Problems with my $75 DK Jr monitor.

cwales

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I picked up a DK Jr for $75 today and the monitor turns on for a second then goes off. I tested power in the jack it plugs into, tested fuses, everything seems ok. Every time you turn it on you hear it for just a second, then nothing.

It's the normal Sanyo monitor that's in these Nintendo machines.
Any ideas?
 
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Most plausible cause is HV shutdown - check b+
Check both fuses on monitor chassis - typically if small fuse is blown either a bad HOT and/or flyback
Ensure ground plug is present on AC cord
Also plan on doing a cap kit ;)

Most people don't know these monitors require a 100V transformer. They will plug them directly into the wall and destroy them. Hope that's not your case.
 
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Most people don't know these monitors require a 100V transformer. They will plug them directly into the wall and destroy them. Hope that's not your case.

You know.. when I first went to look at it a couple days ago, the guy was saying something about plugging it directly into the wall to test it and I said I wasn't sure that was a good idea. And it was staying on when I first looked it it but with no picture or sound. I didn't try it again when I went to pick it up.
 
Aww man that just sucks.
Order a cap kit
Order a new HOT
Order a new flyback.
Then lastly pray nothing else is burned up.
Or send it to chad@arcadecup and let him figure it out.
 
Most plausible cause is HV shutdown - check b+
Check both fuses on monitor chassis - typically if small fuse is blown either a bad HOT and/or flyback
Ensure ground plug is present on AC cord
Also plan on doing a cap kit ;)

Most people don't know these monitors require a 100V transformer. They will plug them directly into the wall and destroy them. Hope that's not your case.

So if he did do that, what would it do? Is it reparable?

There is no ground on the ac cord. Would that really cause this?

The fuses are good.
 
Aww man that just sucks.
Order a cap kit
Order a new HOT
Order a new flyback.
Then lastly pray nothing else is burned up.
Or send it to chad@arcadecup and let him figure it out.

I don't mind replacing all that stuff, I would have done the caps anyhow. But I'd hate to do all that and still have it dead :/
 
Deluxe cap kit w/audio kit.
H.O.T.
B+ Filter Cap
Voltage regulator

"If" it did get plugged directly into the wall, you'll want to check the entire power supply section out real good. (rectifier diodes and such)
 
Deluxe cap kit w/audio kit.
H.O.T.
B+ Filter Cap
Voltage regulator

"If" it did get plugged directly into the wall, you'll want to check the entire power supply section out real good. (rectifier diodes and such)

I don't know for sure if it did but he was talking about it, I didn't know it was such a bad idea so I didn't warn him strongly and he was mumbling about how it'd be worth more if the monitor came on.

Looking at Bob Roberts' page, what voltage regulator will I need?

LM7805CV Voltage Regulator +5 volt $1.00
LM7809CV Voltage Regulator +9 volt $1.00
LM7812CV Voltage Regulator +12 volt $1.00
LM7815CV Voltage Regulator +15 volt $1.00
LM7818CV Voltage Regulator +18 volt $1.00
LM7824CV Voltage Regulator +24 volt $1.00
LM7905CV Voltage Regulator -5 volt $1.00
LM7912CV Voltage Regulator -12 volt $1.00
LM7915CV Voltage Regulator -15 volt $1.00
LM7918CV Voltage Regulator -18 volt $1.00
LM7924CV Voltage Regulator -24 volt $1.00
 
I don't know for sure if it did but he was talking about it, I didn't know it was such a bad idea so I didn't warn him strongly and he was mumbling about how it'd be worth more if the monitor came on.

Looking at Bob Roberts' page, what voltage regulator will I need?

