Toshiba TIMM MM20E45 Vertical Deflection Help

[goldendark007]

Hey all..

I have a Toshiba TIMM MM20E45 that was gifted to me by a friend and I wanted to use it since it supports so many formats. The problem is.. the vertical deflection is shot. Very rarely, I can get the monitor to display an image before collapsing into a single horizontal line. I looked up the service manual here: https://www.manualslib.com/manual/71277 ... =45#manual and found the section on the vertical deflection circuit. I checked the area on the chassis but did not see any bulging capacitors or anything, so after watching a few YouTube videos I saw a method of restoring the image by replacing the vertical deflection IC. After looking in the service manual, I saw this diagram:



I assumed it was IC301 that needed to be replaced (the TA8427K). I replaced it and I still have the same problem. I am just now rereading this manual and wondering if the other chip, IC302 (TA8859AP), was what really needed to be replaced. According to the manual it is the vertical deflection sawtooth wave generator and amplifier. Before I delve any deeper into this, I wanted to reach out and see if anyone had any helping advice. I can take a picture of the area of the PCB where these chips are located when I get a chance.

Thanks

[buttersoft]

Failing caps rarely bulge, saving those produced during the great capacitor plague, i believe. Have you tested the ones in the vertical circuit? Or tried to look at the pulse coming to the yoke?

[goldendark007]

Failing caps rarely bulge, saving those produced during the great capacitor plague, i believe. Have you tested the ones in the vertical circuit? Or tried to look at the pulse coming to the yoke?

I have not testing anything yet - I jumped the gun after not seeing visible signs (ie: bulging caps) and just got a replacement IC301 (Vert. Out IC). I have since gone through the service manual and pulled these two figures out:



The bottom one (fig. 3) is handy in that it lists all of the components which I have compiled in this table here:


R303 C305 D301 L301 Q308
R304 C306 D308 L462 Q309
R305 C308 D309
R306 C309
R307 C311
R308 C312
R309 C313
R317 C314
R320 C319
R329 C321
R336 C332

IC301 TA8427K
IC302 TA8859AP

Are L301 and L461 inductors? Are Q308 and Q309 the Yoke connection points?

I will post pictures of the labeled solder joints on the bottom of the chassis pcb as soon as I get a chance but my plan of action was to reflow all of these components before removing anything. I have a multimeter but I am a novice with all of this and am not sure what I am checking for on the capacitors. If someone would be interested in helping/guiding me in the process - I am all ears. If not, I will look it up after fixing up the solder on all of the components. If anything in the table is incorrect please let me know. From my understanding, the two wires running to the yoke are the green and yellow. Would reflowing these possibly help? As I have mentioned, I already replace IC301 and I can have a new IC302 in the next week.

Thanks again!

[buttersoft]

From what you described about things stuttering, or having deflection and then it failing, reflowing is probably the best idea, now you mention it. Get a flux pen and give it a shot. If you have to start testing further, make sure there's power at various points with your multimeter. There's nothing above 100V in a vertical circuit, i don' think. But be careful, as that's enough to hurt, and the rest is more dangerous, even when it's powered down. Caps in the power supply can store a few hundred volts across them, for example. Safety is essential.

Maybe get a $10 transistor tester from eBay as well, one the tests capacitance and ESR as well. That will be able to test all the discrete components, caps, inductors, resistors, transistors, diodes, etc. You find the marked values of something, and then test it to see if they match.

The prefix Q typically denotes transistors in a circuit. L is for inductors/coils, though in this case i think L462 is the Yoke, which is itself an inductor of course, but it's a little bloody-minded not to identify it better. Then again the schematics were never meant for public consumption

[NJRoadfan]

Did you ever get this set back up and running? My own TIMM is having its own issues, but vertical deflection isn't one of them. A friend's TIMM IS having that problem though.

Best I can tell is my set may have a fault in the area LA7860 (ICH08) which is resulting in loss of sync. Could be bad caps or bad IC.

https://www.youtube.com/watch?v=KqdH2nx1DX8