REPAIR GUIDE - TurboExpress/PC Engine GT: Video Fix

ApolloBoy · 11/03/2010, 05:49 PM

I seem to be having troubles with this. I think the trace for the negative side is gone and now I need to know what to solder onto now. The positive side is fine now, though.

Duo_R · 11/03/2010, 06:14 PM

Dud u see my post?

ApolloBoy · 11/03/2010, 07:09 PM

Quote from: Duo_R on 11/03/2010, 06:14 PMDud u see my post?

Yes, but the highlighted area doesn't make it clear exactly where I should solder to.

Duo_R · 11/03/2010, 07:27 PM

It is a little blury but negative goes to the pin marked on the diagram of the chip marked BA.

ApolloBoy · 11/03/2010, 11:26 PM

Quote from: Duo_R on 11/03/2010, 07:27 PMIt is a little blury but negative goes to the pin marked on the diagram of the chip marked BA.

I just tried that and it still didn't work. As for the positive side, can I solder onto one of the pins on that component underneath the 100 uF cap?

Duo_R · 11/04/2010, 01:57 AM

Pics of what u are doing?

chop5 · 11/04/2010, 02:06 AM

yeah i could use pliers but these caps and the connections are so small il risk tearing off the pad,solder or both. Thats why with friction i hope to leave part of the leg for me to solder on. But sometimes the cap fluid corrodes it so bad the cap can just come off with a touch taking with it the precious solder leaving bare pads.
If this happens to you guys don't worry. If theres just a little bit of solder on the pad you can run a drop of solder from your iron tip to add more. if theres absolutely no solder getting solder to hold wont be a problem. The best way is to put solder paste on your cap leg and pad then a drop of solder from your iron. The solder wont stay on the pad without the metal from the cap leg to react with it. Its like witchery but will hold

ApolloBoy · 11/08/2010, 05:35 PM

Quote from: Duo_R on 11/04/2010, 01:57 AMPics of what u are doing?

I want to know if I can solder onto one of the legs of the component circled in blue. Right now I'm trying to solder onto the trace located on the orange circle but it's a no go.

/2mpyfer.jpg

Duo_R · 11/08/2010, 07:32 PM

Again see the diagram I posted or pm me if you want me to repair

ApolloBoy · 11/13/2010, 05:09 PM

Quote from: Duo_R on 11/08/2010, 07:32 PMAgain see the diagram I posted or pm me if you want me to repair

That didn't really answer my question though. Can I solder onto one of the legs of the component circled in blue, and if so, which one?

Duo_R · 11/13/2010, 06:51 PM

What makes you think you should solder to that chip?

blueraven · 11/14/2010, 04:25 AM

Quote from: ApolloBoy on 11/13/2010, 05:09 PM
Quote from: Duo_R on 11/08/2010, 07:32 PMAgain see the diagram I posted or pm me if you want me to repair
That didn't really answer my question though. Can I solder onto one of the legs of the component circled in blue, and if so, which one?

I'm confused, ApolloBoy. Below is the photo that has the correct solder point. I'm assuming your photo is Duo_R's blown up. On the previous page we have outlined the areas that you can solder to to correct the broken traces. Duo's diagram is about as concise as you can get.

https://www.pcengine-fx.com/forums/index.php?topic=5015.msg150874#msg150874

Quote from: Duo_R on 11/13/2010, 06:51 PMWhat makes you think you should solder to that chip?

Exactly. The answer is no, you should not solder to that chip.

Duo_R · 11/14/2010, 11:45 AM

Apollo do you have experience with soldering electronics? If not send to Chops (he already offered to you for free) or I can take a stab at it. I think I already spent way more time sending diagrams, etc that it would have taken me to have just done it already. lol

ApolloBoy · 11/14/2010, 01:13 PM

Quote from: blueraven on 11/14/2010, 04:25 AMI'm confused, ApolloBoy. Below is the photo that has the correct solder point. I'm assuming your photo is Duo_R's blown up. On the previous page we have outlined the areas that you can solder to to correct the broken traces. Duo's diagram is about as concise as you can get.

This is just weird, because I've tried every area you and Duo_R have shown, and I'm still not getting any video.

Quote from: Duo_R on 11/14/2010, 11:45 AMApollo do you have experience with soldering electronics? If not send to Chops (he already offered to you for free) or I can take a stab at it.

