Main > Monitor/Video Forum
WG K7000 dead... flyback? (SOLVED)
buffett:
Awesome, glad you found the part.
the PACE is a great tool to have.
look ALL over the chassis to see if you have any more cold solder.
the K7000 has a problem with it.
even if it does not seem like it needs solder, ADD some any way, it will not hurt.
pull D10 and see what you get.
let us know.
email me if you need any other advice or parts.
Peace
Buffett
MKFan4Life:
--- Quote from: buffett on October 15, 2016, 01:48:18 am ---Awesome, glad you found the part.
the PACE is a great tool to have.
look ALL over the chassis to see if you have any more cold solder.
the K7000 has a problem with it.
even if it does not seem like it needs solder, ADD some any way, it will not hurt.
pull D10 and see what you get.
let us know.
email me if you need any other advice or parts.
Peace
Buffett
--- End quote ---
I know this is an INCREDIBLY old thread, but came back to this old machine and the problem with it's monitor after a few more years, lol. Been SO MANY things happening in my life since I had time to work on my arcade machines, but I'd like to keep all of this in one thread since it pertains to the same monitor and it's repair.
WELL, when we last left this K7000, it was in high voltage shutdown. I had replaced the flyback, (at the time it had been recapped a few years beforehand), and I had done a reflow. After Buffet and a few others had helped me along, I was ready to pull D10 to see if it would fire up. Well, a day ago I did that, and what do you know! It is working! So I turned it off after a brief check of the B+ on R301. I got a reading of around 167V on one side and about 154V on the other side.
I assume it needs a new voltage regulator, IC4, (from everyone's advice and flowcharts I've seen), and I have that part ready to install. I did check it in circuit, and I observed one short between I think the 3rd and 4th legs of that IC, STR30130.
The problem holding me up now is that I damaged the zener diode D10. I am generally extremely careful, but at the factory, they covered half of D10 with glue where they had sloppily coated the pot to adjust the HV shutdown circuit. I burned away a bit of the glue and thought I had the diode loose, but as I was pulling one leg up that was desoldered, it broke in two.
Can anyone tell me the specs for that diode D10? I appreciate it. And mods, if I need to start a new thread, I will. Just thought this was a continuation of the original repair, but I can edit this to point to a new post or something, in case someone digs this thread up and it ends abruptly.
Thank you.
EDIT: Just saw QRZ earlier said it is a 10V Zener for D10. Anyone have full specs? (Current/Power, Etc.)
grantspain:
On a k7000 d10 is not a zener, its a 1N914b - you could use a 1N4148
MKFan4Life:
--- Quote from: grantspain on May 03, 2020, 03:02:19 am ---On a k7000 d10 is not a zener, its a 1N914b - you could use a 1N4148
--- End quote ---
Thank you! This is definitely not what I was previously told. Found the schematic for the K7000 series and I see, as you state, the symbol for D10 is not a Zener, and the value I was told was wrong. I think there was confusion between D12 and D10, as D12 is indeed a Zener and at 10V.
Funny thing is, I have come across a 1990 article where Randy Fromm states to do the leg-lifting trick with D12 on this K7000 series, but I constantly hear (and SEE on his K7000 flowchart) to do this with D10. Oh, here's a link to the 1990 article: https://www.epanorama.net/sff/Video/Products/Servicing/Video_Servicing_-_Troubleshooting_Horizontal_Deflection_Failures.pdf
Upon looking at the schematic, I guess either would work, as D10 looks like the input voltage and D12 looks like the output (connected to the wiper of the pot for shutdown). So kill the input OR the output, and you kill the circuit, right?
???
grantspain:
D10 will disable xray protection, not sure if doing the same to D12 would have the same affect