My T-90 NOT STARTING AFTER 3 YEARS

[dai phan]

Hi all,

After 3 year hiatus I now get back to RC tanks. I tested all my 12 tanks and all worked fine with the exception of the HL T-90. I tried diffent batteries amd the tank is dead as door knob. It has 6.0S board. Where do I go from here? New board, new battery switch? Dai

[tank_me]

Switch could be bad. So no lights on start up at all? Does it use the old Tamiya type battery connector? The board could be bad, but the 6.0 was pretty reliable.

[keilau]

Hi all,

After 3 year hiatus I now get back to RC tanks. I tested all my 12 tanks and all worked fine with the exception of the HL T-90. I tried diffent batteries amd the tank is dead as door knob. It has 6.0S board. Where do I go from here? New board, new battery switch? Dai

1. Open the tank, unplug all MFU connections and re-connect carefully.
2. If #1 does not work, use a jumper to short out the on-off switch.
3. If #2 does not work, swap the TK6.0S board with one from the working tank.

[Rubicon99]

Hi all,

After 3 year hiatus I now get back to RC tanks. I tested all my 12 tanks and all worked fine with the exception of the HL T-90. I tried diffent batteries amd the tank is dead as door knob. It has 6.0S board. Where do I go from here? New board, new battery switch? Dai

The 6.0 systems had a repudiation failing. Basically they would run fine one day and then just stop working the next. This is one of the reasons they were so quickly replaced with 7.0 systems.

Given the history of the 6.0 I suspect it just died. Hopefully not though.

[dai phan]

Hi all,

The reason was caused by a bad switch and after it was replaced it ran fine. However it ran for only 2 seconds then shut down. I turn off on 3 times and the same. On the fourth time there was burning smell and smoke was everywhere. I opened the tank and the board was melting through the plastic casing. Luckily no other damage. I had a spare 6.0S board and now it runs fine. I only run for 5 seconds for fearing it will catch fire again. Maybe some wires touching causing a fire? Dai

[dai phan]

The 6.0 systems had a repudiation failing. Basically they would run fine one day and then just stop working the next. This is one of the reasons they were so quickly replaced with 7.0 systems.

Given the history of the 6.0 I suspect it just died. Hopefully not though.

Shall I go ahead and order some 7.0 boards and replace all 12 tanks with these Dai

[Rubicon99]

Shall I go ahead and order some 7.0 boards and replace all 12 tanks with these Dai

That is up to you. I would replace them as they stop working with either 7.0 or 7.1 systems.

[dai phan]

What do you guys think the reason for the board to burn? I replaced with new 6.0s board. Is it safe to drive? Dai

[RichJohnson]

They usually burn up from an internal or external short.
if external, any other board will either detect it and shut down if it’s downstream of protection circuits or it will burn up.
try the other 6.0 for a little. It and see if it run ok. The most common external short from the mfu on a tank is the turret motor wires. Following that is the smoker shorting out and then rarely a motor problem, but any of these would only smoke an mfu if you engaged them , like Turing the turret or turning on smoke.

if the mfu is smoking just being turned on, it’s internal, and it happens more than it should with 6.0s. 7.1 units are light years ahead, with metal cases too.

[dai phan]

They usually burn up from an internal or external short.
if external, any other board will either detect it and shut down if it’s downstream of protection circuits or it will burn up.
try the other 6.0 for a little. It and see if it run ok. The most common external short from the mfu on a tank is the turret motor wires. Following that is the smoker shorting out and then rarely a motor problem, but any of these would only smoke an mfu if you engaged them , like Turing the turret or turning on smoke.

if the mfu is smoking just being turned on, it’s internal, and it happens more than it should with 6.0s. 7.1 units are light years ahead, with metal cases too.

After I turn the tank on, it shuts down after one second. I kept turming it back on and on the third time the tank smokes heavily,. I then replaced with the new board and it ran fine although I only ran for 3 seconds fearing it will burn up again. How do turret wires cause a short in the MFU board? Shall I get new turret moitor? I already ordered two 7.0 boards. I wonder if there were any reports of tanks buring up with 6.0S board. You can see the flame/heat strong enough to melt the plastic casing! Dai

[Rubicon99]

After I turn the tank on, it shuts down after one second. I kept turming it back on and on the third time the tank smokes heavily,. I then replaced with the new board and it ran fine although I only ran for 3 seconds fearing it will burn up again. How do turret wires cause a short in the MFU board? Shall I get new turret moitor? I already ordered two 7.0 boards. I wonder if there were any reports of tanks buring up with 6.0S board. You can see the flame/heat strong enough to melt the plastic casing! Dai

Don't overthink the problem it's in the board where the issues is at and many random factors can cause the failure to pop up. It's mostly just bad subcontractors work that built the boards. Fact is HL saw there were some issues back around 2021 time frame and corrected them with the 7.0.

