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The VP-299 predates the TBC-1000. There's multiple generations of both units, with staggered overlapping. What essentially happened here is modifications over time introduced errors, fixed on later units, but then that could create yet new issues. Not unusual for long-production items. So many variables. In the 2020s, issues almost always need recapping. But that VP-299 board can still look bad, even with recap, due to the above long production changes. So removal is best, and most of us have no need for a distro amp anymore. (And if you need a distro amp, better exist, be it Cypress or Extron or others.) Quote:
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The full service manual is lost (according to DataVideo), and NDA anyway (yes, still). When I last spoke to somebody there, I knew more than they did. Their words, not mine. So ... spooky. Sometimes being the smartest person in the room sucks, you're on your own. |
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I've noticed on the amp board, the 12V DC coming from the PSU has one capacitor that goes to ground before it jumps to the power board to convert down to the 5V for the video board. Any reason this is there? The 12V DC from the PSU is already smoothed and level from rectification so why is that even necessary? Maybe just to help prevent under-powering either board?:weird: |
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The capacitor could be doing many duties, without having the board on a bench or a schematic it's really difficult to determine.
It could form part of the amplifier decoupling, bypass, or even part of the amplifier feedback stage, or bypassing there-of. 'Smoothing' is one of the only duties for a capacitor on a board (and it's an infrequent case), capacitors serve many operations functionally and that's why there are so many of them on even quite small circuits. Anything around the amplifier board is most certainly connected to amplifier staging and should be left well alone, it could be part of the feedback network. It's unusual for a manufacturer to leave random components with no use on a board, it happens, but it's not a cost-effective way to have boards made. All of those 5 cent/pence operations start making an impact once you start rolling even a few hundred boards, especially if it's a through-hole electrolytic which can be a comparatively 'expensive' component. It's cheaper to leave it unpopulated, even if the boards are otherwise traced for the component. |
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