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Old 01 September 2013, 22:46   #1
h0ffman
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A600 Audio Filter Always On!

Hope you guys can help. Basically I was trying to setup my A600 and A1200 as a DJ setup using the PT-1210 software I wrote (as previously shown by Akia, hi mate).

I finally got around to setting it up today and the first thing I noticed is the A600 sounds like the filter is on. Direct comparison between the A600 and A1200 playing the same tune definitely sounds like it thats the case.

I know for a fact the code is disabling the filter (standard PT-Replay). Also the A1200 just simply sounds like it should!

Firstly has anyone else ever had this problem?

Secondly, there is a thread on here somewhere which says I can hard disable it by removing the Q341 transistor. I've located it (far right side of the mobo, last in a line of 3)

Has anyone ever done this mod?

Any info would be awesome.

Cheers
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Old 01 September 2013, 22:52   #2
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Did you recap the 2 audio caps? because music will sound dull with old caps.
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Old 01 September 2013, 22:57   #3
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nope, bugger.. that will be what the problem is then as there seem to be leakage! F@*K sticks!
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Old 01 September 2013, 23:06   #4
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looks like new caps then
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Old 02 September 2013, 01:08   #5
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Does the power LED changes intensity when you enable/disable the filter (or just reset the machine)? Because they are hardwired together.
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Old 02 September 2013, 20:44   #6
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yep. definetly does dim when changing the filter. There was crap on the motherboard right around the capacitors so its gotta be that.

Gutted
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Old 02 September 2013, 20:53   #7
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Sounds very likely yes. But when you take them out, be sure to check all the connections before soldering in the new ones as it is likely that something's broken.

Just replacing the caps with new ones will probably not fix the problem.
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Old 02 September 2013, 20:54   #8
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Bugger, I need a professional to fix this then sad times.
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Old 02 September 2013, 21:03   #9
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Bugger, I need a professional to fix this then sad times.
connect U15 (LF347/TL084) pins 8 and 5 for Right Channel and pin 14 and 3 for Left Channel - if audio sounds like Filter OFF then issue is located somewhere around FET transistors (for example issue with U28 MC1488, CIA etc).
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Old 03 September 2013, 00:26   #10
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Also going by my already recapped A600, even with the filter off the audio is a fair bit muddier/duller than an A1200. The difference is not noticeable on a TV but with a Hi-Fi it's obvious.
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Old 05 September 2013, 14:26   #11
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Seems I've found a sollution, a friend of mine is going to do a like for like A600 swap with me. He needs it more for ASCII art than sound

btw all this is leading up to Sundown Demoparty this weekend..... i'll post another thread
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Old 05 September 2013, 21:35   #12
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Seems I've found a sollution, a friend of mine is going to do a like for like A600 swap with me. He needs it more for ASCII art than sound

btw all this is leading up to Sundown Demoparty this weekend..... i'll post another thread

This will not fix problems with dry/leaking caps.
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Old 06 September 2013, 19:29   #13
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I suspect the same here with an A600 Rev1.5. Audio caps and some around the power input all smell fishey and look a bit off!

Im going to send over to the guys at Amigakit, not sure when but re-capping is something I will not even attempt without the correct stuff!

Those two audio caps are so close to the keyboard ribbon slot... how can somebody replace them without causing damage?
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Old 08 September 2013, 13:34   #14
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Quote:
Originally Posted by ElectroBlaster View Post
I suspect the same here with an A600 Rev1.5. Audio caps and some around the power input all smell fishey and look a bit off!

Im going to send over to the guys at Amigakit, not sure when but re-capping is something I will not even attempt without the correct stuff!

Those two audio caps are so close to the keyboard ribbon slot... how can somebody replace them without causing damage?
Take of the top part of the keyboard connector, use some heat protective tape on the bottom part of the keyboard connector, use some flux, and tada.
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Old 08 September 2013, 22:16   #15
h0ffman
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well I tested another working A600 at the weekend and finally found at that basically, the a600 has shit sound circuits compared to the A1200. While at the demo party someone overheard me and said, "I have a spare A1200, you want it? I don't want any money for it" :O so I have two now, and they both sound great.

Aparently its well knows the 600 sound isn't great and there is a way to make it better, but I dont need to now
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Old 08 September 2013, 22:29   #16
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There is a way to change the gain on the A600 audio circuit similar to the hack for the A500, it can be increased or decreased by swapping out 2 resistors of different value
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