--- In Jim Jackson <> wrote:
>
>
> >>> It now boots, but after about 4 or 5 secs it starts constantly rebooting,
> >>> output below, along with board LEDs going fron steady green to red then
> >>> green, then red then green etc. The reset button has no effect.
> >>>
> >>> At first I thought it was the power supply developed a problem, so I've
> >>> tested with another PSU - same thing. I've disconnected everything
> >>> and still same problem.
> >>>
> >>> Anybody any suggestions at all as to what I might check for? If I'm quick
> >>> I
> >>> can get maybe a couple of redboot commands executed, if anything will give
> >>> any diagnostic info.
> >
> > ...snipped...
> >>>
> >>> RedBoot>
> >>>
> >>>>> TS-BOOTROM, Rev 1.02 - built 16:55:24, Sep 14 2004
> >>>>> Copyright (C) 2004, Technologic Systems
> >>>>> TS-7200: Rev A PLD detected, options ( MAX197-ADC )
> >>>
> >>>
> >>>
> >>>>> TS-BOOTROM, Rev 1.02 - built 16:55:24, Sep 14 2004
> >>>>> Copyright (C) 2004, Technologic Systems
> >>>>> TS-7200: Rev A PLD detected, options ( MAX197-ADC )
> >>>
> >>> ....repeated over and over
> >>>
> >> If it is rebooting whilst being held static at the reboot prompt, it must
> >> be hardware. It definitely sounds like power brown-out triggering the
> >> reboot.
> >>
> >> Can you monitor the output of the onboard regulator?
> >
> > Good point. I'll check.
> >
> > It's a bit wierd. After a quick power cycle it starts the constant reboot
> > cycle after about 3 to 4 secs. If it is powered down for a while and then
> > powered up. the reboot cycle starts after about 5 to 7 secs. It could be
> > something heating up and failing.
> >
> > The 3.3v and 1.8v regulators are linear on the 7200, so will be
> > dissipating heat.
>
> Ok so grabbing some Freezer spray, and guess what spray the 1.8v reg. and
> the beast works. So now I know what needs replacing. I've not done SM
> repair before, but there's got to be a first time for everything - need a
> finer solder tip etc.
>
> Thanks Jacques
>
Good luck, SMC repairs are bit like neurosurgery, only more fiddly. ;)
It's pretty rare for integrated electronics to fail like this, especially in a
non definitive way.
Were you able to establish whether the regulator was failing to regulate. the
output was sagging or the output disappeared completely?
I'd still suggest looking for a PCB fault in that area. The heat of the
component and the contraction due to your spray could be causing that small
physical movement that is critical.
Try reflowing the solder of the contacts of that chip and any associated
cmpts., eg capacitors.
I'd recommend a closer look before opting for surgery. The fault may not be the
chip itself.
HTH.
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