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Thread: How to run your gamma at a cool +3V - with a 'factory' mod

  1. #21
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    Wheres gnd mate????



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    ?

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    Ground or earth, is the casing of the receiver, or something screwed to it. If you check for continuity between the point SC6 and the casing, or the tuner module, then you have successfully grounded pin 17.

    A warning though...be careful you don't get near the power supply in that thing...it can kill you. Do your tests with the power off to the box, then when checking the voltage (pwr on) with a blank card in the reader, make sure you stay away from the power supply board.

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    Yeah. Done. All back together. Card in and working. The chip is prob about room temp. If the mod was wrong it would have killed the card staright away?

    Ill keep an eye on it for the next few hours to see if it changes.

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    Room temperature is good. Pull the card after a couple of hours and check it then. Before the mod, mine would burn your lip, now it is just nicely lukewarm.

    Good job

    And thanks again to eyesee for sharing this info...

  • #26
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    Yeah mine used to burn my lip also.

    I did this mod

    Cooled it down alot.

    I did this topics mod to my parents box today. Seems to be working better, and alot easier.

    Will try it on my box tomorrow.

  • #27
    Senior Member CoopsOz's Avatar
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    What contacts would one check to see how many volts the card is getting? I'm a little confused, one of the above posts says that by tying pin3 to 5V, the card operates a 5V.....by tying it to ground the card runs at 3V. Now, in my case.....the pin isn't tied to anything and yet the box still works, surely that means the earth isn't necessary.
    Last edited by CoopsOz; 13-04-08 at 08:57 PM. Reason: Follow up questions

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    Senior Member Farmsky's Avatar
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    Quote Originally Posted by CoopsOz View Post
    What contacts would one check to see how many volts the card is getting?
    Have u read this most excellent thread from the beginning?

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    Senior Member CoopsOz's Avatar
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    Quote Originally Posted by Farmsky
    Have u read this most excellent thread from the beginning?

    Clearly not.....thanks for the hint!

    Quote Originally Posted by eyesee View Post
    ... by inserting the card ... we trigger the micro contact of the reader socket and enable the 'voltage' to turn-on ... we can then measure between pins C1 and C5 which are clearly marked on the PCB ...

  • #30
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    I got no response so I thought I'd find out for myself, with no pin 3 at all it is in fact running at 5v.....as stated above. So now I'm back to the drawing board, I can't solder anything to the chip because it broke off flush. Is GW1's mod now my only option?

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    Quote Originally Posted by CoopsOz View Post
    ... I can't solder anything to the chip because it broke off flush. Is GW1's mod now my only option?

    I don't know your soldering / construction skills - but even if you have a 'flush' broken pin ... there is still some options to make a successful connection to that pin.

    Most packages have at least 1-2 mm plastic coveting the 'pin track' which is not exposed - including this TDA device...

    If you have a very - I mean really very - fine dremil type file - the idea is to shave just 1mm of the plastic of the 'top' area of the flush pin - to expose enough metal to make a solder bond ... this is a tricky procedure - but works well in the hands of a skilled operator .. so don't attempt (or try on anothe broken circuit board) unless you are confident .. or you may destroy the device

    Alternative (you will need a magnify glass and a pair of VERY steady hands) - which has worked for me in the past - is to get an extremely fine needle and just chisel / scrape area around the broken pin - to gauge some plastic away ... even 0.5mm is fine ...

    Once you have done this - you need some VERY thin wire - 0.2 - 0.5 mm

    Dip this wire into some solder flux and 'tin' it with a blob of solder at the tip ... the 'blob' should just cover the wire - so if you are using 0.4mm wire with the 'blob' it will be 0.5mm or there about ...

    Now get the needle and 'scratch' the tiny exposed part of the broken pin ...

    You will need a VERY fine solder tip on our soldering iron - and I mean FINE!

    Get you needle dip it into the solder flux and then try to put a tiny 'blob' of the flux with the needle tip onto the tiny part of the 'scratched' and exposed part of the pin ...

    Now the idea is that we will do a fine bit of reflow soldering onto the tiny part of the exposed pin with our VERY thin wire ...

    You want to 'stick' the wire to the PCB with a 'blob' of hot glue ... at the same time solder the other end to a suitable GND point - closest to the TDA device (see the GND pin from the data sheet).

    Now with fine tweezers align the ‘tinned’ and solder flux dipped end of the wire with the exposed part of the broken pin … use the tension in the wire to act like a mini spring to push itself against the pin – touching the exposed part of the pin 3 metal – no mater how tiny it is ..

