help finding current limiting thermistors

[solman]

hey guys,

my subwoofer recently died recently, it seems that the green cap looking thing blew up. I have discovered that it is a current limiting thermistor "13DSP 104", now the problem is im having trouble locating it.

Any one know where i will be able to get one?

heres a picture of it....

[AndrewT]

is that thermistor in the mains side or the low voltage side?

[solman]

its on the main side, the red and black cables there are the incoming mains to the power board

[AndrewT]

I would expect the mains incomer to have the thermistor and rectifier before it reaches the very high voltage capacitors storing ~300Vdc.
Can you confirm?

[indianajo]

if your subwoofer is older than 10 years, I suspect the high voltage caps in the switching power supply are leaky . They then would have blown either the NTC thermistor or a rectifier. The caps should be measured or replaced.
A GE CL-90 NTC thermistor has 120 ohms cold and 1.2 ohms at 2 amps, I suspect it would work. Download the datasheet from mouser.com or farnell.com, it has all the other GE NTC thermistors on it and you can chose one where the full load current is similar to your input fuse. You can also get an idea of the full load current they expected by looking at the rating on the input rectifier. Datasheets of oriental stuff can be on datasheetcatalog.com. The green thermistors are oriental. GE's are red.

[solman]

andrew: yes the caps are downstream from the thermistor.

i found this webpage with details on it:

Diing Tai Electronics Co. Ltd

its the 13dsp-104 one, it says that it rated to 4amps, and the fuse is 1.6amps

i measure the caps the other day because i was thinking the same but they seemed to charge up to there charge of 220micro farads, and remain there quite find. the sub was working fine till one day i turn it on from the mains after being away then it keep flicking between on and off.....it keep doing this till finally the fuse gave up, i then replaced the fuse and thats when the thermistor blew up.

i've had a look on farnell but not mouser, i have a look there.

thanks for the help

[ArtG]

From the picture that you provided, it looks at if there's "chunk" blown out of the top on the "thermistor".
It may have been defective, I guess, but that sort of failure would make me suspect a very heavy current draw. The measurement of the capacity of your power supply filter capacitors, doesn't tell much about the current leakage. You need to measure the ESR with a special tester, or the actual current leakage of the capacitors. There's also the possibility that there's a problem in the rest of the amplifier, that causing excessive draw.

[indianajo]

farnell.com usa (newark.com) has the CL-90, $4.
ESR measuring meters at newark are $150. I "measure" electrolytics by charging up on ohms scale, then switching to volts scale and seeing how fast the voltage goes down. Too fast, time to replace. Compare against a new cap of similar size. Since shipping is $7-10 you may as well buy the new caps on the same shipment. To save money on shpping check your input rectifier, also before ordering. The thermistor may have saved it.