<TL:DR - the new board has been built and appears to work as designed! New post coming soon!>
I've learned a lot during this project. While the goal has always been to build a reproduction board, I also wanted to better understand the cold start circuit itself. Questions I wanted answered include: How do the components work together? What is the sequence of events? And eventually - is there room for modification?
I've found that the system behavior is different than
Progress on the test harness has moved faster than my blogging. 🙂
I'm excited - harness complete and used to test three OEM cold start timers. One works. The other two have peeling solder traces. Fixable but I won't spend time right now repairing them - once one spot is fixed its only time before another bit pops up.
Super interesting to see the behavior of the system. I'll document it so that folks know exactly what is happening when you turn the key. Have to say it's di
Prior to building a reproduction Tii cold start timer box I examined the two boards I have.
Both are out of '73's and are identical in general appearance. By that I mean they appear to be the same circuit board schematic and all passive components are present. Here is the front and back of one of them:
However, the values of some resistors and transistors vary between the two boards. Could be several reasons for this - the system is much more forgiving than I realiz
We've had two '73 Tiis for about 20 years. Neither car has working cold start timer boxes. Both have the manual cold start injector bypass button under the dashboard.
Both cars run well and always start. They have been without a timer box for so long I stopped thinking about it. But I started to think about it a few years ago as my interest in low voltage electronics increased.
I originally considered about modernizing the timer circuit. Build it out of a micro-controlle