Replacement for Q9 on 91 NSX CCU board

[Apogee13]

Hi all,

I have recently replaced all the caps on the CCU board of my 91 NSX. No big leaks, except for C11 which has flooded the nearby Q9. The three legs of the Q9 are all covered in green gunk and doesn’t look pretty. It seems likely that it won’t be fully working and I would rather replace the component.

The inscription on Q9 has faded away, but from what I gather it is a transistor.

I would be very grateful if anyone of you knowledgeable guys could spell out the inscription on Q9 for me!

If that very breed of transistor is no longer available – is there any modern version transistor I could use as a substitute?

I would truly appreciate your answers!


/Johan

 

[Old Guy]

The transistor at what looks like position Q10 is marked NIL3N K303L. K303L is an N channel FET. K303L does not appear to be easily available; but, its data sheet is available and based upon the specs it should be relatively easy to find a good replacement. So, if you can get a closer look at Q9 and the markings look the same, finding a suitable replacement is doable. If the markings have really disappeared, the alternative is to get someone who has their CCU board out of the car and have them confirm the markings on the transistor. Note that sometimes shining a very bright light across the surface at a very acute angle where the markings were located may reveal residual impressions from the markings allowing you to confirm the part number.

As an observation, the 'guts' of the transistor are usually well sealed by the plastic packaging. The leaking electrolyte from the capacitor may have corroded the FET leads; but, chances are that the FET remains operational unless there was external damage that caused an electrical overload on the FET. If you can confirm the markings on the FET, then go ahead an replace it. If not, chances are that it is still operational.

 

[Apogee13]

Thank you Old Guy for your answer and observation. Much appreciated.

When zooming in I can read the top line on the housing of Q9 and it certainly says NIL3N. So the Q9 and Q10 spots are most likely fitted with the same component. But before I try to find a replacement, I will go the route you suggested in your observation: clean up the legs of Q9 and then try out the board as it is in the NSX to find out if the AC works. Hopefully it does! If not, then I will have to search for a replacement.

Thanks again,
Johan

 

[Kaz-kzukNA1]

I can confirm that the Q9 and Q10 are using the same Tr because I had to remove them in the past.

Knowing the manufacture of the CCU, I think the 2nd digits of the model no. is '1' and not 'I'.
Therefore, it's N1L3N instead of NIL3N.

Most likely, the resistor built-in PNP Tr with 4.7Kohm and 10Kohm inside.
Because it was designed and manufactured in the '80s, almost all of the parts used on the CCU board are not RoHs compliant and thus, very likely to be superseded or discontinued.
Possible candidate: NEC BN1L3N but now the company is called Renesas.

As far as I know, the bottom column of 'K303L' is the Lot # or rank indicator and not the model no..

As [MENTION=26435]Old Guy[/MENTION] suggested, very likely that the Tr is still operational.

I'll be servicing another CCU board very soon so will take a look at the model no..

Kaz

 

[Old Guy]

We have arrived at an interesting world where one vendor's lot or production facility number matches up with another vendors part number. The common practise (but not religiously adhered to) is that the part number precedes the lot / production number. If I had searched for N1L3N instead of NIL3N (NIL3N yielded nothing sensible) the likely candidate would have been obvious since the K303L N-FET is a super obscure piece only listed by an equally obscure vendor, so I would agree that N1L3N is likely the correct part #.

N1L3N appears to be currently available in (at least) 3 different packages AN1L3N, BN1L3N and GN1L3N. The A package is a TO92 package and the B package is the squished version of the TO92 (which looks like what is used in the CCU). In a pinch the TO92 package (AN1L3N) could be substituted for the BN1L3N. The GN1L3N is an SMD package. Substitution of the G package would require that you make a little adapter circuit board so that would be an absolute last resort.

None of the packages are available from the really common vendors (Digikey, Mousser, Allied ...). They are available from some less common vendors; but, come with significant minimum order requirements. The one vendor had a really odd minimum order count of something like 962. I am thinking that they want to clear out all of their remaining stock and if you want one, you need to take all of them. The other vendor had a lower minimum order; but, much higher unit price so the net cost was about the same. With shipping you are probably looking at $200 or more whether you want 1 or 962 pieces. AliExpress has a vendor listing for AN1L3N for 100 pieces going for about $22 with free shipping. That price is more reasonable; however, my experience with free shipping from the Chinese mainland is that delivery is measured in months, not days. I have no direct experience with AliExpress as a retail platform or the quality of the product that is offered (there is good Chinese stuff and junk Chinese stuff).

With a single transistor, as long as the package is compatible, you respect the polarities and the device type, BJT, Darlington, FET, IGBT ...., it is normally fairly safe to substitute by up sizing with the same or greater Vceo, Ic and power dissipation. However, the N1L3N is not a single transistor. It is a single transistor with an internal biasing network for the base circuit (the two resistors that Kaz mentioned). Suitable 'equivalents' are available from Toshiba, Nexperia and a few others. I didn't look very hard; but, this one from Nexperia looks like it would meet the performance requirements

https://www.nexperia.com/products/b...ets-100-ma-single/series/PDTA143X-SERIES.html

Unfortunately, it is an SMD device (SOT package) as are all the others that I happened to look at. This means that you would have to fabricate a tiny 'daughter card' to mount the SMD on and then solder the daughter card in place of the transistor.

So, if it turns out that the N1L3N is dead, fixes are available; but, none of the fixes are straightforward because of quantities, prices, packing and vendor questions. Trying the repair without replacing Q9 is the way to go just because getting a replacement is going to be a hassle.

 

[Apogee13]

Excuse me for my late response – I’ve been rather occupied for the past few weeks.

Thank you very much Kaz and Old Guy for taking your time to put down such informative and in-depth answers. Very much appreciated!

It is good to know that there might be alternatives out there to the N1L3N.

However, for the moment being I don’t really fancy the idea of having to fibble with any SMD’s.

As I previously stated, I will put the board to test in my NSX in its present shape and keep my fingers crossed that it works alright. If not, well then you guys have pointed out possible directions to look for a solution/substitution. I really appreciate that.

Once more – a big thank you!

/Johan

 

[zwujizz]

You can choose a version of the transistor here.

 

[Heineken]

Old post but created a little write-up on successfully replacing Q9 and Q10 with matching SMD transistors and adapter PCBs:

Climate Control Unit (CCU) - Repair - Blogs - NSXCB Forums

Climate Control Unit (CCU) - Repair Heineken's Garage

www.nsxcb.co.uk

 

[Old Guy]

Excellent. Did you use a commercially available adapter board or did you fab your own using somebody like OSH Park? I have some off the shelf SMD adapter boards kicking around; but, the terminal assignments don't come out right for replacement on a circuit board. They are meant more for doing a test set up on a bread board.

 

[Heineken]

These adapter PCBs were readily available from eBay - no PCB design work this time