Will teh NightWolve successfully repair his TurboExpress or fail miserably ? ? ?

Started by NightWolve, 04/28/2012, 07:34 PM

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Day 1: Background: 4/26/2012

So, I had been sore for some time now after having turned on my Turbo Express and finding that it had decided to finally break for good... :cry: I bought it for $99 bucks in 1993 (which makes it just about 20 years old) along with a Turbo Duo (same price) during TTi's "Bye-Bye" clearance sale and while I didn't use it all that much, I did very much enjoy playing Super Star Soldier on occasion with it. Fast forward to a couple of weeks ago. It had been sitting in its chosen storage cabinet for many many years, as it usually did, but for whatever reason, I suddenly felt like firing up SSS on it as I used to do, to see if the thing still worked too, BUT that's not what happened... NOTHING is what happened, just a black backlit screen... I thought it might be a contact problem so I cleaned the pins and I even wound up opening it and resoldering every connection point on the HuCard-side circuit board just in case a pin had broken free of the solder, etc. Then I used a DMM to test continuity and it all checked out fine, which unfortunately indicated that my problem wasn't going to be solved so easily... There went that idea...

I surrendered to the fact that my TE had come to the end of the line, I'd have to let it go... I thought, OK, but maybe I can sell it broken to some interested party at least... However, something more optimistic crossed my mind, maybe I should ask for help over at the PCEFX forums and see what people think based on the breakdown symptoms that it is exhibiting... No boot, no sound, no video, BUT a working LCD backlight lamp at the very least! I also discovered that if I left it on, after 5 minutes the lamp would shut off, but if I press any button, the lamp would come back on! This indicated that some circuitry was still functional, the input board, a timer circuit for screen-saver functionality, etc. demonstrating that the unit wasn't completely dead, just mostly!

... W.I.P. FINISH lead-in stuff - Remaining Outline...
*Didn't think it'd be worth sending off to someone to fix it, better to sell broken
*Asked for how much some here who's actually fixed one would charge
*Came across repair threads talking about capacitor replacement, a video one and 2 sound ones
*Found Red Ghost's TE Capacitor Replacement chart which gave me hope
*Found post show which SMD caps to buy

First order of business following all that was learn all that I could about capacitors, so the quest for knowledge began with...google!


From the articles above, I learned a couple of things: capacitor types, tips on replacing them, and most importantly, that they are the most failure-prone component in electronic devices, meaning, if your electronic device stops working, there's a high probability that the capacitors have failed. Given that primer, it started to seem like an every-man that was even a little bit handy with some basic knowledge of soldering could conceivably fix the problem! A few PCFX forum members were also alluding to this fact, don't just replace capacitors related to video/audio, replace ALL of 'em! It's such a typical occurrence in electronics that the term "recapping" has been popularized for it.


From the Wiki article, another important tip was learned. Basically, the old "use them or lose them" expression applies here! Note the following:
QuoteElectrolytic capacitors are conditioned when manufactured by applying a voltage sufficient to initiate the proper internal chemical state. This state is maintained by regular use of the equipment. If a system using electrolytic capacitors is disused for a long period of time it can lose its conditioning, and will generally fail with a short circuit when next operated, permanently damaging the capacitor.
The last time I turned on my Turbo Express was ~5 years ago, thus I suspect "use it or lose it" was applicable in my case. Age naturally plays a role (NEC hardware is 20+ years old now), but I certainly never reached no where near 2000 hours of playtime on the unit, which is the average life expectancy of an aluminum electrolytic capacitor with normal usage. But bottom line, what I take from that info is that I gotta turn things on once in a while or they'll never turn on again if too much time goes by! So, good tip to know if you wanna keep your electronics alive for as long as possible!

Day 2: 4/27/2012

OK, so I placed an order with Digikey having decided that I'm going to attempt to do this myself! Yay! Here goes nothing! I thought I'd post a more organized parts table (below) which is based mainly on a) marshallh's post, b) the "Total Capacitor Replacement" chart by Red Ghost (so thanks to the both of them), and c) my recent order form. While the table is mostly a rehash of marshallh's post with but working links and current pricing, I figured I'd add it for whatever further help it's worth to somebody else.

Order Form for Original Aluminum Electrolytic Capacitors used by your TE
(Note: I would no longer recommend these. Go with Tantalum: no leaks, last for decades, but more $$$)
Part #
Ext. Price
6493-2088-1-ND"CAP ALUM 100UF 6.3V 20% SMD"
3493-2105-1-ND"CAP ALUM 100UF 16V 20% SMD"
2PCE3859CT-ND"CAP ALUM 33UF 6.3V 20% SMD"
1P5114-ND"CAP ALUM 470UF 6.3V 20% RADIAL"
1493-2118-1-ND"CAP ALUM 22UF 35V 20% SMD"
1493-2083-1-ND"CAP ALUM 22UF 6.3V 20% SMD"
1493-2099-1-ND"CAP ALUM 10UF 16V 20% SMD"
1PCE4304CT-ND"CAP ALUM 4.7UF 50V 20% SMD"
1PCE4643CT-ND"CAP ALUM 4.7UF 35V 20% SMD"
1P1142-ND"CAP ALUM 47UF 6.3V 20% RADIAL"
Quote from: Tantalum versus Aluminum ComparisonAluminum capacitors are made by separating an inner and outer aluminum electrode by a layer of electrolyte paste contained in a porous spacer. When a voltage is presented across the plates, a chemical reaction occurs at the surface of the aluminum, forming an Aluminum Oxide layer on the surface of the aluminum plate. The Aluminum Oxide is a dielectric, and the layer is relatively thin. Two conductors separated by a dielectric make a capacitor.

When the paste dries out, the capacitor is no more. If you reverse the voltage, the dielectric layer breaks down rapidly, gases can form, and the capacitor will go "pop" (or sometimes "boom").

Tantalum capacitors are made by forming powdered tantalum around tantalum wire. The sintered pellet is dunked in an acid bath and DC is applied across the pellet. Current flow causes Ta2O5 oxide to form on the surface. A maganese oxide layer is formed over the pellet by dipping it into Mn(NO3)2 solution and then heating. A wire is then bonded to the outside of the pellet. A tantalum capacitor has extremely thin dielectric, resulting in easily obtained high capacitance values.

Unlike the aluminum capacitor, there is no electrolyte to dry out. Since it is dry, its lifetime is much longer, and it also has a lower leakage current. Tantalum capacitors can also handle some reverse voltage without failing - but not much. Because of their smaller physical size, the voltage rating of tantalum capacitors is lower than aluminum capacitors.
Edit: Use Tantalum types if you're up for it; I made a mistake ordering the typical, leaky-prone Aluminum types... I believe if you're gonna do something, do it right the first time and I wish I had known this before ordering them. I did learn about ceramic types at the time, but while they're extremely reliable, they're not polarized (+/-) for DC electronics. But, I'm being told/corrected that non-polarity doesn't matter, it's an issue that they usually don't support the uF values needed in general.

Day 3: 4/28/2012

My DigiKey order will arrive next week, but what am I to do in the meantime now that I'm all anxious about this? Becoming excited at the prospect of fixing my TE myself, I decided I should at least do half of the labor that is necessary to achieve my goal instead of just waiting around! At first, I second-guessed the wisdom of removing all capacitors at once because, in principle, you should remove and replace an electronic component ONE AT A TIME, that way there are less mistakes! No chance of soldering back on the wrong one and with the wrong polarity (which matters with capacitors as a I learned). But, with a printout of RedGhost's chart (the corrected version), I know where each capacitor type goes, and I figured out how to observe polarity (the black painted side of the Cap must be soldered to the side NOT marked + on circuit board, the unpainted aluminum side is +), so I might as well do it... I wanna know if I can safely remove all of them right now, to understand what I'm up against! Well, here's what I found:

It's a complete disaster! Every last one of them, EVERY ONE, had leaked! I intentionally rubbed the bottom of a few of 'em on the towel so you could see the syrupy electrolyte solution. You can see with 3 of the big capacitors being flipped over that the plastic seat is all gooey and discolored from that stuff... I had a lot of cleaning to do under EACH one! I dunno what the standard recommended solution is, but what I used was automotive Brake Parts cleaner! I would spray it on a small piece of towel, and wipe the affected area down. Now, the stuff is strong, it cleans great and completely evaporates very quickly, but if you get it on certain kinds of plastic, it's game over for 'em (it'll mildly melt 'em)! Anyhow, now I must sit quietly till the new capacitors arrive hoping for the best

Day 5: 4/30/2012

Received order confirmation, final cost ($11.43), and tracking # from Digikey via email today... The wait continues. I was in error before, a package did make it out to a USPS facility at 5:33 pm, so it's in transit!

Day 7: 5/2/2012

Yaaaaaaaaaaaaaay! The package arrived, and all is good in the hood, ladies and gentlemen! I didn't get a chance to begin work on it today, but first thing manana. I'm probably gonna record a little video as I begin the repair work, too!

... (hiatus, distractions)

Day 8: 5/18/2012

I finally resume this DIY project and solder on the new capacitors. A couple of hours and all good in the hood! Below is what my PCB board now looks like. The soldering job I'd say went mostly OK, but there were a few instances where I wasn't happy with the placement of the cap and I kept trying to re-position it better, meaning that I would have to reheat the leads up (and hence the cap) with the soldering iron for far more than necessary (should be in the seconds, not minutes!), which is ultimately NOT good for the cap! The faster you can solder it on, the better, as in the less potential heat damage from the soldering iron that it will suffer! The issue is that these compact SMD type caps are little harder to work with than the standard ones; they also have a plastic seat at the bottom and you will likely melt some of that plastic during the soldering process.


Day 9: 5/19/2012

*Cue the drumbeat*

I finish putting the unit back together... So what happens?





Once Ive got the caps off... i use a cue tip and some acetone (nail polish remover) and clean each pad.  Then I put a dab of liquid flux on each pad and use desoldering braid to clean all the old solder off each pad.  If a pad doesnt come completely clean I scrub it with a fiberglass pen or carefully scrape it with a razor blade.  Then I clean the board again with cue tips and acetone.  If the board is really bad I scrub it with hot wster, a toothbrush and some acetone then I hang it in front of a fan for 12 hours plus.

Thats just how I do it :P
[Sun 23:29] <Tatsujin> we have hard off, book off, house off, sports off, baby off, clothes off, jerk off, piss off etc


Is that the best deal I could've gotten on parts, you think ? Were there, like say, large packs of 100 that have most of the Caps needed leaving you to order a few individually, etc. ?? The other question I have, I guess, is, do you use the standard-sized Caps and try to cram them in there or these compact SMD ones which I guess are pretty close to the originals??


Good luck on soldering on those SMD caps. Without the right equipment and only using standard soldering iron, those are a pain in the a$$ to solder on.
Turbo fan since 1991 after owning my first system.

Check out my website:)



Really? Crap, I would've got those then, but I had read that ceramic capacitors are for AC only! Reliable as hell, but for AC!!


think of it this way
ceramics are for anything that uses caps for signals.
the reason the express doesnt work is the caps arent processing the signals


If you're fancy like steve, you use the solid caps, if you're not so fancy like me, you use leaded caps and just dont reinstall the RF shield plates.  You can use the SMT types, but they are a little more difficult to install.

Regarding cap prices... you can always get them cheaper in bulk, but for just a one off job like what you're doing, the $12 or so isnt bad.  I buy caps by the 200 to 500 each size at a time, but unless you're doing tons of repairs, buying bulk isnt for you.

Seeing your nasty leaky caps is again proof that ALL the caps should be replaced, not just the one or two commonly associated with video / audio problems :P

Also, if you run into trouble and want a set of leaded / radial caps (like what I used in this pic) shoot me a pm.  Alternately, I'm sure steve would sell you a set of solid caps if you wanted.

[Sun 23:29] <Tatsujin> we have hard off, book off, house off, sports off, baby off, clothes off, jerk off, piss off etc



[Sun 23:29] <Tatsujin> we have hard off, book off, house off, sports off, baby off, clothes off, jerk off, piss off etc


Quote from: thesteve on 04/28/2012, 10:05 PMi use ceramic chip caps and tantalum instead.
they cant leak
Oh that would be so much easier!
Can you make out a list of what parts you used in place of what caps?
Can we also do this on the duo etc?



Quote from: thesteve on 04/29/2012, 02:14 PMi use mostly the same values
I ask about values because it was mentioned a few times in this thread that lower tant values could be used in place of large electros...


in fact you could get away with smaller values in most cases when using tant or ceramic to replace aluminum.
i bought a large surplus lot of 100uf 16V SMD tant that i use for all the 100uf caps in the systems.
the thread you linked has one guy arguing against the reliability of tant and he gets 1 point right (they explode if overvoltage surged) so watch your voltage ratings.


