Panasonic TC-2121T No sound, picture ok

Senu · Guest

I have a panasonic Tv Model TC-2121T, The picture is ok But No sound. I just changed the AN5270 but there's no sound just an intermitent sound which comes in & out with low sound ( even the volume is high ) . So what can be the fault , help me plz
Senu

Guest · Posted: Sat Jul 26, 2008 6:36 pm Post subject:

help plz

cogil · Joined: 26 Apr 2008 Posts: 45 Location: Kenya

Had the same problem, but AN 5270, dont seem to work as replacements, if you get one from a similar set it will work, but from the shop no.
Try and get it from panasonic as original part only.
Plus check for correct voltages before replacement, the original is able to handle upto 38v around.
On some we had to built external audio amps and only use the preamp of the sets, when we couldnt get any more original Ics.
there is a small electrolitic cap. on power supply change it I guess 50v, even if they are two, change both whether ok or not.

minnie · Joined: 18 Aug 2005 Posts: 2880 Location: Hell

Speakers turned off?

cogil · Joined: 26 Apr 2008 Posts: 45 Location: Kenya

speakers are on, in in perfect condition, failure comes from the audio ic drivers and biasing.

vtech · Joined: 08 May 2006 Posts: 1264 Location: USA

cogil · Joined: 26 Apr 2008 Posts: 45 Location: Kenya

vtech · Joined: 08 May 2006 Posts: 1264 Location: USA

cogil · Joined: 26 Apr 2008 Posts: 45 Location: Kenya

[quote=vtech]Perhaps your replacements are not EXACTLY the same as OEM devices--- it happense all the time & may need slight modification. Often, device numbers have additional prefix, making them slighty differnt while not documented anywhere. Panasonic is just as guilty as many others ..Still don't undesrtand why such a simple circuit has to be a mystery? [/quote]

Thanks vtech for you diagram - (ic schematic)
Just as much as you think, I too find panasonic as guilty as others, here is a set coming with AN 4270 plain and whether you replace with plain, A, C or D prefix at the end you never get it to function or if it does not normal.
At one time has worked to circuit modifications, got sound with new ic yes, but the tone was never good for the ears.
Set sold so well because of its top dome sound in its days, something must have been done that I still dont know, and they are not telling.
The other point for senu is if the electrolytic cap on supply 35v 100mfd is changed value replace it, however small the change.
Have just been talking to my workshop-tech about it.