I've got plenty of experience with soldering. I've done mods and repairs for people and I've replaced the caps in two Game Gears and another TE, among a few other things. I can do this, it's just that this TE is being frustrating to work on right now.

BlueBMW · 11/14/2010, 01:21 PM

I think we all run into one piece of hardware that kicks our butt. I had a turbo CD do that to me... its now been hacked up to save a few other turbo CDs

Duo_R · 11/14/2010, 01:31 PM

Sorry if you already stated this but has video ever worked on this unit since you had it? Why were u replacing this cap to begin with?

blueraven · 11/14/2010, 02:31 PM

Quote from: BlueBMW on 11/14/2010, 01:21 PMI think we all run into one piece of hardware that kicks our butt. I had a turbo CD do that to me... its now been hacked up to save a few other turbo CDs

I agree. I have a duo that is in chop5's care even though I have replaced every cap, the laser, the motor, and the headphone port.

ApolloBoy · 11/14/2010, 05:24 PM

Quote from: Duo_R on 11/14/2010, 01:31 PMSorry if you already stated this but has video ever worked on this unit since you had it? Why were u replacing this cap to begin with?

I'm actually fixing this for a friend of mine, who bought it on the cheap and found that it didn't work. When I opened it up, I found that most of the caps on the unit had leaked and needed to be replaced. I've succeeded in replacing all of the caps and getting every part of the system working except for that one video cap. My friend actually tried to replace a few of the caps, including the video cap. He didn't do that great of a job replacing them (and admitted this to me beforehand), hence why it still wasn't working when I received it, and hence why both the solder pads for the cap got lifted when I tried to redo it.

Duo_R · 11/14/2010, 05:55 PM

Have u swapped screens with another unit to confirm the screen isn't bad?

ApolloBoy · 11/14/2010, 08:36 PM

Quote from: Duo_R on 11/14/2010, 05:55 PMHave u swapped screens with another unit to confirm the screen isn't bad?

I have a TE of my own, so I suppose I could give it a try. I'll do the swap tomorrow and see how it goes.

Duo_R · 11/14/2010, 09:20 PM

Give that a shot, swap screens on both units and see what happens

nat · 11/15/2010, 09:02 PM

Are you sure the unit is even powering up? Do you hear sound? Sorry if you answered this already back there, I'm way too lazy to backtrack through messages.

If your friend fucked something up when he was haphazardly replacing caps, he could have easily blown the unit's fuse. It goes south at the drop of a hat. Trust me, I've been there.

stimpy · 11/22/2010, 04:47 PM

Hi People!

alas - I was so happy when I found this repair guide, because my PCE-GTE had exactly the symptoms described here (backlight + sound but no piture). I have thorougly followed the instruction and replaced the capacitator. Unfortunately the problem did not go away. The cpacitator seems to be firmly in place. Any hints?

Duo_R · 11/22/2010, 05:03 PM

need more information to really give some guidance. Did this unit work before for you? Did the install go smoothly? Do you have pics of the install area?

Quote from: stimpy on 11/22/2010, 04:47 PMHi People!

alas - I was so happy when I found this repair guide, because my PCE-GTE had exactly the symptoms described here (backlight + sound but no piture). I have thorougly followed the instruction and replaced the capacitator. Unfortunately the problem did not go away. The cpacitator seems to be firmly in place. Any hints?

stimpy · 11/23/2010, 05:13 PM

Yes the unit did in fact work before. However the display went dark after some time leaving the backlight on. When I removed the old capacitor, it seemed that it had actually bled. Please have a look at the picture, to check if the new cap is correctly installed. For me it really appears to be.

hints? O:)

Quote from: Duo_R on 11/22/2010, 05:03 PMneed more information to really give some guidance. Did this unit work before for you? Did the install go smoothly? Do you have pics of the install area?

nat · 11/24/2010, 02:27 AM

The thought occurs that one of the solder pads may have inadvertently been removed when you took off the old cap.

stimpy · 11/24/2010, 04:34 AM

I that turned out to be true - can you think of a way to fix it? Thanks.

Quote from: nat on 11/24/2010, 02:27 AMThe thought occurs that one of the solder pads may have inadvertently been removed when you took off the old cap.

Duo_R · 11/24/2010, 11:58 AM

Which pad was lifted?

stimpy · 11/24/2010, 12:15 PM

Sorry, I meant: "If that turned out to be true ..."

