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NEC TG-16/TE/TurboDuo => TG/PCE Repair/Mod Discussion => Topic started by: bdoi on October 23, 2019, 12:47:58 PM

Title: need PC engine GT Q500 transistor replacement part??
Post by: bdoi on October 23, 2019, 12:47:58 PM
Hello

I have a GT fully reccaped with sound but no display. I point the transistor Q500 which become really hot when I power on the console.
does anyone knows the Q500 ref or a working replacement part?

thanks in advance for your help

(https://i.postimg.cc/4m8ZWW6T/Resized-20191011-121643-5805.jpg) (https://postimg.cc/4m8ZWW6T)
Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: Keith Courage on October 24, 2019, 09:26:54 PM
https://www.aliexpress.com/item/32726193004.html
Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: bdoi on October 26, 2019, 02:44:43 PM
Thanks I will order this and try it . Finger crossed :pray:
Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: Keith Courage on October 27, 2019, 08:03:51 AM
Was the part damaged from old capacitor leakage or did it just fry on its own? If it fried on its own then the Transformer on the board is shorted out and needs replacing. Also, if you didn't order yet I have some extras of that transistor. I wasn't sure if you just needed 1 or if your question was about needing to know for future reference what to order anytime you come across a bad one.
Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: bdoi on November 01, 2019, 03:51:33 PM
I think the part wasn't damage form old capacitor leakage.
So you think the transformer is shorted too... Is it the big square just under the CC900?
Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: Keith Courage on November 03, 2019, 03:10:51 PM
Unfortunately yes that is the part. Does the system still turn on? Can you hear sound?
Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: bdoi on November 07, 2019, 04:14:26 PM
Yes there is still sound . In fact I just tried for few second and feel the q500 getting really hot so I have turned it off. I am waiting for the ordered transistors . As soon as I would received it I will try to change the transformer in the same time and will let you know the result.
Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: Keith Courage on November 07, 2019, 07:47:42 PM
Well, the good news is that since your express still powers on with sound, you could always go the replacement screen route using the composite video mod if you are unable to get things going with the original.
Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: bdoi on November 08, 2019, 04:10:23 AM
Yes it was my plan if the transistor and transformer replacement  don't work.
But it looks really tricky to do :(
Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: Keith Courage on November 09, 2019, 04:22:02 PM
Yeah, the composite mod for a larger screen is difficult and risky if one hasn't ever soldered on small pins like that before. I do these mods if it's something you don't want to tackle.
Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: bdoi on November 09, 2019, 04:27:51 PM
Thanks for the proposition , I will keep this idea in mind. But I am in europe so shipping oversea is really expensive:(
Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: bdoi on November 13, 2019, 04:48:44 PM
I tried to replace the q500, nothing better, replace the transformer, nothing better.
I also tried to replace q900 and q901, same thing  :-\
I have no other solution to try the lcd screen mod
Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: Keith Courage on November 14, 2019, 10:26:37 PM
Not sure if any place in the Uk sells the composite out board but they can be bought here.  https://tg16pcemods.ecwid.com/#!/TURBO-EXPRESS-PCE-GT-COMPOSITE-VIDEO-BOARD/p/100968130/category=0

This is to make the system put out composite video. It can then have a 2.5" or 3.5" screen installed.

I'd start by installing this board first and then just use a RCA cable to test with your TV to make sure you are getting good video.

If you feel comfortable enough to build your own composite board then here are the components needed.

(https://i.postimg.cc/5j2tXRZj/pce-Composite-Video-repair.gif) (https://postimg.cc/5j2tXRZj)
Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: bdoi on November 15, 2019, 02:13:57 AM
Thanks
I saw there are 2 versions : composite and S-Video?
Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: Keith Courage on November 15, 2019, 11:11:25 PM
Well, the s-video would be if you plan to also hook the express up to a TV. I have yet to find a good screen for the express that will take a S-video signal so no reason to go that route unless you plan to use it with a TV that can use s-video. These 3.5mm screens from console 5 are excellent for composite video. They are what I use now. https://console5.com/store/universal-3-5-composite-video-lcd-module-320x240.html

Console 5 also sells the new larger size screen protectors. https://console5.com/store/turboexpress-3-5-glass-lens-screen-cover-for-lcd-swaps-turbo-express.html but they can be bought for less here https://www.ebay.com/itm/Turbo-Express-3-5-lcd-Glass-screen-protector-NEC-pc-engine/233246430957?hash=item364e9216ed:g:rfQAAOSwbzpc9WUO
Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: bdoi on March 16, 2020, 11:11:17 AM
Well, the s-video would be if you plan to also hook the express up to a TV. I have yet to find a good screen for the express that will take a S-video signal so no reason to go that route unless you plan to use it with a TV that can use s-video. These 3.5mm screens from console 5 are excellent for composite video. They are what I use now. https://console5.com/store/universal-3-5-composite-video-lcd-module-320x240.html
Console 5 also sells the new larger size screen protectors. https://console5.com/store/turboexpress-3-5-glass-lens-screen-cover-for-lcd-swaps-turbo-express.html but they can be bought for less here https://www.ebay.com/itm/Turbo-Express-3-5-lcd-Glass-screen-protector-NEC-pc-engine/233246430957?hash=item364e9216ed:g:rfQAAOSwbzpc9WUO

Hi Keith  I ordered the composite board for GT and wired like on this picture but nothing when I put the composite video cable on my tv... 
Where can you take the 10 v for the new screen? Directly on the power jack socket?
Thanks
(https://i.postimg.cc/jLJGFks1/2669becc28087d237f17477f5d08fad4.jpg) (https://postimg.cc/jLJGFks1)
Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: Keith Courage on March 18, 2020, 01:40:52 AM
If you are not getting anything on your TV then something isn't right. You should be able to use a typical RCA plug on your TV.
I wonder if your ground is good. I always run my ground wire to one of the points where the grounding shield connects to the board.



