Yamaha T-100 Tube Guitar Amp designed by Marianno Soldano

[nevetslab]

In the process of sizing up what I need to cobble together for screening preamp and power amp tubes that I've collected over the past 12 years, to see what's useable, I pulled down off the shelves a Yamaha T-100 Rack Mount Guitar amp. It's been sitting up there, or at least got moved up there in March 2009 when I set up shop here at CenterStaging, LLC in Burbank, CA. This heavy 4U rack mount product has been collecting dust all this time up there, no tubes installed, but, it's an interesting piece that I've never seen before, apart from here. Somewhere along the way, I picked up the Service Manual for the product series.

My initial thoughts were to add 1 ohm cathode resistors with test points on the rear panel for screening power tubes (6L6GC's, 5881's), maybe even EL34's with a circuit change. Revise the Slave Output jack to a Preamp Output/Pwr Amp input jack that normal's thru, so there would be direct input to that section of the amp.

Then, while photographing the outsides, I noticed on the rear panel this was Designed by M.J. Soldano, and built at a Yamaha factory in Thomaston, GA. I'll have to plead ignorance for NOT knowing about Marianno Soldano, but no doubt many here on the forum definitely do. He passed away in Nov, 2020, while his company continues on producing his products. I've never seen one myself.







I found the website: https://www.soldano.com/ and while looking under M.J. Soldano, found links to the obituary before finding the company website. So, perhaps this amp that was built by Yamaha has more value than just becoming a suitable tube test fixture.

The Yamah T100 series manual is here:

Yamaha T50_100_SM.pdf

[Jon Snell]

Typical Yamaha service information error.

[TomCarlos]

Yamaha T100 Service Manual Yamaha_T50_100_SM.pdf

[Enzo]

One of my salesmen when I worked at the music store had a combo of that amp. He always referred to it as his Soldano amp. I worked mightily to break him of that. Pete, it is not a Soldano amp, it is a Yamaha amp designed by him.

I first encountered that when he asked if I had Soldano schematics. No, I don't. Then he brought it in and , OH, it is a Yamaha. Well I have ALL the Yamaha docs.

[nevetslab]

With the bottom cover removed, we find somewhat of a rats' nest, but, not all that surprised. I see a date code on the 10W Dale Power Resistor of 9126 (1991, 26th week), so this amp was probably manufactured within a year of 1991.









If nothing else, it DID pass UL inspection and was UL LIsted.

[Enzo]

No date codes on the iron or the revrb pan? Pots usually have dates.

[g1]

As far as I know, it is Mike Soldano, and he is very much still alive.

[The Dude]

Probably a good sounding amp when working. I'd be inclined to get it working and try it out, first. It also looks very heavy.

[TomCarlos]

This amp is most likely identical to the T50 and T100 Combo amps.

I did a spot check on the pc board pics you posted. They look spot on when compared to the amp I worked on.

See my post - Yamaha / Soldano T100C Amp, Clean Channel Low Volume

[tedmich]

These amps are NOT generally reviewed well in spite of the Mike Soldano connection.

He did , after all, have to start his own company to truly do his own thing!

I had a Yammie JX-35 as my first guitar amp, and its amazing I kept going.. that thing was HORRIBLE, as most SS amps of that era were.

[Jon Snell]

Could be 1991.

[drewl]

Yikes, looks like my experimenting chassis/amp

Looks like they were trying to make a Mesa Boogie.

[nevetslab]

This amp is most likely identical to the T50 and T100 Combo amps.

I did a spot check on the pc board pics you posted. They look spot on when compared to the amp I worked on.

See my post - Yamaha / Soldano T100C Amp, Clean Channel Low Volume

Thanks for this link to your previous post. I scanned thru the post, and will go back thru it for more details. Excellent thread for reference in getting started.

I had just released an EVH 5150 to go back to our inventory before pulling this Yamaha T-100 down from the shelves. That amp had everything I'd need to load the T100 up, tube-wise. I'm not sure how often that amp moves in our rentals (we have 4 in stock), but it made it onto my list of amps being considered for cannibalizing for tubes.

I haven't yet powered this chassis up. I'll start there. I already want to replace the 1/2W 470 ohm screen resistors and the 1N4007 rectifiers on the PS/Bias board. I'll slow-start this, as it's been years since it's had power applied.

From my initial thoughts (looking for a chassis to use as a preamp/driver/power tube test fixture), this Yamaha will serve for power tubes....at least 6L6GC's/5881's. Looking at options for setting the output stage up so I can use it for testing EL34's as well. So, larger screen resistors needed, change in bias voltage, and needs the suppressor screen Pin 1 tied to Cathode. I looked at a couple Mesa amps to see what they did. The Lone Star added switched-in 2.7k screen resistors to the existing 470 ohm screens in place for the 6L6GC's, and switched from -51VDC(6L6GC) to -38VDC (EL34) for bias (no bias pot). Nothing shown with regards to the suppressor grid pins. Orange Rockerverb uses 1k/5W screens, has the suppressor grid tied to cathode, and you have to manually adjust the bias. It too has HT fuses, which the Mesa doesn't. I was looking to add quality cathode test points on the rear panel so I can check each tube's plate+screen current for matching. I do, of course have a Compu-Bias Bias probe set with four probes (two at a time).

I won't be making any changes to the amp until I see it's a working amp, and then get approval for pushing forward on setting up for screening tubes. I had always been using discrete amps as the test bed when there were tube issues, and not a dedicated 'tube tester' for some purposes. I do have a Hickock 539A Tube Tester, but its' in need of rebuild/clean-up to fully restore it. It's been far more convenient using amps on the bench to deal with those tube issues anyhow.

I'll probably have to build a simple 9-pin tube test fixture so I can look at both triode sections, each having the same parts for identical voltage gain.

[nevetslab]

While I've been slowly reforming the electrolytic caps bringing up the AC Mains in small increments, I was looking at the power tube socket wiring, and found on V10, there's a shielded cable...shield tied to Pin 8 (Cathode/Ground), and it's core of the shielded cable connected to Pin 1. Then, there's a GRN wire from the Reverb Drive Xfmr secondary connected there at Pin 1. Using the vacant Pin1 of the tube socket as a tie point. Vacant, unless I wire them up for the Suppressor Grids to use EL34 power tube there. Haven't done that yet, of course, but was maybe looking to do that so this could be set up with either EL34's or 6L6GC's/5881's.

What a strange place to put the GRN Reverb Secondary xfmr drive wire! I looked thru Tom's notes on the Soldano T100C, and then followed a thread from Vintage Kids, and did find reference to that GRN wire, but not where it was located in the chassis.

[TomCarlos]

nevetslab:

Going back to my thread, I got a most valuable hint from G1 when my voltage readings seemed odd. His advice was as follows: "specify whether 'bright' switch should be engaged, does it make any difference?" And the answer is YES, it makes a difference. The Bright switch must be engaged in order to see the expected voltages on the preamp tubes.

The other thing is on the Yamaha Service Bulletin for the mod. I would skip that. Back then, I was working on a T50 and T100, one with, one without the mod. I did not hear the problem that was being reported. So I would skip that.