Victor Vos
Well-Known Member
My Mastermind GT seems to have died... There is only faint light in the buttons and main screen is out. I tried te reset but did not do anything. I also tried an other power supply but nothing.. Is this the end? 
end?
- Thread starter Victor Vos
- Start date
Victor Vos
Well-Known Member
Netherlands...
The closest place I know of that could fix it is our dealer in Germany, but if you know of a qualified electronics tech, I could talk to them. When and where did you buy it? If it was from a dealer and within the past 3 years, it would be covered under warranty.
Victor Vos
Well-Known Member
It was in the beginning of 2017... and direct from you...
I'll send it to my local repair-guy. I'll let him know how to contact you if needed. Thanks for that!
Keep you posted...
I'll send it to my local repair-guy. I'll let him know how to contact you if needed. Thanks for that!
Keep you posted...
Victor Vos
Well-Known Member
Fixed! Thanks for your help!
Victor Vos
Well-Known Member
Well, we died again...
The new master board has been working for about 2 years or so?
I don't think I want to try another one...
The new master board has been working for about 2 years or so?
I don't think I want to try another one...
Victor Vos
Well-Known Member
Your help is always welcome... I'm a bit hopeless ...
The small screens light up faintly with no text, main screen is off... I think the same as previous.. I could bring it to my local repair guy to check if something's wrong with power supply ... He did change something (can't remember exactly what..), said it was better now... but that was all before I replaced the motherboard....
Anyhow, the GT10 has served me wonderfully for about eight years and your service and help is amazing!
The small screens light up faintly with no text, main screen is off... I think the same as previous.. I could bring it to my local repair guy to check if something's wrong with power supply ... He did change something (can't remember exactly what..), said it was better now... but that was all before I replaced the motherboard....
Anyhow, the GT10 has served me wonderfully for about eight years and your service and help is amazing!
Victor Vos
Well-Known Member
I found the comment of Bob, who repaired it the first time. Mostly abracadabra to me... I think het sent it to you too...
"
There was a short in the +3.3V supply, which was outputting only 1.1V. Resistance across C51 was only 2.7 Ohms. The +5V and +18V supplies were good. So that pointed to the direction of a fried CPU, but I wanted to be sure it was not something with U14 itself (it got very hot). So I temporarily removed U14 pin 3 (3.3V output) from the circuit and powered the +3.3V rail with my current limited bench power supply. It wanted to draw a lot of current, around or more than 2000mA, so there definitely was something wrong in the circuit áfter U14. My plan was to reduce the maximum current (bench supply in limited Continuous Current mode of around 1000mA, twice the amount U14 could deliver) to see which parts would get hot, the CPU or some of the other digital logic, which would point to a broken CPU or another part. However, after like ten seconds the current dropped from 1000mA to about 160mA and I heard a relay click. After putting U14 pin 3 in circuit again, the output would still be nicely 3.3V . So the short circuit was burnt out of the circuit by providing a little more current, ha! It must have been a tin whisker somewhere, most likely between some of the CPU pins because they are really close together and there were some stains of tin particles. I cleaned the board with IPA. Will test the device for a day, but I think it is a closed chapter now ;-) Also, I desoldered the failure-prone DC-inlet because of some tiny cracks starting to form in the fragile ROHS solder, removed the remaining solder and resoldered it with leaded solder for a stronger, longer-lasting connection.
Groet,
Bob"
maybe it's the same thing...
"
There was a short in the +3.3V supply, which was outputting only 1.1V. Resistance across C51 was only 2.7 Ohms. The +5V and +18V supplies were good. So that pointed to the direction of a fried CPU, but I wanted to be sure it was not something with U14 itself (it got very hot). So I temporarily removed U14 pin 3 (3.3V output) from the circuit and powered the +3.3V rail with my current limited bench power supply. It wanted to draw a lot of current, around or more than 2000mA, so there definitely was something wrong in the circuit áfter U14. My plan was to reduce the maximum current (bench supply in limited Continuous Current mode of around 1000mA, twice the amount U14 could deliver) to see which parts would get hot, the CPU or some of the other digital logic, which would point to a broken CPU or another part. However, after like ten seconds the current dropped from 1000mA to about 160mA and I heard a relay click. After putting U14 pin 3 in circuit again, the output would still be nicely 3.3V . So the short circuit was burnt out of the circuit by providing a little more current, ha! It must have been a tin whisker somewhere, most likely between some of the CPU pins because they are really close together and there were some stains of tin particles. I cleaned the board with IPA. Will test the device for a day, but I think it is a closed chapter now ;-) Also, I desoldered the failure-prone DC-inlet because of some tiny cracks starting to form in the fragile ROHS solder, removed the remaining solder and resoldered it with leaded solder for a stronger, longer-lasting connection.
Groet,
Bob"
maybe it's the same thing...
Interesting - that's the first time I've run into a tin whisker in the PBC. The big problem with lead-free solder is that it can grow these crystals that are effectively little wires that connect things that aren't supposed to be connected. It's possible that it happened again, in which case the solution should work again, as long as the CPU chip is still good.
A more permanent solution would be to flow some leaded solder into the solder joints, or replace the CPU chip with a new one, and use leaded solder when replacing it. If you decide to go the latter route, I can provide the information needed to program the new chip.
Not sure why yours was affected by it and not others, that's the big mystery.
A more permanent solution would be to flow some leaded solder into the solder joints, or replace the CPU chip with a new one, and use leaded solder when replacing it. If you decide to go the latter route, I can provide the information needed to program the new chip.
Not sure why yours was affected by it and not others, that's the big mystery.
Victor Vos
Well-Known Member
I'll take it to Bob, keep you posted...
Victor Vos
Well-Known Member
Bad news from Bob: there is a short in the CPU on the motherboard (wich is relative new!)
Also the soldering on the new motherboard was very poor according to Bob..
Also the soldering on the new motherboard was very poor according to Bob..
Please contact me at support@rjmmusic.com and we can work something out.
Victor Vos
Well-Known Member
Thank you for outstanding service, again.