Radial vs SMD capacitors on Turbo Express

[RetroWeirdo]

Hey guys, as you may have noticed I am new to the forums. There's probably been some discussion on this subject but I did a quick search but didn't find a specific thread for this...

So I was wondering what those in the TG-16/PCE community think about using radial capacitors in place of SMD on the Turbo Express/PCE-GT? As I have heard somewhere that you should replace SMD with new SMD. Are there any real pros to only using SMD besides that they may look and fit better?

Thanks guys

[Duo_R]

Radial works just fine, done it on several TE units.


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[Duo_R]

The spacing / room is the main issue but I never had trouble getting radial to fit.


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[wilykat]

Just make sure you have enough lead left on caps to lay em flat against PCB.  There isn't much room and having them stand up like normal radial caps would prevent you from putting it back together.

[RetroWeirdo]

Cool, thanks for the feedback guys.

[BlueBMW]

Many of us use ceramic capacitors to replace the electrolytics SMDs.  Super clean and surprisingly easy to install.

[leonk]

Many of us use ceramic capacitors to replace the electrolytics SMDs.  Super clean and surprisingly easy to install.

Just because you can do it, and it "works" doesn't mean what you're doing is correct. You can also keep most caps off and it will "work".

EEVBlog a year ago had a very good video on ceramic capacitors and what some people might not know about their capacitance. In particular, how the capacitance can shift by as much as 80% just by introducing a DC bias. Given that most of these caps are used as power smoothing caps (and at least one is for audio!!!) you better believe there's a DC offset, and many times close to the limit of these ceramic caps!!

Bottom line:

- ceramic caps existed when these units were made
- there are ceramic caps on the PCB already
- audio amps always use alumn elecrlytic caps (even today)
- NEC engineers decided to use alumn elect instead of ceramic for a reason. i personally would not presume to know more than they did. On my express, my goal was to restore the unit. Not make my life easier for the install.

[mickcris]

Ceramic caps existed back then but were more expensive than they are today. Not sure they had them in the high values like they do today either.

[mickcris]

Double post.

[crazydean]

I like the new twist on the old classic, the double post.

[mickcris]

Haha. I'm on my phone. I tried to edit but I hit the wrong button

[thesteve]

the ceramics have mostly replaced the aluminum in all but the largest values in modern electronics
ceramics were not available in larger values back then, and cost more per uF
even in the TE most filter aluminum caps have a ceramic across them to buffer the responsiveness of the cap

[blueraven]

When I first joined the forum I was sold on the idea of High-Temp NTK radials, I used them on quite a few systems from 2009-2011, until I was told back then by charlie or steve that Duos and Turbo/PC Engine units wouldn't need the extra upgrade unless they were left on for extended periods of time. I had a habit of leaving my own units on over the weekend so I switched to the regular radials for other people's repairs.

...Although recently I had an epiphany thanks to a recommendation from steve.

The electronics store in my area ran out of 22uf radial caps, so I caved and ordered a roll of SMD's. They arrived, and solved all of the space issues that I was running into reinstalling caps on the bottom of boards, and due to the fact that they are NP (non-polarity) and rectangular, they can be installed any which way. You could even stack them to double or triple the values. The only thing is, you need a tweezers to place them, and have to make sure that you order a cap that is wide enough to go across the +/- pads/via's. I ordered size "1206" and they were wide enough to do the jailbar fix and cut space around the Hu-Card slot for the region-mod.

Anyway, I'm sold on the SMD's! I would definitely use them on a TurboExpress.

[leonk]

Ceramic caps existed back then but were more expensive than they are today. Not sure they had them in the high values like they do today either.

I'm not talking about the 220 or 470uF caps. I'm talking about the 0.47, 4.7 and the most common 10 and 22. They all existed back then and were readily available.

My concern is when every single cap is replaced with SMD. In Express my biggest worry is in the audio amp. SMD caps are know to introduce an audible hum. That's why cans are still used today for this application.

[thesteve]

having done several TE with SMD ceramic and tantalum caps i assure you they dont add hum, they actually reduce it