Rockford 1500-1bd

[impactair]

The meter makes an audible sound and reads "shrt"

 

[impactair]

I did not check it set to ohm's until you asked me to test the resistance and twist the inductor. This meter is pretty new and I am still learning how to use it.

 

[impactair]

I think something is funny with my meter, I read the 0.1 ohm resistors to the left of the inductor and the read 0.1 on ohms, but shrt on continuity. Is this my meter malfunctioning or does it just see low resistance as a short?

 

[impactair]

Anything under 15 ohms, my meter see's as a short.

 

[Perry Babin]

Set the meter to ohms for critical measurements.

If it reads shrt under 15 ohms, you should not use that mode for this type of work.

 

[impactair]

If the meter is set to ohms, an I touch the leads to any resistor or the speaker terminal, I get a reading. If I switch the meter to diode/continuity, the meter reads "shrt" and beeps if I touch the leads to any resistor or the speaker terminals with a resistance below 15 ohms

 

[impactair]

Ok, so my meter just sees the low resistance as a short on that setting. That may explain alot of issues I have had with weird readings on other repairs.

 

[impactair]

So, is the resistance I am seeing on the terminals normal?

 

[Perry Babin]

Not if there were no speakers on it.

Are you sure that you don't have any shorted or leaky output transistors?

Are you sure that the inductor isn't shorted to the board underneath it?

Are you sure that there is no conductive fiberglass?

With the probes clamped into the speaker terminals and reading ~5 ohms, can you move anything on the board that will make the resistance change significantly?

 

[impactair]

All outputs are good
No conductivity on the fiberglass
When I touch a probe to the part of the board where the fiberglass is melted off, then touch the inductor coil, I read short. No resistance.
No change in resistance when I wiggle or move anything.

 

[Perry Babin]

The fiberglass is the material inbetween the copper layers. If it's burned away, what are you touching? A copper trace?

 

[impactair]

If you look in the pictures you can see It's a section of exposed copper, like a super wide trace, right under where the capacitors were. That is conductive with the inductor, as well as the speaker terminals. The black coating melted away and I believe it is a wide trace. But I am not sure if it should be conductive with the inductor and the speaker terminals.

 

[Perry Babin]

It's likely a copper conductor (trace) that's connected to both the inductor and the speaker terminals. That trace passes the audio signal from the inductor to the speaker terminals.

The insulating/protective coating on the circuit board (that burned away) is called solder mask.

 

[impactair]

Ok, so It allows larger amounts of current to pass. I still read a short from one mount hole to the other where the capacitors went. Without the capacitors installed should'nt there be a break in the circuit?

 

[Perry Babin]

Are you reading the same thing that you read across speaker terminals?

You shouldn't use the term 'short'. Put the meter on resistance/ohms and post what you see on the meter's display.

 

[impactair]

Your right I confused myself. I read the same as I did across the speaker terminals. 4.7 ohms. I have the capacitors on order. when I get them in the board that should change the resistance across the terminals right? I apologize for the confusion, I have never seen a meter read this way.

 

[Perry Babin]

What resistance do you read when you touch the probes together?

 

[impactair]

000.0 in ohm's

 

[Perry Babin]

Remove the inductor to see if the resistance across the terminals changes significantly.

What make/model meter do you have?

 

[impactair]

I have 6 ohm's across the speaker terminals. 000.0 across the inductor, and 20m ohms where the inductor was. I have a Radio Shack 22-812 Digital Multimeter with PC interface. Sorry I took a bit I had family over.