LM7805CV Voltage Regulator +5 volt $1.00
LM7809CV Voltage Regulator +9 volt $1.00
LM7812CV Voltage Regulator +12 volt $1.00
LM7815CV Voltage Regulator +15 volt $1.00
LM7818CV Voltage Regulator +18 volt $1.00
LM7824CV Voltage Regulator +24 volt $1.00
LM7905CV Voltage Regulator -5 volt $1.00
LM7912CV Voltage Regulator -12 volt $1.00
LM7915CV Voltage Regulator -15 volt $1.00
LM7918CV Voltage Regulator -18 volt $1.00
LM7924CV Voltage Regulator -24 volt $1.00

None of the above, those are standard +/- voltage regulators.
You need a LA5112N I think they're around $9.00.
 
Reviving an old thread here. I got around to working on this monitor and replaced everything besides the flyback so far. I have an issue now where it blows the fuse by where the power comes in if the monitor is plugged in. It didn't do this before.

What could cause this?


Thank you.
 
Where are those located?

Thanks.

On the monitor chassis, on the corner opposite the flyback, if I remember correctly. In any event, the should be right near the fuse - they're next in the circuit. Been a few months since I had one on the bench. Last time I replaced these, I bought the replacements at Radio Shack, I think they're 3A diodes, but don't quote me on that. I remember being incredibly amazed that Radio Shack had the nerve to sell RECTIFIER diodes in packages of THREE...

-Ian
 
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Keep working your way through the circuit. You're looking for something that's short-circuit. Check through the whole power supply. Double check to make sure you didn't short anything out when you were replacing parts or bridge any traces. Check for caps in backwards. Check to make sure that 2SD1090 is good, etc.

-Ian
 
I tried a test to make sure it was the monitor and not something else, I plugged it into my DK cab and it blew the fuse. So it's for sure in the monitor.

I'm pretty sure I didn't short anything out. After every cap I do i carefully inspect it for polarity and any bridging. I will pull it and check a third time tomorrow.

It wasn't blowing the fuse before I worked on it so it does seem like I messed something up, but I really didn't see anything in what I did. Before it was dead totally, I don't know. I'm getting pretty frustrated with this thing.

I guess I will irritate myself more with it tomorrow :)
 
OK... I took it apart again. I actually found a point that wasn't soldered very well on the sound board. I cleaned it off, re-soldered it now the main power fuse does not blow. The first time I powered it up though there was kind of a buzzing noise, not very loud, then a flash.. The fuse on the monitor blew, the bigger one that's near where the power comes in.

Ideas? :)

Or is everyone as sick of commenting on this as I am trying to fix it?

Could it be the flyback? I didn't change that as Bob Roberts does not have them.. I do see them for like $45 elsewhere. :/

Should that be my next step?
 
Here's the underlying problem. If a Sanyo comes on, then shuts off, there's no reason to replace the flyback and the HOT and most of the stuff everybody else told you to replace. The first thing to do would be try a capkit, mainly because there's a couple caps in the B+ section that could have been the problem. After that, if it was still doing the same thing, you could check the B+ and it could possibly be a voltage regulator issue.

Now that you've switched out all that stuff, you've got suspect all of THAT as well now.

Here's a good thread Dokert started that you should bookmark.

http://forums.arcade-museum.com/showthread.php?t=111041

If you do decide you need a flyback now (I would think if your diodes are good, you've got a bad HOT or Flyback... since you replaced the HOT, if it's still testing good, it's probably your flyback)... if you decide to get a flyback, a good place is chad at Arcade Cup.

www.ArcadeCup.com .

Good luck man, let us know how far down that flow chart you get.
 
It wasn't coming on at all before replacing everything, cap kit included..

After that ,it was coming on and blowing the PS fuse, but I seem to have fixed that.

Now it's blowing F302.. I did pull and test all the diodes as it states on that flowchart, they all test perfect so I'm stumped. According to the chart, the other fuse should blow if it's the flyback, but I'm running out of things to replace :)

I don't really know much about HOTs, I did see the thread on testing them. I get 0.000. Is that bad? Seems bad to me :/ Or does that just mean it's open = good?
 
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