Yamaha G50-112 Schematic Needed

[carageae]

series III

I got the Yamaha G50-112 III for 50 euros, in good looking condition, but the input stage - the clean channel is dead.
Does someone have the schematic for the 3-rd series?
It is esentially different from 2-nd series - there is different input stage and different final stage - complementary transistors in my amp, not both NPN.

[wizard 651]

I got the Yamaha G50-112 III for 50 euros, in good looking condition, but the input stage - the clean channel is dead.
Does someone have the schematic for the 3-rd series?
It is esentially different from 2-nd series - there is different input stage and different final stage - complementary transistors in my amp, not both NPN.

any luck on getting a schematic for this. I need one too. Series III

[carageae]

Yamaha G50-112 III

Not yet...still searching...the amplifier stays open under the working bench...

[wizard 651]

Not yet...still searching...the amplifier stays open under the working bench...

I have a G50-112 III that works, up to the "headphone out" and "pre-amp out". Nothing from the output stage is working, (speakers and "direct out")

I have everything BUT the schematic for the G50-112 III. I have a 15 pg "service manual" consisting entirely of exploded diagrams, parts listings and pictoral of circuit board parts lay-out, but I am missing the actual schematic. The schematics for series I and II are different than the III series.

I have a working G100 III head, and G100 III schematic. Putting aside the differences in preamp circuitry, the G50-112 III output stage looks like "half" a G100 output stage, in basic design. I have been trying to "extrapolate" from my G100 schematic, and voltages taken from the working G100 head, what is wrong with the G50...to no avail.

Since I do not understand the theory behind the circuit, I have been replacing parts from the output xstrs, forward, still without success. Having the actual G50-112 III schematic would be better than trying to guess from what i have.

[JoeM]

YAMAHA G-20-110 lll / G50-112 lll AMP. SERVICE MANUAL - Cleveland - Bonanzle

I bought mine from this seller when he was still selling on e-bay. (Includes schematic)

[upstairsdave]

G50-112 Owners Manual Needed

Greetings Folks,
Does anyone have a linkfor downloading the G50-112 owners manual or know where I can buy one?
Thanks
Dave

[micachee]

g50 112 series III

i am also in need of the electrical and parts list
found that some of the transistors are no longer available
ktb688 pnp made in korea
ktd718 npn made in korea

[Enzo]

2SB688 I find in stock at MCM and B&D Enterprises.

2SD718 shows subs in stock at both places.

[wizard 651]

I finally have the full so called "repair manual" for the G112-50III, including schematic, and parts list. I don't have scans of the parts list, but most of the parts are included on the schematics.

[jrfrond]

Thanks for the assistance.

However I have FINALLY worked out my Amp is the above model, heavily modded by previous owner though so that the reverb is removed from the Pre-Amp Board, and the tremelo effects and pre-set volume PCB are gone altogether! Quite bizarre...

Any truth in the notion I read on line that these Amps were designed by Soldano?!?

Original:

The Yamaha/Soldano was the T50, and quite a nice find, IF you can find one. However, with the new Soldano-designed, China-built Jet City amps on the market, you CAN get that Soldano sound a about 1/3 the price of the USA-made versions.

[micachee]

G50-112 III

Replaced drivers and main output transistors still no output and blowing 3 amp fuses
please if any one has the prints for this amp could you please post it
it only has one main board , sub board for speaker out jacks
thank you

[JoeM]

Replaced drivers and main output transistors still no output and blowing 3 amp fuses
please if any one has the prints for this amp could you please post it
it only has one main board , sub board for speaker out jacks
thank you

I posted above where I bought a schematic from, mainly because the schem is on very large paper, and I didnt own a scanner. But if you just need one section (power amp), let me know. I have a scanner now, and maybe can do this for you. Is it just the output section you need?

[edit:

This didnt turn out too well, but maybe there's enough to help.

[micachee]

g50-112 III

thank you it is a start is it possible to get from the transformer to the drivers?
there are no more of those books listed anywhere
is there a print of the main board layout some traces were burnt out so i have to add jumpers and i think i got one wrong

[JoeM]

thank you it is a start is it possible to get from the transformer to the drivers?
there are no more of those books listed anywhere
is there a print of the main board layout some traces were burnt out so i have to add jumpers and i think i got one wrong

I had to do these in 2 sections. Let me try again for the transformer to driver section.

[JoeM]

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