yaesu ft290r strange fault

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mastercare
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yaesu ft290r strange fault

Post by mastercare » 22 Jun 2017, 18:24

Hi ive been looking at a fellow hams ft290 which has a strange problem, i cant get my head around.
symptons are it tx on about 143.900 but seems to vary up and down a bit, it also seem to receive on that freq. the front vfo although it shows freq does not vary the actual freq at all.
im convinced the problem lies in the pll area as the chip seems to have a very strange voltage on pin 8 that is .751v on working ft290 its nearly 5v
cyrstals have been checked by swapping from good ft290r along with pll chip. the strange thing is the ref osc crystal 5.6mhz across pins 2>3 is not oscillating on the faulty ft290 take crystal agn from working ft290 same problem.
the voltages on pin 2 and 3 are a bit lower?
has anyone any ideas where to look next.. please see voltage comparison on chip
cheers
paul
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DX-Digger
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Re: yaesu ft290r strange fault

Post by DX-Digger » 22 Jun 2017, 19:50

I seem to remember a similar fault a while back and turned out to be a leaky capacitor hidden underneath the metal screening plate on the solder side of board. It was a long time ago so I may be wrong but worth a look see
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ClubbaUK
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Re: yaesu ft290r strange fault

Post by ClubbaUK » 15 Feb 2018, 17:24

Check it hasn't been modded to extend coverage 144-148, one of the rear switches is usually used and could be faulty.

Sorry just realised topic date {bnghd}

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