dr bob

Just a reminder to folks swapping in different chipsets-- Mark the old chips so you know which box they came out of. One needs to be marked LH and the other EZK. On the off chance that you might someday want to return the original chips to service (maybe you need to pass smog...) it's pretty handy to know which chip goes in which box.

John Speake

Hi Eric,
Any mechanical switch device has a poor reliabilty record, especailly ones carrying very little current. MTBF analysis always tells you that.

I wouldn't like the thought of a switch in there, but that's just my personal opinion !

Glad to hear you're enjoying your car the full 12 months !

regards,

John Speake

Shane said:
"Do you also do cruise control brains? Mine need some help".

hi Shane,
Not at present, although they are on my list, they seem to fail quite often.

I will get round to it, but I have several new projects in hand at present........

Regards,

BC

Doz - can you send me that instructions set?

Thanks

BarryW

Mine were in sockets. If you do have a soldered prom, replace it with a socket if you're removing it anyway.

Erik - Denmark

John,
Thanks - I buy your point and will ask the electrician to remove the old EPROM (I do not use it) and install the new EPROM direct by soldering.

When the switch can be a problem the sockets must be a even bigger problem - - of course all depending of the quality of the switch or socket

I think he mounted the switch because we got the program for the EPROM (Standard Porsche program) from Mr. Muller in Germany via e-mail, so maybe he was not 100% sure that would work - but it works perfect!

Regards from Erik in Denmark

John Speake

Hi Erik,
Well, I would say that an IC socket is better - it has a much greater contact area than a switch. Contact pressure is also much greater, so that keeps air out of the contact areas.

Glad you got your car sorted out OK !

Erik - Denmark

He John,
I talked to the el-technician, he said:
- You are right about the MTBF - (For us not el-freaks that means: 'Mean Time Between Failure')
- The contact used: Gold plated on Nickel 12V 500mA nominal 10mV / 1mA min 24V max, and therefore he is not worried, but
- As soon as he/we have confidence with the new program, he will remove the old EPROM and install the new by soldering

John Speake

hi Eric,
I think you have the answer there - the low current taken by the ports into the EPROM are probably less than the 1mA min rating of the switch.

It certainly looks as though most LH 2.2 EZKs have soldered EPROMs.

Erik - Denmark

John,
Thank you - Also today I learnt something!
Regards from Erik in Denmark

dr bob

As often as the chipset on my car gets swapped (three times in four years...) I guess I should be hunting a set of those fancy ZIF (zero insertion force) sockets for the proms. Add some Dzus fasteners for the two boxes and conductiobve velcro for the covers, and I'll be good to go.

Those ZIF sockets look like they are a lot more rubust than the original friction-fit sockets, FWIW. The probably weigh like five times what a standard set weights, so I'll have to trim a wipre blade someplace to maintain the perfect F/R balance in the car. (!!)

John Speake

Dr Bob,
Why are you changing chips so often ? Have you changed for the better ?

I'm intrigued !

ZIF sockets are good, I use one in my EPROM reader/writer, although I think the contact pressure and air seal won't be as good as the ordinary socket.

The ECus are near the mid point of the car, so I guess you won't need to worry too much about the balance :-)