I can't believe they didn't deface that IC.
That IC accepts the triangle and audio waveforms and generates the PWM output. If you have audio (it could be shifted or straight DC if the feedback circuit is working properly) on one input and the triangle waveform on the other input and DC offset on the output, it's likely that the IC is defective. Generally, when they fail, both outputs of the IC swing the same direction (both go high or both go low). That's not possible if the IC is in proper working order.
If it's like some of the other amps that use that IC, there are unused pins. The unused pins have solder pads that lift easily when heated. To prevent damage to the board/pads, use chip-quik solder (desoldering system). It's relatively expensive but you don't need much. chip-quik will send you a sample for free. Digi-key sells it when the sample runs out.
http://www.chipquik.com/
That IC accepts the triangle and audio waveforms and generates the PWM output. If you have audio (it could be shifted or straight DC if the feedback circuit is working properly) on one input and the triangle waveform on the other input and DC offset on the output, it's likely that the IC is defective. Generally, when they fail, both outputs of the IC swing the same direction (both go high or both go low). That's not possible if the IC is in proper working order.
If it's like some of the other amps that use that IC, there are unused pins. The unused pins have solder pads that lift easily when heated. To prevent damage to the board/pads, use chip-quik solder (desoldering system). It's relatively expensive but you don't need much. chip-quik will send you a sample for free. Digi-key sells it when the sample runs out.
http://www.chipquik.com/
For amps that use those ICs, the IC next to the blue crystal generates the carrier wave (square wave ~80kHz).
There is an op-amp that takes the square wave and converts it to a triangle wave (op-amp used as an integrator).
There is another op-amp that compares the output to the preamp signal and corrrects for errors (simple servo/feedback circuit).
These op-amps may be on the same IC or on different ICs. It varies by amp.
The triangle waveform and the audio drive waveform (out of the op-amp being used for error correction/feedback) are driven into the lm361 (could also be an NE529). The 361 drives the outputs through a driver stage.
If you post the voltages on all of the pins of the lm361, it will help in troubleshooting.
There is an op-amp that takes the square wave and converts it to a triangle wave (op-amp used as an integrator).
There is another op-amp that compares the output to the preamp signal and corrrects for errors (simple servo/feedback circuit).
These op-amps may be on the same IC or on different ICs. It varies by amp.
The triangle waveform and the audio drive waveform (out of the op-amp being used for error correction/feedback) are driven into the lm361 (could also be an NE529). The 361 drives the outputs through a driver stage.
If you post the voltages on all of the pins of the lm361, it will help in troubleshooting.
well kinda hard now to i was testing the voltage on the pins of the lm361 and i touched one of the pins with my meter probe and well the power supply decided to take a crap on me it poped a trace from the remote wire to the diode took out the diode and i fixed the trace and the diode but now the amp is in protection
How did you blow a diode in the remote turn-on circuit (this may help in troubleshooting)? That's nowhere near the 361 in most amps. Were you probing the 361 when it the damage occured?
Whenever testing an amp, you should always use an inline current limiter (resistor or headlamp if your supply doesn't have current limiting) or a fuse rated no higher than 10 amps. These won't always provide complete protection but they will save many components from damage when something goes wrong.
Since I don't have any notes on a 1500, you may need to post some photos (better than those on ampguts).
justonemoreamp may have a schematic to help you troubleshoot the protection circuit if it was damaged.
Whenever testing an amp, you should always use an inline current limiter (resistor or headlamp if your supply doesn't have current limiting) or a fuse rated no higher than 10 amps. These won't always provide complete protection but they will save many components from damage when something goes wrong.
Since I don't have any notes on a 1500, you may need to post some photos (better than those on ampguts).
justonemoreamp may have a schematic to help you troubleshoot the protection circuit if it was damaged.
sorry perry it was a long day ok for starters i had a friend helping me out on that amp and writing down the voltage on thoose pins of the lm361 well i finally got it out of him he said with the neg lead of the meter he had it on the ground terminal of the amp and he touched the diode with the pos lead with the amp powerd on thats when it took out the diode so i was like whatever but the amp itself whent into protection before that he said he put on lead on the emitter of a transistor in the power supply and the other on a collector of the same transistor and heard they relay click inside the amp and right then it went into protection mode so now not sure where i go from there i was working on the colossus amp at the time thats why i had him help me well guess i shouldnt have now i have more problems wrong with the amp
Since I have no experience with the amp, no schematic and no photos, I can't help much.
If he burned a trace, he likely shorted two pins together. You need to check the components in the area where he was probing the circuit. check the transistors for opens and shorts.
You need to determine if the supply is operating. If you have rail ±rail on the source of the outputs, the supply is operating.
If the power supply is in operation, the amp may be OK other than the protection circuit.
If he burned a trace, he likely shorted two pins together. You need to check the components in the area where he was probing the circuit. check the transistors for opens and shorts.
You need to determine if the supply is operating. If you have rail ±rail on the source of the outputs, the supply is operating.
If the power supply is in operation, the amp may be OK other than the protection circuit.
perry to me you are a god i wanna thank u very much for telling me what to check i replaced 2 transistors in the protection circuit and amp is not in protection anymore now i gotta figure out the rca inputs im gonna check the lm361 like u said to see if its bad the is a transistor in the output side right next to the lm361 the number on it is 431a when i check it in circuit from collecter to emmiter it says its shorted when outta circut reads good and when its outta circuit i touch my meter leads on the board where it goes and from emmiter to collecter it says its shorted wondering if this is normal or if it will read like that if that lm361 is bad?
There has been a problem on some amps of similar design where some surface mount tantalum caps short. Check all black 2 terminal SMD devices in the area. They will have board designations Cxxx. If you find any shorted, lift them and check them off of the board. They may also leak (electrically) instead of being shorted to zero ohms so sometimes they are difficult to find.
The tantalums can be somewhat sensitive to high temps so turn your iron down a bit (if it's temp controlled) if you have to remove them. It's better to replace them if you remove them but some people reuse them with no problems.
Do the transistors have any other markings like DF or 3B?
The tantalums can be somewhat sensitive to high temps so turn your iron down a bit (if it's temp controlled) if you have to remove them. It's better to replace them if you remove them but some people reuse them with no problems.
Do the transistors have any other markings like DF or 3B?
The 431 could well be a shunt reg. That design uses a regulator set ~12 volts off of the rails for the drivers. Most use zener regs but this one could be different.
Before I found any information on the IC (all were defaced), I used input, output, power and ground connections to determine that an NE529 was a good sub. I've used several in kicker amps. Of course, it's always best to use the exact replacement.
Before I found any information on the IC (all were defaced), I used input, output, power and ground connections to determine that an NE529 was a good sub. I've used several in kicker amps. Of course, it's always best to use the exact replacement.
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