Sony TA3200f Issue - diyAudio
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Old 13th March 2013, 12:56 PM   #1
Champ is offline Champ  Canada
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Default Sony TA3200f Issue

Hello All,

Before and after a full Electrolytic recap I am still getting a crackling noise much like the sound of a dirty vinyl record. It comes on after about 5 minutes from power up and last for about the same time then disappears. It is independent of the volume control which has no effect on the noise.

I have checked all the solder joints through out the amp board and power supply which seem fine, I have removed all the out put transistors and cleaned the contact and put new thermal pad on. I am now thinking component failure. There are a number of those nice old brown carbon resistors on the amp board
(none of the resistors look burnt - generally this amp is in good condition). My thought is to just replace them. If this were a transistor issue would the amp just fail? I am also assuming that the issue is very likely on the amp board and not power supply. All controls are clean.

Any thoughts and help I can get as to where I should go from here is most welcome. Images attached for reference.

Also the Offset is 0V DC both channels and Bias is 25mv per channel as per the service manual. All measurements stable.
Cheers,
Clive I think this should be in the DIY section, but not sure how to move it.
Attached Images
File Type: jpg PreRecap.jpg (559.6 KB, 149 views)
File Type: jpg SonyTD3200fboard.jpg (851.7 KB, 144 views)
File Type: jpg AmpBoardBack.jpg (787.7 KB, 127 views)

Last edited by Champ; 13th March 2013 at 01:09 PM.
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Old 13th March 2013, 03:06 PM   #2
pdlemen is offline pdlemen  United States
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If the noise is coming from both channels,look for bad frame metal to pcb ground screws loose. Many of the older Sony's relied on solder pads contacting the metal frame for circuit grounding. Most of the time you can just tighten the screw to improve the connection. If the noise is from just one channel at a time,chances are you have leaky transistors in the differential. 2SA705. The 2SA706's should be replaced as well.
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Old 13th March 2013, 03:44 PM   #3
The Dastardly Dad of Three
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Or use the old serviceman trick of freeze spray around the pcb in small spurts while the crackling is going on (or maybe after it goes away.) Either way it is sometimes a super way of localizing the problem.
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Old 13th March 2013, 03:55 PM   #4
Champ is offline Champ  Canada
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Thanks guys for the response. pdlmen I see 2SA706's on the Power Supply. The parts list has 2SC632A, 633A and 634A,s. There are 6 705's in total on the board. What would suitable replacements be?

kasey197 I may give this a try.

Last edited by Champ; 13th March 2013 at 04:14 PM.
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Old 13th March 2013, 06:24 PM   #5
pdlemen is offline pdlemen  United States
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You could try the KSA992F for the 2SA705. Mouser--->KSA992FBU Fairchild Semiconductor | Mouser or MCM --->Denon Electronics Original Transistor | 9600196205 | Denon Electronics or you could use a 2SA953 from B&D ---->2SA953 - B&D Enterprises International.
Just make sure you watch your pinouts;ie ECB vs. CBE. I don't recall the 705 or 6 being cbe but I could be wrong.
You could try the 2SA1241 from B&D --->2SA1241 - B&D Enterprises International for the 2SA706.
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Old 13th March 2013, 07:33 PM   #6
Mooly is offline Mooly  United Kingdom
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Is the problem on both channels ? That's a big clue.

If it is both then check things like the mains switch (arcing), fuse holders, plug top wiring etc. Don't assume anything is good unless checked.

If its one channel then suspects would include tantalum caps, compressed disc ceramic caps and semiconductors. For inexplicable reasons, Japanese semiconductors of the type often used for drivers etc. (in other words medium power devices) often fail intermittently, sometimes noisy in the way you describe.
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Old 13th March 2013, 07:36 PM   #7
Champ is offline Champ  Canada
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Quote:
Originally Posted by Mooly View Post
Is the problem on both channels ? That's a big clue.

If it is both then check things like the mains switch (arcing), fuse holders, plug top wiring etc. Don't assume anything is good unless checked.

If its one channel then suspects would include tantalum caps, compressed disc ceramic caps and semiconductors. For inexplicable reasons, Japanese semiconductors of the type often used for drivers etc. (in other words medium power devices) often fail intermittently, sometimes noisy in the way you describe.
Left Channel only. There is a tantalum cap in the photo ( the one at the top that looks like a small orange ball ) that appears to have burn marks where the leads go into the board. Think that means anything?
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Old 13th March 2013, 07:39 PM   #8
Mooly is offline Mooly  United Kingdom
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Tants are favourite failure items. They often go noisy and leaky or even short. Just pop and ordinary electro in its place.
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Old 13th March 2013, 07:40 PM   #9
Mooly is offline Mooly  United Kingdom
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And yes, it does look a wee bit distressed
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Old 13th March 2013, 07:51 PM   #10
Champ is offline Champ  Canada
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Quote:
Originally Posted by pdlemen View Post
You could try the KSA992F for the 2SA705. Mouser--->KSA992FBU Fairchild Semiconductor | Mouser or MCM --->Denon Electronics Original Transistor | 9600196205 | Denon Electronics or you could use a 2SA953 from B&D ---->2SA953 - B&D Enterprises International.
Just make sure you watch your pinouts;ie ECB vs. CBE. I don't recall the 705 or 6 being cbe but I could be wrong.
You could try the 2SA1241 from B&D --->2SA1241 - B&D Enterprises International for the 2SA706.
Thanks pdleman, I will keep this info if it indeed turns out to be the trannies.
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