PCE GT Button 1 not working

Cordelay · 04/09/2018, 07:35 PM

Hello to all! New member here! Just got my hands on a "untested" PCE GT off eBay and to my surprise it outputs video and has decent sound through earphones, though it clearly needs new caps. The issue is that the button labeled "I" doesn't work at all.
I rushed to see if there were any leakage and/or corroded traces but it looks quite clean on the main board, the only cap that had what I presume was some electrosauce was the one on the controller board.
The traces and the carbon contacts look quite clean, so I've cleaned with some IPA the leak (the residue was only on the cap pins), the board contacts and the rubber contacts. Once evaporated I've tested again but no luck.
I won't be able to change caps for a couple of weeks yet since I've had to order a new soldering iron, but if possible I'd like to know:
-Could this be an issue with the controller board cap?
-What's the recommended temperature to desolder the main board caps without harming the pads?

Thank you all for your help!

Keith Courage · 04/09/2018, 10:41 PM

Did you try re bending the rapid fire control slider? Lots of times these get bent from people pushing too hard on them. Bend the contacts out more so they press on the board with more pressure once put back together again.

Cordelay · 04/10/2018, 04:23 AM

Hi, thanks for the quick answer!

I've tried to re-bend the pins, clean them with IPA, and also swap places with the 2nd button slider, but nothing worked (2nd button turbo works perfectly with any of the two sliders, though). It looks like the bottom pin of the capacitor connects to the bottom pin of the turbo slider, so maybe the cap could be the culprit?

I have to say that I'm a complete newbie in electronics, I know what a resistor and a capacitor are, and I've been soldering guitar cables for many years, but I don't know if a failing cap could lead to a carbon contact not working

I've included a couple of links to pictures of the board in case they are of any help.

https://i.imgur.com/SAw9ypy.jpg
https://i.imgur.com/4xmpyQL.jpg
https://i.imgur.com/DX1oLOH.jpg

soop · 04/10/2018, 06:15 AM

I don't know my way around a GT board that well, but my first thought was a broken trace. However your board looks pretty well taken care of, and I can't see any breaks. I know there's a ribbon cable for the D-pad, but I also know if there's a problem with that, the screen is affected. You might be right about that cap, but from what little I know, I'm guessing it won't be too hard to fix.

Cordelay · 04/10/2018, 06:38 AM

I was also thinking about a bad soldered pin on the ribbon cable, since it looks a bit ugly with all the residual flux or whatever that is, but you're right, if that was the case the system wouldn't turn on.
I'm buying the replacement cap set next friday and I hope I get my new tools soon.
Thanks a lot for the info

soop · 04/10/2018, 06:42 AM

I can''t believe you're doing it yourself, that's some balls you've got. Do me a solid though, practice on something similar first if you can. Maybe go to a goodwill and find some $5 hi fi amp or something an pull a few caps on that. I'd rather you wreck some old junk than a $200+ console - that's an expensive electronics lesson!

Keith Courage · 04/10/2018, 07:00 AM

It's not uncommon for these to get bad traces. Might need to send the controller board out for repair which I can do for you. Also, another option is Turbokon is selling replacement controller boards now https://www.pcengine-fx.com/forums/index.php?topic=23047.0

Cordelay · 04/10/2018, 07:56 AM

Yup, gotta practice for a while before doing it. I have a couple of kits to practice and get the grip of the new iron.
About sending it I'm afraid living in Spain would make the shipping and repair more expensive than buying one of the new replacement boards.
From what I've seen in the forum post and on their website the new boards don't include the IC located in the center of the board, do they?

Keith Courage · 04/10/2018, 06:37 PM

Quote from: Cordelay on 04/10/2018, 07:56 AMYup, gotta practice for a while before doing it. I have a couple of kits to practice and get the grip of the new iron.
About sending it I'm afraid living in Spain would make the shipping and repair more expensive than buying one of the new replacement boards.
From what I've seen in the forum post and on their website the new boards don't include the IC located in the center of the board, do they?

I'm not positive. Send tubokon a message and ask him. They are fairly new so I haven't gotten one from him yet. I just repair them

Cordelay · 04/11/2018, 03:42 AM

Quote from: Keith Courage on 04/10/2018, 07:00 AMIt's not uncommon for these to get bad traces.

