How to defeat the standby circuit in the Seleco BS700 tv chassis

Some time ago my 14" Seleco TV started to exhibit a problem:
exactly 5 minutes (and when I say exactly 5 minutes, I mean exactly 300 seconds) after startup, it turn back to standby (here is a post about that here).

I 've found this problems is related to the processor's NVRAM (C.I.1 - NVM3060) that lost its content.
I managed to reprogam it (using the ponyprog programmer I have written a post about), but the solution wasn't definitive. After a while the NVM3060 lost its content again and the problem raised as before...

So, to get around the problem,  I decided to try to defeat the standby circuitry. I've requested help on some repair forum with no success, so I dived a little in the bs700 diagram. I was not able to fully understand how that circuit works, however I was able to realize that grounding Pin 16 of the TV processor should have done the job. And it does! This is what T1 and T2 manage to do depending on the various ORed conditions required to exit the standby mode (press P+ OR press P- OR command from the remote OR ...) . T1 in particular keeps pin 16 down to ground through R14 while the TV set is running.
A side effect of this approach is that every 300 seconds the screen flashes black for less than a second. This is due to the processor still trying to turn the tv in standby as the default sleep time times out; it's a command internally executed by the processor I cannot do anything about.

So the modification more than trivial as ground jumper is very close to R14. Just have a look at the following pics to see how I've made the connection.

Good luck with your bs700!
Emanuele.

Before

After

A cd player error's dance (aka, how to monitor read errors in a CD player with TDA1541 chipset)

NOTE: THIS POST IS A COMMENT TO WHAT YOU CAN WATCH IN THE ATTACHED VIDEO.

Today I wanted to investigate the behavior of the error signal in one of my Philips CD-670 players.

The error signal is coming out from the decoder chip (SAA7210)  to advise the following interpolation &digital filter chip (SAA7220) that errors have occurred while reading samples out from the playing cd.

Again on Philips CD670 and the CDM/2 cd transport

During the last year BOTH my Philips CD670 cd players have began to express annoying symptoms:

• randomly unable to read the TOC even with CDs that yesterday successfully played many times;
• randomly stopping playing with "error" message on the display (mainly when playing your preferred piece of music of your preferred cd...), even with CDs that yesterday played ok many hours;
• being very very very sensitive to mechanical shocks (I was attempted to use them as earthquake warning tools ...). Even a strong "bass" tune could lead to  the "error" condition as well as my son just walking by in front of it - the cat didn't have the same effect, however...).

A ponyprog EEPROM programmer implementation

To fix a tv set I had to build a EEPROM programmer for NVM3060 EEPROMs.

At first I believed it was possible to use my i2c EEPROM programmer I use for 24CXX memories, but I have soon realized that NVM memories follow a different signaling standard called IM-BUS.

Googling around I've found the PonyProg project from Claudio Lanconelli (http://www.lancos.com/prog.html), an EEPROM programmer able to rely with this kind of memories. It is a funny programmer built of a "mother" board and many "daughter" boards, one for each memory and PICs family the programmer is able to deal with.

So I implemented the motherboard and the daughter board for NVM memories.

The motherborad was simplified as I considered it a little redundant. In fact the external power supply circuitry (Q4,Q6)  is, in my honest opinion, not needed and can be replaced by a simple jumper.
Aside is my modification manually depicted on the original diagram. JP2 is in fact used to switch between the external power supply and the internal power recovered from the RS232 by mean of D1, D2, D3.

I tested it in both configurations. Trying to deal with an NVM chip using the internally recovered power supply leads to read/write errors because the NVM is pulling too much current. Switching to the external supply things went fine with no problem.


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Seleco BS700.4 turns in standby after 5 minutes

My Seleco 14SE112 (BS700.4 chassis) started suffering a weird problem: it turned back in standby mode after exactly 300 seconds (5 min) since startup.
Observing the screen picture carefully I also noticed that colors were too shining, like the color setting was set to MAX.
While tuning brightness and contrast from the OSD menu worked fine,  color setting had no effect.
To make a long story short it was the processor EEPROM that lost its content.
It is an NVM3060 chip, a not so common EEPROM type.

Googling around I found the PonyProg project from Claudio Lanconelli (http://www.lancos.com/prog.html), an EEPROM programmer software. One of the suggested hardware interfaces, the SIProg interface, is able to manage this kind of memories. It is a funny interface built of  a "mother" board and many "daughter" boards, one for each memory and PICs families the programmer is able to deal with.
So I spent some night in building the motherboard and the NVM daughter board (I've slightly modded the motherboard to keep it as simple as needed - see my other post about ponyprog/SIprog implementation/modding).

I have been also able to find a ROM image for the bs700.4 on the Internet..
Loading the EEPROM with the new image fixed the problem.