Want your bad FZR600 Ignitor Boxes!

[TomJ]

So I have two older (is there anything else?) FZR's one with a good, one with a burned ignitor box and procured another bad box from a yard. Being a "repair everything" person (from tech/electronics to diesel engines to mechanical watches to race cars), I immediately pulled apart the burned box and found the issue (probably caused from a bad VRR no doubt, been replaced since with a 5-pin from later model). So I ordered replacement transistors and have the resistors and diodes. Replaced everything, tested on bench, then on bike, all's well with the world again.

So I'm thinking, these parts cost me a whopping $6 total and about 1/2 hour R&R time on the components (not including removing the damned conformal coating from the heatsinks so they can actually WORK, instead of being insulated by the coating..., duh!!) and there are probably a lot of boxes that could be repaired instead of tossed in the rubbish tin. So..., I'll pay for shipping (and maybe $5 for the box?) if people are willing to send me their bad boxes. Then if you want to pay for my time and components (I can't see all of that being more than $35 or so), I'll send the repaired box back. Or pay you the $5 or so for it and for the shipping to me, repair it and make available to other members.

I've not been a member here for very long at all, but been a mechanic for over 30 years (with engineering background) and on Peachparts Mercedes forum for over a decade, also doing mods like this and other repairs for members there on classic Mercedes diesels (tomj or colorado biodiesel there).

Anyway, sound off if you have some boxes or even if you have one and want to delve into repairing it yourself. I bought a bulk-lot of the replacement power transistors that the board uses and that goes out and can "kit" together the repair parts needed to do it yourself if you have a soldering iron and like hobbying stuff like this (like I do). Not selling anything to make a profit, will sell at my costs plus whatever minimal first class shipping might cost for the components.

Here's pics of the bad (burned) board repaired. First shot still didn't work, but I had only replaced the power transistor and the resistor/diode array you can see in the pic. After further testing, one cap was bad too (the 100uf electro next to the resistor array) and one of the NPN transistors adjacent to the burned power transistor. Of course what they used was an ECB pinout, not EBC like what I replaced it with, so I had to swap the leads around, but it works like new now..., sheesh...



Here's the back of the board where it almost burned through the FR4 (and did burn a trace):


Here's side view of heatsink modified for better cooling and the one NPN in the foreground that was also burned:


And here's a pic of a good board:

[DonTZ125]

I've been repairing these things for a few years; kept a few of them out of the rubbish bin. A few comments, if I may - while I don't disagree with the suggestion to keep the heat sink free of 1/8" thick (!) silicone goop, I don't think that drilling holes will accomplish much (no airflow). What WILL help some is a teeny smear of thermal conductive grease between the transistor and the heat sink.

I always replace both transistors at once. If one died, the other took a shock sufficient to kill it - it may be working today, but for how much longer? Also, different transistors have different switching characteristics; different transistors may very well give you different effective spark advance on the two channels.

I use the really-hard-to-get Bosch BIP373 triple Darlington transistors; logic-level operation with serious protection - thermal shutdown, over-voltage and over-current cut-off. The guys at DIY Autotune did some stress testing awhile back, and the previously-used (in their EFI kits) VB921devices went like popcorn under loads that didn't even have the BIPs warm!

[TomJ]

I've been repairing these things for a few years; kept a few of them out of the rubbish bin. A few comments, if I may - while I don't disagree with the suggestion to keep the heat sink free of 1/8" thick (!) silicone goop, I don't think that drilling holes will accomplish much (no airflow). What WILL help some is a teeny smear of thermal conductive grease between the transistor and the heat sink.

I always replace both transistors at once. If one died, the other took a shock sufficient to kill it - it may be working today, but for how much longer? Also, different transistors have different switching characteristics; different transistors may very well give you different effective spark advance on the two channels.

I use the really-hard-to-get Bosch BIP373 triple Darlington transistors; logic-level operation with serious protection - thermal shutdown, over-voltage and over-current cut-off. The guys at DIY Autotune did some stress testing awhile back, and the previously-used (in their EFI kits) VB921devices went like popcorn under loads that didn't even have the BIPs warm!

Hey, thanks for any input. The holes are just to increase surface area and since there is not flow, it's a way to create a micro heat-pump, but prob minimal. And I always use thermal grease, actually MX-4 arctic silver (not just white thermal compound). I thought about replacing the other trans, but tested fine. After your suggestion, I'll just do that. Weird thing is, this is the only one of the two I've ever seen bad in these? Matching them (even though this is supposed to cross) is a good suggestion. And these were the only transistors I could find that were a direct cross. Bought ten of them. I'll look for the 373's though. Suggestions on who might have? Not Mauser. Looks like Ali express has for $4/ea. Have you ordered from them before? I haven't.

[DonTZ125]

The only place I've seen carrying them retail is DIYAutotune; US$8.50 each including the TO-220 installation kit. This last really isn't necessary for a TCI repair, and you can request the transistors without the kit (slightly cheaper).

[TomJ]

Well, might have to swap those 373's in. Bike runs, idles with this one, but sounds "ratty," not sure how else to describe that. Like it's a bit lean, but lots of smoke (like inefficient burn). With a known-good box from the other bike, doesn't smoke (as much) and "throatier" sound. Could be one coil is firing weird too, two plugs are black, two are carmel.

[DonTZ125]

Yup - sounds like one channel (1-4 or 2-3) isn't working, and you're running on two cyls at least part-time. Swap out that other driver ...

[TomJ]

Yup - sounds like one channel (1-4 or 2-3) isn't working, and you're running on two cyls at least part-time. Swap out that other driver ...

Yeah, I did swap the other driver. That's how it runs with both the MJE5742G's in there. Could be some other bad component in one channel, very likely with the way it's burning. Have limited test capabilities here though, even for discreets. Perhaps I'll find the correct cross for the amp (I replaced with a std 2n4401, had to swap the c-b as the one in there pins out at ECB). NTE85 is the equiv, but local places are out. Prob should just wait till I can get that part..., sigh...

[TomJ]

Hi Don,

Bought the BIP373's from Megasquirt and R&R'd them. Now won't run and backfires. Weird. The old (burned) box with the MJE drivers runs the bike fine, swap to this (good) box I swapped-in the 373's into and won't run, tries to, backfires, etc.

Can you tell me more about these. If they can be swapped-in as-is, or are they a reversed EBC or something? Odd that the MJE stock equiv does fine, these just don't run at all. And yes, was a mil-spec solderer and P/T time tech in the day, have breadboarded circuits for decades, checked solder joints, etc., all seems dandy. Thanks for any help.

BTW, didn't use a 330ohm res as I have no idea where (in series with base?)