[PERPETUAL] EDIT. IN. PROGRESS.
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...
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
/endFirst order of business following all that was learn all that I could about capacitors, so the quest for knowledge began with...google!
http://antiqueradio.org/recap.htm#why http://antiqueradio.org/PhilcoF4626MTelevision.htm#RecappingPCBoardsFrom 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.
http://en.wikipedia.org/wiki/CapacitorFrom the Wiki article, another important tip was learned. Basically, the old "use them or lose them" expression applies here! Note the following:
Electrolytic 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 $$$)
Aluminum 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?
1)
and
2) 
Topic: Will teh NightWolve successfully repair his TurboExpress or fail miserably ? ? ? (Read 650 times)