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| Classic II bad sound. |
Posted by: falen5 on 2020-02-13 15:59:44
My old classic II started making strange noises few weeks ago. Cleaned the board to no avail
Got worse until sound totally died.
looking at the board the chip 34119 an audio amplifier has blown.
I have a TL071 chip from a dead se30 board.
anyone know if the TLO71 will do as a replacement for the 34119
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Posted by: cheesestraws on 2020-02-14 02:28:33
As far as I know those are completely different chips; the TL071 is just a dual op amp whereas the MC34119 has a bunch more going on (if I'm reading the datasheets properly). A bit of cursory googling suggests Maxim have a replacement for the MC34119 but in a more restricted range of packages; there are likely other replacements out there.
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Posted by: falen5 on 2020-02-14 05:10:56
Thanks for that Cheesestraws.
I found a replacement 34119 from china but it only comes in lots of 5.
Ill just have to wait.
And with that virus that wait could be much longer. Im over due on usual shipping times from china on some other items.
I can wait on that chip , those poor people have bigger concerns in China than my chip. God bless em all out there.
Thanks again cheesestraws.
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Posted by: falen5 on 2020-02-16 22:25:28
I found a classic 2 board in one of my box's of bits that had died from a battery leak , and the 34119 was looking good.
used it to replace the damaged one and now i have good sound again.
but now there is a new random problem.
if i flex the board , in any way, it causes a reset.
I imagine i have a bad connection somewhere around the area of the sound chip. But a reset would point to something like power , or the clock crystal
Have spent ages trying to find the bad connection, reflowing all the resistors, capacitors and chip legs i can but just cant find it.
Does anyone know of a way to find a bad connection on a board , that only shows if you flex the board a tiny bit ( even raising one corner of the board causes this reset)
thinking of putting the board in the over, or 'hot air gunning ' half the board , the idea fills me with a sense of dread !!!
how do you find 1 bad connection !!!!
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Posted by: bibilit on 2020-02-17 00:00:54
IIRC the reset is done through the sound chip
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Posted by: falen5 on 2020-02-17 06:54:49
Thnaks for that biblit - never knew reset was done through sound ship. Same for all 68K macs ?
The chip is soldered on to all pads good - pretty sure its not the connections on the chip - metered out pin to pads and closest via's while 'flexing board' , cant find any problems
must be something close by after using hot air gun to remove old chip
This is a nightmare
you ever get that feeling that you know you are just making it worse!!
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Posted by: Bolle on 2020-02-17 06:58:29
Same for all 68K macs ? Most of them, yes.
The Sony DACs (and the integrated soundchip/DAC combo ICs on later machines) have a feedback built in to measure the 5V rail and hold the logicboard in reset if the voltage level is too low.
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Posted by: falen5 on 2020-02-17 08:32:45
Thanks for all the help everyone - I found it with the meter.
Trace
probabbly half eaten by elctrolite from when i recapped it.
Eyes are just not what they used to be.
Great stuff !
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