I have two Mk176 with the following LEDs not working Leds 1-4 , 8-12, .15-18 , 22-25. I can jump from t1 to ld4 and ld3-1 will come on…like wise with all the other transisters jump from t2 to LD 11 and 8-10 will come on. etc etc… but I need to know what ould make the above leds not work.
Miles
Most likely an assembly problem.
Sorry, this forum does not allow picture uploads
If you can provide LINKS (e.g. by using a free online picture base) to HI-RES and SHARP pics of your assembly (both solder- and component side)
then we can take a look and provide some feedback.
Ok I will take the pics and provide a link where they can be seen.
Here is a link for the pics you asked for may take a minute to come up since they are large.
myit-solutions.com/my_mk176.htm
Sorry, but soldering looks rather poor. Numerous joint need rework. Make sure not to damage/overheat tracks/pads.
Hereby a link to the diagram of the kit, to help troubleshoot: http://www.velleman.eu/images/tmp/MK176diagram.jpg
Ok thanks for the reply, however, you cant point me at check this resistor or that transistor. I have checked the resistors and transistors to make sure they are working properly. LEDs 5 -7 work but LEDs 1 - 4 dont. The circuit appears to broken between T1 and LED4 but I dont know how to effectively test or trace that. Any help would be appreciated.
We are puzzled. Why did you place 4 jumpers, when only LD1…LD4 does not work?
By doing this, you turn off LD4, LD11, LD18 and LD25.
smiles…
I was wondering when you were going to ask. I jumped them because when i would short led4, LEDS 1,2,3 WOULD WORK so forth and so on. but I could not figureout why they would not work without the jump to LED4. So to summerize with out the jump to LED4 from T1 LEDS 1,2,3 will not work. With the jump LEDs 1,2,3 will work.
OK, that explains 1 jumper, but why 4? Do the other leds behave the same way?
yes, as explained in the original post.
I have two Mk176 with the following LEDs not working Leds 1-4 , 8-12, .15-18 , 22-25. I can jump from t1 to ld4 and ld3-1 will come on…like wise with all the other transisters jump from t2 to LD 11 and 8-10 will come on. etc etc… but I need to know what ould make the above leds not work.
What is your input voltage? Could it be that it is lower than 6.8V?
I will check the voltage and report back…
WOW thanks you are the greatest… input voltage was 6.76. I put in a fresh battery… cut the jumper from t1 to led 4 and it worke. I removed all the other jumpers and they all work now. Thank you soo much. My question now. Is there anywhere that I should have looked to tell me the minimum voltage was 6.8 volts? I dont recall seeing that any place. Or should I have done the calculations to find that out?
The manual says 9 to 15 Volts so less than 9 is not a good idea.
6.8 Volts = 4 RED leds in series (= 4 x 1.7 volts voltage drop/led).
Thank you very much. Ok so let me sure I understand even though seven lights are coming at one time. I need only be concerned with part of the circuit that has the most lights coming at one time in series. Which would be 4 x 1.7. Again thank you very much I learned plenty just through this.
