Unknow component in a power amp

[ne0]

Hi all, I need your help, I have a power amplifier a subwoofer (AXYS Uniamp 700), which has no voltage on the diode bridge, the only component that seems not right is this: KVR 10-471, according to the pcb is a NTC but can't find information about it, if anyone can offer any type of information you would appreciate with well cold beers you come for Spain!
Thank You!

[g1]

I thought it was a varistor, 10mm 470V.

[Jazz P Bass]

Yeah, it is an NTC varistor.
The 'NTC' implies that its a type Negative Temperature Coefficient.
It will start at a high resistance & as it warms up the resistance will drop.

[oc disorder]

So are we all off to Spain then for some beer G1 and JP Bass ?

I put KVR 10-471 in google first "hit" =

Vatronics MYG GENERAL PURPOSE VARISTORS

http://www.vatronics.com/Upfiles/down/201171885402.pdf


Nominal Varsitor Voltage at 1mA DC 470

Rated Voltage (V)
ACrms 300
DC 385

Clamping Voltage (V)
810 - 775

[J M Fahey]

Just beer?

I'd ask for some Paella:

[tedmich]

I believe Spain's Paella is wurst after the bailout...

[Mick Bailey]

THe NTC marking on the board is a little confusing. An NTC usually goes in line with the supply and a Varistor is a shunt device that behaves somewhat like a pair of opposing-series Zeners, or a gas-discharge tube. AN NTC anti-surge protector has a low resistance (just a few ohms) that falls as it warms up and acts as a soft-start. A Varistor does not conduct under normal operating voltages but will do so when a particular threshold is reached. Sometimes they're placed after a fuse so that the fuse deliberately blows under higher-voltage conditions.

They do get tired if the breakdown voltage is repeatedly approached and can fail on their own, sometimes with no other fault present.

[diydidi]

Mick is right.
So I guess the question is, is it connected parallel to a source or in series with whatever load there is?
If parallel, certainly is a MOV; Series, most certainly an NTC of some sort.

[g1]

THe NTC marking on the board is a little confusing.

There is also a marking on the board right by there that says Var2. So I'm wondering if they use one or the other?

[ne0]

That's the first thing I did yesterday. But it's a Varistor no a ntc, Thanks

So are we all off to Spain then for some beer G1 and JP Bass ?

I put KVR 10-471 in google first "hit" =

Vatronics MYG GENERAL PURPOSE VARISTORS

http://www.vatronics.com/Upfiles/down/201171885402.pdf


Nominal Varsitor Voltage at 1mA DC 470

Rated Voltage (V)
ACrms 300
DC 385

Clamping Voltage (V)
810 - 775

[ne0]

Yes, the NTC is connected in series with the diode bridge, the question is what kind of ntc is? Thanks!

Mick is right.
So I guess the question is, is it connected parallel to a source or in series with whatever load there is?
If parallel, certainly is a MOV; Series, most certainly an NTC of some sort.

[ne0]

That's not paella, The "real paella" is this

I believe Spain's Paella is wurst after the bailout...

[km6xz]

I am surprised at the confusion, NTC1 is the part designation for a NTC Thermistor that is in series with the load, as a slow start mechanism. Very many amps have them and they are not that uncommon to go bad.

[Mick Bailey]

I am surprised at the confusion, NTC1 is the part designation for a NTC Thermistor that is in series with the load, as a slow start mechanism. Very many amps have them and they are not that uncommon to go bad.

I think the confusion arises from it looking like a MOV, being spec'd as a MOV, but being marked NTC and connected in series.

[km6xz]

Spec's as a MOV? It says 470 ohms on it, it has a board designation of NTC1. The original probably works, not burned as is the normal failure mode, just the lead broke possibly due to vibration.