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AuthorTopic: -Low Sound in A1200  (Read 1944 times)

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Offline rkauer

Re: -Low Sound in A1200
« Reply #15 on: November 24, 2009, 04:50:43 AM »
Quote from: dreamcast270mhz;531038
Couldn't you replace the electrolytic w/ tantalum ines, which (I think) don't leak

 They don't leak, they flash.

 Taken from Wiki:
Quote
Tantalum capacitors possess very low electrical leakage (high leakage resistance), and will retain a charge for a long duration. They are also more tolerant of hot operating environments, unlike standard aluminium electrolytic capacitors. Tantalum capacitors are relatively expensive, particularly the military grades. They are not particularly tolerant of heavy charge and discharge currents, particularly those of a repetitive nature. Their effective series resistance (ESR) is quite high when compared to aluminium electrolytics.
 As with all electrolytic capacitors, correct polarity must be observed otherwise the capacitor will depolarize and the dielectric oxide layer will be reduced back to the metal, reducing the resistance of the device and causing it to become very hot and possibly explode. Tantalum capacitors are less prone to "drying out", causing a decrease in capacitance as is often the case with aluminium electrolytic capacitors particularly when used in hot environments. They maintain their designed capacitance under such conditions over long periods (decades).
Goodbye people.

I\'ll pop on from time to time, RL is acting up.
 

Offline Castellen

Re: -Low Sound in A1200
« Reply #16 on: November 24, 2009, 05:54:56 AM »
The above notes about tantalums are indeed correct.
It's also worth pointing out that they will work fine for audio coupling and will be OK in the Amiga if you want to use them.  The problems you might have is the mechanical mounting of them since the PCB pads for SMD electrolytics are different to those used by SMD tantalums.

Tantalums should generally not be used on DC power supply rails for AC decoupling.  The reason is that the low equivalent series resistance of the tantalum capacitor results in a very high momentary inrush current when the power supply is turned on.  The high current flow causes the capacitor to heat up internally, which can result in it going short circuit and sometimes exploding.  Google 'explode' and 'tantalum' to find out more.
 

Offline DrDekker

Re: -Low Sound in A1200
« Reply #17 on: November 24, 2009, 01:12:52 PM »
Before working on your Amiga - try swapping your PSU for one that's known to be good.
 
One of my PSU's developed a fault which allowed ac to be passed through to my A600, causing a machine gun rat-tat-tat sound through the speakers (and graphical glitches/system crashes too).
A1200, M-Tec 1230 @28MHz, FPU, MMU, 8Mb fast ram, SCSI card, 512Mb HD, Power CDROM drive, PS2 optical mouse
 

Offline Drummerboy

Re: -Low Sound in A1200
« Reply #18 on: November 25, 2009, 02:44:49 AM »
Ok,

I was checking inside and and the apparently the acid only was in the Capacitors base, but never put many atention to this compnentes in the A1200, and see i cant replace the componentes my self, becouse my soldering tool its not properly, then i be need do with any people have the right soldering tool.
Anyway, for now y clean the motherboard and the bad capacitors.

But here born a new thing!, becouse inside the A1200 i sew 2 more capacitors the same Rating, and other capacitors, diferent number rating, but the same look, then the Question is..

Exist any damage report in this other capacitors?..
Amiga 1000, 500, 600, 2000, 1200, 4000...

C= VIC 20 / 64 /SX64/ 128

Atari 600XL (SIC Cartdridge)
Atari 800XL (SIO2SD unit)

Jay Miner`s Atari 2600 - Wood front -

\\"Amiga, this Computer have a Own Live\\"--\\"Silence When the Drums are Talking\\".... DrummerBoy
 

Offline Drummerboy

Re: -Low Sound in A1200
« Reply #19 on: November 25, 2009, 03:25:11 AM »
Quote from: DrDekker;531101
Before working on your Amiga - try swapping your PSU for one that's known to be good.
 
