Yamaha G100-112 II

[antares]

www.google.com/search?q=yamaha+G100-112&lr=&prmd=svin&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjNloOgqYHMAhVBaRQKHT5KArsQ_AUICSgD&biw=360&bih=477#imgrc=Fb8F1WBNpOzVyM:

Guys I've had one of these Yamaha takes on the Roland JC120 clean option theme since 1980. I've always loved it (and I'm in some pretty stellar company on that score...)
On Wednesday, I landed another one for about $100 sterling equivalent- ostensibly as a spares resource.
I thought that the parametric EQ was NFG but I was wrong. I've bought some replacement knobs off eBay (always a weak spot on these amps- the satin anodised knob cap trim falls off) and a replacement handle because this one has split, and weighing up the massive 12" loudspeaker magnet and hefty transformer, it's heavy for a 1x12. The jewel is missing and someone has replaced the power switch upside down. Perhaps they preferred it that way? I sure do but it should be "up for on" in the American fashion.
This is no spares machine, it's a good'un!

So, it rattles. One of the two Accutronics reverb tank springs has gone walkabout inside the tray. The two tiny grain of wheat magnets have parted company with the end anchors and I cannot see any way to re-solder the tiny beryllium copper wires onto the magnet. At about $32 on eBay (again!) I figure the headache free way is to swap out the tank. This grieves me (throwing away a serviceable piece of kit that still (sort of) works with just the one spring.) I suspect that I could pull the wire through the bead magnet, thread some replacement wire through to solder on to (easy to say / write!) and fashion a new hook for the springs, but I believe that life is indeed too short!

Does anyone have any other suggestion as to how to reconnect the tiny magnets before I pull the trigger on a new reverb tank?

When I'm done, I'm going to arrange four amps, one in each corner of the room and hook them up to the four outputs of my Akai E2 Headrush looper / delay pedal !!! Can't wait. Like a little kid!

Steve.


e&oe...

[Deleted]

I would put a new tank in it. They are not that expensive. I just put a new MOD in my classic Peavey 30. Sounds so much better than the old one.

I have a Rolland jazz 120. Bought it new in 1985. Still sounds great! It has never let me down. The Rolland is one reason I am thinking of going back to solid state amps. If I do go back to that, it will be another Rolland or Orange. I am thinking of going to the Orange. I had one not too long ago, but like always, needed money and some guy was over in my music room, and made me a good offer on it, so out the door it went. Now I want another one. But not in a big hurry.

I love my tube amps. But they sure can be fussy...

EB

[antares]

Thanks Eddie. I'll take your advice.
If you should happen upon a Yamaha G50 or G100, give it a good listen. It has to be the second series though. They were about the first guitar amps to use mosfets. They are reputed to have had the Soldano touch! These second series ones have chrome corner protectors unlike the first series. The third series has multi coloured knobs and extra helpings of distortion but that's not what we want in an amp like this.
I have a MOD saved in my eBay watch list right now. The seller seems to offer a smörgasbord of mods, repairs, components, servicing and so on. He or she also talks common sense regarding the supposed mojo attached to certain discrete electrical components so I've added the shop to my eBay favourite sellers list.
Thanks again EB, appreciated.

e&oe...

[antares]

Well, that decides it. I thought I'd just try to pull the bead magnet off what remains of the hook ended wire to see if I could indeed replace it. Too small to grip. Gently now with pliers. Dust! You were spot on EB!
New tank winging its way to me right now.

e&oe...

[Deleted]

ha! I have tried to fix some things in the past. Some worked out OK, but I always end up replacing it later on down the road. Somethings can be replaced with little money. I am all for keeping things original, but when they need new stuff they need new stuff.

Just read about, " filter caps" in amps. They were saying if an amp is 12 to 15 years old, the amps need to have the filter caps replaced.

I remember a few years back, I was selling an old Fender tube amp. This guy was getting all over me because I told him that the filter caps had been replaced. (I got the amp that way) This is what he told me; " it's not all original then!!!" and hung up on me. I thought, if the caps are bad the amp wont work, right>>> Anyone that messes with electronics, should know, that electronics do go bad over time. But I do run across people like that once in a while.

Let us know how the new reverb works out.

EB

[antares]

There are much larger DC voltages in a tube amp than a solid state, you know that better than me! Electrolytics do suffer degradation in the dielectric over time if not used, but these can often times be reformed if you have a variac. I had an 8 amp variac but I sold it decades ago for a song not realising how useful it might become. The thing is, old or new, stressed or cossetted, used or unused, an electrolytic going south is no fun with the stink and the mess which covers everything inside the cabinet, so yeah, I reckon changing out the filter caps periodically is probably a good thing, but leaving well alone is more my mantra!
I guess because I am a "ham", I don't buy into all this electrical component mojo thing- the electrons only know about lumped constants in a circuit, but that's the obsessive purists' loss IMO.

e&oe...

[hoz]

All of my amps are over 30 years old. None of them would be functioning if they were ALL original. That guy was just foolish or just beating you up over the price.

My '66 Fender Bassman head has had the most stuff replaced in it. I've owned that amp for over 17 years. I believe it still sounds as good as when I first got it. Of course, that is just my opinion and I may have a little more hearing problems now!

[antares]

The MOD reverb tray is fitted and working nicely. It was working of sorts with the old tray with one spring, but I suspected an impedance mis-match with the circuit driving the reverb.

Incidently, one of the channel indicator LEDs is not lighting up. I went round re-flowing the associated solder joints and everyone I touched made a distinctly audible fizzing sound. I have never experienced that before. I wonder whether it was the flux used originally? It still doesn't work but both channels are fine, so the circuit and switching arrangements are A-OK. It's either going to be the LED or its associated dropper resistor or both.

e&oe...

[Jon]

Apr 9, 2016 12:14:45 GMT -6 antares said:

Thanks Eddie. I'll take your advice.
If you should happen upon a Yamaha G50 or G100, give it a good listen. It has to be the second series though. They were about the first guitar amps to use mosfets. They are reputed to have had the Soldano touch! These second series ones have chrome corner protectors unlike the first series. The third series has multi coloured knobs and extra helpings of distortion but that's not what we want in an amp like this.
I have a MOD saved in my eBay watch list right now. The seller seems to offer a smörgasbord of mods, repairs, components, servicing and so on. He or she also talks common sense regarding the supposed mojo attached to certain discrete electrical components so I've added the shop to my eBay favourite sellers list.
Thanks again EB, appreciated.

e&oe...