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Blast City monitor (MS-2931) not turning on

They use the same flybacks as the 2930. Its the 2933 that uses a different flyback and a revised HV Control IC board similar to a Toshiba PF.

The flybacks like to die on these chassis's sometimes. The most ideal solution is send it to a pro maybe Sharp or PNL. They can verify the health of the flyback and other circuit blocks.
 
advans14 said:
No way to tell if its dead without proper diagnostic tools - ringer or the circuit being operational.
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Yeah you need to do a ring test to check for shorts between windings, you can also ohm out each winding to check for shorts in the same winding, and then ideally you want to load test the flyback too.

Most all of that requires special tools and experience.
 
GeekMan1222 said:
Man

Man this is some good troubleshooting tips right here.

Also chirping can sometimes generally be assumed as a power supply issues sometimes (at least to my understanding) The power supply is trying to cycle up and cant do it fully because of something in the power supply or something later down the line causing issues that cause the PSU to shutdown and restart if you will. (at least this is some of my understanding).

The 2930 and 2931 are alot different compared to many other monitor chassis's.
Nanao didnt truly revise most of the chassis until really the 2933 (a larger revision to the 2931) where they started using a different flyback and a different HV Regulation daughter board to go with that.

If your trying to get your hands dirty then first step is check your B+ voltage and HV (if you have the meter for that) tbh but if you get no neck glow and or cant hear the deflection running its likely entering a shutdown situation (of which theres a number of different reasons that can trigger)

Take the chassis out inspect for bad solders. The MS2930 I seen alot where they get some cold solder joints in the primary power supply and a few other areas. Touch up any bad solders.
You should check the HOT for shorts, and the Mosfet by the Flyback because the HOT alone does not drive the flyback on this chassis.
(would follow the steps moffet mentioned because isolating the HV and Horizontal Output Stages is a really good way to narrow stuff down (theres alot of stuff going on).

Best of luck.
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Thanks everyone for this! I purchased two last cities from revrun that "worked" only to have dead machines. Been recapping & testing components. Even purchased another 2930 chassis from eBay that was "tested working" but had blown fuses and a q901(701?) mosfet that has a short... I will have a working blast one day :).
 
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Damn. Sold working machines that went toast? We all know they are temperamental, but that is sad. No seller assistance?
 
bergalon said:
Thanks everyone for this! I purchased two last cities from revrun that "worked" only to have dead machines. Been recapping & testing components. Even purchased another 2930 chassis from eBay that was "tested working" but had blown fuses and a q901(701?) mosfet that has a short... I will have a working blast one day :).
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Damn. Mine is also from Revrun.
 
mmmmaerk said:
Damn. Mine is also from Revrun.
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Yeah he sent pics of it working and then my wife (as an anniversary present!) drove the 800 miles to get them and neither worked at all. Unplugged the ballast on one and got a game playing but both the 2930 and 2931 (with wrong chassis) are dead (although one showed a moment of life). Bummer dude.
 
I called a different repair guy, thankfully this guy understands that I want to keep the original monitor. He said if I get a new flyback he can clean up the chassis, install the flyback, and hook it all back up. I was thinking of buying this flyback:

https://www.ebay.com/itm/2249748399...uid=nTp_8b1jQBq&widget_ver=artemis&media=COPY

If you think I should avoid the local guys and just send it to Sharp/PNL I can look into that. About Revrun, he sold quite a few Blasts here, right? He didn't seem shady when I talked to him (he helped me with some issues over a video call the day my Blast arrived) but 3 bad Blasts seems pretty crazy.
 
mmmmaerk said:
I called a different repair guy, thankfully this guy understands that I want to keep the original monitor. He said if I get a new flyback he can clean up the chassis, install the flyback, and hook it all back up. I was thinking of buying this flyback:

https://www.ebay.com/itm/2249748399...uid=nTp_8b1jQBq&widget_ver=artemis&media=COPY

If you think I should avoid the local guys and just send it to Sharp/PNL I can look into that.
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The flyback isn't the only thing that can go bad on this chassis. Worst case scenario, a malfunctioning chassis can even break your tube (PSA). That's the last thing you want.

Send it to Sharp, they have a known track record of getting this chassis up and running again.
 
nem said:
The flyback isn't the only thing that can go bad on this chassis. Worst case scenario, a malfunctioning chassis can even break your tube (PSA). That's the last thing you want.

Send it to Sharp, they have a known track record of getting this chassis up and running again.
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The issue with them killing the tube is quite unfortunate, however thankfully, not super common and the Toshiba D29 PF monitors can also have this happen I think.
I always wondered if maybe its some absolute catastrophic byproduct scenario of when the chassis is shutting down due to an out of control HV spike because of a failure in the flyback or HV generation blocks and in a really off chance the chassis just cant switch off fast enough to prevent the Anode voltage from arc'ing back to the neck internally. But im no expert.

Sharp is the people you want to send it to. At least thats who I have used.
 
advans14 said:
those flyback work fine. just research the threads on here before buying.
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Yep what @nem said send it to Enrique at Sharp. Pray that you don’t need a fly back. Those replacement eBay ones are junk. Pray that you have neck glow as again @nem is right sometimes they fry tubes when they go. I’m a ms2934 guy now I have a backup ms2931 and a modded 2932 but I’m good on using the 2931. Ive sent 4 chassis to sharp and they have done great work imo. Local guys know less than me but more when it comes to K7000s and domestics. I would never take my stuff to anyone local. We have experts now with years of experience.
 
It arrived today and I hooked it back up. It clicks while powered on and I get no picture on the monitor. I can see the neck board flashing as it clicks. I've never hooked a chassis back up so there's certainly a chance I did it wrong. For what it's worth, here are some pictures I took of it inside the Blast.
 

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Yep, pull the rings and yoke, you'll find the crack. Happened to one of my FW900s a bit ago (but they're kinda known for it).
 
Is it reasonable to look for a replacement tube? I assume they cost a ton to ship. This entire Blast endeavor has been a disaster :S
 
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