Just built MK 131 kit, however light never advances. Always green in two directions, always red in other 2 directions. Resistor pot has no effect. Troubleshooting help? I have checked all solder joints and replaced 4017 IC. Suspect bad transistor
Probably oscillator circuit is not working.
Check T1, T2, T3, R1…R4, R13, RV1, C3, C4
If any doubt, replace.
Apologies for bring up a dead thread. But I’m having the same problem. How do you check them and what do you check for?
Thanks
Just check if they are correctly mounted, if they are properly soldered and if they have the correct value.
I have that same problem, and i have checked the soldering points and i have checked the components! ANY HELP!
Anybody a solution yet?
I have assembled 2 of this kits
1 kit ‘runs’ but in the middle of a cycle (middle leds) go all out.
2nd kit stay’s on and the led’s don’t run (outer red leds are on/inner green leds stay on)
All of the weldings are checked out, the IC is ok, Changing T1 T2 and T3 did’n do anything about the problem.
Help wanted
Did you place the right transistors at their right places? One of them is a PNP (557) while the others are NPN (547). So the transistors are not interchangeable and should be mounted at their exact locations!
Hello
Yes i did put them on their places.
I have 1 kit that is all working fine also.
I measured the T’s and they seem to bee allricht with +/- 900 Ohms.
I’ve cheked every weld…
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.
Hi Support!
At just created Traffic lite not works yellow lights in both directions. What may b ea problem ?
Help please!
Most likely an assembly error.
Please check the numerous posts on this item.
can i use the PS905 for this kit or PS915 ?
Tnx
Not the PS915. You COULD use the PS905 but as this can deliver a high output voltage (not stabilised), it is not recommended. Best you can do: PSU03R or equiv. (stabilised).
High ripple from some power supplies might cause undesired behaviour.
Unit has been designed to run from batteries.
Might work fine when a properly stabilized power supply is used.
NewUser1, having just successfully built this, and made pretty much every conceivable mistake along the way, here’s some ideas how to debug this.
First, make sure you get the assembly manual from the velleman web site, which contains a circuit schematic (the kit I bought didn’t have one; maybe it was older).
On the schematic, you can see that the yellow lights are LD5/LD6 facing toward/away from you, and LD7/LD8 facing sideways.
The three primary errors that would explain your situation are:
(1) The timing line not being connected properly. If this happens, then the RED lights in the opposite direction will also turn off when the yellow lights are supposed to be on (but are off). If that’s what you see, check Q3 and Q9 (pins 7 and 9 on the IC).
(2) The diode not being connected properly. If you see red but not yellow on the yellow cycle, check the cathode (ring side) of diodes D9 and D16. You should see a “high” signal during the yellow cycles. If you don’t, check the connection from pin 7 of the IC to the anode of D9, and pin 9 to anode of D16. I had some comparable problems with my kit, either due to manufacturing error, or due to damage from my amateurish soldering, and had to solder in some jumper wires for faulty connections. If the connections look OK, check the diodes.
(3) The LED not being connected properly. If the cathodes get the right signals, check the LEDs. Do you get “high” signals on the cathode (ring) sides during the yellow cycles? If you don’t, check the connection between cathode of D9 and R7, and R7 and anode of LD5. Same with cathode of D16, R10, and anode of LD7. If you do get signals, check that the LEDs are mounted the right way around (e.g. with the diode tester of a multimeter). Ring side should be ground (negative), other side positive.
Hi support,
I have an “odd” question regarding this kit. the reason so is that I´m going to use it as a controller of an big old danish traffic light running 12volt bulbs. I will do this by having relays instead of the MK131 kits Led´s.
My question is what kind of voltage relays should I buy? and should I leave out some resistors to get more voltage for the relays?
Cheers and thx!
Dan from Denmark, Copenhagen
Sorry, this circuit is not suited to drive relays.
We suggest to replace the leds by opto-couplers and run the relays from the opto-coupler secondary.
My son had this same issue after he assembled this kit. We did some troubleshooting and discovered three problems. One was his fault, two were Velleman’s.
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He hadn’t realized that there are two different types of transistors, although they all look similar. He had swapped T2 and T3.
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The printed pcb shows wrong polarity for C3 and C4. Follow the traces and compare to the schematic, they should be installed reverse of what is printed.
Solving the above two issues resolved the problem of the lights not cycling, but the yellow lights on the front and back weren’t lighting at all. Looking a little further showed that:
- The pcb was completely missing the trace that is supposed to connect the two front/back yellow LEDs in series. We soldered in a wire to connect the two.
Overall, I was pretty disappointed with the quality of this kit. The design is great, but the implementation poor. Caveat emptor.