I'll need to check first.

Quote from: Duo_R on 11/24/2010, 11:58 AMWhich pad was lifted?

Duo_R · 11/24/2010, 01:25 PM

If you did we can find somewhere else to solder. But need to know specifics.

stimpy · 11/25/2010, 08:29 AM

OK then - after having a closer look, i would say that the left pad (see picture above) is still in place. If you look at spot where the left pin of the cap is attached to the board - you can notice some black spots around the solder. That may indicate that the right pad was in fact lifted. I bought a desoldering wick today. Should I detach the new cap?

Quote from: Duo_R on 11/24/2010, 01:25 PMIf you did we can find somewhere else to solder. But need to know specifics.

Duo_R · 11/25/2010, 01:39 PM

Do u have an ohmmeter?

stimpy · 11/25/2010, 05:32 PM

No - I'm not a soldering freak to be honest. Perhaps a friend of mine can lend me one.

Also - of course in my last post I was talking about the _right_ pin having black spots around the attached area - sorry.

Quote from: Duo_R on 11/25/2010, 01:39 PMDo u have an ohmmeter?

stimpy · 11/28/2010, 04:43 PM

Hmmm ... it seems I cannot get my hands on an ohmmeter so easily. AFAIK, those things are expensive. Do you think I definitely need one for the fix?

Quote from: stimpy on 11/25/2010, 05:32 PMNo - I'm not a soldering freak to be honest. Perhaps a friend of mine can lend me one.

Also - of course in my last post I was talking about the _right_ pin having black spots around the attached area - sorry.

Duo_R · 11/28/2010, 05:11 PM

I bought a cheap one at Harbor Freight.

BlueBMW · 11/28/2010, 05:33 PM

You should be able to pick up a cheap one at sears for less than $20 also.

Duo_R · 11/28/2010, 06:56 PM

I don't hardly recommend this, but if you are on a budget and have a store near you would be worth it just to check out your problem. just be warned it is a cheepie.

harborfreight.com/7-function-digital-multimeter-63759.html
wayback.harborfreight.com/7-function-digital-multimeter-92020.html

Quote from: Duo_R on 11/28/2010, 05:11 PMI bought a cheap one at Harbor Freight.

Charlie · 11/29/2010, 06:46 PM

As an FYI, there are already two places on the board that are ideal spots to connect the new capacitor. To find them, draw (mentally, of course) a line between the center of CC500 and CC501. The location is half way down that line, almost dead center between the two caps. Note that one is a hole; the other is a TestPoint that is covered with solder. But it's still a good mechanical connection.

The positive of CC501 goes to the hole close to Q500, the negative goes to the test point close to D502.
Based on the picture above, it looks like you have to dig out the latex to see them!

Picture showing open hole (positive connection) and test point(negative connection):

Charlie

(Edited 12/1)

ApolloBoy · 12/14/2010, 05:39 PM

Quote from: Duo_R on 11/14/2010, 09:20 PMGive that a shot, swap screens on both units and see what happens

I finally got around to swapping the guts between my friend's TE and my TE (which was easier than swapping the screens, and the screen is not the issue. Something must be seriously wrong here since I've tried everything to get the video working on this unit.

cornacchia · 01/03/2011, 12:30 PM

Hey everyone, so ApolloBoy tried to fix my turboexpress and could not get it going. I was wondering if anyone else would be willing to look at it and see if they could do anything.

BlueBMW · 01/04/2011, 09:17 PM

I dont mind giving it a shot. Let me know

Or alternately, chop5 is a magician when it comes to this stuff

nat · 02/13/2011, 06:57 PM

Rather than start a new topic, I thought I'd post this here. Question mainly aimed at Charlie, since he seems to have these PCB layouts down pat:

I've got a GT PCB that has an odd problem. Something on the board is causing the LCD backlight to "pulsate" while the unit is on. Pulsation happens the same on both battery and AC power. It's really quite distracting while playing, and I'd like to isolate the cause but so far have been unable. The problem is definitely on the PCB itself rather than in the LCD/backlight assembly, as I have several TurboExpress and PCE GT units that I've swapped the PCB into and the problem definitely follows the PCB.

I haven't replaced all the capacitors on the PCB, but I've replaced all the ones I know to be related to the video. Doesn't mean there aren't others that I'm unaware of, however.

