The bias should be working. Connect one of your meters across the lamp and adjust one of the bias pots. Does the voltage across the lamp increase when you turn it clockwise?
Just leave it powered long enough to see if the voltage changes.
This can also be done by measuring the DC voltage across the 0.1 ohm resistors but the test above will be easier.
Just leave it powered long enough to see if the voltage changes.
This can also be done by measuring the DC voltage across the 0.1 ohm resistors but the test above will be easier.
Didn't you try this earlier and the light didn't light up?
Set the bias pots to the point just before the voltage across the lamp starts to increase.
I think you can check for audio now. You can try it with the lamp in series or with a 5 or 7.5 amp fuse. Only play it at low volume for short periods, monitoring the temperature of all of the heatsink mounted components.
If both channels produce clean audio, order parts.
If I'm not mistaken, you confirmed that there was no significant DC across the speaker terminals (well under 1v). If not, do that before connecting speakers.
Set the bias pots to the point just before the voltage across the lamp starts to increase.
I think you can check for audio now. You can try it with the lamp in series or with a 5 or 7.5 amp fuse. Only play it at low volume for short periods, monitoring the temperature of all of the heatsink mounted components.
If both channels produce clean audio, order parts.
If I'm not mistaken, you confirmed that there was no significant DC across the speaker terminals (well under 1v). If not, do that before connecting speakers.
When I tried before, you said turn it up until the light gets brighter. I probably didn't go far enough to illuminate it before.
I am not seeing any voltage across the speaker terminals. I tried both channels as well as bridged.
I'm off tomorrow and it's supposed to be a nice day here in Illinois. Perfect for testing in the vehicle.
Concerning parts ordering. You suggested MMBTA06FSCT-ND and MMBTA56FSCT-ND. Am I correct in assuming you want to use those instead of the 3904 and 3906's that came out?
Should I switch the Z44 out for an IRF3205 when the parts order comes in?
Is a sub good for testing or, should I try to find a full range speaker?
The 06/56 were mainly for the power supply drivers. If you're going to leave the 3904/06 there, order the 3904/06 to replace the stolen protection circuit transistors, If you're going to work on more Rockford amps, order all 4 part numbers.
Yes. Replace the Z44. Order extras of the 3205 in case you overheat the replacements. After replacing everything power up through the lamp before reinstalling to confirm that there isn't any excessive current draw.
You can test with the sub. It's likely to survive if the amp fails for some reason but you should test on full range speakers to see if it's producing clean audio.
Yes. Replace the Z44. Order extras of the 3205 in case you overheat the replacements. After replacing everything power up through the lamp before reinstalling to confirm that there isn't any excessive current draw.
You can test with the sub. It's likely to survive if the amp fails for some reason but you should test on full range speakers to see if it's producing clean audio.
Looking at the datasheet, it appears the 06/56 have higher voltage ratings. I'm guessing they are a little more robust and thus more reliable?
What do you think of this fan if I can find a way to get it in there?
http://www.ebay.com/itm/121880732676?_trksid=p2060353.m1438.l2649&ssPageName=STRK:MEBIDX:IT
I'm watching a few Fluke 12's. They hold a good value I see.
Fluke 12 Multimeter with Factory Leads | eBay
What do you think of this fan if I can find a way to get it in there?
http://www.ebay.com/itm/121880732676?_trksid=p2060353.m1438.l2649&ssPageName=STRK:MEBIDX:IT
I'm watching a few Fluke 12's. They hold a good value I see.
Fluke 12 Multimeter with Factory Leads | eBay
There are trade-offs when choosing virtually anything. The A06/56 handle more current which can help them to survive when PS FETs fail but they have lower current gain which may make them less suitable for the protection circuit. Voltage isn't an issue for the ones you replaced but can sometimes be a determining factor in choosing transistors.
I purchased 4 of those fans after I it was mentioned n this thread. They're a bit noisy but may be acceptable when under a rear seat with the carpet to absorb some of the noise. They move a good bit of air. If you can get the fan within about 18 inches of the amp, it will move enough air to make a difference in temperature. At 18 inches, it's not going to be a hurricane but any moving air is better than none.
Any fluke 12 in perfect working order is worth $100 shipped in my opinion. The fact that the 'beep' is so quick when the leads are touched together or when testing components makes it worth the price. Check the local pawn shops (call around). It looks like a simple meter and people tend to dismiss them as junk so they sit on the shelves for a long time. You may be able to find a good deal.
I purchased 4 of those fans after I it was mentioned n this thread. They're a bit noisy but may be acceptable when under a rear seat with the carpet to absorb some of the noise. They move a good bit of air. If you can get the fan within about 18 inches of the amp, it will move enough air to make a difference in temperature. At 18 inches, it's not going to be a hurricane but any moving air is better than none.
Any fluke 12 in perfect working order is worth $100 shipped in my opinion. The fact that the 'beep' is so quick when the leads are touched together or when testing components makes it worth the price. Check the local pawn shops (call around). It looks like a simple meter and people tend to dismiss them as junk so they sit on the shelves for a long time. You may be able to find a good deal.
I was worried about those fans being noisy.
I'm puzzled Perry. I have the amp in the truck. I have NOT hooked up B+. I have 12V at the remote terminal but, no power light. Ground lead on the same ground coming into the amp so it has to be good. I verified the power LED plug is securely plugged in. I am reading 4.4V at the emitters of all 4 driver transistors. I have the same 4.4V at the gate of Q6 and Q7.
I have nothing on the center legs of the rectifiers but, I can't remember if you need B+ for that or not?
I'm puzzled Perry. I have the amp in the truck. I have NOT hooked up B+. I have 12V at the remote terminal but, no power light. Ground lead on the same ground coming into the amp so it has to be good. I verified the power LED plug is securely plugged in. I am reading 4.4V at the emitters of all 4 driver transistors. I have the same 4.4V at the gate of Q6 and Q7.
I have nothing on the center legs of the rectifiers but, I can't remember if you need B+ for that or not?
You will only have drive voltage without B+. All else is powered by the secondary of the power supply which is dead without B+.
http://www.bcae1.com/temp/speakerlevelfancontroller01.gif
http://www.bcae1.com/temp/speakerlevelfancontroller01.gif
Ahh ok. Evidently I "thought" I had it lit up without it but, was mistaken. I figure better to ask than destroy something.
After hooking up B+ I now have the power LED. I shut it off and hooked up the sub. It does not play and the power LED is very dim and faintly blinking. Is it possible the headlight is robbing too much current to drive the sub?
I'm tempted to insert one of my meters and check current but, it only goes up to 10A. Might not be a good idea
I'm tempted to insert one of my meters and check current but, it only goes up to 10A. Might not be a good idea
Use a 5 amp fuse. You can have your meter in series as well if you want to monitor the current.
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