Rag-time4's Duo repair project

[kattare]

Yikes, I hope the reverse polarity on that one cap didn't cause more damage.  If you powered it on with the polarity reversed there's a 90% chance that cap is bad now tho.  You're lucky it didn't blow up on you.  ;-)  You'll want to snag a new one and try again I think.

[rag-time4]

I've installed new 47uf caps, but I'm getting the same symptom: solid color screen with audio hum.

I notice that if I insert a HuCard, I can see some scrolling on screen. There is a horizontal section slightly darker than the rest which scrolls upward.

[D-Lite]

I've installed new 47uf caps, but I'm getting the same symptom: solid color screen with audio hum.

I notice that if I insert a HuCard, I can see some scrolling on screen. There is a horizontal section slightly darker than the rest which scrolls upward.

Does it change with HuCard?  All the indications are you've got a short somewhere.

[rag-time4]

I've installed new 47uf caps, but I'm getting the same symptom: solid color screen with audio hum.

I notice that if I insert a HuCard, I can see some scrolling on screen. There is a horizontal section slightly darker than the rest which scrolls upward.

Does it change with HuCard?  All the indications are you've got a short somewhere.

Dean, the change is only slight. With or without hucard I get a solid color screen with an audio hum. The only change is that with a HuCard, there is a slight scroll in the video. It's like there is a horizontal bar that is slightly darker than the rest of the screen. The dark part scrolls upwards. With no HuCard, there is no scroll.

[kattare]

I hate to say it, but you may have to go through and pull out your caps, test 'em, check the board out, and re-install 'em.  Not that I think a bunch of 'em are bad, but I think your board may need an inspection for shorts and/or cuts/breaks.

[rag-time4]

I hate to say it, but you may have to go through and pull out your caps, test 'em, check the board out, and re-install 'em.  Not that I think a bunch of 'em are bad, but I think your board may need an inspection for shorts and/or cuts/breaks.

Kattre, I think you're right. I pulled 3 caps near the sound amp, but I'm gonna stop here and send the Duo over to chop before I cause any more damage. Hopefully he can get it back up and running.

[Duo_R]

The new 10uf cap should only affect your sound circuit, that shouldn't be causing the no screen issue. however, you do want that cap correctly installed. Once technique I used when I first did this install and lifted the solder pad was I passed through the cap legs through to the bottom of the Duo PCB, and on the underside I reconnected that cap to pad that traced and was more easier to solder to. Take a look on the underside and see if you can find a point like that.
                ____
                |    |   <--- 10 uf Cap
                |__ | 
                 |   | <--- Cap leg
     =========|=========== <--- PCB
                     
                     /\
                      l
                      l
              Apply Solder Here
 
So you would apply the solder on the underside when the cap leg passes through a small hole (usually where the original cap passed through)

[rag-time4]

The new 10uf cap should only affect your sound circuit, that shouldn't be causing the no screen issue. however, you do want that cap correctly installed. Once technique I used when I first did this install and lifted the solder pad was I passed through the cap legs through to the bottom of the Duo PCB, and on the underside I reconnected that cap to pad that traced and was more easier to solder to. Take a look on the underside and see if you can find a point like that.
                ____
                |    |   <--- 10 uf Cap
                |__ | 
                 |   | <--- Cap leg
     =========|=========== <--- PCB
                    
                     /\
                      l
                      l
              Apply Solder Here
 
So you would apply the solder on the underside when the cap leg passes through a small hole (usually where the original cap passed through)

I got that 10uf cap through the proper holes... but the soldering got a bit messy. In the process of working in that area I may have damaged traces as well.

[Necromancer]

I got that 10uf cap through the proper holes... but the soldering got a bit messy. In the process of working in that area I may have damaged traces as well.

Stop!!  This is the e-police!  Put down the soldering iron and step away from the PCB. 

It's a bit too late for your Duo-R, but you (and anyone else with a similar lack of experience) might be better served by practicing your soldering skills on a few junk PCBs before risking damage to something good.

[D-Lite]

I got that 10uf cap through the proper holes... but the soldering got a bit messy. In the process of working in that area I may have damaged traces as well.

Stop!!  This is the e-police!  Put down the soldering iron and step away from the PCB. 

It's a bit too late for your Duo-R, but you (and anyone else with a similar lack of experience) might be better served by practicing your soldering skills on a few junk PCBs before risking damage to something good.

I've been cringing through this thread as well.

[kattare]

Heh, I gotta give the guy credit for tryin' tho.  How many other folks just throw away stuff like this?

[DragonmasterDan]

Heh, I gotta give the guy credit for tryin' tho.  How many other folks just throw away stuff like this?

I ruined a Turbo Express (it wasn't lighting up anyway) and several game gears trying to soder.

[D-Lite]

Heh, I gotta give the guy credit for tryin' tho.  How many other folks just throw away stuff like this?

Oh, I agree.  Still makes me queezy.

[rag-time4]

I got that 10uf cap through the proper holes... but the soldering got a bit messy. In the process of working in that area I may have damaged traces as well.

Stop!!  This is the e-police!  Put down the soldering iron and step away from the PCB. 

It's a bit too late for your Duo-R, but you (and anyone else with a similar lack of experience) might be better served by practicing your soldering skills on a few junk PCBs before risking damage to something good.

Chop told me to practice soldering on junk boards.... Unfortunately I don't have a lot of junk boards laying around. I think I got a lot out of the experience.... now hopefully my Duo can be salvaged!!

[Duo_R]

Part sale! Part sale!