Took a chance... MM content.. package arrived

[ToneMerc]

Well. I'm very dissapointed.

The add said chassis, panels and showed pic of them, plus the main board and a second small chassis. I only received the small chassis, no MM chassis, panels, main board. Plus I paid $30 for shipping and she sent in a $15 flat rate box. I can only surmise that a second box has not been received yet. I sent a message to the seller, waiting for a reply.

I can't quite match up the xformer leads to any of the diagrams I've seen yet but I'm very colorblind. The numbers are 1-65 and EIA606 737 which I also can't locate. I could hook it up but I won't disconnect anything until I hear from the seller or receive the rest of the parts.

Any help is appreciated.

I believe the solid red is going be your "hi tap"

good luck

TM

[talbany]

Bob
Can you pull the tubes and measure the voltages on the various windings and post them.. Also does he have the B +set up with the voltage doubler.. I'll look around for info on that transformer.. Good Luck

Tony

[FUCHSAUDIO]

Did you look the p/n up on the Music Man website ??

www.musicmanamps.com

[Bob-I]

Bob
Can you pull the tubes and measure the voltages on the various windings and post them.. Also does he have the B +set up with the voltage doubler.. I'll look around for info on that transformer.. Good Luck

Tony

Well, the connections weren't complete so I pulled them out and started by measuring resistance to see which leads belong to the same winding. With some help seeing colors from my little girl...

Green-Green = .2 (heaters)
White-Black =3.2 (primary)
Red-Red/yellow=11.6 (HV?)
Orange-Orange=4.7 (bias?)
Red/black-Yellow/black=.4 (?)

No single winding has a CT

I'll connect this to AC/fuse/lightbulb limiter later and take voltage measurements.

[Bob-I]

Did you look the p/n up on the Music Man website ??

www.musicmanamps.com

Other than the Ernie Ball schematics I don't see any part numbers. This PT doesn't match anything on the EB schems.

[FUCHSAUDIO]

Most Music Man amps can have a 3 wire primary (for hi/lo power and a pilot lamp tap usually). The high voltage should be three wires too for hi/lo power (the early amps actually switched the line voltage to lower the whole amp...later changed). The low voltage shit was usually 3 wires as well, used to make bias, and run the low level solid state shit.

A chassis number would help....

[talbany]

Bob
Just to make clear is the 2475 the amp model # or the # on the PT.. If not do you have the all the # stamped on the PT.. usually like 220-130 something

Tony

[Bob-I]

Chassis isn't here yet.

I thought that the MM stuff was all 3 wires as well, but that's not what I'm seeing on this one. The OT is also a single 8 ohm tap, the MM's I've seen are all 4 and 8 ohms.

When I get the rest of the stuff I'll have more info.

[Bob-I]

Bob
Just to make clear is the 2475 the amp model # or the # on the PT.. If not do you have the all the # stamped on the PT.. usually like 220-130 something

Tony

Yes, the PT is stamped 1-65, the OT 3-65 and both have the EIA606 number on them, PT is 737, OT is 744.

The seller claimed 1975, which is very early MM.

[FUCHSAUDIO]

Certainly not standard.....I got a Bassman-100 off E-bay with a replacement power transformer (2- actually to replace one). I filed a paypal grievance and told the dude I need to buy THIS transformer (attached link to Mojo) to make this amp work, and he paid for it !! lol.

Sometimes the cheap shit is hacked, burned-up etc....never fun. The hi/lo primary switched amps are okay as along as you don't try doing hi/lo power on the modded amp. More of a hassle than it's worth.

The ones with the switched b+ secondaries can be slick. I've done full and half power (by turning off two tubes) AND also using a hi/lo power switch, so you can do 100, a couple of different 50-W modes, and a lower power mode too...takes some extra work, but very cool outcome if the chassis has the room.

Let me know if you get jammed Bob. I might be able to help you out.

[FUCHSAUDIO]

deleted duplicate post

[talbany]

Bob
My notes here say the 1-65 is an older obsolete later replaced by the 100-65-120.. There were some issues concerning the switching wiring on the 100-65 later addressed in the # service bulletin #4.. Here...So you could cross the 100-65 ..

http://www.pacair.com/mmamps/Documents/ ... n%204m.pdf


Tony

[Bob-I]

Thx Tony and Andy.

I think I located a schematic with a 1-65 but it's pretty blurry and hard to make out. It even has the single tapped OT.

http://www.music-man.com/techinfo/old_amps/2100-65.pdf

After a second measurement it looks like the low power switching was done on the primaries, bad idea but no problem for me. I can build the amp as planned, it the PT doesn't cut it I'll just replace it and use it as a paper weight.

I'll compare to the engineering note and take some measurements later this weekend. As long as the OT is good and the rest of the parts come I think I'll have gotten my money's worth.

[ToneMerc]

I think I located a schematic with a 1-65 but it's pretty blurry and hard to make out. It even has the single tapped OT.

http://www.music-man.com/techinfo/old_amps/2100-65.pdf

Bob, both of those OT have 4 & 8 tapped secondaries. The first one which is labeled type 3, has Grn-8 and Yel-4 taps, while the one labled 3-65 XFMR has the 4 & 8 taps wiring colors transposed.

I don't what that single tapped OT is. I haven't run across any MM docs that has an amp with a single output tap.

http://pacair.com/mmamps/Documents/MM%2 ... al%20m.pdf

TM

[Bob-I]

Voltages are: