Rockford Punch 100ix

[seankane]

Hello this is my first post. I have a old rockford punch 100ix that I am repairing. The original problem was weak sound in one channel and a delay in the sound coming on. I replaced all the IRF540 output fets, I replaced the gate drivers, I replaced the emitter resistors, and still the same problem. The bias sets on the channel fine like it should. Usually when one of the surface mount components go bad it makes static or draws current. This amp does not draw current or make static, just weak sound in one channel. Something else though when you turn the amp off then back on it takes about 30 seconds for the sound to come on again. Possibly the pwm chip TL594C or the LM339?? Any help would be great.....thanks

 

[Perry Babin]

Is the sound in the weak channel perfectly clean?

Do you have a scope?

 

[seankane]

Its hard to tell if its totally clean but to my ear it sounds clean just alot less output than the other channel. Yes I have a tec 465b dual channel but I am not very familiar with it and unsure what settings to use or exactly how to use it. I am self taught and have been reparing for about 7 years now speacializing in fosgate. I have always used my fluke 787 for everything. I would appreciate any help I could get. Thanks again....Sean

 

[Perry Babin]

Look at the output with the scope. Start with 2mS on the timebase and 5v/div on the vertical amp. If you can't get a locked trace, post a photo of the front of the scope showing the settings for all of the switches.

 

[seankane]

Ok thank-you Perry but how do I post pics on the forum? Please let me know and I will post a pic of my scope.

 

[seankane]

Can anyone tell me how to post pics on the forum?? Anyone??

 

[Perry Babin]

Click the 'Go Advanced' button below. On the next page, scroll down and locate the 'Manage Attachments'.

 

[seankane]

I keep getting an error message and it wont let me upload maybe my internet?

 

[Perry Babin]

Look carefully at the dialog box after the file fails to upload. There's generally an indication of why it won't upload. Generally it's due to files that are too large.

 

[seankane]

If this is the case how do I shrink them down?

 

[Perry Babin]

I use Irfanview. It's extremely simple with that program. You can either resize the image or reduce the quality. First try reducing the quality. When saving as a jpeg, you will have an option to set the quality. start with 85%. Go as low as 65 if you need to. If that doesn't get it down far enough, resize it. Use IMAGE >> RESIZE/RESAMPLE and set the size you want.

 

[seankane]

Im not sure if I did it right it uploaded after reducing size. Anyways here is the pic of my scope.

 

[seankane]

Here a a few close up pics sorry for the blur and I sent a pic of the new leads I recieved with it.

 

[Perry Babin]

It looks like it should be OK to view the output. Drive a sine wave into the amp and check both channels to see if you see any distortion.

I'm assuming that you have set the gains the same for both channels.

 

[seankane]

yes the gains are set the same but I am unsure how to drive a sine wave into the amp. I really have no idea how to use the scope i guess is what I am trying to say. What channel to use or what setting to use. I was hoping for some help on how to use it, just the basics for now. Thank-you

 

[Perry Babin]

Timebase: 2mS
Vertical amp: 5v/div
Input to Ch 1
Scope probe set to x10

The sine wave can come from a sine wave generator or a test tone played from a head unit (or other audio device).

 

[seankane]

I guess I am going to have to dig through the owners manual and do some reading. I really dont know what I am looking for on the scope to determine distortion and/or how to use the probes. I am not 100% I even have it set as you said the volts/div is easy to set but the delay time is on the opposite side and doesnt seem to make a diiffernce where its set. Is there a switch or button to turn on the time delay?

 

[Perry Babin]

Timebase, not time delay.

 

[seankane]

ok well I guess I am not seing a time base setting or just dont know how to set it. Maybe this scope is not suited for what i need??

 

[Perry Babin]

That scope is perfectly suited for this. The knob on the right with the red knob in the center has time delay above it but it's the timebase. It's set to 2mS in the photo. Turn the red knob fully clockwise.