Radial vs SMD capacitors on Turbo Express

RetroWeirdo · 04/10/2016, 01:02 PM

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 · 04/10/2016, 01:02 PM

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

Duo_R · 04/10/2016, 01:03 PM

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

wilykat · 04/11/2016, 04:23 PM

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 · 04/18/2016, 11:14 AM

Cool, thanks for the feedback guys.

BlueBMW · 04/18/2016, 11:15 AM

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

leonk · 04/18/2016, 08:12 PM

Quote from: BlueBMW on 04/18/2016, 11:15 AMMany 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 · 04/19/2016, 01:29 AM

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 · 04/19/2016, 01:38 AM

Double post.

crazydean · 04/19/2016, 01:45 AM

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

mickcris · 04/19/2016, 02:01 AM

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

thesteve · 04/19/2016, 03:03 AM

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 · 04/19/2016, 03:07 AM

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 · 04/19/2016, 11:01 AM

Quote from: mickcris on 04/19/2016, 01:29 AMCeramic 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 · 04/19/2016, 04:50 PM

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

leonk · 04/19/2016, 08:33 PM

Quote from: thesteve on 04/19/2016, 04:50 PMhaving done several TE with SMD ceramic and tantalum caps i assure you they dont add hum, they actually reduce it

i liken can replacement with SMD replacement to all the different "hacks" people were attempting to reduce Jailbars with NEC consoles. It wasn't until Tim Worthington, in my opinion a brilliant electronics engineer, approached the problem from a fundamental electronics point of view that we now have (what I believe to be) a universal solution (with explaination) to that problem.

When another brilliant engineer (Dave Jones) puts out a video explaining why replacing cans with SMD sometimes is a bad idea, and proves it with measurements on oscilloscopes and calculating on the white board using proven electronics equations; I listen.

I just wanted to bring this up because there are some really good modders out there, but it doesn't mean they're good electronics engineers that can design circuit boards from scratch. I for one know I couldn't.

choijimmy · 04/20/2016, 12:21 PM

Quote from: leonk on 04/19/2016, 08:33 PM
Quote from: thesteve on 04/19/2016, 04:50 PMhaving done several TE with SMD ceramic and tantalum caps i assure you they dont add hum, they actually reduce it
i liken can replacement with SMD replacement to all the different "hacks" people were attempting to reduce Jailbars with NEC consoles. It wasn't until Tim Worthington, in my opinion a brilliant electronics engineer, approached the problem from a fundamental electronics point of view that we now have (what I believe to be) a universal solution (with explaination) to that problem.

When another brilliant engineer (Dave Jones) puts out a video explaining why replacing cans with SMD sometimes is a bad idea, and proves it with measurements on oscilloscopes and calculating on the white board using proven electronics equations; I listen.

I just wanted to bring this up because there are some really good modders out there, but it doesn't mean they're good electronics engineers that can design circuit boards from scratch. I for one know I c
Quote from: leonk on 04/19/2016, 08:33 PM
Quote from: thesteve on 04/19/2016, 04:50 PMhaving done several TE with SMD ceramic and tantalum caps i assure you they dont add hum, they actually reduce it
I just wanted to bring this up because there are some really good modders out there, but it doesn't mean they're good electronics engineers that can design circuit boards from scratch. I for one know I couldn't.

Unfortunately, we need a good modder in this forum because you/we are in "TG/PCE Repair/Mod Discussion" forum. I do understand most of us are not good engineer but our goal is simple ---> repair and mod pc engine / tg

People(or modders in your term) in here indeed help tons of people to repair their consoles, from bring them back to alive , reduce the hum, etc... We all know they are not rocket science or not backup by tons of engineers who got PhD. However, the bottom line, it works. Sorry that this forum is people want to share their repair/mod experience and help each other which you may feel this is not academic enough.

Just share what I feel and to be fair

leonk · 04/21/2016, 12:21 AM

I totally understand. That is what I'm trying to do here - have an open minded technical discussion.

Just because something "works" doesn't mean it proper, or safe. I can stick a quarter into my fuse panel and the electricity will flow .. it doesn't mean that it's a proper, safe solution that everyone should now do if they blow a fuse!

blueraven · 04/21/2016, 03:25 AM

Donnie, You're out of your element.

BlueBMW · 04/21/2016, 11:49 PM

I don't know if thesteve has an EE degree or not, but he's probably the most knowledgeable electronics person I know. I usually trust what he says.

I havent had one defect or problem with a system I've used ceramic caps on yet. No complaints of noise or anything like that and its been a few years since I started using them. I guess time will tell.