105 transformer?

[MesieBooga]

Anyone know what a "105" transformer is? Or why it may be preferred?

 

[Boogiebabies]

The 105 is the IIC+ power transformer and was the IIC+ power transformer. The 105 is just the beginning of the part number. An early IIC modded to a + may not have the 105. The MK III did not have it either. You can tell because it is a huge and heavy tranny. The specifics are that it is a 480V multi tapped transformer with taps for the bias at 67 volts and a tap for the heaters at 6.3 volts. In my opinion it is better than any prior or post PT's due to the fact that it does not sag and maintains a very consistent constant voltage to the plates. Most later Mesa transformers are 1/2 the size and just do not have the iron in them. They are also putting out 460V. under load they may sag to 420 volts or so under load, but the 105 during heavy settings still maintains around 478 volts under load.

Note: Some early IIC+'s did not have the 105. Also, the K series and Export series did not use the 105. The true IIC and very, very early or modded before shipment IIC+ had a much smaller stack. Very few of these around so beware. If it has the small tranny and a Pull Deep face plate, it probably went back at a later time for the mod. If it is a Gain Boost it would have left the factory that way.


You asked!!!

 

[MesieBooga]

How can this transformer be distinguished?

 

[Boogiebabies]

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7353187794&indexURL=1&photoDisplayType=2#ebayphotohosting


This is a 105. All you have to do is ask the seller what the first three numbers on the PT are. If you find one locally, get your head in there and see what is stamped into the bell housing. It should say Mesa -
EIA 606-3XX - 105 XXXXXXXX. It is also pretty thick in terms of stack size for a Mesa transformer.

 

[Boogiebabies]

The only other way it can be distinguished is in a Tuxedo, sporting a pencil mustache and playing craps in Monte Carlo puffing on a cuban while guzzling Crystal or Dom.

LOL !!!

 

[MesieBooga]

Looks like my new one coming has the 105.

 

[Boogiebabies]

Sure looks like a 105. I guess you will know when you get it.

 

[MesieBooga]

I checked my Jan '85 IIC+ head (loaded but no SimulClass) and it shows a 105 number in there. The Transformer also says Mesa on it but the number is EIA6064XX ... rather than the 3. The 105 shows up with another set of numbers after it something like 105 xxxxxxx. I can't make the middle ones out.
This must be why this particular IIC+ sounded better and more punchy than the "twin" I sold.

 

[Boogiebabies]

Right. The part number is 105 blah, blah and the EIA-606 is Shumacher the maker and the 4XX is the year and week of production. The 4 would be 1984 and the next two digits are the week in 1984 it was made. Same for the OT. It was Shumacher, SC 152019B (Simul) EIA606-3-4XX. I have never owned a 60/100 so I do not know the OT number.

 

[MesieBooga]

It looks like the tranny on my new baby is a 100. Does that sound right? It's a Simul-Class and sounds awesome. I still am just tweaking and comparing with my other.
Is it possible to rip the 105 out of the one and pop it in this one?