The car: 1985 VW Quantum (car with parts made of unobtainium). The problem:The instrument panel cluster is back-lit by three 1.2w bulbs in plastic holders. Only one of the bulbs is being lit. The reason: the copper contacts in the film type circuit board are damaged, and the other two bulb holders are no longer making contact at those points. My proposal: solder a wire from the good bulb contact areas (metal tabs in the plastic holder) to each of the other bulbs contact areas (also in the plastic holders, thus completing a circuit. The next question: In soldering the wires, should the wire form a loop from the working bulb holder to the next bulb holder, then to the next bulb holder, and then to the opposite side of the first bulb holder? Looks like the current should pass through each holder and make the lights work, with this method. Right or wrong? Thanks.
Wiring them in series like that means that each subsequent one is slightly dimmer than the one before it. To get them all equal for brightness, you want to have them wired in parallel. I would draw a wire for each one from the wire that leads to the circuit board. The other option is that you can get replacement circuit boards. The other problem is that the electrical system in 85 was partially multiplexed, and having the wrong feedback can cause other systems to malfunction.
Instrument panel lighting...... MikeT1961.... Thanks for the reply. I wasn't sure about the wiring in series vs. parallel. Wasn't sure which method was which. I've looked at getting a replacement board for the past 6-7 months, and no luck on one for the Quantum. Had the same problem in getting a fuel sending unit, so finally adapted a universal type to my pump housing, and it seems to work well. I will probably wire the lights in parallel as you suggest, just have to find the starting point (I'm electrically challenged). Do you mean start at 12v power source, and wire from that point to each of the bulb holders so they all come on when the key is turned on? Also do the same for 12v negative for the ground to the bulb holders? Actually, each bulb being slightly dimmer would not bother me too much, except for the fact that the bulbs are only 1.2w each, and are somewhat weak on lighting the cluster now. 2w bulbs are available for this application also. Could I use the 2w bulbs in the two holders not currently working? Thanks.
Instrument cluster lighting...... DocZombie... I wasn't going to solder to the PCB itself, but rather to the metal contacts in the bulb holder, then jump to the non working bulb holders. Where the non working holders are, there is no contact left on the PCB. The holder fits to the PCB backing, as the PCB is a film (flexible) overlay on the board. On the one working bulb, the contact points are OK. I've tried to solder to a PCB before, and you are right...it's a PITA.
Instrument cluster lighting.... silverfox.... Thanks for your suggestions. The Quantum was not a popular car, even when new, and parts are much harder to find for them than for say, Rabbit, Jetta, etc. Most parts are unique to the Quantum. Salvage yards in this area of the country usually don't keep much over 5-6 years old. Foreign car salvage yards, about the same, with the exception of a few Rabbits, and newer Jettas. I also belong to a number of VW forums, and very little Quantum activity there. Thanks.
Instrument panel lighting.... KevinVarnes.... Thanks for your reply and making note of the eBay cluster. The car is a gas burner. I believe I am going to solder the wires, and that should take care of the problem. Just bought some new bulb holders/bulbs to do the job. Another cluster would be OK, but there is a slight difference between this cluster and a regular cluster. This car is 100% Euro spec. The cluster is in km/h (no mph markings anywhere), different face lettering/numbering, and is totally different from the US spec car. Fuel gauge is measured in litres, not gallons, and the temp gauge is in C rather than in F.
Instrument panel lighting. Update on the panel lights: The problem has been solved, temporarily. I have soldered wires btween the bulb holders/bulbs, and now have panel lights. However, they are still as dim as those supplied from the factory, which was not a good design to begin with. I have now ordered some 12v LED lights, which I will wire in. I am going w/ the LEDs after trying some from a toy. Those from the toy were designed to run off of two 1.5v "D" cell batteries, so you can well imagine what happened. Worked great for about 30 seconds, and had a more than adequate amount of light. The 12v LEDs should do the trick. I'll post a pic when the job is completed. Thanks for everyone's advice and recommendations.