For a replacement screen you can tap power from the power switch itself.
Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: bdoi on March 18, 2020, 02:05:53 PM
If you are not getting anything on your TV then something isn't right. You should be able to use a typical RCA plug on your TV.
I wonder if your ground is good. I always run my ground wire to one of the points where the grounding shield connects to the board.



For a replacement screen you can tap power from the power switch itself.

thanks Keith
 I checked for my groud and it is a real ground so no issue with that. And I used RCA cable (that works with my nomad)
So I think my last chance to make it alive is dead  :cry:
there  is no improvement, still just sound but no display.

Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: Keith Courage on March 18, 2020, 03:33:35 PM
I've never come across a system that has had no video output what's so ever while still putting out audio.. Even if the 6260 video chip is faulty, you generally get a glitchy image of some sort.

Try reflowing solder over your pins on the video board that you installed again. Also, give the second video output on the board a try just in case that first transistor is faulty.

Also double check that there's 5 volts on that power wire you've run.
Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: bdoi on March 18, 2020, 05:27:34 PM
i have double checked:
 solder are ok
I have 4,78V for the 5V so i assume it's ok
and I test the second video ooutput on the board and same issue.

I tried a bit longer  (with bomberman 94) and during all the beginning , on this game there is a "presentation video" and after this presentation you have the title screen. I realized that I have a bad display on my TV (just for the title screen, if I wait a bit longger the presentation video restart and so black screen on my tv.
here a video of the display issue:
https://www.dropbox.com/s/05n595ngt4cakuf/20200318_215408.mp4?dl=0
Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: Keith Courage on March 18, 2020, 11:29:41 PM
I've never seen that before. Looks like a sync or grounding issue.

Also, dumb question. That isn't a Pal signal TV is it?

Also, why does the solder look all weird, wrinkly, and lumpy on some of the new caps you installed? The negative pad looks really bad on the cap you pulled 5V from and so does the positive connection for CC703. Might want to check the solder for the new caps again.
Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: bdoi on March 19, 2020, 08:09:09 AM
The picture I posted is one I took here :https://www.pcenginefans.com/forum/index.php?topic=22810.0

Mine are there ;)
https://i.postimg.cc/3JL80MLH/20200319-081843.jpg
https://i.postimg.cc/XYzYmMFg/20200319-081851.jpg
https://i.postimg.cc/PqCP5fhc/20200319-082007.jpg
https://i.postimg.cc/ZYGsCP0J/20200319-102659.jpg

So I don't think I have bad solder...
I set the 5V at really 5V as you said and remove the 2 4,7F caps: same issue.

and my screen is ok I thnink beacause I can see my sega nomad display with the same rca cable

Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: bdoi on March 19, 2020, 10:34:30 AM
My mistake!! :-[
the pin 39 and 40 were shorted!
Now it works!
thanks Keith for your time ;)
Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: Keith Courage on March 19, 2020, 03:44:57 PM
Yay! Another system Resurrected. :dance:
Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: bdoi on March 20, 2020, 01:59:58 PM
Keith
I still have one GT with sound issue (the sound is really weak).
al capacitors have been changed, I also tried another controller board with another speaker (which works great on another GT) and same issue.
I tried to switch sound amp too and potentiometer but nothing change.
Do you know if I can find somewhere a GT schematics (at least sound part)?
thanks
Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: Keith Courage on March 23, 2020, 05:01:58 AM
Weak out of both headphones and speaker or just the speaker?
Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: bdoi on March 23, 2020, 12:53:52 PM
Weak out of both headphones and speaker or just the speaker?

no just weak with speaker, it normal and good with headphone
Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: Keith Courage on March 24, 2020, 12:39:08 AM
Did you try another headphone jack?  There is a switching portion of the headphone jack that tells the system whether to use the external speaker or not.
Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: bdoi on March 24, 2020, 04:02:57 AM
Did you try another headphone jack?  There is a switching portion of the headphone jack that tells the system whether to use the external speaker or not.

Yep, I tried to switch head phone jack and same issue. That's why I asked if some schematics exist at least for sound part?
Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: Keith Courage on March 24, 2020, 06:01:05 AM
Not sure if they exist. I don't have any.

Besides a different speaker, did you also try another controller board? Could be a bad lead in the white ribbon cable for the controller board.
Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: bdoi on March 24, 2020, 06:56:52 AM
Yep I also tried to switch controller board + speaker and it Worked fine on other GT , and another controller board +speaker on this one and same issue.
Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: Keith Courage on March 24, 2020, 09:50:14 PM
Just fixed an express with this exact issue. The problem was a bad trace for one of the 33UF caps. Via hole connection was also bad. So I soldered an extra cap lead through the via hole, then used a wire to run the trace to the positive end of the 33uf cap.
Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: bdoi on March 25, 2020, 03:14:38 AM
Great ! Thanks Keith!
I will check more precisely 33uf caps tonight ;) and let you know
Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: bdoi on March 26, 2020, 03:10:42 AM
Just fixed an express with this exact issue. The problem was a bad trace for one of the 33UF caps. Via hole connection was also bad. So I soldered an extra cap lead through the via hole, then used a wire to run the trace to the positive end of the 33uf cap.

I checked and indeed it was a bad trace through the pcb. I fixed it, the sound is now loud!
Many thanks Keith! 2 GT fixes in one thread!! :clap:
Title: Re: need PC engine GT Q500 transistor replacement part??
Post by: Necromancer on March 26, 2020, 10:06:48 AM
Nicely done, you guys.  That's some good teamwork!