Despite changing all the smd Co. Points I know of on these amplifiers,
4.7r, 0r, 4401-4403, both the driver card and the power curcuit.
The Amp remains in pulsation protection. I have removed all of the protection 10k resistors one at time.
Protection always remained the same, pulsation about. 7amps of current. Never turning on?
4.7r, 0r, 4401-4403, both the driver card and the power curcuit.
The Amp remains in pulsation protection. I have removed all of the protection 10k resistors one at time.
Protection always remained the same, pulsation about. 7amps of current. Never turning on?
Pulled them all. All of them are good. That's why I'm so stumped. After nothing seemed to bring it out. I changed all the 2x transistors on the card. Pulsating protection.
I can't seem to find the dp52, lifting dp4 has same result.I found a d52 in the center of the pwm card when lifted the Amp draws current.
Correction D52 not DP52. D52 hangs off of IC3-LM358 comparator monitoring the B+ line and sends a error signal to U14-Pin 16.
Replace DP4 and D52. Look at the DC voltage at the anode of D52, same as IC3-Pin 7. Normally this voltage will read low near 0 volts.
If it reads high remove the mosfets Q24,25,28,29-IRFZ46N. Check the DC Volts around U14 and look at waveforms at Pins 5, Pins 9 & 10. Post your results.
Replace DP4 and D52. Look at the DC voltage at the anode of D52, same as IC3-Pin 7. Normally this voltage will read low near 0 volts.
If it reads high remove the mosfets Q24,25,28,29-IRFZ46N. Check the DC Volts around U14 and look at waveforms at Pins 5, Pins 9 & 10. Post your results.
If its an older amp then I would start by changing electrolytics in protect circuit as they age first.
Tl494c voltage.
1.) . 883
2.) 3.693
3.) 0.054
4.) 0.029
5.) 1.445
6.) 0.001
7.) 0.000
8.) 0.000
9.) 10.21
10.) 5.23
11.) 0.008
12.) 13.19
13.) 4.891
14.) 4.872
15.) 4.871
16.) 4.117
As soon as I add the fets the pulsing starts, using irf3205's still have the 100R gate resistors, should I lower the resistance to say 47R?
1.) . 883
2.) 3.693
3.) 0.054
4.) 0.029
5.) 1.445
6.) 0.001
7.) 0.000
8.) 0.000
9.) 10.21
10.) 5.23
11.) 0.008
12.) 13.19
13.) 4.891
14.) 4.872
15.) 4.871
16.) 4.117
As soon as I add the fets the pulsing starts, using irf3205's still have the 100R gate resistors, should I lower the resistance to say 47R?
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The voltages you listed for Pins 8 through 11 can't be correct, considering the waveforms you posted. But based on those waveforms the power supply is working. I'll have to get back to you about the gate resistor values, but the 100 ohm resistors shouldn't cause the amp to pulsate.
Check the resistances between speaker and power GND's
OK, now I have been through the entire curcuit. No failed components. Drive is good. I removed all the outputs and lifted the output protection resistors. R33, R34, R88, R89. Powered up the amp, current. So I go to Check the ps fets one is shorted. I remove it and power it up again. Current. Removed them all drive is 100% Good 30khrz square wave. All resistors and capacitors check good. So I'm leaning towards the transformer has a short somewhere.
To be sure the diode pack for BR1 is common cathode. That leaves BR2 to be common anode.
The schematic shows a U1620C-BR1 and U1620A-BR2.
I'm assuming the rectifiers at location BR1 and BR2 are not shorted.
Also, to be sure the current draw is caused by the transformer and not something in the output stages, remove BR1 and BR2 and check again for current draw.
OK so without the rectifiers and no outputs in the curcuit. The amplifier does the same strange pulsating.
post a pic of the transformer and surrounding area and one overall top and bottom side.
Does the transformer have any hotspots, discolored windings? Is the core cracked? If you twist and turn the transformer does the pulsing stop?
Does the transformer have any hotspots, discolored windings? Is the core cracked? If you twist and turn the transformer does the pulsing stop?