    Once you have prepared this and all is primed – ensure that the whole area of pin and tip of wire is covered with solder flux …

    The next step is to get your fine soldering iron tip ‘wet’ with a tiny dab of solder … then VERY VERY carefully just touch the tip of the tinned wire which is touching the broken pin under its own tension. If all went well – the melting flux will create an ideal micro ‘chamber’ as it boils away to make a perfect tiny ‘bond’ between the broken (but partially exposed pin) and the ‘solder tinned’ part of the wire.

    DO NOT pull the wire to test if the connection was successful.

    If the connection was successful it will ‘break’ if you touch – hence we had to secure the wire BEFORE the soldering process and not after – otherwise it will break.

    To test you need to power up the receiver and push into the card reader the REAR end of your card – so not to touch any chip contacts – this will activate the power to the pins C1 ..

    You should be reading +3 volts between pins C1 (Vcc) and C5 (GND) if your solder attempt was successful ... these pins are clearly markd on the Strong card reader PCB.

    If you are not reading +3 Volts - then your soldering was not successful

    TRY again AFTER cleaning the surfaces and re-tinning the tip of the wire with a blob of solder.

    This is a fine art and you might have to try several times.

    If you have the correct soldering iron tip and solder flux and VERY thin wire – you will be able to make a successful connection …

    GENERAL WARNING: When initially trying to unsolder pin 3 – you MUST be very careful and use a very fine solder wick applied to pin 3 … heat the solder wick … it should ‘suck-up’ some of the solder from pin 3 … then get another ‘clean’ section of the wick and apply to pin 3 whilst having tip of soldering iron (fine tip) on the wick AS YOU DRAG the wick under the tip of the soldering iron whilst applying pressure on the wick …

    This technique will ‘mop-up’ any remaining solder.

    You will then need to take a fine sewing needle and poke under the arched part of pin 3 gently levering it UP off the adjoining pin (either pin 2 or pin 4 – depending from which side you applied the needle) … whilst you apply TINY (I mean tiny) pressure to the needle trying to lever ‘up’ pin 3 – you need to ‘touch’ the flat part of the pin – now with no more solder – with the tip of your ‘CLEAN’ (no solder on tip) soldering iron.

    This will ‘melt’ the solder under the pin – just enough to enable you to ensure that the pin ‘lifts’ easily with slight pressure from the needle ‘lever’.

    Hope the above technique in trying to connect to a broken pin AND how to unsolder and ‘lift’ the pin successfully is helpful to those of you not skilled at soldering techniques …

    ADDITIONAL WARNING: Once pin 3 is ‘free’ and unsoldered – DO NOT lift the pin more than 1-2 mm above the pad – just to clear the pad and ensure its not making contact with anything. Do not try to bend the pin into an upright position or you will most certainly break it. SMD pins are not designed to bend as much as conventional IC pins – so be careful

  • #32
    Senior Member CoopsOz's Avatar
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    Wow, thank you for all the time and effort you put into that post......I will have another crack at it when I get home this evening.

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    Heh. I think you have stuffed you card reader, as I have.

    I was desoldering something and it bloody ripped half the circuit board off.

    Im trying to source where to find another one. Ill let you know how i go.

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    I have used the dremel method as described by eyesee, to cut back a playstation chip my friend broke a leg off and it worked perfectly.

    To note the gw1 humax mod definately runs cooler than my strong with the 3rd leg lifted. Interesting considering the humax runs 3.3v and the strong @ 3v.

    cheers
    ktm200

  • #35
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    Cool Confusion reigns supreme again.

    Quote Originally Posted by jsmith View Post
    Well, you are probably stuck with a 5 volt box, unless there is a bit of the leg you can solder a piece of wire onto..

    Pin 17 needs to be grounded to switch to 3v mode I think, from the spec sheet.
    My interpretation of the TDA8004T and TDA8024 block diagrams suggest that this is totally incorrect.
    Pin #17 is the Vcc for the card #1.
    Much of the confusion in previous thread was caused by mis-interpretation of the function of these two pins, #3 and #17.
    This explains why some were able to get mods to work or not.


    Very Kindest Regards, " The Druid ".

  • #36
    Senior Member CoopsOz's Avatar
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    Quote Originally Posted by under- View Post
    Heh. I think you have stuffed you card reader, as I have.

    I was desoldering something and it bloody ripped half the circuit board off.

    Im trying to source where to find another one. Ill let you know how i go.
    Admin has them over at Jerahs playground...$45 pre modded.

    I tried to scrape some plastic away as I don't have a dremel.....the card is still running at 5V so I guess I'm not making contact. I think I will do GW1's mod now.