First post updated to reflect this:

Day 9: 5/19/2012

I finish putting the unit back together... So what happens?



Quote from: turbokon on 04/28/2012, 09:34 PMGood luck on soldering on those SMD caps. Without the right equipment and only using standard soldering iron, those are a pain in the a$$ to solder on.
You know, I had noticed they'd be a problem given that you'd melt the plastic seat somewhat in order to take them off. I realized this, but as far as soldering them back on, I had an idea even before they had arrived. You have them flipped over, take a razor blade and scrape both leads so they're nice and shiny, add a little flux and heat some solder onto them, then flip it over and try to solder it onto the PCB board. This way, since you can't reach underneath and having pre-soldered the leads, you'll have your workaround to that problem. You can check the first video link and see if it all worked out. ;)

Quote from: BlueBMW on 04/28/2012, 10:29 PMIf you're fancy like steve, you use the solid caps, if you're not so fancy like me, you use leaded caps and just dont reinstall the RF shield plates.  You can use the SMT types, but they are a little more difficult to install.
Originally, I thought I needed to put the RF plates back, you know, in principle, you should use the same parts and put things back the way that they were, it was all done for a reason. I didn't bother to put the shield back even though I could've, just in case there was a problem later and having read your post.

Anyway, thanks for the rest of the info, fellas! I only wish I had learned about the tantalums the day before I placed my order with DigiKey. When thesteve came, the order had already been made so it was too late; had to use the standard compact ones I had ordered based on that info I found myself from the TE Capacitor Chart thread. All in all, a very satisfying DIY project!!


the ceramics likely would have cast a bit more, but they are easier to work with


Question: My old Mod for the power connection presented a problem; it used to physically disconnect the positive lead from the battery source when you'd insert the 3.5 mm plug, but given that it was too big internally and I had to melt it somewhat, it no longer works properly, so the + lead from the batteries does not reconnect (when you remove the plug). I didn't want to just connect the + lead to the same place as the external power supply and then always remember NOT to have batteries inside the unit at the same time.

So, I was thinking, just to do it right, how about using a diode on the positive lead from the batteries ??? Basic ones can stop 20 amps of current from going in the wrong direction, no? That way, if you forgot the batteries in there and plugged in the external power source, you wouldn't be recharging them, something you most especially would not want to do if using alkalines. Minor issue as I never took the unit anywhere and I always used the power supply, but I just feel like doing it right and closing up the unit for all time, where there should be no reason to ever open it up again, etc.


Well, I looked around in my attic and I found an old electronic device that had the same kind of connector that'll mechanically disconnect the + lead from another circuit when you insert the plug.

I did buy a new diode from RadioShack, but what I found was that they're not 100% after testing it with a 9V battery. With no diode, the 9V battery read 10 Volts on the DMM. With the diode in place and in the proper direction, it read 9.43 Volts. So, a little resistance is added, and given how quickly the batteries are depleted in a TE, it'd be a bad idea to use it...

And finally, flipping the diode resulted in a .43-1.43 Volt measurement... so it doesn't even accomplish what was needed, I would still have to remember to remove the batteries before using the external power supply!

Anyhow, thanks for the info PMs! This was a fun little project!

BTW, I broke in the capacitors fully today, played a full game of Super Star Soldier and got to the last stage ( 8 ) only to get my ass handed to me... Interesting false alarm in the beginning though: in the 1st stage, the game kept crashing half way in, so I thought maybe something didn't quite go right with the cap replacement, but I took out the HuCard, cleaned it up a little with glass cleaner, put it back in and everything was peachy after that, aside from me being terribly rusty at the game.

But yeah, working good now! I figured it had to be the game more so than the caps, cause Air Zonk was working fine and I got up to stage 4 on that one!


Just a quick note to say well done, and thanks for the useful info.  I doubt I'd ever be able to trust myself to take apart my GTs, but it's good to know that if I do, there's some great info here.
Quote from: esteban on 04/26/2018, 04:44 PMSHUTTLECOCK OR SHUFFLE OFF!


Thanks soop, I set out to try to make it fun and informative, but it looked like not too many cared about it after I was successful. ;) Still didn't finish editing the lead-in story for it, either...