Friend found amp in storage shed when cleaning and gave it to me.
Hooked it up to 12v and immediately blew fuses with no remote wire hooked up.
Popped it apart to find a crusty board with blown IRFZ44's in the power supply. Cleaned it up a bit, jumped a blown trace or two, slap some new IRFZ's in there and it now turns on and works great on the test bench.
One issue, when input board is connected as soon as power is connected amp turns on with no remote wire connected. Disconnect signal board and remote terminal acts normally. This is with low level inputs being used, happens even with RCAs disconnected.
Does anyone have any suggestions on what to check from here?
Hooked it up to 12v and immediately blew fuses with no remote wire hooked up.
Popped it apart to find a crusty board with blown IRFZ44's in the power supply. Cleaned it up a bit, jumped a blown trace or two, slap some new IRFZ's in there and it now turns on and works great on the test bench.
One issue, when input board is connected as soon as power is connected amp turns on with no remote wire connected. Disconnect signal board and remote terminal acts normally. This is with low level inputs being used, happens even with RCAs disconnected.
Does anyone have any suggestions on what to check from here?
I guess I should have mentioned remote terminal shows ~1+Mohm resistance to Batt. Terminal and no visible signs of solder bridges or anything of that sort.
Since input board and rest of amp are seperate poked around high level inputs and did not see voltage there (amp has signal sense turn on). Poked around the board interconnect cable and found a 12 and 5v line, tried depinning those and still same.
Since input board and rest of amp are seperate poked around high level inputs and did not see voltage there (amp has signal sense turn on). Poked around the board interconnect cable and found a 12 and 5v line, tried depinning those and still same.
In the 300.2 owner's manual that I found, I didn't see the signal sense.
If it has signal sense, power it up with no signal input. If it comes on, leave it on for several minutes to see if it shuts off. I've seen amps with signal sense have the amp come on but after a few minutes go off if there is no signal. The initial turn on could be inadvertent (due to a fault) or part of the design but if it goes off with no input, it may not be a real problem.
If it has signal sense, power it up with no signal input. If it comes on, leave it on for several minutes to see if it shuts off. I've seen amps with signal sense have the amp come on but after a few minutes go off if there is no signal. The initial turn on could be inadvertent (due to a fault) or part of the design but if it goes off with no input, it may not be a real problem.
I could swear I've left it on for an hour with nothing but PWR + GND connected. Let me hook it up again to make absolutely sure.
This manual states amp has signal sense: (very bottom of page)
http://www.manualslib.com/manual/612108/Orion-Cobalt-Co300-2.html?page=4#manual
This manual states amp has signal sense: (very bottom of page)
http://www.manualslib.com/manual/612108/Orion-Cobalt-Co300-2.html?page=4#manual
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Started following the high level input circuit and found a PC-17K1 Optocoupler, With opto removed remote turn on terminal now operates as expected.
I think the storage shed was. 😛
Took a closer look and what do we find? CRUSTINESS!
Couldn't see it when in the board due to nearby components obscuring the view.
Scraped the crud from bridging those contacts, cleaned the board side, tinned the leads to get the crud of them and it now acts normally with opto in place. About to try the high level inputs to see if signal sense operates as it should.
Took a closer look and what do we find? CRUSTINESS!
Couldn't see it when in the board due to nearby components obscuring the view.
Scraped the crud from bridging those contacts, cleaned the board side, tinned the leads to get the crud of them and it now acts normally with opto in place. About to try the high level inputs to see if signal sense operates as it should.
Tried signal sense, amp came on just fine. Disconnected wires from high level inputs, waited for one minute and heard a click and saw amp shut off.
Would be great except for the fact that the click was the main fuse popping (had a 5A in there). Slapped another in and popped instantly. Time to pull the darn board out again. 😡
I ran it for 4 hours straight the other day with nary an issue besides the turn-on/off stuff.
Would be great except for the fact that the click was the main fuse popping (had a 5A in there). Slapped another in and popped instantly. Time to pull the darn board out again. 😡
I ran it for 4 hours straight the other day with nary an issue besides the turn-on/off stuff.
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