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CTC187 intermiitent RF

Set came in with the usual complaints: "goes snowy, and sometimes a
vertical problem". Customer said that the set was never worked on so I
figured I would do the tuner sheild and that would be it. I found that
the soldering had in fact been done at some point and it actually
looked pretty good. I have seen this repair done before on a
symptomatic set and after re soldering the problem was resolved. I
understand that there is a "template" for this repair, but I have
never used it and have not had any problems with returns. I redid all
the points on this set and reinstalled the chassis. I noted that
tapping on the top of the tuner causies an intermittent loss of RF. I
opened it back up and re did the sheilds as well as all the points on
the board within the tuner area. I must be missing something but I
can't for the life of me see what it is. I still have intermittent RF.
Has anyone seen this before? Thanks, Lenny Stein, Barlen Electronics.
 
Lenny:
Either you "missed" a solder point, that is why the template is
nice.... or there is a solder bridge, cracked trace, or cold solder
joint.
electricitym
 
K

kip

Jan 1, 1970
0
Lenny get out the Biggest Mag glass you can get ,what
I use is an old lens from PTV works wonders.


kip
 
T

Tom MacIntyre

Jan 1, 1970
0
Set came in with the usual complaints: "goes snowy, and sometimes a
vertical problem". Customer said that the set was never worked on so I
figured I would do the tuner sheild and that would be it. I found that
the soldering had in fact been done at some point and it actually
looked pretty good. I have seen this repair done before on a
symptomatic set and after re soldering the problem was resolved. I
understand that there is a "template" for this repair, but I have
never used it and have not had any problems with returns. I redid all
the points on this set and reinstalled the chassis. I noted that
tapping on the top of the tuner causies an intermittent loss of RF. I
opened it back up and re did the sheilds as well as all the points on
the board within the tuner area. I must be missing something but I
can't for the life of me see what it is. I still have intermittent RF.
Has anyone seen this before? Thanks, Lenny Stein, Barlen Electronics.

Jumper wires done also?

Tom
 
T

Tom MacIntyre

Jan 1, 1970
0
Which jumpers are you referring to?

Jumper wires which are backups for the various solder grounds.
Reliability through redundancy. I worked in a Thomson warranty shop,
and it was the manufacturer's standard for the repair. Some maintain
that they are not necessary if the repair is done correctly, just like
some don't think the flexible solder is necessary.

Tom
 
A

Art

Jan 1, 1970
0
Also be advised, Rare but it does happen! Occasional the glue that was used
to secure the smd devices becomes slightly conductive, esp after a few years
of operation. This may contribute to your symptoms, however, IMHO: follow
the leads, get some good flux cleaner and clean the area of the tuner,
solder side. Diligently inspect all the connections for the coils located
within the tuner. comparing the top of the board with the bottom will
indicate where the coils come through and are soldered. Do not ignore other
devices and the probability of a small solder "dot" or splash that errantly
is conducting. Good luck, these can be a bugger at times.
 
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