DCC900 Repair, taking the plunge

[Richard_Symes]

Hi, new to the forum and the museum and loving it so far!
I have a couple of DCC900 decks which I’m sure have the capacitor issue. I have soldering experience so I am going to attempy a recap on the read/write board. Would I be correct in thinking that I should use modern radial caps instead of the original surface type? I’m guessing it is best to use a heat gun to remove the existing caps? Apart from this board, are there any other caps I should replace? I ask this because I’ve just repaired a couple of DCC951’s with no sound, but the caps I had to replace were the 10000uf, 4700uf and 2200uf electrolytics in the digital power section of the main board which bought them back to life. Sorry to hit you with all this but would like to get it right!

Thanks, Richard.

[drdcc]

Hi Richard and Welcome,

We use the original surface mount as we like to keep it original if possible, but it really does not matter.
The heat gun is the best option, but you have to be careful not to overheat it, as the acid leaking from the caps will act like a glue. You also have to be precise and not hit/move around other components that will be affected by the heat applied. You only need to replace the (I believe 17) smd caps on both audio and read-write boards.

Regarding the 951. Great solution, but personally I have not seen those caps failing causing audio to stop working.

[Richard_Symes]

Thanks for the advice, much appreciated. Interesting that I should get two 951’s with power cap problems then! Hopefully they should be servicable for some time to come.

[dfrangu]

Hello, on my Technics RS-DC10 (twin brother) I used normal capacitors. But the 2 boards were heavily damaged by the leaked capacitors, so they needed some work for the lines also…
I had this “to do” list:
2,2µF/35V/BP - 1 - Nichicon UMP1V2R2MDD
4,7µF/16V/BP - 2 - Nichicon UMP1C4R7MDD
10µF/16V - 9 - Nichicon UMV1C100MFD
22µF/6V3 - 1 - Nichicon UMV0J220MFD
68µF/10V - 4 - Panasonic EEA-GA1A680

But I bought all Nichicon, these models:
UEP1H2R2MDD
UEP1V4R7MDD
UVR1C100MDD
URZ0J220MDD
UPM1A680MDD

[Richard_Symes]

@dfrangu Thanks very much for the list, that helps a lot. As soon as I can put some time to it I’ll get them changed and let you know. Cheers.

[dfrangu]

@Richard_Symes The guy I took the list from also wrote:
"All capacitors has to be changed except non-polarized ones :

PW03 = both 4.7µF 16V (C103 & C143)
PZ03 = 2.2µF 50V (C426)

Unsolder them to clean the PCB underneath !!! But these were OK on my PEAK Altas ESR70 so you can refit them.

Don’t forget to clean well the PCB (for my part I use Acetone) before installing new capacitors !!! "
Good luck.

[Richard_Symes]

Hmmm. first attempt at cap removal with a heat gun. The can came off but the pins and plastic base remained. Any ideas what i’m doing wrong?

[Max]

Use a suitable and some flux to carefully remove it with tweezers without pulling too hard which can lead to breaking the pads.

[chorazy3]

Or just cut a cap horizontally in half with side pliers and then carefully remove the remains of a cap. They are useless anyway. I always do it that way. No pads ever broken.

Some people twist them off.
Grab capacitor with pliers, keep a gentle pressure downwards (the rubber bottom will basically make sure the pads on pcb won’t lift this way) and slowly twist the capacitor a few degrees left and right until it breaks off.
But in this case this method is more risky because of electrolyte that already leaked and partially destroyed soldering pads.

[drdcc]

When applying heat, the tweezers need to touch the black base as well. Otherwise the metal cap might come off, just like happened here.

Ralf

[Richard_Symes]

Thanks for all the good advice but as thie picture shows, I’m still not having much luck. I bought some decent tweezers but the can still came loose from the base. I kept the heat on but the pins that were left behind did not seem to budge. What is the ideal temperature? I’m using 350 but I seem to be heating longer than in @drdcc video and I do not want to damage other components. What about air flow? I have a medium setting but is this right? Sorry if this seems basic to you guys but I would really like to get one of my DD82’s and 900’s fully working again. It could be that this type of repair is beyond my ability but lets hope not.

Thanks again.

[Max]

Use some good solder flux, it can definitely help a lot.

For example Amtech NC-559-V2-TF is the choice of Louis Rossmann who is famous for repairing MacBook boards with a similar level or worse corrosion.

[Jac]

350ºC seems a little low to me. At this time I don’t have an air station but I use 375 for soldering with an iron and leaded solder. I turn my Hakko up to 400 when needed, e.g. to melt bigger areas or to melt unleaded solder.

You have to play it by ear a little. Start with a low temperature like 350 and if things go too slow, turn it up. If you notice that plastic things start to melt, turn it down. If you do it a couple of times, you’ll get the knack for it.

=== Jac

[Richard_Symes]

Thanks a lot guys, I put plenty of flux around the caps and turned the heat up to 380 and the smaller caps came off in seconds! A little longer for the larger ones but I’m pleased with the result. What do you think? I haven’t got the non polarised caps yet but at least I can start refitting the others. Finally getting somewhere.

[drdcc]

This looks promising. You better remove the 4.7uF as well. Acid will be under them from the other caps.
Ralf

[Max]

Looks about as good you can get it with this amount of corrosion! Good work !

[Richard_Symes]

Thanks for your support, much appreciated.

[Mario]

Just a follow-up question. I have no soldering experience but wanna try: is it correct to state that using radials caps is easier to solder on the board than the original surface caps?

[drdcc]

Hi,
Yes they are easier. The difficulty is removing the old caps safely.

[Mario]

Why is the removal so difficult? I mean, what is the risk?