PAL mod from Darren King

[andrew]

G'day thought I'd just let you know that I got my PAL kit from Darren King. He's a top bloke so if you want one, get on to him at www.kingey1971.com

Hope it's ok to post this Darren

Andrew

[Darren King]

Yeah no problems

[BadaBing!]

How much does a compatable pal tuner cost? I ca install it myself. Is there any on the market I can desolder and solder onto the tivo?

[Darren King]

Full costs and descriptions are on my website in my signature. You are quite welcome to get me to do all the work or do it yourself as per the wording on the website.

[Professor Yaffle]

I have been looking into the PAL mod, and I am no expert with hardware mods (I am more of a software guy) but I am trying to understand how and have a couple of questions. Specifically regarding the mono mod.

1. Why does the audio output have to be connected directly to the Micronas Chip? Isn't tuner pin 21 is audio output on both the NTSC an PAL tuners, how do things differ such that audio needs to be patched directly to the Micronas chip?

2. Is it necessary to lift Micronas pins 56 and 57 from the board to attach the audio cable? What would happen if you connected it without lifting and using just an single capacitor?

3. This is where my lack of electronics knowledge becomes really apparent , but what is the purpose of those inline capacitors?

Obviously things have been done the way they have for good reasons, I am just curious... Apologies if these questions have been answered elsewhere.

Cheers

[Darren King]

1. Why does the audio output have to be connected directly to the Micronas Chip? Isn't tuner pin 21 is audio output on both the NTSC an PAL tuners, how do things differ such that audio needs to be patched directly to the Micronas chip?

Because the SIF (sound intermediate frequency) output pin from the tuner is incompatible with the stereo decoder built in the existing Micronas 3430G chip on the board which cannot decode the stereo sound standard we use. Therefore we must use the demodulated sound output pin instead (it is a different pin), which is only mono, and feed it into the basic left/right audio pins on the micronas and a small software modification (which is done in palmod and transparent to the end user) looks for baseband audio sound on pins 56 and 57 of the chip.

Alternatively for NZ thanks to Catdog you can now add-on a NICAM decoder board for stereo in a similar fashion to the older Australian "Mark 1" stereo decoder board, or for Australian people I have been replacing the 3430G chip for a 3410D version for a couple of years now which is known as the "Mark 2" stereo decoder.

2. Is it necessary to lift Micronas pins 56 and 57 from the board to attach the audio cable? What would happen if you connected it without lifting and using just an single capacitor?

The lifting of the pins is to make it easier to attach the capacitors. The PCB pads do not go anywhere so if you want to not lift the pins then that is OK too, however you will need to use two capacitors (read below)

3. This is where my lack of electronics knowledge becomes really apparent , but what is the purpose of those inline capacitors?

To provide DC isolation. Attaching both pins 56 and 57 to a single capacitor OR not using capacitors at all is detrimental to the input pins of the Micronas chip. Even the audio inputs from the rear panel A/V input is connected to the Micronas via another set of pins through small surface mount capacitors on the PCB (namely C71 and C76).

To be honest if your experience is not in electronics then you might consider it worthwhile to find someone who is. Working with surface mount parts is delicate and repairs costs will outweigh an unsuccessful attempt. Just my 2c

[Professor Yaffle]

Thanks for the info Darren.

Because the SIF (sound intermediate frequency) output pin from the tuner is incompatible with the stereo decoder built in the existing Micronas 3430G chip on the board which cannot decode the stereo sound standard we use.

I think I get it. Do I understand correctly that an unmodded Tivo does not use the demodulated mono sound pin so if there is nothing compatible coming through the SIF it has nothing to fall back on?

To be honest if your experience is not in electronics then you might consider it worthwhile to find someone who is. Working with surface mount parts is delicate and repairs costs will outweigh an unsuccessful attempt. Just my 2c

This is generally my feeling, I wish I was better at the hardware side of things. Is there anyone in NZ who can do the mod for me or even better in Wellington that could do it and let me watch/assist. I am very interested in this stuff.

Thanks again.

[Darren King]

I think I get it. Do I understand correctly that an unmodded Tivo does not use the demodulated mono sound pin so if there is nothing compatible coming through the SIF it has nothing to fall back on?

It's a two-part answer:

1. An unmodded TiVo has a tuner module not compatible with the transmission standard used in Australia or NZ which is why it is swapped for the PAL tuner module. Even if you were to utilise a demodulated audio pin on the original tuner it still won't work due to the tuner designed to receive a totally different sound and vision transmission standard.

2. A TiVo modified with a PAL tuner module has both an SIF pin and a demodulated mono sound pin. The SIF pin of the PAL tuner module is in the exact same place as the SIF pin on the original tuner module however the 3430G micronas chip's design cannot detect the sound standard of either Australia or NZ transmissions and therefore the result is no audio. To get around this there are the various sound hardware modifications as previously discussed depending on whether you want mono or stereo sound from the PAL tuner.

[Professor Yaffle]

I understand the broadcast standards are different. I guess what I was trying to say was, does the Tivo use the mono output from the tuner by default (via the circuit board as is)? I was interested in that if SIF and mono are both passed from the tuner to the Micronas (unmodded), that it doesnt just switch to mono if it doesn't understand the SIF signal.

Thanks again, I'm learning all the time

[Darren King]

I guess what I was trying to say was, does the Tivo use the mono output from the tuner by default (via the circuit board as is)?

No. It uses the SIF output pin as that is what is wired to the Micronas chip by virtue of how the PCB is manufactured. The mono demodulated audio pin is not wired on an unmodded PCB.

I was interested in that if SIF and mono are both passed from the tuner to the Micronas (unmodded), that it doesnt just switch to mono if it doesn't understand the SIF signal.

No. There is only one audio path to the Micronas chip on a standard unmodded PCB. There is no demodulated audio path. If there was there would be no need for the modification how-to describing how to do a mono hookup the way it does