Hi all, hope everyone is doing ok.

I've got a 2002 e-machine e-view 17s old stock CRT (with TECO tube in it , not Samsung) I bought back in December 2024. It worked fine with my retro 486 machine, but when I connected an AMD Athlon XP machine to it and changed the resolution to 1280x768 it worked for 10 minutes, then the picture started shrinking back and forth (with a sorta degaussing sound). I turned it off, connected back to my 486 but the effect was the same: collapsing and then restoring picture. I turned the monitor off. Waited for a while and then turned it on. The picture was gone. It looks like it's getting to the x-ray protection.
- The monitor is very clean inside (it was really a new old stock, so I was the first one who opened it)
- I checked the flyback by placing a small neon lamp against it and when I turn the monitor on the neon lamp glows for a second, I hear the energizing static sound, then neon lamp dims and the high voltage is gone.
- I measured HOT and I can say for sure there is no short between emitter and collector.
- I checked every electrolytic capacitor (in circuit) with GME ESR meter and all of them are just fine
- I checked the voltage regulator and it seems to be ok: the input voltage is showing 10v and the output is 5v. (I have no idea what actual voltage should be there since I didn't manage to find any schematic for it)
- I think I checked B+ (again no schematic) at a positive lead of the couple first filtering capacitor right after transformer output: one of those shows 57v (which is kinda low if it's B+ but I can't imagine what else can it be) and another one is 10v
- I discharged HV anode under the rubber cap ( I guess in this monitor it's not required really but I always do before doing anything) then removed the cap and made sure that it all clean under it (the monitor was sealed in a box and plastic when I bought it so it's very clean inside).
- when it presumably goes to x-ray protection there must be a zener diod somewhere. I found 4 of them on the PCB and couple of them is clearly linked with one of the flyback leads (must be the low voltage leg for x-ray protection I guess) and those zeners are connected to two different ICs (i have no idea what are those, but they don't look like oscillators, still zener might cut the HV by sending 5v to one of those ICs probably)

Now I'm puzzled. It looks like it's going to x-ray protection, but whatever I could guess I checked. Being not experienced in fixing CRTs (this is my third CRT I've opened in my life and the first not working) and not having schematic I'm stuck.
Maybe it's a flyback itself still causing it despite that it's trying to turn on, but something might short inside and this is causing it to shutdown. Maybe something else.

That presumably-B+'s 57v is a concern, but I'm not sure maybe for this monitor 57v for B+ is normal. I checked it when the monitor turns on and even before it shuts the HV down that presumably-B+ remains the same 57v.

I'm just hoping that maybe somebody here could give me a hint what to check next
or maybe someone knows where to get schematic for e-machine e-view crt monitor ?

P.S. But frankly I probably should just take it to the e-waste site and forget about it.

Thanks a lot for reading this,
Sincerely Yours, Eugene Kiselev

 

Overall, it is incredible that you could get a NOS monitor. Congratulations!

eMachines were not known by their top notch quality, so keep that in mind when considering the manufacturer's choice of parts. That said, the closing of the horizontal scan with the degaussing sound might be indeed due to a problem on this section of the circuit - caused either by the power supply to the flyback circuit (verifiable measuring supply voltages), or a flyback transformer shorting itself. Given the monitor is new and in excellent physical shape, there is a small chance that environmental factors (temperature, humidity) stressed the flyback transformer itself.

With an equipment of this age, naturally the suspicion falls in the aluminium electrolytic capacitors especially from the early 2000s where the capacitor plague was very active. From this standpoint, I would definitely remove each capacitor and test their rated value and ESR with a good capacitor tester and leakage with a power supply at or near its maximum rated voltage.

Another aspect are solder joints, especially around the high power and heavy parts (transistors, transformers, large capacitors). These are sometimes hard to spot but very safe to track (the monitor should be fully disconnected and its capacitors discharged).

Overall, this looks like an interesting project but indeed the absence of schematics complicates things. Did you try the badcaps forum? The folks there sometimes have schematics pulled from very hard-to-find places. Good luck in your endeavour.

 

Thank you, I managed to make it show a picture by simply turning it on and off: https://youtube.com/shorts/zkhhZDGjVCQ?si=Et_i0kitqRvQepNv but whatever it's showing is probably indicating the flyback failure: because the rest of it looks ok. I even unsoldered HOT and connected in a simple bulb to where collector goes with other lead connected to the frame to check steady B+ supply: 100w bulb glows with no flickering, so I assume PSU supplying B+ is fine (yeah kinda weird , but I just wanted to see if collector gets steady power). I double checked every single electrolytic capacitor in the circuit and their ESR shows fine. Also confirming the not top notch quality: I surprisingly easily lifted couple pads while was unsoldering transistors just by sucking up those pads along with a solder (when I use my desoldering gun I don't touch pads , I heat up the leads, still pads were lifted). I assumed that if some element is heating very badly then probably it managed to lift one of those pads, but I checked everything with a thermal camera and nothing is heating and there is not burning traces anywhere. (ok the power regulator converting 10v to 5v is warm like 36-40 Celsius, which is expected, I guess)
So I convinced myself this is flyback issue and decided to take this monitor to e-waste site this week.

 

forgot to mention that I posted on Acer's community forum (emachines CRTs were made by Acer) if anyone can find the emachines eview CRT schematics but of course nobody answered. Thanks for the hint about badcaps forum! I haven't found anything in there and I probably won't even register to ask, because I feel nobody has this schematic. Also considering absence of emachines eview 17s on ebay, these were either extremely rare or just of so bad quality so neither of them survived by today and I just happened to find one of the last NOS-es which rushed to the CRT Valhalla after the rest of its kind. Acer ... all we need to know

 

just in case anyone curious this is how I think I isolated flyback from PSU (using a 100w bulb I mentioned above) to measure volts: https://youtube.com/shorts/CzA3L1xxV4M?si=D26Wj148O42QBw_3 , there are three outputs in DC part of PSU: one which is ~57v I assume is B+, another one 12v is for deflection controller (TDA4857PS) which actually only gets Vcc of 10v somehow, not 12v. And 5 volts which are going to CPU with unknown origin with name "Sampo" on it.

 

From the video indeed these "teck-teck-teck" sounds seem to be originated around the flyback area - a possible premature failure originated in manufacturing or simply unfavourable storage conditions that severely reduced its lifespan.

Also confirming the not top notch quality: I surprisingly easily lifted couple pads while was unsoldering transistors just by sucking up those pads along with a solder (when I use my desoldering gun I don't touch pads , I heat up the leads, still pads were lifted). I assumed that if some element is heating very badly then probably it managed to lift one of those pads, but I checked everything with a thermal camera and nothing is heating and there is not burning traces anywhere. (ok the power regulator converting 10v to 5v is warm like 36-40 Celsius, which is expected, I guess)

Assuming you didn't overheat the pads using a torch , some low quality PCBs indeed have issues with the copper-substrate bonding, especially after years of use (not your case). I also have seen tracks with hairline cracks that were almost imperceptible, which can sometimes be found by slightly warping the board up or down - something not quite safe to do with the voltages employed in this equipment. BTW, the temperatures seen are more than normal for these types of parts.

And 5 volts which are going to CPU with unknown origin with name "Sampo" on it.

Sampo used to be a large IC contract manufacturer and had some branded products themselves. Being from Taiwan, it is understandable they would be largerly employed by these Taiwanese OEMs.

I know now all this is history now. May this monitor rest in peace.

 

Amen