Magnavox 27MS5402/17 CRT - no picture, flashing green light

[sudz28]

I'm going to assume my beloved Magnavox CRT is toast, but also figured maybe this was a good opportunity to dip my toes into he circuitry waters and maybe learn something new. Also, I don't want to trash it if it's a fairly cheap/easy fix!

My 20-year-old Magnavox has gotten me and my kids through many a gaming console change and worked great up until the other day. Following a long distance move, it sat in our garage for a year and now that I brought it in and turned it on I get no picture; instead, a green light blinks on the front of it; 7 flashes, one long flash, then 3 more flashes, and another long flash. After that the pattern repeats. I have no service manual or anything to decode what these flashes may mean, and no experience with troubleshooting tv's or really electronics in general to begin with. Any chance someone here is at least passingly familiar enough with these to either day "Oh yeah, the entire thing is not worth savings, sorry for your loss!" or "Oh that is almost certainly just a bad capacitor or a broken solder joint - check <here> for an issue!"?
Many thanks for any assistance!

[R_J]

Re: Magnavox 27MS5402/17 CRT - no picture, flashing green light

What voltages have you checked so far? Did you download the service manual for this tv? if not start with that: https://www.manualslib.com/manual/69...s-A02u-Aa.html

7 flash = Under-voltage protection
3 flash = +8V error (missing/protection active by checking MPIF ASUP bit)
Check the standby +11 volts, this might be low.

[nomoresonys]

Re: Magnavox 27MS5402/17 CRT - no picture, flashing green light

If you can't fix it, check craigslist they give crt tvs away pretty much daily.

[sudz28]

Re: Magnavox 27MS5402/17 CRT - no picture, flashing green light

What voltages have you checked so far? Did you download the service manual for this tv? if not start with that: https://www.manualslib.com/manual/69...s-A02u-Aa.html

7 flash = Under-voltage protection
3 flash = +8V error (missing/protection active by checking MPIF ASUP bit)
Check the standby +11 volts, this might be low.

Thank you, I had been trying to find something online that would tell me what the green flashes meant; I assumed they were a specific code that a service person would know, but I wasn't sure how to go about divining them.

So on Sunday I had taken the back off thing to look for 'obvious' problems (not really sure what I was looking for, but figured if I saw something on fire that would be bad) and cleaned off circuitry as best I could with qtips and rubbing alcohol; it still wouldn't work, so I figured it was a bigger issue. Tonight I power it back on just to double-check the light sequences and what do you know but that it's working again! I have no clue how or why, it still wasn't working after my 'cleaning' I gave it on Sunday, but it seems to have come back to life. At least for now.

To answer your specific question, I hadn't checked for any voltages yet because although I own a multimeter, I haven't used it for anything more than checking car and riding mower batteries and have no idea how I'd go about checking anything on this set. This was what I was hoping to get guidance on, but it seems that now I don't have to?

[dskall]

Re: Magnavox 27MS5402/17 CRT - no picture, flashing green light

Sounds like a capacitor issue. Electronics that sit around can have problems when restarting.

[sudz28]

Re: Magnavox 27MS5402/17 CRT - no picture, flashing green light

Sounds like a capacitor issue. Electronics that sit around can have problems when restarting.

Based on this, I'm guessing then that going forward sometimes the set may turn on just fine and other times it may not? Or are you saying the fact that it sat around for a year could be why it had a hard time firing up initially, but now that it's working it should be good to go from now on? Hmmmm, maybe it's worth taking the back off again and doing what I can to check the capacitors better.

[dskall]

Re: Magnavox 27MS5402/17 CRT - no picture, flashing green light

Electrolytic capacitors lose their insulating properties over time. And have to be reformed to work. Applying power to them reforms the insulation unless to much is lost. In which case they will short out and be permanently damaged. They may have only been leaky and caused a problem until they reformed their insulating properties. Capacitors are about the only component that has an operational lifetime.