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From: b on 26 Nov 2009 07:26
I'm trying to fix this European ELBE E12D chassis tv. The inital
problem was this:

http://www.fileden.com/files/2007/6/4/1143893/DSCF8209.JPG
http://www.fileden.com/files/2007/6/4/1143893/DSCF8210.JPG

As you can see, there is a venetian blind effect, and considerable
foldover. The voltages around the IC seemed normal. It looked like a
pumpup cap failure, but a change of several caps didn't alter
anything, so I got a new TDA 8178S frame chip. that produced only the
usual horizontal line. A TDA 8170 (which was in the schematic for the
set) also did the same. Re fitting the original brings back the
initial fault.

Is this likely to be a case of requiring the original TDA8178 part or
could there be somethign else I should pursue?
-B
From: stratus46 on 26 Nov 2009 14:13
On Nov 26, 4:26 am, b <reverend_rog...(a)yahoo.com> wrote:
> I'm trying to fix this European ELBE E12D chassis tv. The inital
> problem was this:
>
> http://www.fileden.com/files/2007/6/4/1143893/DSCF8209.JPGhttp://www.fileden.com/files/2007/6/4/1143893/DSCF8210.JPG
>
> As you can see, there is a venetian blind effect, and considerable
> foldover. The voltages around the IC seemed normal. It looked like a
> pumpup cap failure, but a change of several caps didn't alter
> anything, so I got a new TDA 8178S frame chip. that produced only the
> usual horizontal line. A TDA 8170 (which was in the schematic for the
> set) also did the same. Re fitting the original brings back the
> initial fault.
>
> Is this likely to be a case of requiring the original TDA8178 part or
> could there be somethign else I should pursue?
> -B

IMO you have some really bad capacitors in that vertical output. An
ESR meter, even a modest one like this

http://www.matelectronics.com/acatalog/Mat_Electronics_Test_Equipment___Other_61.html

(scroll down to IN CIRCUIT CAPACITANCE TESTER)

will give you good info but keep in mind some models have large values
(1000uF) in the feedback loop. Even a very mild deterioration can
cause significant linearity issues. The tester _will_ show it as not
as good as a new one but still seems OK. Don't be fooled.

G²
From: b on 29 Nov 2009 12:56
Got the schematic.
measured the voltages around IC 301 TDA 8178S, All seems Ok except pin
3, with about 12v, (1.4v on schematic) and pin 5 with about 18v.
(13.8v)

Already changed c304 103k, 25v rectifier D301 1n4001. I had previously
changed C308 2200UF and C310 220UF, no change.

Before I fit the new IC, I would like to rule out the possibility of
something amiss on the circuit. Something does not seem right with
those voltages, but I don't know if it is caused by :
a) faulty TDA8178S IC (leaky)
b) misprint on schematic
c) the fact the ic fitted - tda8178s - differs from that specified on
schematic (tda 8170)
d) some problem in the vertical (frame) circuit

Any advice gratefully received. I am currently trying to upload the
extract form the schematic, will post link here when I do.

From: b on 29 Nov 2009 12:58
I am currently trying to upload the
> extract form the schematic, will post link here when I do.

see here
http://www.filefactory.com/file/a1fbe5d/n/ELBE_E14_vert.jpg

From: Franc Zabkar on 1 Dec 2009 06:30
On Sun, 29 Nov 2009 09:58:52 -0800 (PST), b
<reverend_rogers(a)yahoo.com> put finger to keyboard and composed:

> I am currently trying to upload the
>> extract form the schematic, will post link here when I do.
>
>see here
>http://www.filefactory.com/file/a1fbe5d/n/ELBE_E14_vert.jpg

Have you changed the electrolytic capacitor on the 25V rail near the
FBT???

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
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