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Hantarex MTC 9000 image squashed vertically
grantspain:
yeah all good
read r46 and r40
be77amyX:
R40 - 118.8kOhm
R46 - 2.1 Ohm
R46 says its 1% tolerance, 1.8Ohm so shouldn't be that far out of spec should it? but R46 on my donor board reads exactly the same..
grantspain:
check the value of all your caps on the vertical circuit
this sort of fault is extremely rare on 9000, tbh i have not seen this vertical issue except a bad ic once and i have repaired hundreds of these in last 30 odd years- this normally means its what someone has done to the chassis rather than failure
be77amyX:
I hear ya ;D, Checked the values of all the electrolytics on the board. they all match (higher voltage is OK right?). Gonna work my way through the rest of the components in that circuit now! considering getting a new IC1 because the one I've swapped in isn't proven!
Thanks for all this help btw! really appreciate you taking the time to help me out!
be77amyX:
Checked all the resistors around IC1 and they all have the correct values when read with a meter. Pulled c12 and c13 as that looks to be related to vertical linearity from the TDA 1670a drawing in the manual and tested them on the ESR meter and they both showed up as 50nF instead of 100!? swapped them out with ones from my donor board and ended up with the image squashed down to half the size in the center of the screen!
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So i replaced the caps with the ones I'd just removed to see if the fault returned to what it was before and now it looks like this!
V-Size fully one way
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V-Size fully the other way
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Unfortunately I damaged the donor caps removing them the second time so I've ordered replacement 100nF caps and a new TDA 1670a