I thought the customer must have dumped it and got a new one by now but it
turns out they had been away for a week.

Previously it wouldn't display anything other than its setup menus despite
being unplugged for half an hour.

So we got it as far as the customer's kitchen table (I'm sure glad I didn't
have to move it further.)

After removing the back I poked around the UV board where the MM1313AD A/V
switch chip lives. Plenty of electrolytics but no obvious leakage or other
issues. My next move would have been to take the board off to check for
solder joint deterioration followed by an oscilloscope to see if there were
signals going in to the chip but none coming out.

But I decided to do a signal test first.

At power on there was the usual delay and up came exactly what you'd expect
from a tuner with no signal. So we fixed up a DVD player and up came perfect
DVD playback.

No amount of tapping the UV board with a screwdriver handle produced any
disturbance in the picture.

So we put the back on and reinstalled it in the living room.

That was about three hours ago. I told the customer to leave it unplugged
overnight if it happens again.

So now I'm wondering what to charge for taking the back off and putting it
on again. They need an A/V cable for the VCR which I'll deliver tomorrow.

Old Guy

On Thu, 23 Aug 2012 21:40:49 -0400, "John Smith"
wrote:

I thought the customer must have dumped it and got a new one by now but it
turns out they had been away for a week.

Previously it wouldn't display anything other than its setup menus despite
being unplugged for half an hour.

So we got it as far as the customer's kitchen table (I'm sure glad I didn't
have to move it further.)

After removing the back I poked around the UV board where the MM1313AD A/V
switch chip lives. Plenty of electrolytics but no obvious leakage or other
issues. My next move would have been to take the board off to check for
solder joint deterioration followed by an oscilloscope to see if there were
signals going in to the chip but none coming out.

But I decided to do a signal test first.

At power on there was the usual delay and up came exactly what you'd expect
from a tuner with no signal. So we fixed up a DVD player and up came perfect
DVD playback.

No amount of tapping the UV board with a screwdriver handle produced any
disturbance in the picture.

So we put the back on and reinstalled it in the living room.

That was about three hours ago. I told the customer to leave it unplugged
overnight if it happens again.

So now I'm wondering what to charge for taking the back off and putting it
on again. They need an A/V cable for the VCR which I'll deliver tomorrow.

Old Guy


$30 + travel expenses with no warranty, $100 if you give them a 30 day
warranty.

A very bright guy who worked for me had a mantra - "Problems that go
away by themselves will come back by themselves." Somewhere in this
set is a bad contact. The flexing associated with moving it caused
the two parts to rub against one another and establish continuity. It
is certain that just as E=I*R, the problem will reoccur.

PlainBill

wrote in message
...
On Thu, 23 Aug 2012 21:40:49 -0400, "John Smith"
wrote:

I thought the customer must have dumped it and got a new one by now but it
turns out they had been away for a week.

....
So now I'm wondering what to charge for taking the back off and putting it
on again. They need an A/V cable for the VCR which I'll deliver tomorrow.

Old Guy


$30 + travel expenses with no warranty, $100 if you give them a 30 day
warranty.

A very bright guy who worked for me had a mantra - "Problems that go
away by themselves will come back by themselves." Somewhere in this
set is a bad contact. The flexing associated with moving it caused
the two parts to rub against one another and establish continuity. It
is certain that just as E=I*R, the problem will reoccur.

PlainBill

Problems like this can also cause friction between repairer and customer if
not handled well, but in this case the customer saw everything I did.

I'll report back if the problem comes back.
I'll also take the UV board out and put it back in (after solder joint
inspection).

Old Guy