Has anyone mapped the addresses in RCA TV EEPROMS to the service parameters?
In particular, I wonder where the audio mute problem is coming from. I do
not have a chipper check but use a generic programmer and would like to be
able to salvage service parameters on some EEPROMS and salvage chips with
the audio mute problem.

I don't keep a selection of the chips in stock anymore and would like to be
able to turn the sets around faster with less inventory and parts ordering.

Searched the archives, likely repair groups, and the FAQ and did not find
anything on the actual addresses of the parameters.

Leonard

I disconnected the base drive to the transistor that mutes the audio.
Works fine, just a slight pop when you turn the power on or off but no
big deal.

But I wouild like to know the answer to your question as well.

Mark

Google this group for the procedure to turn the speakers back on, easy
to do.

I have replaced several blown speakers, especially in the 175 series,
where someone prior tech bypassed the mute circuit and the constant pop
blew it out. I would recommend against the hack approach.

David

Leonard Caillouet wrote:
Has anyone mapped the addresses in RCA TV EEPROMS to the service
parameters?
In particular, I wonder where the audio mute problem is coming from.
I do
not have a chipper check but use a generic programmer and would like
to be
able to salvage service parameters on some EEPROMS and salvage chips
with
the audio mute problem.

I don't keep a selection of the chips in stock anymore and would like
to be
able to turn the sets around faster with less inventory and parts
ordering.

Searched the archives, likely repair groups, and the FAQ and did not
find
anything on the actual addresses of the parameters.

Leonard

Blowing speakers from a pop seems kind of unlikely. How in the heck
LOUD do they pop? I never heard a pop out of one with the mute disabled
or saw one I repaired or any other tech repaired with a blown speaker.
Of course better off to fix the set right though. Not that I recommend
it, but an easier way to disable it, should anyone choose, is to take 3
seconds to solder bridge the B-E of the mute transistor. Not
recommended of course. I believe the corruption is just the eprom has
the speakers adjusted to "off" and since the set up menu on the
effected models, mainly low line models with no external jacks does not
include the option to turn speakers on and off, there is no way to turn
the setting back to "on".I believe the mute is basically just there to
enable the speakers to turn on/off on models with that option. I'm not
sure about the "pop" theory. I sure never heard it.
wrote:
Google this group for the procedure to turn the speakers back on,
easy
to do.

I have replaced several blown speakers, especially in the 175 series,
where someone prior tech bypassed the mute circuit and the constant
pop
blew it out. I would recommend against the hack approach.

David

Leonard Caillouet wrote:
Has anyone mapped the addresses in RCA TV EEPROMS to the service
parameters?
In particular, I wonder where the audio mute problem is coming
from.
I do
not have a chipper check but use a generic programmer and would
like
to be
able to salvage service parameters on some EEPROMS and salvage
chips
with
the audio mute problem.

I don't keep a selection of the chips in stock anymore and would
like
to be
able to turn the sets around faster with less inventory and parts
ordering.

Searched the archives, likely repair groups, and the FAQ and did
not
find
anything on the actual addresses of the parameters.

Leonard

There is a very easy way to allow the menu to turn the speakers back on
for any technician.
The mute line to the audio outputs is there to prevent the dc surge as
the power supply comes up from getting to the speakers.
Do not forget that these sets have something like a 1 watt speaker in
them.
David

David,

I am familiar with the procedure you mentioned and did a search of the
archives and the FAQ, as I mentioned. I would still like to know the
mapping of the addresses to be able to extract service parameters and do the
correction to the mute address. If I have to desolder one pin I might as
well pull it and read/archive the data from the EEPROM. I am getting a
pretty good collection of EEPROM data that has proved useful for testing.
The question of what parameters are where in the hex addresses is still an
open one. Occasionally I get a dead set that I can still extract data from
the EEPROM and the tuning parameters would be nice to pull. Most dead ones,
of course, are impossible to get any data from.

BTW, I think disabling the mute circuit in hardware is a half-assed patch.
I had one come in with a bad speaker like this as well, and discovered after
I replaced the speaker that the resistor had been pulled. These speakers go
out without the transients all the time. Why take the chance when the right
fix is so easy and cheap?

Leonard

wrote in message
oups.com...
Google this group for the procedure to turn the speakers back on, easy
to do.

I have replaced several blown speakers, especially in the 175 series,
where someone prior tech bypassed the mute circuit and the constant pop
blew it out. I would recommend against the hack approach.

David

Leonard Caillouet wrote:
Has anyone mapped the addresses in RCA TV EEPROMS to the service
parameters?
In particular, I wonder where the audio mute problem is coming from.
I do
not have a chipper check but use a generic programmer and would like
to be
able to salvage service parameters on some EEPROMS and salvage chips
with
the audio mute problem.

