Hat sich jemand schon mal einen Diagnosest. selber gebaut? | Posts 16+

I'm a little surprised by something now...

I followed the circuit diagram exactly, keeping all the resistors the same because the optocouplers and transistors have almost identical values to those originally specified.

I recently had this part installed in a Seat Ibiza from 1995, which still has an L-line connection. It works great...

Today I worked on a Passat and an Octavia. No problem.

CU Gremlin (slightly puzzled).

Hi,

@ Draven

Which optocouplers did you actually use? The CNY17 is slower than the original, and you need at least a current transfer ratio of -3, preferably -4.
I built the interface using an ILQ615-4 and I no longer experienced any issues (it used to occasionally get stuck) after increasing the value of R7 to 10k ohms. Although it's against the specification, there's even a 27k ohm pull-up resistor inside the VAG 1552.

@ZEKA

Do you have a source for the 0.81 DE value?

I got myself a cny17-4... but it still didn't work.

Hi,
My last post was not entirely correct (one should not compare the timing of the saturated operation with that of the unsaturated operation ). I have re-read the datasheets for the ILD/Q615, PS2501, and CNY17. The CNY17-4 has almost identical values to the ILQ615-4 and should therefore function similarly.
If you're still interested in tinkering, please increase the pull-up resistor on the K-line to 10k ohms (this resolved the issue for me).

Thank you for your help; I'll try it again this afternoon.
Even though I've already ordered the cable, I really want the circuit to work! X
I replaced the diodes with LEDs; it shouldn't be a problem, right?

Hmm...
Optocouplers (transmitter diodes) have the problem that they can only withstand a few volts in reverse bias. The antiparallel-connected diodes limit this voltage to approximately 0.7V, protecting the transmitter diode. LEDs have a higher forward voltage, and their switching times are often significantly longer than those of 'normal' diodes.
It should definitely work with LEDs, but I would use a 1N400? or a 1N4148 diode.

I have one more question...
I just noticed this now, but VAG-Com always tells me 'Adapter found / Ready.'

I once read that the adapter is only correctly recognized when the ignition is turned on in the car. (or something similar).

I just connected the interface for fun and removed the optocouplers from their sockets.
Still the same message: Adapter found / Ready.

Could that be possible?

Hmm...
'Since I've reduced the size of my adapter, I unfortunately can't test it without an optocoupler.'
It is quite possible that the program can also detect the presence of an adapter through the resistors and diodes on the PC side.

Between contacts 2 and 4 (D9 connector), you have the 1.5 kΩ resistor; this indicates that something is connected to the RS232 port. The software doesn't perform any further checks.
Lukas.

I initially suspected the same thing. However, that's not enough.
VAG-COM still reports 'Adapter Status: 3 - Not Found or Not Ready.'
Since TxD and RTS can accept negative voltages, the two protection diodes (D1, D2) may sometimes operate in the forward direction, which could potentially be interpreted by the software (in some way).

Sorry, bringing up old topics again...

I also want to build one of those adapters. I have the instructions from Jeff Noxon, but I don't understand one thing:

In the circuit diagram, there's a chip in the center (presumably an optocoupler?) with 12 pins (6 on each side). Since this part is no longer available, it's suggested that you can use three CNY17-4 components as a substitute.

How do you install them? Do they ever have 4 pins? Or do you need to completely rewire the circuit?

Does anyone happen to have a link or the schematic diagram showing only the components, and where I can purchase those parts?

Sure, here's the translation:

'It would be really nice.'

Thank you in advance...
David.

Okay, forget my previous post...

I had overlooked the PDF file with the 'correct' circuit diagram.

Sorry.