One of my PSU's developed a fault which allowed ac to be passed through to my A600, causing a machine gun rat-tat-tat sound through the speakers (and graphical glitches/system crashes too).


Humm.. intersting.. and any problem with the sound?..
Amiga 1000, 500, 600, 2000, 1200, 4000...

C= VIC 20 / 64 /SX64/ 128

Atari 600XL (SIC Cartdridge)
Atari 800XL (SIO2SD unit)

Jay Miner`s Atari 2600 - Wood front -

\\"Amiga, this Computer have a Own Live\\"--\\"Silence When the Drums are Talking\\".... DrummerBoy
 

Offline Damion

Re: -Low Sound in A1200
« Reply #20 on: November 25, 2009, 03:26:48 AM »
Quote from: Drummerboy;531188
Ok,

I was checking inside and and the apparently the acid only was in the Capacitors base, but never put many atention to this compnentes in the A1200, and see i cant replace the componentes my self, becouse my soldering tool its not properly, then i be need do with any people have the right soldering tool.
Anyway, for now y clean the motherboard and the bad capacitors.

But here born a new thing!, becouse inside the A1200 i sew 2 more capacitors the same Rating, and other capacitors, diferent number rating, but the same look, then the Question is..

Exist any damage report in this other capacitors?..


Definitely! Replace them all. On the few boards I've repaired, they seem to fail somewhat randomly (some worse than others). If the leakage is minor it might not be visible (yet), so IMHO go ahead and clean around all of them until you can get it repaired.
 

Offline DrDekker

Re: -Low Sound in A1200
« Reply #21 on: November 25, 2009, 01:01:18 PM »
One of my PSU's developed a fault which allowed ac to be passed through to my A600, causing a machine gun rat-tat-tat sound through the speakers (and graphical glitches/system crashes too).
 
Quote from: Drummerboy;531190
Humm.. intersting.. and any problem with the sound?..

Take a guess! :hammer:
A1200, M-Tec 1230 @28MHz, FPU, MMU, 8Mb fast ram, SCSI card, 512Mb HD, Power CDROM drive, PS2 optical mouse
 

Offline Drummerboy

Re: -Low Sound in A1200
« Reply #22 on: November 26, 2009, 01:44:16 AM »
Quote from: Damion;531191
Definitely! Replace them all. On the few boards I've repaired, they seem to fail somewhat randomly (some worse than others). If the leakage is minor it might not be visible (yet), so IMHO go ahead and clean around all of them until you can get it repaired.


Ok, i will do, replace all them ..

thanks
Amiga 1000, 500, 600, 2000, 1200, 4000...

C= VIC 20 / 64 /SX64/ 128

Atari 600XL (SIC Cartdridge)
Atari 800XL (SIO2SD unit)

Jay Miner`s Atari 2600 - Wood front -

\\"Amiga, this Computer have a Own Live\\"--\\"Silence When the Drums are Talking\\".... DrummerBoy
 

Offline Drummerboy

Re: -Low Sound in A1200
« Reply #23 on: November 26, 2009, 01:48:07 AM »
Quote from: DrDekker;531241
One of my PSU's developed a fault which allowed ac to be passed through to my A600, causing a machine gun rat-tat-tat sound through the speakers (and graphical glitches/system crashes too).
 

 
Take a guess! :hammer:


With other PSU, the same failure!..
Amiga 1000, 500, 600, 2000, 1200, 4000...

C= VIC 20 / 64 /SX64/ 128

Atari 600XL (SIC Cartdridge)
Atari 800XL (SIO2SD unit)

Jay Miner`s Atari 2600 - Wood front -

\\"Amiga, this Computer have a Own Live\\"--\\"Silence When the Drums are Talking\\".... DrummerBoy
 

Offline rkauer

Re: -Low Sound in A1200
« Reply #24 on: November 26, 2009, 04:47:40 AM »
That's a discussion which may solve your problems: let's change those capacitors!
Goodbye people.

I\'ll pop on from time to time, RL is acting up.