KIA car radio TVS diode blown, need help identifying it

[CapLeaker]

Someone gave me his original KIA car radio for repair. I did find that the 5.5V Super Cap was leaking and a TVS diode shorted. The problem is that I have no idea what value that diode is. It is a glass style TVS with one yellow or gold band in the middle (D101 on the bottom right of the picture). It goes between the antenna input of the tuner module to GND. What value should this diode be?

[Andrew F. Ali]

Re: KIA car radio TVS diode blown, need help identifying it

I would try a NTE 519 Diode (depending on which section of circuitry it resides.

[CapLeaker]

Re: KIA car radio TVS diode blown, need help identifying it

I suppose I could just chuck just about any lower voltage bi-directional TVS diode in there. But I'd still like to figure this original diode out. I haven't seen any TVS with a single yellow or golden band yet and I can't find it in any chart either.

[budm]

Re: KIA car radio TVS diode blown, need help identifying it

What ever you out in probably should be low capacitance since it is in the RF section.

[redwire]

Re: KIA car radio TVS diode blown, need help identifying it

Are you sure it has shorted? In-circuit you will get low Z reading from the antenna to GND from the tuning inductors. The TVS is for static electricity buildup on the antenna rod. I have not seen any look that big.

On second thought, that looks more like a gas tube surge protector:
http://www.diytrade.com/china/pd/128...rge_tubes.html

[budm]

Re: KIA car radio TVS diode blown, need help identifying it

The designator is D101 and the printed symbol on the PCB also shown as TVS diode.
He should lift one leg up and test it again.

[Andrew F. Ali]

Re: KIA car radio TVS diode blown, need help identifying it

I think any TVS you may have at hand or easy access to should work. Before replacing though test a known good one and compare the results with the one you are working with.

[CapLeaker]

Re: KIA car radio TVS diode blown, need help identifying it

What ever you out in probably should be low capacitance since it is in the RF section.

Yes, I agree... it does have to be a low capacitance diode, because of it being in the RF section. Yes, the diode is shorted out of circuit, it's done for. I doubt the voltage rating is going to do much as long it's under 30V or so. The capacitance of the diode is more important. The bi- directional TVS is just a protection of the antenna port of the tuner there isn't any voltage there. Hence the reason, that one could just about any low voltage, low capacitance diode in there without any ill effects.

[CapLeaker]

Re: KIA car radio TVS diode blown, need help identifying it

I've ordered a couple of TVS diodes. Hard to find a low capacitance TVS through hole style. SMD No problem.

[budm]

Re: KIA car radio TVS diode blown, need help identifying it

I remember in the early day when they started using MOSFET in the RF Front end of the tuner, they had lots of failure due to lack of protection.

[CapLeaker]

Re: KIA car radio TVS diode blown, need help identifying it

Well... I am getting my share to repair ham TRX's from our club. Some transmit from one radio into the other one, the other gets somehow 120V through the antenna port TWICE! The usual Kenwood, Yaesu, Icom and PSU problems, failing IF amps, PLL unlock, blown up this, broken that. However I have to come across a glass style TVS with one yellow color band yet.

[redwire]

Re: KIA car radio TVS diode blown, need help identifying it

The KIA radio pcb is SMT and this lone TVS is big through-hole. I find it a weird part too.

I usually see low capacitance diodes for antenna protection on Rx and gas-discharge tubes for lightning protection on Tx gear.

[CapLeaker]

Re: KIA car radio TVS diode blown, need help identifying it

The KIA radio pcb is SMT and this lone TVS is big through-hole. I find it a weird part too.

I usually see low capacitance diodes for antenna protection on Rx and gas-discharge tubes for lightning protection on Tx gear.

I hear ya. Same here.