Rockford Punch 100ix

[Perry Babin]

One channel at a time.

Does heat or vibration affect the signal on the left channel?

Do you lose signal on either terminal of the coupling cap to the power amplifier stage (Cx09)?

 

[seankane]

I have a clean signal at C109 and C209 at all times no matter what.

I hit the amp up and down against the bench and tapped on numorous components with a wood handled wire brush. Nothing seemed to make a difference, still no signal.

I heated the channel in various areas with my heat gun and no signal still.

Niether heat nor vibration SEEM to affect the channel as of now.

 

[Perry Babin]

Have you checked for a signal on the output transistors instead of at the terminals?

 

[seankane]

Not yet do I check it on the drains or source of all 4 IRF 540's?

 

[Perry Babin]

Two drains and two sources will have audio if it uses all IRF540s.

 

[seankane]

It does use all four because I checked the other channel first as a reference.

As you said 2 drains and 2 sources.

There is no audio signal at the output fet legs in the channel.

 

[seankane]

Once the amp gets the signal it keeps it and it is clean. I have a signal now, is there something I can test while the signal is emitting?

Maybe it is best to determine what is interupting it first?

 

[seankane]

Since the right channel is faulty could something in the protection be interupting the left side?

The right channel is very distorted and the higher you turn the volume up the higher the DC climbs on the bridging terminal.

Should I fix the right channel first and go back to the left?

 

[Perry Babin]

Is the voltage the same with/without signal across R166?

 

[seankane]

The first pic is the output of the right channel.

The second pic is of the left channel (one we are working on) when it gets signal.

 

[Perry Babin]

Let's work on getting the left channel repaired completely first.

 

[seankane]

The voltage acroos R166 with a signal is 0.080 vdc

The voltage across R166 w/o a signal is 0.001 vdc

 

[Perry Babin]

Does R266 have similar voltage when the left channel is working/silent?

 

[seankane]

Yes

0.044 vdc w/signal

0.000 vdc w/o signal

 

[Perry Babin]

Post the voltage on pins 8, 9 and 14 of the LM339 with and without audio.

 

[seankane]

w/o audio

pin 8 : 1.140 vdc and rapidly climbs until audio is achieved.
pin 9 : 3.479 vdc
pin14: 4.47 vdc

with audio

pin 8 : 3.650 vdc (this is where it stops climbing when audio is achieved)
pin 9 : 2.932 vdc
pin14: 0.099 vdc

 

[Perry Babin]

This is normal. Is the turn-on delay too long?

Or is the left channel working properly 100% of the time?

 

[seankane]

The turn on delay is extremely long!!!

If the amp is powered down and right back up it seems to work fine.

The longer the amp is powered down the longer it takes to turn on.

When the left channel finally turns on it seems to work 100%

Could turn on in 45 seconds, could be 5 minutes.

 

[Perry Babin]

C3 may be leaky. Replace it.

 

[seankane]

Replacing C3 made the left channel turn on quickly. The turn on delay is about 3 seconds now. Seems to work fine.

Alot of the caps that I de-solder smell like dead fish if you will which leads to believe they are leaking fluid with that smell. I think probably all the aluminum 10uf 16v caps should probably be replaced on this amp.

Now for the right channel?

What we know:

Very distorted sound cuts in and out

DC on terminal increases as volume is increased

No DC on terminal at idle