M6496 17" Studio Display CRT makes a sparking noise then the picture comes on and off

[rockyhill]

I recently purchased 17" Apple Studio Display CRT monitor model M6496. I plugged it into my latops' VGA port and powered it on.
An image of my desktop began to appear but then disappeared as it made a clicking sound. The image kept flashing on and off as it clicked.

The click sounds like a high voltage spark which leads me to believe it's related to the flyback transformer. I carefully removed the plastic housing and then the EMI shield to look for sparks in the dark. To my surprise the monitor works while disassembled with an occasional click and a slight picture jump. I haven't seen any sparks nor can I see bad solder joints at the flyback pins. My fear is that the flyback is internally shorting.

Has anyone experienced this before and more importantly has anyone been able to find a solution?

 

[paru]

I have a M6496 as well and have the same problem except that it sparks only once or twice a day. I've figured out a few things so far: 1) it could be a static charge build up, as evidenced by the almost-consistent spark every 6-8 hours in my case, and also, if i degauss/power down the monitor within the timeframe it stops sparking. 2) it could be something related to the power supply, as the image blacks out for a second if i connect another item to the power strip and my other crt monitors don't. I've also tried slightly varying the humidity in the room but haven't found any conclusive evidence that it might be the environment. Funny thing, it just sparked now after an hour of use with the window open during wet weather. Anyways, I've been considering hauling it to a tv repair shop and let them figure it out, but I'll do that when I've got the time and money.

 

[rockyhill]

I have a M6496 as well and have the same problem except that it sparks only once or twice a day. I've figured out a few things so far: 1) it could be a static charge build up, as evidenced by the almost-consistent spark every 6-8 hours in my case, and also, if i degauss/power down the monitor within the timeframe it stops sparking. 2) it could be something related to the power supply, as the image blacks out for a second if i connect another item to the power strip and my other crt monitors don't. I've also tried slightly varying the humidity in the room but haven't found any conclusive evidence that it might be the environment. Funny thing, it just sparked now after an hour of use with the window open during wet weather. Anyways, I've been considering hauling it to a tv repair shop and let them figure it out, but I'll do that when I've got the time and money.

You've just given me some interesting thing to try out.

I hadn't though about degaussing and adding a load to the same power outlet, good idea.
Hopefully it's something cheap and readily available that I can buy and replace.

Thanks for the input!

 

[bd129]

• Have you checked the transformer insulation with a meter? A low voltage test won't be the most effective, but it's better than nothing.
• What condition are the big electrolytics in?
• Have you asked over on the EEVBlog Forums?

Also, obligatory don't poke at High Voltage stuff unless you know it has fully discharged and you know what you're doing...

 

[rockyhill]

• Have you checked the transformer insulation with a meter? A low voltage test won't be the most effective, but it's better than nothing.
• What condition are the big electrolytics in?
• Have you asked over on the EEVBlog Forums?

Also, obligatory don't poke at High Voltage stuff unless you know it has fully discharged and you know what you're doing...

Thanks for the input!

I haven't checked the transformer insulation with a meter and on the surface the capacitors look good, I don't see any bulging or leakage.

I try to be careful when I'm working around high voltage but I have been shocked more than once in the past......

I have not tried to ask in the EEVBlog forum, I'll give a try.

Thanks!

 

[Alexis Trinquet]

Sorry for upbringing this thread from the dead, and I hate to be the bearer of bad news but unfortunately these monitors are notorious for faulty flyback transformers.

The ticking you're hearing is HV arcing out, in some cases it's due to contamination (by either conducive dust or some kind of greasy compound) on the anode cap (the big suction cup at the top of the CRT) or in more severe cases the arcing is internal to the flyback itself.

I don't remember very well the specifics (never dug that further on the matter, I don't really have access to one of these units) but the consensus seems to point at either finding a compatible FBT or harvesting one that hasn't yet failed on another dead M6496 (rumor has it that some were recalled and had new FBTs swapped in).

 

[rockyhill]

Sorry for upbringing this thread from the dead, and I hate to be the bearer of bad news but unfortunately these monitors are notorious for faulty flyback transformers.

The ticking you're hearing is HV arcing out, in some cases it's due to contamination (by either conducive dust or some kind of greasy compound) on the anode cap (the big suction cup at the top of the CRT) or in more severe cases the arcing is internal to the flyback itself.

I don't remember very well the specifics (never dug that further on the matter, I don't really have access to one of these units) but the consensus seems to point at either finding a compatible FBT or harvesting one that hasn't yet failed on another dead M6496 (rumor has it that some were recalled and had new FBTs swapped in).

Hi Alexis and thanks for the input.

I've pretty much accepted that the flyback is failing so I am currently on the hunt for a flyback that isn't too expensive.
I recently bought a monitor board with a flyback but they are not the same so the search continues.......

thanks

 

[swamprock]

One more thing to check: the solder joints on the flyback. If you have the chassis out of the monitor, look underneath the flyback while gently rocking the flyback back and forth, and see if the pins move at all. Also look for any rings around the pins in the solder. The fact that it worked while disassembled may give a clue that board flex plus cracked solder joints may be causing your issues.

I assume that you know all of the safety steps required while working with high voltage. Getting bit while it's off is one thing (and doesn't really bother me anymore), but while on? I still have the scar on my right hand where the anode cup fell off and landed on it over 20 years ago. Ouch. Luckily, it was my right hand, and low-amp DC voltage...

Sorry for upbringing this thread from the dead, and I hate to be the bearer of bad news but unfortunately these monitors are notorious for faulty flyback transformers.

The ticking you're hearing is HV arcing out, in some cases it's due to contamination (by either conducive dust or some kind of greasy compound) on the anode cap (the big suction cup at the top of the CRT) or in more severe cases the arcing is internal to the flyback itself.

