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Sony CDU-33A repair

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First post, by BLockOUT

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hey guys
i was reading this article and i remembered i had an old sony cdu-33a in the closet that i used during the 90s.

https://goughlui.com/2012/11/12/tech-flashbac … ary-interfaces/

i opened and i saw basically the same thing that on the pictures, on my model the blown capacitor was the one with the yellow arrow, and the dark green goo was even worse than on that website because it reached even more areas (maked them with yellow lines). Also there were other capacitors below that (yellow circle) that are just wasted becase the legs look green.

i started to clean it with vinegar and it was not very helpfull, did not make any difference. then i took a really soft sandpaper and started to apply on the green stuff to remove the coating untill i saw copper, luckly the area did not have traces that could be affected is just a big ground trace with many bias that i would need to check later on, then cleaned multiple times with isoprophyl alcohol.

the list of square caps is like this:
22 10v
JS6 (not sure what that is since its really small)
4.7 10v
JW6 (not sure what that is since its really small)
15 10v
22 10v
47 10v

im taking this as a long hobby to see if the drive can be repaired after replacing all the caps. Not sure if the drive will survive. if it doesnt work i will just use it a a dummy front cover. but there are some parts i have no clue on what they are with markings JS6 and JW6
anyone knows?

cdu33a.jpg

caps.jpg

Last edited by BLockOUT on 2021-04-25, 20:14. Edited 1 time in total.

Reply 2 of 5, by BLockOUT

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snufkin wrote on 2021-04-25, 20:02:
https://www.vishay.com/docs/40182/tmch.pdf […]
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https://www.vishay.com/docs/40182/tmch.pdf

According to that...
JW6 - 6.3V 6.8uF
JS6 - 6.3V 4.7uF

Pictures look about right.

thanks, great find, im wondering if those can be replaced with yellow tantalum capacitors 6.8uf and 4.7uf at 25v, thats the only thing i found on the shop i normally buy from. because 6.8uf electrolitic go to 200v or more.

Reply 3 of 5, by snufkin

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I'm not sure. Probably. That chip by the cluster of caps looks to be the focus and tracking controller, so it may be particularly sensitive to the exact spec of the capacitors, but I can't find a good datasheet for it to make it clear what it needs. If the existing ones are like the ones in that datasheet then the ESR isn't very low (~4 ohm) and the precision isn't too exact, so they don't seem to be very exotic.

I think the case size is 'A' (3.2mm x 1.6mm?), and from a quick look I'm not sure if 25V parts will be in that case size. Small caps seem to tend to leak less, so there's a chance those ones may still be ok. Might be worth checking there aren't any shorts across them before applying power.

Reply 4 of 5, by BLockOUT

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i will order replacement next month. smd caps are a no go for me here, but i will fix this using radial electrolitic caps placing them horizontally, and i also need to order some green solder mask,

there is no point on wasting more money on smd caps since im not really sure if this is going to work or not.

do you know if any UV light , like those 20w uv light bulbs will work for drying the solder mask?

thanks for the data !

Reply 5 of 5, by snufkin

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BLockOUT wrote on 2021-04-26, 01:04:

i will order replacement next month. smd caps are a no go for me here, but i will fix this using radial electrolitic caps placing them horizontally, and i also need to order some green solder mask,

there is no point on wasting more money on smd caps since im not really sure if this is going to work or not.

Fair enough. It may be worth getting a component tester (I got a cheap one for <£10 a few years ago and it's been useful several times) so you can identify which caps are actually bad. The smallest ones may be ok and not need replacing, and they'll be the ones trickiest to swap with radials.

do you know if any UV light , like those 20w uv light bulbs will work for drying the solder mask?

Probably. You can get various wavelength bulbs, so check what the solder mask needs. Most UV solder masks look to be cured by UV-A, ~400nm. If you get some decent sunny weather you can always leave it outside in direct sunlight.

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