I am working on a Panasonic cordless phone (dead). On the main circuit board in the base unit that are all SMD. The parts that I need are ID'D by SA101 and SA104(I don't know what an "SA" is). The number on the part is QAJC517 and is black with no other marks on it. Thanks
On Wed, 02 Aug 2006 18:00:17 GMT, "Dick" put finger to keyboard and composed:
Surge Arrestor? Does it have 2 pins?
The "QAJ" looks like a suffix. Are you sure the number is correct?
- Franc Zabkar
-- Please remove one 'i' from my address when replying by email.
The number is correct but it is a surface mount small block with 3 lines on lettering with two solder pads ,one on each end . the first line has a logo ST E, the second line QAJ and the third has C517 . If it is a surge arrestor ,how do I test them? With an Ohm meter ?
Thanks
On Wed, 02 Aug 2006 21:59:26 GMT, "Dick" put finger to keyboard and composed:
ST = ST Microelectronics ?
I would think that surge arrestors should test open circuit at normal voltage levels. I suspect such devices would be near the tip and ring inputs. Are there two other SAs, ie SA102 and SA103? If so, do they have recognisable part numbers or logos?
If the devices are indeed surge arrestors, then you could probably remove them for troubleshooting purposes.
- Franc Zabkar
-- Please remove one 'i' from my address when replying by email.
I couldn't find SA102 or SA103,I did find a blank spot that was marked SA102 on the circuit board. I removed SA101 and it tested open with my ohm meter,then I removed SA104 and it tested short and that looks like it comes off of the power supply input. I don't know what is right . I couldn't tell where SA101 was off from as I couldn't follow the trace because it is on both sides of the board and had been coated . Is there any place a person could look up the ID numbers and find out just what these components are ? I went to ST's web site and I couldn't even find the number's there. Used to be you could cross numbers from RCA,NTE.ECG books and find just about anything about semi conductors, but that was years ago. I do believe someone out there has a book , but I am having trouble finding that someone.
Thanks
I have just looked through my Panasonic phone equipment manuals, and all employ devices designated " SAxxx ". On all of them, the parts list shows " varistor ( surge arrester ) ", so Franc is definitely right that this is what they are. This being the case, I would expect them to read open circuit on a normal multimeter. Looking on the schematics, these devices are connected across the line connections to protect against surges caused by near-hit lightning, inducing big spikes in the service provider's lines. If this is the case, then they need to be rated well beyond the peak ring voltage that the phone will encounter. I would think that they could be readily replaced with similar devices from any phone, or even from a scrap dialup modem board. My friend who builds computers for a living, has these boards coming out of his ears these days.
Arfa
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.