I don't keep a selection of the chips in stock anymore and would like
to be
able to turn the sets around faster with less inventory and parts
ordering.

Searched the archives, likely repair groups, and the FAQ and did not
find
anything on the actual addresses of the parameters.

Leonard

Just for the heck of it for my own info on the =93popping=94 issue, here=92s
a couple stats. Normal sound vs. (modified)
Set turn on mvdc readings 507 (598) falling to 13 (-61) average 52 (48)
duration 1.2 sec (1.5)
Set turn off mvdc readings =96451 (-1224) rising to =9635 (476) average
=96268 (-97) duration .3 sec (.7)
Set turn on mvac readings 273 (294) falling to 20 (32) average 84 (108)
duration .9 sec (.9)
Set turn off mvac readings 301 (1065) falling to 16 (17) average 86
(224) duration 1.2 sec (1.2)
No difference in any readings during normal viewing, changing channels,
ect.
So going by the readings there is a noticeable difference, and
definitely more pop will be heard if the circuit is modified, mostly at
turn off, so my opologies, definately a pop issue

Meant to mension the readings were simply across the speaker itself,
and don't know where the ? symbols came from. sorry.

On Sat, 16 Apr 2005 06:26:01 -0400, "Leonard Caillouet"
put finger to keyboard and composed:

I am familiar with the procedure you mentioned and did a search of the
archives and the FAQ, as I mentioned. I would still like to know the
mapping of the addresses to be able to extract service parameters and do the
correction to the mute address. If I have to desolder one pin I might as
well pull it and read/archive the data from the EEPROM. I am getting a
pretty good collection of EEPROM data that has proved useful for testing.
The question of what parameters are where in the hex addresses is still an
open one. Occasionally I get a dead set that I can still extract data from
the EEPROM and the tuning parameters would be nice to pull. Most dead ones,
of course, are impossible to get any data from.

IMO any TV design that cannot bootstrap itself from a blank EEPROM is
extremely shoddy. I recommend that the designer be beaten about the
head with a blunt instrument. Is it asking too much for a programmer
to have seeded the uC's ROM with a basic working configuration which
could be automatically downloaded into the EEPROM in the event of a
checksum error? Apparently so.

Anyway, it surprises me that nobody (?) has taken the trouble to map
out the EEPROM addresses. It would seem to me that the most logical
way to uncover the locations of the various functions is to socket the
EEPROM and dump its contents after each parameter change. shrug

BTW, I think disabling the mute circuit in hardware is a half-assed patch.

I'm curious about this turn of phrase. It begs the question, is there
a full-arsed anything? ;-)


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

my set does not have the mute featutre avaialbe for the user

I have had the the mute signal disconnected for a few years, the set
does pop on turn on and off but nothing bad enough to damage a speaker
and the speakers seem fine after several years.

But if there is an easy way to get into a menu and turn the mute off so
i can reconnect the mute signal, I would like to know that.

Please let me know where I can find this.

thanks

Mark

"Franc Zabkar" wrote in message
...
On Sat, 16 Apr 2005 06:26:01 -0400, "Leonard Caillouet"
put finger to keyboard and composed:

I am familiar with the procedure you mentioned and did a search of the
archives and the FAQ, as I mentioned. I would still like to know the
mapping of the addresses to be able to extract service parameters and do
the
correction to the mute address. If I have to desolder one pin I might as
well pull it and read/archive the data from the EEPROM. I am getting a
pretty good collection of EEPROM data that has proved useful for testing.
The question of what parameters are where in the hex addresses is still
an
open one. Occasionally I get a dead set that I can still extract data
from
the EEPROM and the tuning parameters would be nice to pull. Most dead
ones,
of course, are impossible to get any data from.

IMO any TV design that cannot bootstrap itself from a blank EEPROM is
extremely shoddy. I recommend that the designer be beaten about the
head with a blunt instrument. Is it asking too much for a programmer
to have seeded the uC's ROM with a basic working configuration which
could be automatically downloaded into the EEPROM in the event of a
checksum error? Apparently so.

Anyway, it surprises me that nobody (?) has taken the trouble to map
out the EEPROM addresses. It would seem to me that the most logical
way to uncover the locations of the various functions is to socket the
EEPROM and dump its contents after each parameter change. shrug

BTW, I think disabling the mute circuit in hardware is a half-assed
patch.

I'm curious about this turn of phrase. It begs the question, is there
a full-arsed anything? ;-)


- Franc Zabkar

Frank,

Thomson is half-arsed, Philips is full-arsed.

Leonard