GT-100 - What type transistor used for "Q4"

Started by lynessmy, October 19, 2016, 11:01:55 PM

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lynessmy

Helping a friend to restore his GT100.
Just notice that the Q4 is removed by the previous repairer.
Any one have the schematics around this area?
Or have any idea what should be reinstalled to Q4 place?
The pad look like a SOT89.
Any helps are appreciated.

lynessmy

#1
Any kind souls to the resque?

sixeight

#2
Sorry,  I  don't have a Gt100 and AFAIK there is no service manual online.

But the most likely scenario is that Q4 is not supposed to be there.  Are there clear indications that the part has been removed?

Elantric

#3
POST A PIC OF THE PC BOARD

(MANY ARE HERE)
http://www.tonymckenzie.com/roland-gt-100-review.htm


lynessmy

Seen the pic there. But can't clearly read out the part no. The unit are not able to power on now.
Looking at the picture, look like it Is not only missing q4, q1or q17 Is not there too.

sixeight

Ok, that counts as a clear indication the part was removed.  :o

Maybe somebody with a GT100 is willing to open it up and take a good picture of the power side of the main board...


Elantric

#7
Here is your GT-100



Its curious that your "serviced" GT-100  is missing both Q1 and Q4 - but has Q17 occupied


Below is my working GT-100 - but this one "opposite" yours - mine has both Q1 and Q4 occupied, but Q17 is missing.

Boss GT-100 "Q4" is in the power supply region of the GT-100 Main Digital Board  and is a 5 pin SMD Transistor in  "SOT25" size package marked  "U17"

Google revealed this SMD Transistor marking identifier resource site:

http://www.s-manuals.com/smd
http://forum.s-manuals.com/index.php?board=3.0
http://www.s-manuals.com/smd/u1



SMD Transistor with top marked "U17"  = ROHM QS5U17 



2.5V Drive Nch+SBD MOS FET

http://www.s-manuals.com/pdf/datasheet/q/s/qs5u17_rohm.pdf

Mouser sells them
http://www.mouser.com/ProductDetail/Infineon/QS5U17TR/?qs=4kLU8WoGk0srE8hwkNDIRQ==


Pic of a GT-100 is below - but observe the middle "Q17" transistor is missing on my working GT-100


Elantric

#8
More pics

But this should be repairable by an authorized Roland Service center - I feel you are flying blind without a proper GT-100 schematic 

lynessmy

TQ very much.
I had got the replacement Q4 and installed it.
It resurrected the the Gt100.

The problem was diagnogsed by previous tech and he left the owner with spare Q4.
However, the spare had gone missing before the owner manage to sent to me for installation.
I'm not sure why he didn't proceed to install that Q4 for the owner.

I got the spare component from China; 5pcs for $4.5 shipped. But waiting time is more than 30 days. :)