bump in the nite

[acebaker]

Ok so the Extreme 400 is "bumping" on startup and "pop-ing" between tracks. It also "burbles" after the startup bump. The speaker moves rapidly and erratically. I checked all the fet's and ouput t's and all were consistent. It settles down and plays but on car batt voltage it "crackles" on the bench 10a pwr supply it seems fairly quiet. Can't turn it up too loud of course with only 10A.

[Perry Babin]

Are you using the same signal source on the bench and in the vehicle?

Does having the engine running make a difference?

[acebaker]

No, not the same signal source. However the other two amps in the system make no noise and when the 400 is replaced with a Cobalt 265 the system sounds great. Engine on equals more noise. On the bench I'm using a Pyramid 10A pwr supply. When I power the amp up with a JVC deck the speakers give off a pop then rumble for a few seconds then settle down and play. I can barely hear the static noises using the Pwr supply but they are very prominent in the vehicule. Basically the same thing is happening on the bench as the car but the "crackling is louder in the car. The fact that I can only draw 10a limits my ability to turn it up to the same level as the car. The other two amps in the system are an Extreme 800 with the phase switches removed and hard wired 0-180 bridged into a Older kicker 8ohm sub and an Extreme 200 running a pair of Bravox Kevlar/aluminum co-axials at 4ohms/ch. The fronts are Bravox 6.5 Kevlar /aluminum components.

[Perry Babin]

Do you have a scope?

[acebaker]

Actually I do have one. It's a Tek 2235 but I haven't tried to use it yet. I'm still in my infancy of electronic repair and haven't found the time to learn how to use it. One thing I noticed this morning was that this amps been worked on before. I took the clips off the output side and found that all the transistors are Motorola 2n6491's and 2n6488's but one channel has nl906 stamped on them and the other has 738 on the 6491's and 840 and 843 on the 6488's. I'm assuming these are lot numbers. The soldering is clearly different on this channel. Another thing I noticed was I put the ohmeter on the + speaker outputs and the large resistor that is attached to it and there's a .8 ohm dfference though both resistors are the same value. (6.0 and 6.8)

[acebaker]

The resistors Im talking about are between the + spkr terminals and the two green capacitors right behind the 5pin speaker/remote plug. One is showing 5.7 ohms and the other is showing 6.5. both were measured on a Fluke 75 and a Fluke 10, same results. I can tell they are 1w 5% resistors but the color codes are black. Even the tolerance code is quite discolored compared to other 1w resistors in the amp. Can anyone tell me what there supposed to be? It looks to me that both have been running hot. Orion Extreme 300. Tanks:

[Perry Babin]

Learn to use the scope today. Page 73 of my car audio site will give you the basics. Post whatever other questions you have.

Post a photo of the resistor you're referring to and a photo of the entire amp board.

Is this an extreme 300 or 400?

[acebaker]

I'll try Perry but the railroad is consuming far too much of my time. I have a 500 that I opened up for comparison and the two resistors were in perfect shape. They are 5.6ohms. Both of these were the same on the Fluke and the color codes were very brite. Not to mention the fact that the blue was brighter as well. Compare them to the 300's which are unreadable. The value stripes and the multiplier are all black. In fact the second value stripe on the resistor with the higher actual resistance is partially peeled off. These puppies were working hard. I'll throw in a pic but the wife had the good camera.

[acebaker]

of course the pic didn't work

[acebaker]

k here's the pic.resitors 2.jpg