Automotive diodes replacement

[Alessio]

Hello,
I must replace two smd diodes:

GG74GI

EKP71GI

if you have any idea about equivalent diodes please tell me.

You can see the board where they are installed.
Please ignore the orange circle ( it's a ?-channel Mosfet )

Thank you.

[bigtoy]

I took a look in the Turata SMD codes book for you (this book is found on this site by the way).

For the EKP it only had one entry: a Vishay TPSMC22A TVS (tranzorb). Google will give you a datasheet pretty quick, and you can choose a suitable replacement from digikey if you like.

For the GG the book had several entries:

GG 3T130A Thy-SPD         Vdrm=120V, Vs=160V, Ipp=50A, 40pF DO-214AA          1d 1a          Mde
GG BAR63-02W PIN-diode        Sw, RF, 100V, 100mA, Vf<1.1V(50mA), < 0.3pF SCD-80 6d 1u          Inf
GG DDZ3V3A Z-diode 3.3V±10%, Izt=20mA, 500mW SOD-123 5d 1d          Di
GG GF1G Si-diode          Rectifier, 400V, 1A, Vf<1.1V(1A), 2µs DO-214BA          1d 1k          Vs
GG P1300SA Thy-SPD         Vdrm=120V, Vs=160V, Ipp=50A(1ms), Bidirectional DO-214AA          1ba          1j Mde
GG PZU8.2B Z-diode 7.76..8.64V, Zzt=10Ω(Izt=5mA), 310mW SOD-323FL        7d 1a          Phi
GG T130AB-LC Thy-SPD         V Of-St=120V, Vs=160V, Ipp=50A(1ms), Bidirectional DO-214AA          1ba          1j Wtr
GG Z2SMB-9V1 Z-diode 9.1V±5%, 2W DO-214AA          1d 2j Fag

You'll have to do a little sifting to determine which one your mystery part might be.

[solutions]

Looks to me like a freewheeling diode to snub the back EMF from the relay coil (can't be 100% sure from just looking at your picture - check that the diode is across the coil to verify).  General rule of thumb is 6X the applied voltage on the coil for the kickback spike (for those that can't do the math, about 90V with the alternator running). Faster is better, so that eliminates the use of a zener pretty quickly.  Current rating in the diode is sized for the peak forward current in the relay coil (an inductor).  Preference is to a Schottky, but an Si diode will do.

That should narrow the list pretty quickly.

[GunMage]

I took a look in the Turata SMD codes book for you (this book is found on this site by the way).

Link? The search function fails me. I can not seem to locate it.

Thanks

[Faros]

@Alissio

The book name is just mis-typed so it didn't pop up in your search, the correct name is Turuta and here is the post:

http://www.sonsivri.to/forum/index.php?topic=40380.0

it seems that all links are dead by now ...

Edit: Found one on the web for 2010 version:

http://www.4shared.com/get/ZufFi9Zi/Turuta-SMD-2010.html

link is valid (so far) ..

[Alessio]

Ok, I must set up this tread:
I) Thank you all 
II) These aren't diodes, they looks like diodes but they are...TRANSIENT VOLTAGE SUPPRESSOR.

In particular, EKP is like an open circuit if voltage is below 18.8V, it could begin to work at 20.9V, but
 only if voltage applied is 23.1V or more it start to clamp voltage at its maximum designed value: 30.6V.

So if dude try to jump start a 12V vehicle with 24V battery the TransVoltSuppr will (probably) save this board.

BUT...
You could till the field with a lot of TransVoltSuppr, then comes the super dude: it will reverse battery cables
 + with -, - with +, this means negative voltage = negative current, wrong current direction instantly kills mosfet, TransVoltSuppr are placed near the mosfets, mosfets explodes, TransVoltSuppr shorted.

Board with serious damage, car with no more door lock, no electric windows or automatic roof and dude in panic, with jump cables still in his hands.

Fortunately, engine ECU is designed to survive to reverse polarity, so super dude could drive home with
 his half broken car instead of remain blocked in the desert.