The leds do not flash on this product. How is this solved?
By searching for any mistakes…
- components correctly mounted>
- good quality of soldering joints
- …
As always: a very sharp and big photo of component and soldering side might help us here. Upload pictures to a free hosting service and post the link here.
My MK 102 does not flash either. One LED lights up. I examined the solder joints under a stereo microscope and they all look OK. I have had problems with another Velleman kit as well, the MK 127. (With this kit the tiny motors were almost impossible to attach, even though I have experience attaching such things to a PCB. Maybe Velleman is working so hard to keep costs down that the components are just too cheap to be reliable.
Would appreciate advice on the MK 102
randy
Make sure both LEDs and C1 & C2 have correct polarity
Which LED stays on?
Our experience tells us that the most unreliable part of a kit usually is the assembly and/or soldering job.
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.
Yes, Velleman tries to keep the costs down (so YOU have a good kit for an honest price!) but NO, they don’t use bad components! Yes, I am a dealer of Velleman but that decision was MINE! Velleman did not force me. I just CHOOSE Velleman because of all bad experiences I saw with other brands of kits. Believe me: Velleman kits are one of the best kits in the world. Even the Velleman kits I bought and assembled as a kid are still working! And I’m not alone: many of my customers have very old Velleman kits that are still working perfectly. Most problems are indeed bad soldering. And it is sad to say but 90% of the kids that leave a technical school can’t solder correctly even though they think they can…
Quoted for truth!
They think they only need the right equipment and it will do the job, like a $300 soldering station and such. The most expensive part of my assembly station is my digital multimeter. I’m still using my cheap 15W Radio Shack soldering iron. I added a nice stand with sponge and tip tinner/cleaner, but that’s it. A new $2.50 tip for it every other year is all it needs.
It is amazing what can be done with such basic tools. Like the radio in the picture below. The assembled “kit” is about 19x19 cm (7.5x7.5 inches) big, came with empty PCBs and well over 1,000 components organized in bags of bags. This kit goes to the point where one has to wind the toroidal coils for the RF filter board (the six things of copper wire around ferrite rings in the upper right corner).
The trained eye will see that there is a tiny little “air borne” copper wire going from pin 2 of op-amp A2 to the resistor nearby. I don’t know if I damaged the PCB pathway by ripping it off or overheating it when I had to desolder A2 (because it needed to be turned around 180 degrees). The important detail for this discussion is that the tool that found the problem wasn’t a magnifying glass. It was my multimeter.
So you see, Randy, the only person who never made an assembly mistake is the one, who never assembled a kit. Like the only guy who never spilled a beer sure doesn’t drink beer. Your problem may be very similar to the one I just described. Take out your multimeter, set it to Ohms and start poking around in your turned off kit. If the schematics (I think Velleman provides those for all kits) say that there is a connection between one component and another, then those pins should read 0 Ohms. If you don’t have a multimeter, buy a digital one or forget about electronics as a hobby. And do NOT get the cheapest one … something around $50 will serve you a long time. Anything below is useless junk.
Click on the image to get the full resolution. (Depending on your browser you may have to click on it twice - in full resolution you can read the part numbers).
Regards,
MostlyHarmless
Thanks. I see the photo. What is the part number for the op amp you describe?
Randy
[quote=“rand95060”]Thanks. I see the photo. What is the part number for the op amp you describe?
Randy[/quote]
A2
There are 3 small boards mounted vertical in the center of the main PCB. A2 is on the left side of the middle one.
To Velleman support: I would like to ship you my LED Flasher MK 102 for inspection. You would not need to ship it back to me, just let me know if you find a mistake. I have successfully completed a significant number of other kits involving soldering and not had these problems. My other kits include a cyborg robot and an Elenco auto scan radio model FM-88K.
If you are willing to do this send me your address. If you dont want to post your address let me know and I will email you.
thanks
Randy
It might be easier and faster if you post clear and sharp pictures on a free service
I have posted photos of the MK 102 project on:
postimage.org/gallery/13w0gbjk/
Note that I clipped off the red and black power leads and also that I clipped one corner of the board as a reminder that it doesn’t work yet. Let me know if you need better resolution.
Thanks.
Randy
It looks like there maybe a couple of problems.
It’s hard to tell but it look like the LEDs maybe shorted and the trace between the positive coming in from the battery to the wiper of RV2 maybe shorted.
The inside leg of RV2 (I think should be open) is shorted to 9 volt trace above it.
From what you have indicated it sounds like you have a working MK102.
If you have a DVM compare continuity between each post of RV2 to the positive lead.
There should only be one leg that should show continuity
Let me know if you understand what I’m saying
Thanks for your detailed response. I assume the wiper refers to the “upper” RV lead. I purchased another MK 102 kit and will photo it before starting work. I plan to use about 10 of these at the local boys and girls club in santa cruz california, so especially appreciate your help.
Randy
Rand,
Yes the upper RV lead