I don't remember very well the specifics (never dug that further on the matter, I don't really have access to one of these units) but the consensus seems to point at either finding a compatible FBT or harvesting one that hasn't yet failed on another dead M6496 (rumor has it that some were recalled and had new FBTs swapped in).

I heard that it was due to moisture contamination, during manufacture, in the earlier flyback units. After so many hours, the windings would just corrode and short. An old flyback/yoke ring tester is a good tool to have if you work with CRTs, and nowadays, they're very cheap.

 

[rockyhill]

One more thing to check: the solder joints on the flyback. If you have the chassis out of the monitor, look underneath the flyback while gently rocking the flyback back and forth, and see if the pins move at all. Also look for any rings around the pins in the solder. The fact that it worked while disassembled may give a clue that board flex plus cracked solder joints may be causing your issues.

I assume that you know all of the safety steps required while working with high voltage. Getting bit while it's off is one thing (and doesn't really bother me anymore), but while on? I still have the scar on my right hand where the anode cup fell off and landed on it over 20 years ago. Ouch. Luckily, it was my right hand, and low-amp DC voltage...



I heard that it was due to moisture contamination, during manufacture, in the earlier flyback units. After so many hours, the windings would just corrode and short. An old flyback/yoke ring tester is a good tool to have if you work with CRTs, and nowadays, they're very cheap.

Wow, I'm sure you wear your scar as a badge of honor! I do have respect for the high voltage being generated so thanks for the safety tip.

I have looked at the solder on the board and it looks pretty solid but I know that isn't fool proff soI'll have to come with a safe way of flexing the board while it's on.


I've never used a flyback tester but you're right, they are pretty cheap. I might just go ahead and buy one.

Thanks!

 

[swamprock]

Wow, I'm sure you wear your scar as a badge of honor! I do have respect for the high voltage being generated so thanks for the safety tip.

I have looked at the solder on the board and it looks pretty solid but I know that isn't fool proff soI'll have to come with a safe way of flexing the board while it's on.


I've never used a flyback tester but you're right, they are pretty cheap. I might just go ahead and buy one.

Thanks!

More like a badge of stupidity. I still feel like a dolt when I think of the simple step I could have taken to avoid that from happening (you know, like making sure the damn thing is clipped on!).

Check the caps and other board-through soldered components on the board for cold solder joints as well. It might be a cap or regulator that might have broken loose. Take your multimeter and check that the voltage regulators and any other transistor with a heat sink is isolated from the sink itself, as heat and time can cause the insulator to fail and short them to the heat sink.

 

[rockyhill]

More like a badge of stupidity. I still feel like a dolt when I think of the simple step I could have taken to avoid that from happening (you know, like making sure the damn thing is clipped on!).

Check the caps and other board-through soldered components on the board for cold solder joints as well. It might be a cap or regulator that might have broken loose. Take your multimeter and check that the voltage regulators and any other transistor with a heat sink is isolated from the sink itself, as heat and time can cause the insulator to fail and short them to the heat sink.

I poked and prodded and went over a bunch of solder points but still the same issue. Luckily I found a new replacement
flyback for about $60.00 so I ordered it and it should be here sometime next week. Last night I removed the flyback and the process was a lot cleaner than I anticipated so great.
Fingers crossed.

 

[rockyhill]

I just received a replacement flyback but the footprint is a little different that the original. I messaged the seller
to see if he can provide any more info because the documentation is sparse..... If anyone has seen this before it would be great to hear what you think.

Below is the message I sent and a picture.

"The item seems like it's new and it looks like it is mostly pin compatible with my old flyback.
I realize that replacement parts are sometimes manufactured in a universal configuration in order to fit many models and I think that is the case here however, before I install the part I want to make sure I can do what I think I need to do.

I've included a picture with the new flyback on the left and the old flyback on the right.
-The new flyback has two extra pins on the bottom left that do not line up with any vias on the circuit board, can I cut these pins?
-There are two missng pins that I've labeled Pins A & B. On the circuit board I see that a trace shorts PINS A & B to PIN C.
I'm assuming that it is o.k. to ignore these as they are probably shorted on the inside of transformer."

 

[rockyhill]

Here are two more pictures of what the flyback looks like.

 

[Alexis Trinquet]

Hi again and again sorry for the topic bump, but I've found some information about possible replacement parts. (meant to post this since a while but real life got in the way, yadda yadda nothing really interesting anyways)


But first, to me it looks like that "pin A" is just a orientation thingy, doesn't seem to serve any purpose other than prevent you from inserting it in the wrong way, although that theory doesn't seem likely given the layout of the pins.


Second, I found out there's a company (HR Diemen) that make replacement flybacks, and they happen to have two that might be a correct match for the M6496:

- HR 46162
- HR 46323

Now, getting ahold of one of these seems to be a tricky affair.. I haven't searched if they also have replacement FBTs for the 21" monitor.

I'm just putting this out there for reference, feel free to correct me if I'm wrong.

 

[rockyhill]

Thanks for that, I'll check it out.


Thanks!

 

[rileyjud]

Apologies for the bump, but has anyone resolved this issue? I recently came into two of these 17" Blueberry monitors myself and one of them just went. Occasional popping and screen dimming turned to frequent, until it finally just blew today. Would be really appreciative if anyone has any insight into a replacement.

 

[rockyhill]

No problem,

The situation with these monitors seems to be the fly-back transformer. I searched and searched and could only find
one replacement flyback that was designed to fir several model boards. Unfortunately the flyback I bought was not compatible and after installation and powering it on........ Lets just say it was a loud lightshow.

 

[yakult121]

Sorry to hear about the "lightshow". Any ideas if the FBT can be remanufactured?