Cracking sound - Page 2

Chucky · 02 May 2018, 22:50

As I have had it on machines.. and then it was vias around C305 that was bad.
even so far as R303 etc.. and it was most noticed by right mousebutton did not work and when you pressed it.. you heard a "click" in the speakers..
And if you look on paula.. C305 and R303 is exactly around that corner that have Left and right output from paula.

Sim085 · 03 May 2018, 18:32

I checked the voltage on the C324 and this vary between 2.25 and 2.35. For the C334 the voltage vary between 2.05 and 2.5. Are these readings normal?

Quote:

Originally Posted by Daedalus

Yep, C324 and C334 are likely contenders. If they appear to be fine, it's also worth checking the ceramics in the audio circuits, C321-C323 and C331-C333.

Chucky · 03 May 2018, 18:50

sounds ok. but do check traces around those components if they are whole..
especially if there is a via close to it.

Sim085 · 03 May 2018, 19:12

If I read the ground from the power connector and the voltage from the capacitor then doesn't mean that the traces are ok?

Quote:

Originally Posted by Chucky

sounds ok. but do check traces around those components if they are whole..
especially if there is a via close to it.

Chucky · 03 May 2018, 19:18

no as I want to you test signal-traces AROUND close to those caps etc.. if there are a via that have been corroded of leaking electrolyte etc. as this is a quite common issue.

Sim085 · 03 May 2018, 21:00

Visually looks ok (even back side).. should I do some continuity checks?

Also since sound comes out ok then can I exclude problems with paula?

Quote:

Originally Posted by Chucky

no as I want to you test signal-traces AROUND close to those caps etc.. if there are a via that have been corroded of leaking electrolyte etc. as this is a quite common issue.

Chucky · 03 May 2018, 21:52

yeah do continuity checks. use pcbexplorer as an aid.

yeah Paula is fine. MIGHT be opamp..

Sim085 · 04 June 2018, 22:02

Strange as it might sound this resolved all by itself. I left this A1200 untouched because I had other stuff to do, I switched it back on and I could no longer hear that cracking noise which was previously running all the time even when playing no music!

Could it be that it needed time after the re-capping?

I have used it a couple of times now and can't hear the cracking sound anymore.

Chucky · 04 June 2018, 22:46

No I guess leakage have damaged the board so the trace is AAAaaaalmost off.. so sometimes depending on temperature it will work..

Sim085 · 04 June 2018, 23:23

So if I put A1200 motherboard in fridge, get it out, and try I again should get the cracking noise?

Quote:

Originally Posted by Chucky

No I guess leakage have damaged the board so the trace is AAAaaaalmost off.. so sometimes depending on temperature it will work..

Chucky · 04 June 2018, 23:29

maybe.. yes..

Sim085 · 06 June 2018, 14:50

So I put the motherboard in freezer for about 5min, got it out, switched it on and that cracking sound didn't come out.

Having said that - trying to be positive - I was wondering, instead of leakage having eaten the tracks could it be that it was a dry joint?

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02 May 2018, 22:50	#21
Chucky Registered User Join Date: Mar 2015 Location: Karlstad / Sweden Age: 52 Posts: 1,210	As I have had it on machines.. and then it was vias around C305 that was bad. even so far as R303 etc.. and it was most noticed by right mousebutton did not work and when you pressed it.. you heard a "click" in the speakers.. And if you look on paula.. C305 and R303 is exactly around that corner that have Left and right output from paula.

03 May 2018, 18:50	#23
Chucky Registered User Join Date: Mar 2015 Location: Karlstad / Sweden Age: 52 Posts: 1,210	sounds ok. but do check traces around those components if they are whole.. especially if there is a via close to it.

03 May 2018, 19:18	#25
Chucky Registered User Join Date: Mar 2015 Location: Karlstad / Sweden Age: 52 Posts: 1,210	no as I want to you test signal-traces AROUND close to those caps etc.. if there are a via that have been corroded of leaking electrolyte etc. as this is a quite common issue.

03 May 2018, 21:52	#27
Chucky Registered User Join Date: Mar 2015 Location: Karlstad / Sweden Age: 52 Posts: 1,210	yeah do continuity checks. use pcbexplorer as an aid. yeah Paula is fine. MIGHT be opamp..

04 June 2018, 22:02	#28
Sim085 Registered User Join Date: Apr 2009 Location: N/A Posts: 962	Strange as it might sound this resolved all by itself. I left this A1200 untouched because I had other stuff to do, I switched it back on and I could no longer hear that cracking noise which was previously running all the time even when playing no music! Could it be that it needed time after the re-capping? I have used it a couple of times now and can't hear the cracking sound anymore.

04 June 2018, 22:46	#29
Chucky Registered User Join Date: Mar 2015 Location: Karlstad / Sweden Age: 52 Posts: 1,210	No I guess leakage have damaged the board so the trace is AAAaaaalmost off.. so sometimes depending on temperature it will work..

04 June 2018, 23:29	#31
Chucky Registered User Join Date: Mar 2015 Location: Karlstad / Sweden Age: 52 Posts: 1,210	maybe.. yes..

06 June 2018, 14:50	#32
Sim085 Registered User Join Date: Apr 2009 Location: N/A Posts: 962	So I put the motherboard in freezer for about 5min, got it out, switched it on and that cracking sound didn't come out. Having said that - trying to be positive - I was wondering, instead of leakage having eaten the tracks could it be that it was a dry joint?

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