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Old 14th May 2024, 5:36 pm   #1
mediaseller
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Default Sony TR-620 Speaker and Capacitors.

I bought one of these from eBay. It came from Italy.

It does work, though it sounds a bit tinny, so is it me that's used to modern audio equipment?

Anyway, the speaker grille dome had been depressed in the past and I managed to reform it to the best of my ability, though I noticed that the cone of the speaker protrudes out, beyond the speaker rim by about 1mm. Is the protrusion normal? See pictures.

The caps have never been changed and seem to be good with no signs of leaks. I haven't tested them with the ESR tester yet. I'm loathed to take them out if the radio is working. Are the caps of this type reliable?

Perhaps re-aligning would help if the caps have gone adrift?

Can anyone advise, please?

Thanks in advance.
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Old 15th May 2024, 1:35 am   #2
Graham G3ZVT
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Default Re: Sony TR-620 Speaker and Capacitors.

If you suspect the electrolytics have dried up (not unreasonable in a set of this age!)
you can simply bridge them one at a time with a capacitor of a similar value. If you hear an improvement, at least you will know that replacing it/them won't be in vain.

Bad electrolytic caps shouldn't affect alignment, but if you've got a sig gen there's nothing wrong with giving it a tune-up when you've finished repairing it.
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Old 15th May 2024, 8:56 am   #3
marceljack
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Default Re: Sony TR-620 Speaker and Capacitors.

The speaker seems perfectly normal.
Regarding the "tinny" sound I think it's probably normal for an AM only radio of this small size.
Regarding the electrolytics I would be surprised if they were bad, it's rarely the case in transistor radios working on low voltage and not submitted to high temperatures, contrarily to valve radios.
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Old 15th May 2024, 10:48 am   #4
smiler411
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Default Re: Sony TR-620 Speaker and Capacitors.

sometimes I have seen speakers with the centre of the cone pushed out, can happen with a large DC or pulse in one direction and they stay in that position. May not be case with yours of course, if you could supply a small DC voltage that you can control in reverse (ie so the cone moves towards the magnet) you could see if the speaker moves back in in a controlled manner or suddenly flips in in case the cone has over extended and stuck in that position. Need to start at a low level. If the cone has flipped out it will sound very distorted though I should think
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Old 16th May 2024, 8:39 am   #5
marceljack
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Default Re: Sony TR-620 Speaker and Capacitors.

If you look at the outside of the loudspeaker, you will see that the metallic part has also an "inverted" shape, this is to reduce the depth of the loudspeaker.
So I think the cone is its normal position.
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Old 16th May 2024, 10:04 am   #6
stevehertz
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Default Re: Sony TR-620 Speaker and Capacitors.

All looks fine to me, I'd leave well alone and enjoy looking at it and using it.
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