a post, and then says I can't because of the elapsed time.

How much time is reasonable? How about 30 minutes?

I didn't noticed at what time it is set-up right now, but 30 min would be better indeed. What I found the most annoying as I said is to to be able to edit the post, but not being able to save it.

About the Red Box, what is connected to a console with the 48V Phantom supply? That would explain the smoke more than the 9V battery.

But after looking at the damage again, the damage looks to be on the 9V. Strange.

Gilles

[Paul Marossy]

About the Red Box, what is connected to a console with the 48V Phantom supply? That would explain the smoke more than the 9V battery.

+1 

[Ken1]

Thanks for all the help!!

It was run on a regular battery, and it was just plugged into the back of my mixer,
and I used it for maybe 7-8 month or so without any problems ..
and all of a sudden that happened .. and I hadn't tampered/rewired/moved anythign at all
it just went up in smoke..

Now those things you are refering too

----quote from zpyder --
I would certainly think that the 22uF caps are likely suspects.  Either C13 or C14... My guess as to why it blew would be, as aron said, that D1 shorted.  It doesn't make much sense to me, however, that this would happen unless you were using an adapter rather than a battery and you said you were using a battery... So... ---

it goes over my head, is there a place where I can order these things? because if I just order components I am not smart enough to know if I got the right stuff ... so I could potentially make a mess ... but if I know I have the right components I can surely solder it on..

could someone please help me find those products ? (they have to be shipped to sweden, but I reccon that wount be a problem)

thanks again..

have a good one

//Ken1

[George Giblet]

Here's an overlay for the RB2 (following Gilles C's numbering),

http://www.geocities.com/george_giblet/effects/redbox2_overlay.jpg

The dead part appears to be C13; R17 and maybe C3 don't look that great either.

When you replace C13 you need to get the polarity correct.  Hopefully I got that right.

[zpyder]

Check out SmallBear at www.smallbearelec.com

Steve there sells all sorts of components intended for DIY pedals...

Looks like you're going to want:

1x 22uF Tantalum Capacitor: http://www.smallbearelec.com/Detail.bok?no=561 (this is C13)
1x 10k Resistor: http://www.smallbearelec.com/Detail.bok?no=268 (this is R17)

Hopefully that's it.  Other components around the burn look kinda bad too, as George Giblet said.  C3 looks a little crispy and unfortunately so does your IC, but IC's might hold up pretty well, I'm not sure.

NOTE: Tantalum capacitors MUST be put in one way and not the other.  Most tantalums are marked with a + sign.  This side MUST go toward the positive voltage, and the other side MUST go toward ground.

zpyder


PS.  Anybody confused like me???  Looks like D1 is going to block all 9v from the supply!?

[Gilles C]

....PS.  Anybody confused like me???  Looks like D1 is going to block all 9v from the supply!?

The 9V battery is supplying +9V to the circuit through the diode D1, and the jack for an external supply seems to just disconnect the battery (red wire), and connect the supply where the battery was connected before. I just realised I forgot to add the jack for the external supply in the schematic.

Here's an overlay for the RB2 (following Gilles C's numbering),....

Cool! I didn't have time to do it, and was sure I already did it before, but couldn't find any trace of that on my PC...

Gilles

[Gilles C]

I just found them in a renamed directory... sorry 

http://www.gtechblues.com/images/RedBox_parts1.jpg

http://www.gtechblues.com/images/RedBox_parts2.jpg

Gilles

[Paul Marossy]

Tantalum capacitors MUST be put in one way and not the other.  Most tantalums are marked with a + sign.  This side MUST go toward the positive voltage, and the other side MUST go toward ground.

Yep. Tantalum caps are extremely sensitive to polarity. A polarity reversal more than maybe a few seconds will certainly damage them, and if for an extended period of time, they will literally blow up!

[Ken1]

Check out SmallBear at www.smallbearelec.com

Steve there sells all sorts of components intended for DIY pedals...

Looks like you're going to want:

1x 22uF Tantalum Capacitor: http://www.smallbearelec.com/Detail.bok?no=561 (this is C13)
1x 10k Resistor: http://www.smallbearelec.com/Detail.bok?no=268 (this is R17)

Hopefully that's it.  Other components around the burn look kinda bad too, as George Giblet said.  C3 looks a little crispy and unfortunately so does your IC, but IC's might hold up pretty well, I'm not sure ........

zpyder

Thank you very much for guiding me to those components, since they are cheap I will get a couple of each ...
you also mention ... C3 .. and the IC ... are those hard to find items ?
wouldn't I might as well change those too ? since I'm ordering the parts from USA to sweden .. I would rather buy one component too many than find my self short when starting to repair it ..

Thanks again you all for your patience and support
//Ken1