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Yamaha G100-112 - Journey

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

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dlbraly

This Yamaha had a think piece of plastic and some kind of thermal paste between a couple of the diodes and a big heat sink.

Do you just use CPU thermal paste?
They are mounted vertically, so if it was something runny it might run down the side.

Enzo


dlbraly

guess I need to shrink the photo sizes

dlbraly


dlbraly

wow thats huge
sorry about that

Testing attachment size

dlbraly

Note to self 780x585 is better

dlbraly

Should I stick to one post and change the subject to just Yamaha G100-112?

phatt

Quote from: dlbraly on July 18, 2018, 09:30:28 PM
Should I stick to one post and change the subject to just Yamaha G100-112?
Yes that would be easier to follow. :tu:

Adding;
Those are not diodes,, them big suckers is Power transistors.
TR311 &TR312 on the schematic.
The white goo is thermal paste, Yes same for CPU's,, all the same stuff.

The plastic pad is a mica isolating washer which isolates the case (which is also the collector) from the heat sink.
The newer pads maybe synthetic types which are are not so brittle but mica works just as well.
The thermal paste is to help transfer the heat from the collector across to the heat sink,,, and Always use it!! :trouble

When you reinstall those power transistors with washer and paste check with meter to make damn sure that the both collectors (The transistor case) is actually isolated from the heat sink otherwise it will end in tears at switch on. :o
Phil.

dlbraly

Quote from: phatt on July 18, 2018, 10:53:06 PM
Quote from: dlbraly on July 18, 2018, 09:30:28 PM
Should I stick to one post and change the subject to just Yamaha G100-112?
Yes that would be easier to follow. :tu:

Adding;
Those are not diodes,, them big suckers is Power transistors.
TR311 &TR312 on the schematic.
The white goo is thermal paste, Yes same for CPU's,, all the same stuff.

The plastic pad is a mica isolating washer which isolates the case (which is also the collector) from the heat sink.
The newer pads maybe synthetic types which are are not so brittle but mica works just as well.
The thermal paste is to help transfer the heat from the collector across to the heat sink,,, and Always use it!! :trouble

When you reinstall those power transistors with washer and paste check with meter to make damn sure that the both collectors (The transistor case) is actually isolated from the heat sink otherwise it will end in tears at switch on. :o
Phil.

Thank You - Will do

dlbraly

OK, so changed the subject so that everything will be one place.

dlbraly

#10
Some Pictures
Those first ones are the dirty PA board
Then The DC board before and after

dlbraly

The MA board before and after I put everything back on

Enzo

Um, blanking a board like that is not a good idea.  You run the risk of damaging parts in the process and making reassembly mistakes, soldering errors can occur as well.

dlbraly

Quote from: Enzo on July 19, 2018, 02:17:07 AM
Um, blanking a board like that is not a good idea.  You run the risk of damaging parts in the process and making reassembly mistakes, soldering errors can occur as well.
LOL now you tell me.
Yeah, I'm learning a lot from my mistakes. I should have asked questions before starting was one HUGE mistake. Could have been a quick fix.

phatt

Yes, tiss a bit like pulling out the engine because you found a loose wheel nut. :duh
Remember that just about any part on the pcb is replaceable,, except the pcb itself. :o
On old pcb's it easy to de-laminate the pads which can be a nightmare to fix.
So be very careful not to damage the traces and pads. :-X
Phil.