I have bought a MK134 from Maplins today and have assembled it, I am very experienced at soldering circuit boards as it was part of my work, fitted a new battery and although the steam sound and whistle are audible it is very volume. Any ideas as to the problem and what voltages shoud be found at parts ot the circuit.
Have rechecked the assembly again and found voltage low at C8, checked voltages on IC1 and found incorrect voltage across pins 2 & 3, checked the board using my magnifying specs and found a solder overspill bridging contacts 8 & 9 on IC1, separated and now working fine and realistic sounds obtained.
Thanks for you forum for putting me on the right track
Difficult to solve without being able to check your circuit.
Most likely 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.
I have found a general problem which seems to affect a number of the Velleman kits, and the MK134 steam engine noise generator in particular. It is the separation of the copper lands from the substrate of the printed circuit board.
These kits are intended for beginners, who may not solder very well as they start. The printed copper lands do not seem to adhere very strongly to the fibreglass board, and if you move a component after soldering - even just nudging it - you risk breaking the copper land underneath the varnish coating.
I am not a beginner, but I have just built an MK134, and I have had to mend 7 (!) such breaks. The problem seems particularly acute for the capacitors. These are tall components, so any nudging on their tops after they are soldered is magnified at their base by leverage.
C10 is a classic example of this problem. It feeds the speaker at one side, so a break here stops all sound. On the other side it takes a feed from the T3/T4 amplifier, so a break here means that the volume will be very low.
If you have problems with the MK134 I would suspect a break in the lands next to a capacitor. You can usually mend these by adding wire onto the solder side of the board. Another useful tip is to solder the capacitors last, to minimise chances of bending them. Do NOT be tempted to straighten a component out after soldering - this is just asking for trouble.
Perhaps Velleman could consider improving the adhesion of the copper lands in some way? They are some of the most delicate I have ever worked with…
7 broken traces on a kit like the MK134? That indicates something else to me. PCB traces coming off is caused by overheating.
May I ask what type of equipment you are using? What is the power of your soldering iron? What kind of tip are you using and in what condition is it (photo would be good). What thickness of solder, with or without rosin core? Do you use a wet sponge and tip cleaner/tinner regularly while working? Do you have extra flux and a tiny brush at hand?