If your 6.0 shuts down repeatedly and the battery is fully charged you have a bad MFU, just change it out with a newer version.

[dai phan]

Don't overthink the problem it's in the board where the issues is at and many random factors can cause the failure to pop up. It's mostly just bad subcontractors work that built the boards. Fact is HL saw there were some issues back around 2021 time frame and corrected them with the 7.0.

If your 6.0 shuts down repeatedly and the battery is fully charged you have a bad MFU, just change it out with a newer version.

Shut down does not concern me. It is the fire that could destroy the whole tank. Had I did nothing likely the hull would be burned down. Dai

[Rubicon99]

Shut down does not concern me. It is the fire that could destroy the whole tank. Had I did nothing likely the hull would be burned down. Dai

It was shutting down as it is designed to. This keeps it from melting down as it did. When you restarted it over and over it finally shorted out...and poof.

If the 6.0 shuts down more then a couple of times and is forced to restart immediately afterwards "issues" are possible to occur.

Will one meltdown again? Maybe...maybe not. If you are not confident in the 6.0 reliability then replace them with 7.0s.

Accept that there is no rhyme or reason the 6.0 series was just not up to snuff and has been replaced with a very safe and reliable new system.

HL or whoever you purchase from is not going to refund or give you a new system. They did do that for a short while but not any longer.

[dai phan]

Hello all,

This morning before work I ran the 90 for about 10 minutes with gentle turret turnings. No smoke detected and no shut down encountered. I have read both the 72/90 have hull flaw design that tend to crack so I did not drive heavily. Rubicon 99 talked about re-enforcing the weak area with wires and glue so I would like how it is done in pictures if possible. Dai

[Meter Rat]

This is the internal bracing I did for my T72. Made from 25mm angle, and 25mm flat bar. Note that the upper hull is held on with magnets. Fixed in with 4mm bolts and JB Weld.

[dai phan]

This is the internal bracing I did for my T72. Made from 25mm angle, and 25mm flat bar. Note that the upper hull is held on with magnets. Fixed in with 4mm bolts and JB Weld.

So you glue the bar via epoxy to prevent from spreading? Dai

[Meter Rat]

So you glue the bar via epoxy to prevent from spreading? Dai

Yes. All installed with JB Weld, a two part resin/epoxy type glue which can be filed, drilled, sanded and tapped to receive a thread. There are now four bolts holding the side pieces in place. I may look to further reinforce the front mounting where the idlers attach.

[dai phan]

That is lots of work that should not be on the buyers. I think I just run the tanks gently on the carpet. Dai

[Rubicon99]

That is lots of work that should not be on the buyers. I think I just run the tanks gently on the carpet. Dai

If you don't want to do the work needed to make some tanks durable enough to use outside the house then you need to look at Tamiya tanks kits and paying $1000+ just for the tank. The TX/RX will set you back another ~ $200 - $400. Tamiya currently only produces five tanks, Abrams, Tiger 1&2, Centurion and M4. Kinda limited selection.

So given the HL much lower prices and the minimum amount of work needed compared to the cost and time building a 2000+ part Tamiya kit, is it really a lot of work modifying a HL tank?

My T72/90 front end strengthening modification takes most people about an hours. It takes an hour because the epoxy has to dry. Is it not worth it to pay 2/3 less for a tank with a little of your time.

[dai phan]

If you don't want to do the work needed to make some tanks durable enough to use outside the house then you need to look at Tamiya tanks kits and paying $1000+ just for the tank. The TX/RX will set you back another ~ $200 - $400. Tamiya currently only produces five tanks, Abrams, Tiger 1&2, Centurion and M4. Kinda limited selection.

So given the HL much lower prices and the minimum amount of work needed compared to the cost and time building a 2000+ part Tamiya kit, is it really a lot of work modifying a HL tank?

My T72/90 front end strengthening modification takes most people about an hours. It takes an hour because the epoxy has to dry. Is it not worth it to pay 2/3 less for a tank with a little of your time.

Is it possible to see how you re-inforce this area? I do not have the machine to cut out the metal plates like Meter Rat. Dai