RC Tank Warfare community hobby forum

For anybody interested in the issue with the Light outputs, please see this thread for ongoing discussion.

Until I hear back from HobbyKing on exactly what component they used, or until jhamm can confirm with a part swap, I can't say with absolute certainty what the issue is, but it does appear very likely to be the MOSFETs. If so, this could potentially effect in addition to the light outputs also IR transmitting and stock recoil/airsoft functionality.

Somewhat surprisingly I myself do not yet posses an actual unit from the production line, so there is a limit to my ability to troubleshoot. I would have thought HK would send me a copy to test before releasing to the public, but for whatever reason they did not.

It would be helpful if anybody else with a production unit could test the light outputs on their board and let us know whether they work or don't work. Please post in the thread listed above so we can have all the information in one place.

Hobby King seems to have pulled the product, anyway the link returns a 404 error now. It is only just now Monday morning in Hong Kong so they are still trying to define the issue on their end. They have however re-affirmed to me they will replace any customer's board found to be faulty. 

Again, it would be helpful if anyone else with a board can confirm whether they can get their lights to work or not. On jhamm's board the lights merely remain on all the time,
and can't be turned off. Whether yours do the same or something else, I would like to know.

I will post more when I know more. 

Did they not make a prototype and send it to you for testing?

They made multiple prototypes; I tested two of theirs personally in addition to the many I made myself. All functioned perfectly fine. There is nothing wrong with the design when built to specification.

Although it would seem clear what happened, I am loath to cast aspersions before they have a chance to explain themselves. I am still waiting for a clear answer.

Hello,
good News!
I rework one TCB and replace Q1 to Q8 by the specified Type of Mosfet.
The Board now work perfect!
The Lights work as speciefied.
Here a Video:

Jhamm fantastic work Can you show a photo of the mosfet you replaced and the new one?

What do you think, can be seen on the photo?
A tiny little bug with tree legs... size = 1,5x2,9mm
Both Mosfet look the same, the only difference is the labeling.
Eight Mosfet have to replace - Q1 to Q8 each one cost 0,21 €
Needed Time for rework 30 Minutes ....

Might be an idea if you can test every function on the board, that way all of the problems can be resolved and a 100% functioning one can be put into production. It would be a shame if one fault was fixed but there were another three that no one knew about?

I am amazed that HK didn't put these boards through User Acceptance Testing, it wouldn't have taken more than a couple of days to check that the boards had been built in accordance with the specification documents.

I am re-posting this here from the RC Universe thread:

What we know so far:

1. At least some but perhaps all boards manufactured by Hobby King were built with an incorrect component. Specifically MOSFETs Q1 - Q8 were replaced with non-functional versions. These control all the light outputs as well as the airsoft motor.
2. User jhamm has confirmed that when these components are replaced with the correct MOSFETs, the board works as expected. Thank you jhamm for your help!
3. Hobby King made several prototypes before production, two of which I tested personally: one in October 2016 and the second in January 2017. Both worked flawlessly. That is not to count the many boards I built myself, several of which have been sent to other users including Erik at Taigen, none of which have shown any hardware issues to date.
4. In short, there is nothing wrong with the Open Panzer TCB design.
5. I provided Hobby King a bill of materials identical to the one posted publicly on the Open Panzer website. The version I gave them also had an extra bit of information - which components they were free to substitute with equivalent parts in order to save money, and which component must not be substituted. MOSFETs Q1 - Q8 were on the do not substitute list.
6. Nevertheless, for reasons unknown, Hobby King did substitute those parts, and the board is therefore lacking several functions.
7. I specifically requested a board from the production line before they went on sale and was told repeatedly it was being sent, but to this day I have never received it and as of yesterday they admitted it still hadn't even been shipped.
8. HobbyKing was notified of this issue Saturday when jhamm notified me. Monday in HK has now come and gone and all they've managed to accomplish is pull the product listing and tell me they are looking into it and will let me know the results when they have completed their tests. I told them we already know the results, and what we need is a statement from HobbyKing indicating what they plan to do about it.

So that's where we're at. We know what happened, but not how or why. Maybe it was a cost-saving measure, although these MOSFETs cost roughly 10 cents a piece in the quantities they would have needed. No doubt there are substitutes that would have worked equally as well, so if they were going to deviate from the specification at least you'd think they'd choose a functional replacement. For that reason I wonder if maybe it was a simple mistake, maybe a tech loaded the wrong thing into the pick-and-place machine. Hopefully they will let us know. If they deliberately used a non-functional part then we can assume 100% of the boards are defective. If they just made an accident at one point in the production run, potentially some boards may have turned out ok. Without a clear answer from them I can only speculate at this point.

Obviously this is incredibly frustrating to those who ordered boards as well as everyone who has waited so long to see this project gain some legs. It is definitely a disappointment and a setback.

I will keep you updated as I get more information from Hobby King.


Luke

Luke what mosfets should I get and where can I source them for my board? I'll gladly change them myself. Thanks in advance