Just wondering out of my ignorance, wouldn't the broken traces be noticeable?
So the failing cap being the culprit is just out of the question?

Sorry if I'm bothering you with too many newbie questions, don't have enough money this month to send the board out to repair or even buy Tubokon's replacement board,
I was hoping that replaceing that cap would do the trick.

Thanks for the help, the advice and the info

Keith Courage · 04/11/2018, 04:17 PM

well your capacitor there could be bad but that wouldn't explain why all your other buttons are working fine.

do you have a multimeter? Check the Trace that goes from the rapid fire slider contact to the button one contact.

Cordelay · 04/11/2018, 07:26 PM

I'm away for work for a couple of days, but will try checking that on friday and post results asap.
Thanks again.

Cordelay · 04/16/2018, 03:55 PM

Tested it this weekend and it was just like you said, Keith.
I scraped a bit of the solder mask and got a copper filament soldered in place, and got it working!!!
Thanks for the info and the help!!
Now I just gotta practice installing and removing caps in a couple old motherboards, I don't want to risk damaging the pads

Keith Courage · 04/18/2018, 08:48 PM

I find with express systems that I have better luck removing the caps by grabbing them with a small pair of pliers and then twist/spinning them to break them off the board. This usually saves the pads better than snipping or desoldering on express systems. Especially since most of the caps will most likely have leaked making it more difficult to heat of the solder that is on the pads to remove them.

Cordelay · 04/19/2018, 09:33 AM

Twisting like constantly left right left right until legs break? Or full turn grabbing it vertically?
I've been trying to desolder smd caps from an old broken ide dvd drive and man, what a mess, broken traces and pads everywhere. Soldering radial caps is not that big of a deal, but after the massacre I felt like Frank Constanza in the cooking episode.

soop · 04/19/2018, 10:11 AM

Quote from: Cordelay on 04/19/2018, 09:33 AMTwisting like constantly left right left right until legs break? Or full turn grabbing it vertically?
I've been trying to desolder smd caps from an old broken ide dvd drive and man, what a mess, broken traces and pads everywhere. Soldering radial caps is not that big of a deal, but after the massacre I felt like Frank Constanza in the cooking episode.

There won't be legs per se in the same way radial caps have legs, so it should just snap the solder from the pad once enough shearing force has been applied.

the other way I've seen used (which I posted not too long ago) is snipping the caps off at the base using short nosed pliers.

Honestly the whole thing terrifies me, even though I should reasonably be skilled enough by now.

Keith Courage · 04/19/2018, 05:52 PM

I literally grab each surface mount capacitor and then twist it to the right as far as I can. If it doesn't break off keep twisting the same direction. Don't go right left right left over and over again. So just pick a direction and keep going that way till they twist off. Do not pull up in anyway. just spin it One Direction Until It Breaks Loose.

Sometimes pads can still get pulled up using this method. However I find that it is the least likely to have it happen.

soop · 04/20/2018, 06:19 AM

Quote from: Keith Courage on 04/19/2018, 05:52 PMI literally grab each surface mount capacitor and then twist it to the right as far as I can. If it doesn't break off keep twisting the same direction. Don't go right left right left over and over again. So just pick a direction and keep going that way till they twist off. Do not pull up in anyway. just spin it One Direction Until It Breaks Loose.

Sometimes pads can still get pulled up using this method. However I find that it is the least likely to have it happen.

Out of interest, have you tried applying heat with a hot air wand thing and lifting them then? I don't want to teach my grandmother to suck eggs, but that way sounds pretty foolproof in my mind

senkun · 04/20/2018, 01:02 PM

Since I only occasionally dabble, I could never justify a hot air station/gun though it would be really nice to have. I've seen pros grab and twist smt caps/resistors off but never found the courage (pardon the pun ;) to do that.

What works for me is a nice broad tip iron, plenty of flux, heat both ends at the same time for 2 secs and nudge, the smt part literally slides off. Won't work in tight spaces or groups, but if there's room to maneuver it's quick and neat.