Thanks Martin, After reading that through 3 time I think it has sunk in..... Thanks for helping me with that one I owe you one now. Cheers Paul ----- Original Message ----- From: "Martin Gutkowski" <webmaster@xxxx> To: <dmcnews@xxxxxxxxxxxxxxx>; <doc-uk@xxxxxxxxxxxxxxx> Sent: Friday, December 28, 2001 10:35 PM Subject: [doc] Door Lock Module - some technical musings... > Hi All, > > I've spent some of my quiet time this Christmas looking at the DeLorean > door lock module. Having spent time previously examining Dave Swingle's > pain-stakingly documented layout diagram and circuit diagram on the > DMCnews tech page, I've discovered some things and re-engineered two > modules already for reliability and longevity (for at least the next 20 > years :-) > > This was prompted by Paul Salsbury complaining that his didn't work at > all, and sending it to me to fix. > > Firstly, referring to the circuit diagram here > > http://www.dmcnews.com/Techsection/graphics/lockcircR1.jpg > > some errors: > > 1) Transistors Q1 and Q11 are in fact BFR39 and NOT BRF39 as stated. > BFR39's are pretty common and still available. I got ten on sample from > www.diamondelec.co.uk > > 2) R1 and R11 are in fact in series between D2 and the emitter of Q1 > (and likewise between D12 and the emitter of Q11). C1 and C11 connect > directly between ground and Q1 and Q11's emitters respectively. > > What do we know about the module and it's problems? > > 1) The relays can stick shut energising the solenoid until it burns out > or the curcuit breaker trips (if present) or the battery flattenns. > > 2) Referring to Nathan's notes on the module, the transistors are > vulnerable to spikey voltages resulting from intermittent earthing > during the lock or unlock cycle. He also notes that he'd put a diode in > series between point A and output pin 2. > > 1: The original relays are open to the air and have a pathetically small > contactor. This is a recipie for sparking casing gumming up of the > contacts. Regular cleaning with a switch lubricant like servisol10 is > likely to prevent the contacts sticking, though it's an underrated > device. (A small fact which may be of interested to some is that the > explosion aboard Apollo13 was traced back to the use of an underrated > relay getting stuck closed - you have to read the book to get the > detail!). I found a nice 10A miniature relay made by Siemens available > from Maplin for £1.49. It's almost the exact same size as the stock > relays. > > 2: When I tested Paul's module, I discovered that one "side" of the > circuit was functioning correctly, but the other was failing to charge > its capacitor (the one that energises the relay). The likely culprit was > the transistor Q1 so I replaced it (I also replaced the two capacitors > on principle. On re-trying the module, I found no change. This was a > puzzle because there's not a helluva lot else on the board that can go > wrong! Remember this board is actually two identical circuits in > parallel - one performs the "lock" function, the other the "un-lock" > function. Paul's would unlock but not lock. It was after a lot of > head-scratching that I noticed something strange... D5 has no "partner" > on the "lock" side of the circuit. Even stranger, my own working module > had D5 mounted by hand to the underside of the board, with the track > cut. Pauls was evidently a later board with a position for D5. NEITHER > board had a place for the same diode on the lock circuit. The lock relay > on Paul's board was sparking badly when manually closed it, so I > concluded that Q1 was being blown due to a spike on the base. I cut the > track from pin 2 to point A and added in a diode (marked "D" on the > diagram). I also added the protection diodes from point A and B to the > 12v supply. Hey presto the module works fine, with a lovely blue flash > ever time the lock relay is triggered. So I removed the stock relays and > replaced them with the Siemens ones. It required some creative > additional wiring, but you can use the holes for the original relays to > feed to the underside of the board. It's very easy to solder direct to > the tracks on the underside as it was never coated. > > > > > > > > DOC UK Website: www.delorean.co.uk > Unsubscribe: doc-uk-unsubscribe@xxxxxxxxxxx > ** Unless otherwise stated, all messages posted to the group are assumed public and may be printed in the club magazine ** > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ > >