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
yaesu ft290r strange fault
-
- Super Member
- Posts: 141
- Joined: 28 Feb 2016, 19:17
- Call Sign: g4sbx
yaesu ft290r strange fault
You do not have the required permissions to view the files attached to this post.
- DX-Digger
- Top Poster
- Posts: 1092
- Joined: 27 Jul 2009, 22:01
- Call Sign: TM205
- Location: ... - --- -.- . --- -. - .-. . -. -
Re: yaesu ft290r strange fault
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
ʎɐqǝ uo pɹɐoqʎǝʞ ɐ ʎnq ı ǝɯıʇ ʇsɐן ǝɥʇ sı sıɥʇ
- ClubbaUK
- Regular
- Posts: 87
- Joined: 26 Jan 2011, 19:20
- Location: Wolverhampton
Re: yaesu ft290r strange fault
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
Sorry just realised topic date