[TechAssist] Re: Magnavox 20MS233S, no or very little sound

From: "Dave Huston" <HustonTV@xxxxxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Date: Tue, 25 May 2004 19:16:10 -0400

Here's what Force32 has on this set:


Symptom:
No Sound.  A small number of Model 20MT133 may be found with no sound.
Cause:
CLUE:
The voltage on pins 5 and 8 of Audio Out IC 7800 is very low (normal is 5.2
v)
Resolution:
Replace 7800 using Service Code 4835 209 88542.
Applies To:
13J8, 13MT143S, 13PR20C121,  19PR21C121, 19PR21C122, 19PR21C125, 19PR21C222,
20MT133S, PR1306C121, PR1320C121, PR1392X121, PR1906C121, PR1906C122,
PR1906C125, PR1921C121, PR1921C125,

Symptom:
There is a lack of sound at maximum volume setting.
Resolution:
Replace resistor 3615 (2K2) with 4822 051 20332 (3K3).  This is SMD part
located behind the connector which is just to rear of AV jacks.
Applies To:
13MT143S, 13MT143S99, 20MS233S, 20MS233S99, 20MT133S, 20MT133S99, J8

Symptom:
No sound or low sound on tuner, OK on AV input.
IC 7000 ( 9322 152 70671) has failed.
Cause:
Electrical Over Stress of IC from CRT arc due to lead dress.
Resolution:
Dress black wire from 0227 on chassis to 0227 on Stereo CBA
away from black wire that grounds CRT dag coating.  Also dress 0227
wire away from CRT.  This is very important to avoid future failures.
Applies To:
20J8, 20MS233S

Symptom:
SOUND ONLY ON AV INPUT
Cause:
IC 7000 (signal processor) on the main CBA
Resolution:
Replace with Part Number 9322 152 70671.
Applies To:
13J8, 13MT143S, 13MT143S99, 13PR20C121, 19J8, 19PR21C121, 19PR21C122,
19PR21C125, 19PR21C222, 19PS57C121, 19PS57C125, 20J8, 20MS233S, 20MS233S99,
20MT133S, 20MT133S99, PR1306C121, PR1320C121, PR1392X121, PR1906C121,
PR1906C122, PR1906C125, PR1921C121, PR1921C125, PS1947C121, PS1947C125

Hope this helps,
Dave Huston
Huston TV & Electronics
2846 Marion-Cardington Rd.E.
Marion,Oh 43302-8919
Phone/Fax: 740-389-5726
email: HustonTV@xxxxxxxxxxxxxx
----- Original Message -----
From: <daryls_tv@xxxxxxx>
To: <TechAssist@xxxxxxxxxxxxx>
Sent: Tuesday, May 25, 2004 5:20 PM
Subject: [TechAssist] Magnavox 20MS233S, no or very little sound



Hi,
This Magnavox, model 20MS233S, mfg. 7/2003, has very little sound on some
channels an no sound on some.  The stations that are broadcasting stereo
displays "mono" on the screen.  The audio jacks work and the volume bar also
functions.  I have ESR'd the electro's, looked for open resistors and poor
connections.... none found to be the problem.  I did find a service manual
listed but $50 plus S/H is out of the question plus the repairs.  This set
will not justify those kind of expenses.  I should go buy a new set at $79
and tell the customer I repaired it and collect the money.  However, I don't
think the customer is that gullible.
Any help or advice would be appreciated to save this repair.
Daryl
Daryl's TV
2402 Wyoming Ave.
El Paso, TX  79903
daryls_tv@xxxxxxx
www.angelfire.com/tv2/daryls_tv


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References:
- [TechAssist] Magnavox 20MS233S, no or very little sound
  - From: daryls_tv

[TechAssist] Re: Magnavox 20MS233S, no or very little sound

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