Power 1501 BD

Hexhclass

Member
2010-06-22 6:08 pm
usa
This amp will power up and produce good audio.After about 15mins it goes off.5mins later it will come back on and repeat the cycle.Am not sure if it is thermal problem but i lift the two thermistor away from the heat sink but saw no change in the cycle.Any idea what is happening there?
 

Hexhclass

Member
2010-06-22 6:08 pm
usa
I forgot to check the signal on the outputs.

working
1:4.37
2:4.37
3:15.02
4:0.286
5:1.654
6:3.786
7:4.97
8:0.683
9:1.272
10:4.97
11:7.15
12:0.001
13:4.36
14:0.001

shutdown
1:3.702
2:3.688
3:12.43
4:0.001
5:1.421
6:4.12
7:4.31
8:0.185
9:0.185
10:4.32
11:7.76
12:0.001
13:3.714
14:0.001
 
I think the readings drift because the amp is slowly recovering from what shut it down.Taking the reading is a challenge because the amp recovers very fast when i remove the bottom cover.
I pull both thermistor just to make sure they not triggering the shutdown.Maybe an IC is thermally shunting down?
 
Went back to this amp today.I see good gate signal on all PS FET.

SG3526
working --- shutdown
1:4.96 ----- 4.23
2:3.778 ---- 0.002
3:4.22 ------ 0.109
4:4.69 ------- 0.008
5:4.18-------- 0.022
6:0.001------- 0.000
7:0.001 ------ 0.000
8:4.33 --------3.365 pulsing to about 3.772
9:3.735 ------ 3.082
10:1.995 ----- 1.794
11:0.003------- 0.002
12:4.63 -------- 4.15
13:6.66 -------- 0.001
14:15.65 -------12.59
15:0.001 ------- 0.000
16:6.67 --------- 0.001
17:15.67 --------12.59
18:4.96 ----------4.33
 
Last edited:
I think the IC may be defective. I checked the voltage with and without B+ as well as with the shutdown pin grounded and the regulated output on pin 18 was a constant 5.01v.

It could be that the regulated voltage is being pulled down, causing the IC to shutdown but that wouldn't make the IC overheat?

Do you have another IC to replace this one?

If you replace it, you may have to temporarily remove R34 if the new IC won't function.