68kMLA Classic Interface
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| Unable to center horizontally after Color Classic Re-cap | |
| Posted by: thegarse on 2021-01-28 08:35:10 Hello, I recently performed an unsuccessful recap on the analog board, when I powered on RL54 started to smoke so I turned everything off. Recently I re-checked ESR on all caps, triple checked polarity, replaced the 30 ohm 4w resistor on RL54 (there is some confusion here as the fried resistor I pulled was 30 ohm but I see multiple sites indicate a 330 ohm resistor is used there). Reflowed a few joints, reinstalled board, winced, then powered on. It didn’t fry the resistor this time. But now my horizontal centering pot doesn’t seem to have an effect/change on the horizontal positioning on the screen. Bad pot? Or bad something else within that circuit?   | |
| Posted by: thegarse on 2021-01-29 17:27:43 Removed the pot for centering horizontally, it measured appropriately out of circuit. Could a load affect the pot? What components control horiz that I can test? | |
| Posted by: Plasticoat on 2021-01-30 21:38:45 I feel your pain, these damn machines are so temperamental, I’ve just recapped analogue board and it was working fine, then this morning , hard disk not recognised, and later no power! I hope someone can help you, I have a feeling the pot is not at fault. | |
| Posted by: thegarse on 2021-02-01 04:32:22 This may or may not be associated but I noticed this inductor (located at LL2) came off it's glue/base and was very wiggly, it is somewhat close the yoke connector but I have no idea what it is. I'd figure replacing it couldn't hurt but I don't know what it is or what the 95 represents. My transistor tester seems to not read it correctly and I can't seem to find a reference for LL2.    | |
| Posted by: techknight on 2021-02-01 08:49:16 95 Microhenry. It is also very unlikely it is bad, unless the legs are broken clean off and you have nothing to solder to. | |
| Posted by: thegarse on 2021-02-01 13:23:57 Can someone with a CC board tell me what the reading on PP1 is, I have a feeling this is related based on a section in https://powercc.org/640x480/  | |
| Posted by: thegarse on 2021-02-02 05:18:42 Re-glued the inductor back together, reinstalled and same issue (I didn't expect anything different). PP1 isn't easy to get to so I'd rather set it using a MM once someone is able to provide a solid reading. | |
| Posted by: thegarse on 2021-02-10 19:27:57 Fixed update: I went on a wild goose chase and it paid off. Traced the pot on the underside of the board testing all resistors. This little dude measured 9Mohms. That can’t be right. Found a reference guide online (which can be wrong btw) that said it should be 1k ohms. Used the rework station, replaced resistor using salvage parts, turned on, winced again, this time I had horizontal adjustment! Wow, what a ride! Thanks to all that helped!     | |
| Posted by: cheesestraws on 2021-02-10 22:49:15 well found! | |
| Posted by: techknight on 2021-02-11 00:45:53 Yea, I can see the hole blown in it. Thats weird how that happened. :-/ | |
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