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    Quote Originally Posted by beer4life View Post
    My interpretation of the TDA8004T and TDA8024 block diagrams suggest that this is totally incorrect.
    Pin #17 is the Vcc for the card #1.
    Much of the confusion in previous thread was caused by mis-interpretation of the function of these two pins, #3 and #17.
    This explains why some were able to get mods to work or not.


    Very Kindest Regards, " The Druid ".
    Hi Druid,

    Yes, you are correct, I meant pin 3 not 17...(don't know why 17 came into my mind), but doesn't pin 3 have to connect to GND to go low and switch to 3v operation? On my box, with Pin 3 floating, I had 5v mode, and it only switched to 3v on connecting Pin 3 to GND.

  • #38
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    Cool That's correct.

    Quote Originally Posted by jsmith View Post
    Hi Druid,

    Yes, you are correct, I meant pin 3 not 17...(don't know why 17 came into my mind), but doesn't pin 3 have to connect to GND to go low and switch to 3v operation? On my box, with Pin 3 floating, I had 5v mode, and it only switched to 3v on connecting Pin 3 to GND.
    G'Day Cobbers,
    Thanks to the opening post in this thread by "eyesee",
    Member. We have taken a quantum leap forward in solving this problem.
    I'm unable to check, but I suspect that there has to be a better way of changing the input V on #3 than lifting the IC pin #3.
    Surely there is provision on the card reader boards, Either/and/or, to be able to switch this #3 input.
    I would be aghast to find that this is not so.
    Where does that track on pin #3 go. It appears that it only needs to be open circuit for 5 V on pin #17, and earthed for 3 V.


    Very Kindest Regards, " The Druid ".

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    I think that each manufacture configures the chip and board for their own particular application. In the case of the Strong, a 5v smartcard perhaps... These are el cheapo boxes, remember.

    It would be relatively easy to place a switch in the circuit to change between 5v and 3v.

  • #40
    Senior Member gw1's Avatar
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    It's probably not a good idea to change the switch while there's a card inserted

    Those with an overheating problem might find a switch like that handy - that is, for receivers using a more modern card interface IC with untapped multivoltage capability. I'm surprised to hear there are receivers out there containing interface ICs with unused multivoltage support! But I guess just because a receiver uses a modern IC doesn't necessarily mean its firmware is smart enough to drive it. Perhaps there is method to their madness though: there may be cards out there that don't give correct indication (in their ATR) about their voltage requirement. Fortunately, for the time being at least, most cards seem to be 5v tolerant.

    For reasons of VCC voltage accuracy, a 100 nF capacitor with an ESR < 100 mW should be tied to CGND near to pin VCC, and a 100 or 220 nF capacitor (220 nF is the best choice) with the same ESR should be tied to CGND near card reader contact C1.
    These design rules from the IC manufacturer are important for stability. Cheapo boxes often omit as many parts as possible to shave cost but it's foolish.

    A note to experimenters: there's an upper limit on decoupling when using the TDA80x4 chips, depending on load and the quality of the capacitors already fitted. In some tests I found that if I tried to add a 1uF multilayer ceramic (X7R) it'd prevent a gamma from working. The problem is overcurrent protection, preset to 65mA average (allowing momentary spikes up to 200mA) but the whitey I tested in an unmodified Humax 5400 at 5V drank an average 59mA even after settling down (at 49.7 degrees btw). Adding a low ESR 1uF was enough to cause the interface IC to shut down.

    The fault by the way is signalled via the /OFF flag: it's primarily for indicating card presence to the CPU prior to card insertion but also doubles as a fault indicator. Fault signalling works as follows:
    1. IC detects the fault (overcurrent, over temperature, brownout or card removal)
    2. IC shuts down the card (asserts /RST, stops clock, tristates pins, ramps Vcc down to 0V, stops charge pump oscillator)
    3. IC asserts /OFF (pin 4 on Humax 54x0 connector), ie pulls it low
    4. Receiver CPU interrupts, terminates its card comms session, clamps down on RSTIN (which by this time is being ignored anyway) and deactivates /CMDVCC (withdrawing its permission to power up the card).
    5. In response to /CMDVCC high the IC clears its error condition (provided the fault no longer exists, eg over temperature) and deasserts /OFF, making it possible for the CPU to restart card comms when it's ready.


    It's up to CPU firmware when/if it resumes operation following a fault. Some receivers using the TDA80x4 family are really good at restarting while others are hopeless, requiring a powerdown or card wank before they'll restart card comms. Such cases aren't the fault of the hardware or the card. Several gadgets have been devised over the years to try and improve fault recovery (simulated card wanking etc) but ultimately if the card and/or the interface IC notices a problem the best they can do is put their hand up and cease communicating; it's up to the software whether it wants to restart its CAM or not.

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