I have a Helix MKII amplifier stuck in protect, was playing fine when I got it but only for 10 or so minutes at low volumes before going into protect and staying there. Bought it with the knowledge of it being stuck in protect before so knew I was going to have to mess with it. Has the orange “short protection” LED.
Input voltage 13.6v (the 5.1v on pin 16 is present as soon as I attach the remote, but within a second it drops to 0)
3525
1) GND
2) 0
3) 0
4) 0
5) 0
6) 0
7) 0
8) 0.520
9) 0.010
10) 0
11) 0
12) GND
13) 0.399
14) 0
15) 0.399
16) 0
LM339 (there is two on this amp, both by each other) Left/towards power terminals
1) 0.006
2) 2.038
3) 10
4) 0.007
5) 7.14
6) 7.14
7) 8.58
8) 7.35
9) 0.985
10) 0.688
11) 7.14
12) 0.001
13) 10
14) 0.078
LM339 Right/towards speaker terminals.
1) 8.66
2) 8.66
3) 10
4) 7.14
5) 9.68
6) 7.14
7) 9.67
8) 8.66
9) 7.14
10) 7.14
11) 8.66
12) 0.001
13) 0.006
14) 0.047
Input voltage 13.6v (the 5.1v on pin 16 is present as soon as I attach the remote, but within a second it drops to 0)
3525
1) GND
2) 0
3) 0
4) 0
5) 0
6) 0
7) 0
8) 0.520
9) 0.010
10) 0
11) 0
12) GND
13) 0.399
14) 0
15) 0.399
16) 0
LM339 (there is two on this amp, both by each other) Left/towards power terminals
1) 0.006
2) 2.038
3) 10
4) 0.007
5) 7.14
6) 7.14
7) 8.58
8) 7.35
9) 0.985
10) 0.688
11) 7.14
12) 0.001
13) 10
14) 0.078
LM339 Right/towards speaker terminals.
1) 8.66
2) 8.66
3) 10
4) 7.14
5) 9.68
6) 7.14
7) 9.67
8) 8.66
9) 7.14
10) 7.14
11) 8.66
12) 0.001
13) 0.006
14) 0.047
Last edited:
Looks like I may have issue with a channel, I was observing the outputs of each channel and had set the trigger to 300mv. Upon start up (hooking remote) there is a 3v DC spike then appears to shut down amplifier.
Any good replacements for the TO3 cans? Labeled T220NF and T219PF…MJ15015/16? Those things are stupid expensive lol.
Unless the originals are darlingtons, the 15015/16 should work. Wait a bit to see if anyone has a more definitive answer.
It’s not a Darlington BJT, reads as regular BJT on my DCA75. When testing a TIP102 it reads it as a Darlington, please correct me if I am wrong. I’d like to let you, Perry, know that you’ve taught me sooooo much and am very very grateful for all your help.
Shows the PNP BJT as hFE 152 at IC=5mA VBE=0.598V at IB=5mA. I have a bunch of other outputs BJT’s as well such as 2sa1943/2sc5200 that I wouldn’t mind modding if needed and possible.
Shows the PNP BJT as hFE 152 at IC=5mA VBE=0.598V at IB=5mA. I have a bunch of other outputs BJT’s as well such as 2sa1943/2sc5200 that I wouldn’t mind modding if needed and possible.
Last edited:
I'm not sure what you're asking but the TIP102 is a darlington. I emailed someone who repairs a few of the Helix amps to ask what he uses. I should hear back within a day.
I was just referring to the test on my DCA75, it actually distinguishes Darlington devices, the Helix‘s TO3 BJT is not a darlington device (according to DCA75), unless I am missing something. Was stating that when I pulled a TIP102 from my parts bin, the DCA75 read it as a Darlington.
I will patiently wait, no hurry. Thanks.
I will patiently wait, no hurry. Thanks.
The tech I emailed didn't have an answer. After repairing, test thoroughly.
Drive to thermal protection while checking the idle current at various intervals to confirm that bias current isn't drifting.
Also test at those intervals with a low level sine wave to about 20kHz to confirm that there is no crossover distortion.
Drive to thermal protection while checking the idle current at various intervals to confirm that bias current isn't drifting.
Also test at those intervals with a low level sine wave to about 20kHz to confirm that there is no crossover distortion.