RC M90 resistance prob...

[bredgeo]

Hey Guys and Gals,

I would need help with a resistor in an RC M90!!!!!!!

This one:

Did you GET THE PICTURE....

Ham, Hum.... Well, all my stuff is in la France, so I was only able to use my handy pocket ohm meter... And I got "No Resistance":

Help me !!!!!!!

And, Dank yea varry moosh!

Brian the humble...

 

[Superduper]

Depending on the scale of your VOM, it may not be accurate enough. That resistor is almost 0 ohms so you would need to make sure you've zero'ed properly first since it looks like you don't have it zeroed.

I believe the resistor you are referring to is FR704: It should be a 1/2w fusible resistor, 4.7ohms.

 

[bredgeo]

Well, unfortunately it is zeroed.... The zero point is on the left. What we see here is the reading of the resistor. It reads above the final zero..... no resistance... HELP!!!!!!

Is the resistor dead? No.... 'cause all is working in my RC M90.

I really need the reading for another M90 owner in France who does not post here or anywhere. His resistor is dead, 100% sure. He has replaced it with a temporary resistor (all is working) but he would really like to put one with the correct resistance.

Thanks

 

[Superduper]

I disagree. 4.7 ohms is very little resistance and even the leads can have that much resistance. Your reading is to the right of the zero meaning it has less than zero resistance?? No. If you had zeroed the needle prior to taking a reading, you should get a reading to the left of the scale. If it was truly zeroed then a zero ohm reading would be at exactly zero. It should NOT be reading in the opposite direction. Also, make sure that the boombox is NOT powered when taking a reading.

As for the the value of that resistor, I am telling you exactly what the service manual calls for with respect to FR704, and that is 4.7 ohms 1/2 watt fusible resistor. There is no reason to take a reading. It is what is specified and prescribed for by JVC. Again, 4.7 ohms is very little resistance and it is the correct value for that resistor. You can take that to the bank.

 

[bredgeo]

Got ya!!!!!!!!

like I said, my little meter might be totally screwed!!!!!!!!!! I need to get a nes one!

If you say that it is 4.7, than 4.7 it is. I thank you a lot!

Will be passing that on to Pascal (the other M90 owner).

 

[eldorado]

and again measuring components while on board is not very acurate sometimes,

depending on board settings.

but 0 ohms is not a usual value...

it means , direct current, like a wire.

 

[bredgeo]

Well I had unsoldered one end of the resitor before taking its value (well, at least trying to take it... :annoyed: )

Later!

 

[Superduper]

Make sure it is a 1/2 watt resistor. Normal / common value is only 1/4 watt. Also, make sure that it is a fusible resistor. It is designed to protect that circuit by blowing. A normal resistor might not blow fast enough. Just FYI. 4.7 ohms is not much. If there is a parallel path while in circuit, it will read even lower.

 

[bredgeo]

Okay,

That is probably why it blew.... it was/is fuseable. Pascal told me that's what he thought!

I copied and pasted what you wrote here!

 

[monchito]

yes that correct as mostly those fusible links go bad very often i was lucky to be able to fine 1 or 2 but some of the other ones were no longer available so you might want to check and see if you can find some

 

[bredgeo]

Where did you find yours, internet or store?

 

[monchito]

i bought some from mouser electronics here in usa

 

[bredgeo]

Okay, a store... I just found this:

http://megatone.manufacturer.globalsour ... istors.htm

Could you tell me if the colour code fits to the ones you have! Mercy, mercy buckets!!!!!

 

[monchito]

it looks like the ones in the pic but i found only 2 part numbers thats all they showed on there website .. the part num 594-nfr25h0001008ja5 thats the mouser part number the description was 1/2 watt i ohm 5% fusible resistors....and that was only one the other package i did not find...

 

[bredgeo]

Have you used the one (ones) you've bought? If so, did/does it work?

 

[Superduper]

Brian. I'm pretty sure that the M90 would work perfectly fine with nothing more than a plain jumper wire in place of the blown resistor. The problem is that the wire will not limit current and does not afford fusible protection.

 

[monchito]

Brian. I'm pretty sure that the M90 would work perfectly fine with nothing more than a plain jumper wire in place of the blown resistor. The problem is that the wire will not limit current and does not afford fusible protection.

thats why i did not go that route and yes it works as i only had that one bad all the other ones were fine

 

[bredgeo]

I am quite sure it could work with just a wire... but I would not go that route niether... But true, it would still be a possibility!

keeping the M90 as close to original is best though.

 

[Superduper]

I am not suggesting by any means, that you actually use a wire. What I was actually trying to say is that you are overthinking the situation -- that the application is not so particular or specific that a replacement resistor not actually work. You could get a resistor that is 2.2 ohms or 6.8 ohms, or maybe even 10 ohms and I believe it will still work. You can get a wire and it will work. The most important thing is to make sure it is a 1/2watt fusible type. Therefore, the replacement resistors WILL work if you get a 4.7ohm fusible resistor.

 

[bredgeo]

Yep.

I wiil let you know if Pascal finds an original value FR.

But no, I would not put a wire any ways.

Later.