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Yamaha G100-112 - Journey

Started by dlbraly, July 18, 2018, 08:16:58 PM

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Not only that, but it is a mistake to assume the problems are always caused by bad parts.  You could have a crack in a copper trace.  You could replace every part on the board, but the cracked trace would remain.


Yeah, I've been known to jump in with both feet.  :o


Picked up some thermal Paste, got the amp back together.
I bought 2 NTE458 transistors to replace the bad transistor 2SK30A (replaced the pair of them).
I did not not try the amp without the transistors like Enzo suggested. I was there getting the paste...
The amp is now loud like it should be.

There is a very loud popping noise. Ive twisted all the pots and it doesn't seem to make a difference in the popping.
Turn the amp on with or without guitar after about 15 or 20 seconds it starts a loud sporadic popping. Turn the amp off, then back on another 15 seconds or so it starts again.

I did notice that sometimes when you turn the amp off, you can hear some static sound from the speaker for a few seconds. Im not sure if that is normal for this amp.

Would the 2 transistors I replaced (TR206 and TR207) cause that type of fault?

I have NOT done the adjustments yet that the service manual says to do. Figured I'd post here first. Then go back in and see if I can do that.


OK, so TR206 and TR207 can cause that popping!
I removed them, and I cleaned the pots.
Enzo rocks! I should have just listened to him in the first place. Thanks.

I will mess around with it some more, and to make sure nothing else is wrong with it. I also need to do some very minor cosmetic stuff to it.
There is a tiny tear that I don't want to get any bigger.
and someone replaced a pot, but put one in that the shaft was too big, and just cut it off to fit. but the knob doesn't stay one. I'm going to try and cut a slit it in it since it now longer has one.

I think my Dad will be happy with it.


That Yamaha Amp really sounds good.  :dbtu:
My Dad asked me if I wanted to use it a little longer. I told him he better take it because all I'm dong is playing on it. I'm not getting my other stuff done.

Yamaha really made a sturdy amp. the wood in the cab was real thick and heavy!
Im curious if the Series II and III are as heavy duty.
Anyone have any idea?
What are your thoughts on Yamaha Amps? Good, Bad, just OK?

I blogged on it. Nothing more that is not posted here.
My Blog


All the old Yamaha stuff was quality gear.