[PLUG-AV] Found failed part on the dead Numato

[Harry McNally]

Cheers Nick

I am prevaricating on the order until I get some more details from another 
supplier.

So, if you are happy to use the CC and get some in, I will get one on the 
board and see if it will "boot"

Just let me know if you get time to order so I don't order as well :-)

All the best
Harry

On 22/2/21 9:08 am, Nick Bannon wrote:
> Heya, Harry! Sure, if you've got an order going in, grab 'em now.
>
> (I haven't done an order yet, though I'm sure I can get a minimum shipping
> order together, still happy to. Yes, PLUG has a credit card handy for
> online orders, or can reimburse promptly.)
>
> Thanks,
> Nick.
>
> On Sun, Feb 21, 2021 at 10:18:29PM +0800, Harry McNally wrote:
>> Ah ha! I see a PLUG + POSH do on March 14. Do you think we can fix the
>> Numoto by then ?
>>
>> The stock detail on that part is:
>>
>> "*197* available for 4 - 5 business days delivery"
>>
>> which means it is coming out of the UK. So that should be enough time. I
>> have some parts I may order shortly. If I do, I will give you a text or ring
>> to see if you have odrdered some and, if not, add to my order. Or let me
>> know if/when you have ordered. I realised PLUG may not have a CC which is
>> the easiest way to place a guest order.
>>
>> All the best
>> Harry
>>
>> On 11/2/21 11:18 am, Harry McNally wrote:
>>> Hello Both
>>>
>>> On 11/2/21 9:45 am, Nick Bannon wrote:
>>>> Heya, Harry, Patrick!
>>>>
>>>> On Wed, Feb 10, 2021 at 01:11:24PM +0800, Harry McNally wrote:
>>>>> Hi Nick
>>>>> See attached. U8 had failed in the 1.5 volt supply and was overcurrent for
>>>>> the 1A plugpack. Plugpack shut itself down after 45mS then retried to start
>>>>> after a second which is why the Numato LEDs were flashing. I think this may
>>>>> have saved the board; fingers crossed.
>>>> Fabulous! Was that all hardware diagnosis?
>>> Yes. I used my low impedance meter to see where on the board the
>>> resistance was lowest across the 12V supply and this led to that PSU
>>> circuit and the TI switcher was the only possible cause. Once removed,
>>> the impedance matched the good board (well .. "open circuit" from a low
>>> impedance perspective).
>>>
>>>>    and/or have you tried talking to the firmware on either board over USB?
>>> You've got me. Many months ago I was shopping for a Xilinx JTAG
>>> programmer clone and settled in a Open PCB to build up (hasn't arrived
>>> even now) I did this assuming I had to bring up a bricked board (and to
>>> test the FPGA spoke back to me etc).
>>>
>>> Because of that expected entry point I didn't realise that there was
>>> also USB access to JTAG. So I haven't tried this access to either the
>>> good or the dead board yet.
>>>
>>>>> This is U8:
>>>>> https://www.ti.com/lit/ds/symlink/tps54625.pdf
>>>> ooh, up to 6.5A output...?
>>> It may not be used to deliver 6.5A although 1.5V supplies in FPGAs (like
>>> PC CPUs) can be quite high currents.
>>>>> I have removed it and that has cleared the 12V supply loading but I don't
>>>>> want to power the circuit in case 1.5V is necessary to prevent failures
>>>>> elsewhere.
>>>>>
>>>>> I'll will add some of these parts to another order (or freight is $15).
>>>>> Element14 have them:
>>>>> https://au.element14.com/texas-instruments/tps54625pwp/ic-sync-step-down-650khz-htssop/dp/3007368?ost=tps54625
>>>>>
>>>> Lovely - and don't be out of pocket, we're happy to pay.
>>>> Thank you for your time so far.
>>> I'm a bit away from another order so, if you like, jump on the element14
>>> site and order say three pieces with a CC as a guest (no difference in
>>> price). Sometimes element14 run specials for free delivery but I haven't
>>> seen that offer code come through recently. So freight will be $14 or so
>>> which doubles the price of three pieces unfortunately. I suggest three
>>> in case some intermittent short exists on the 1.5V rail. I can't see any
>>> now and the TI part should current limit and protect itself but not much
>>> point in buying one then "*smoke* oh, we actually need another one now"
>>> scenario.
>>>
>>>> I'm hoping we can get together for an AV hack session very soon, I'm sure
>>>> the new PLUG VP, Patrick, is up for it. We'd want to use a "working"
>>>> Opsis board, and probably a cheap black-box hdmi2usb widget too - but
>>>> debugging is really hard if every setup is a unique snowflake.
>>> Ok. Well what about if you get parts and I repair the PCB and see if we
>>> get the blue "loading" light (then off) like the good board. After that,
>>> have a good look at USB programming etc at the following AV meetup ?
>>>
>>> We can try the board access through USB and decide if we want to by an
>>> off-the-ebay Xiling JTAG debugger clone (around $30US vs $200US for the
>>> genuine Xilinx device).
>>>
>>>> We'd rather start with replicating someone else's system than figure it
>>>> all out for ourselves, or we just don't end up getting very far in a day:
>>>>
>>>> - https://debconf-video-team.pages.debian.net/docs/hardware.html
>>>> - https://debconf-video-team.pages.debian.net/docs/opsis.html
>>>>
>>>> Every Second Sunday - including this Valentine's weekend coming -
>>>> is an opportunity, but maybe we need something else to kickstart the
>>>> process again.
>>> Yes. I won't have the PCB ready by Sunday but happy to repair then
>>> attend the next meetup.
>>>> Had a lovely PLUG talk on Tuesday - but we were running around getting the
>>>> basics working at the last minute, like any kind of audio out, as usual...
>>>> https://meetings.ucc.asn.au/b/nic-4cd-3jg
>>> Listening and viewing now ..
>>>>> When I get them I need to use hot air to re-install (it has a heatsink tab
>>>>> underneath the package). But probing around the circuit, I cant see anything
>>>>> shorting the 1.5 volt supply rail so U8 alone may fix it.
>>>>>
>>>>> Smalls steps but progress none the less :-)
>>>>>
>>>>> All the best
>>>>> Harry
>>>> Thank you!
>>>> Nick.
>>> More than welcome Nick. It is a small contribution back to PLUG.
>>> Apologies I put this aside waiting for the JTAG PCB.
>>>
>>> All the best
>>> Harry