Andrew, Good question and others who are have or are thinking of wiring an expensive head unit into their 1600 could benefit from having a read also, as most of you know the wiring system used in a 1600 is just short of weird.
When wiring in a head unit in a 1600 and you use a relay (recommended) to power the accessory then it is important to wire in a diode in the accessory switched supply past Pin 87 as the wiring in a good quality relay should not allow any back feed up Pin 86. If you have not used a relay then I would recommend that you wire in a diode on both the power feed and the memory feed, and even if you use a relay you can hurt anything with wiring in a diode on Pin 86 either (Andrew's question). Some head units have what is called a "logi" circuit capability which among other things mainly allows you to power the accessory for a length of time with the sense circuit unpowered i.e. with the ignition or accessory feed turned off so the logi circuit powers the unit through the battery feed that powers the memory functions - many Phillips & Kenwood units have this capability but strangely enough not all models come standard with an inline diode pack or filter of any kind to protect the unit - my old Phillips (ex R31 Radio/Cassette) with no logi circuit actually has a filter but my much newer CD unit with logi technology as a feature strange as it may seem didn't. After blowing the original CD unit up under warranty and figuring out what happened they replaced it with a new unit without much fuss other than inconvenience. Phillips said that they had no idea that there are cars still out there that are wired like a 1600 but they said they were happy to wear the cost of the occasional blow-up instead of fitting diode packs on all their products - reasonable explanation I guess but none the less in my view very strange logic. The problem with "logi" circuits on a 1600. If you are running the head unit on the logi circuit and the 1600 starts to fog up so you turn the ignition key to accessories to enable you to run either the wipers and/or heater fan, everything is fine until you then turn off the heater and wipers by just turning off the accessory power at the key, then the head unit will instantly back feed and attempt to power the heater and/or wipers etc result is caboom inside the head unit - she blows the crap out of the memory circuit and also if you've got it cranked up at the time it kills the output circuits more times than not too. Every time the head unit it turned on from that point on it behaves as if it is started up from a cold boot i.e. asks for code etc, and it looses all the pre-sets, time etc. and this as you can imagine is a pain in the bum and that's if you got away with only the memory functions blown up. I hope that this explains it a bit better for you - questions welcome as always. regards, Terry Hi Terry A while ago you discussed wiring headunits and things via diodes to stop backfeeding other accessories (see msg below). In the case of a headunit requiring both a constant 12V and accessory switched source, is a diode required in both lines, or just the accessory-switched supply? Thanks Andrew From: Terry Rudd Subject: RE: wiring confirmation Date: Mon, 14 Oct 2002 02:12:13 -0700 ---------------------------------------------------------------------------- ---- Andrew, I've been told you can also use an IN4007 but I've always used the IN4004 with results as expected so far. I've wired a hypo amp this way and an earthquake in another 1600 and it's still running great (buggers a 1600 boot seals badly if you run it closed with that baby and doesn't do the battery much good either.) You only need to use the diode in the 12v feed from the relay from Pin 87 or 12v power source past the pickup point if you opt not to wire in a relay. It is important when you use a diode to power a head unit, amp etc to never ever wire in another accessory past the diode, i.e. one wire with diode for one accessory, more than one accessory then use a separate feed and another diode on the output from Pin 87. Things can and often will go bang if you don't follow this rule as one unit can back feed off the other - draw a diagram to illustrate the circuits if you don't understand why this happens. Also, there is no point wiring the diode on the feed to Pin 30 as it allows back feed up the sense wire (Pin 86) if the relay ever chatters (usually happens when you kill the sense source like when you turn the Ign to Off) and this can power whatever the sense wire source is - i.e. Acc Heater etc and that's what you are protecting your head unit from with the relay & diode. Hope this makes sense for you, you've gotta love the behaviour of the electrons in the 1600 method of wiring. regards Terry --membersozdat------------------------------------------------------- OZDAT Mailing List Please Note:- Send (un)subscribe requests to [EMAIL PROTECTED] Send submissions to [EMAIL PROTECTED] No unauthorised redistribution of this email http://www.ozdat.com/ozdatonline/index.htm http://www.ozdat.com/ozdatonline/listindex.html http://www.mail-archive.com/[EMAIL PROTECTED]/ ---------------------------------------------------------------------