Ideas?

Charlie · 02/14/2011, 02:02 PM

Typically, the pulsation occurs because of:
1. inadequate power. on batteries, you may have dead batteries (DUH!), but on AC you should not have that with an adequate power supply.
Make sure the power supply you are using has enough current to handle the TE. I'd go at least 20% above the TE specs.
(Edit: you can often tell this is the problem if the pulsation occurs more strongly when any loud sound effects occur. Turn the volume up full and see if you can see a correlation between the pulse and the audio)
2. bad cap (or possibly other part) on the display high voltage line. The high voltage is some 200+VAC generated by an inverter circuit.
This circuit needs not only a really heavy voltage source, but a really "clean" (ie, noise-free and ripple-free) source as well.

We'll need a VOM or 'scope to go further.

Charlie

nat · 02/14/2011, 10:05 PM

Quote from: Charlie on 02/14/2011, 02:02 PMTypically, the pulsation occurs because of:
1. inadequate power. on batteries, you may have dead batteries (DUH!), but on AC you should not have that with an adequate power supply.

This problem has been going on for a number of years, through countless sets of batteries.

QuoteMake sure the power supply you are using has enough current to handle the TE. I'd go at least 20% above the TE specs.

I'm using the OEM TurboExpress AC adapter. Works fine/without issue with the other GT/TE units I have.

Quote(Edit: you can often tell this is the problem if the pulsation occurs more strongly when any loud sound effects occur. Turn the volume up full and see if you can see a correlation between the pulse and the audio)

Will do... This I have not done.

Quote2. bad cap (or possibly other part) on the display high voltage line. The high voltage is some 200+VAC generated by an inverter circuit.
This circuit needs not only a really heavy voltage source, but a really "clean" (ie, noise-free and ripple-free) source as well.

We'll need a VOM or 'scope to go further.

I've got my VOM ready!

Also, one thing I noticed I failed to mention... It only happens after the the unit warms up. The first 30 minutes of play are pulsation-free. This is what points me in the direction of a bad capacitor somewhere....

Charlie · 02/15/2011, 03:13 AM

There are either 4 or 5 caps in the inverter circuit. Plus a coil, a transformer, a transorb/PTC, and a few other things I don't remember. Yes, caps is the obvious choice.

Three other items....
1. Does the pulse change if you tap or bang on the PCB, particularly in the inverter circuitry?
2. Does the whole screen pulse at once, or does the pulse "travel" in a wave up/down the screen?
3. Does playing with the contrast control make any difference to the pulse? Obviously, it WILL affect the display contrast overall!

Charlie

nat · 02/15/2011, 03:20 AM

Quote from: Charlie on 02/15/2011, 03:13 AMThere are either 4 or 5 caps in the inverter circuit. Plus a coil, a transformer, a transorb/PTC, and a few other things I don't remember. Yes, caps is the obvious choice.

Three other items....
1. Does the pulse change if you tap or bang on the PCB, particularly in the inverter circuitry?

Will get back to you....

Quote2. Does the whole screen pulse at once, or does the pulse "travel" in a wave up/down the screen?

The whole screen. It seems like it's the backlight that is pulsating and not the image itself, although I could be wrong.

Quote3. Does playing with the contrast control make any difference to the pulse? Obviously, it WILL affect the display contrast overall!

No, aside from the intended effect of using the control.

Charlie · 02/15/2011, 09:46 AM

At a quick glance, active caps are CC501, C502, C501, C500,C504....but I don't think all of them are electrolytic.

Also involved: D502, Q500, R500, L500, DZ500, Q501, D503...but I would put them at a lower expectation of failure.

You might want to check the backlight voltage at the connector, see if the VOM shows a fluctuation that matches the pulses. Probably yes.

Charlie

Edit: Also involved CC900, C901, CC901, T900, L900, D902.

thesteve · 04/17/2011, 03:21 AM

although unlikely a failing lamp can cause pulsation, typically after warmup.

nat · 04/17/2011, 07:28 PM

Like I said, the problem follows the logic board. I moved the logic board from one GT to another GT (with a completely different backlamp) and the issue follows the board.

thesteve · 04/17/2011, 08:13 PM

ceramic cap failures are not unheard of in inverter circuits.
did the problem occur with or without use.
if it developed the prob on the shelf it will be electrolytic caps, due to drying.