'67 100 watt board layout

Post by **VelvetGeorge** » Thu Aug 11, 2005 4:53 pm

With all of the interest in earlier 100 watts lately, I thought a diagram might help. This is the circuit and layout in my '67.

George

Post by **VelvetGeorge** » Thu Aug 11, 2005 4:55 pm

Here's a smaller copy of the jpg.

George

gnugear · Post by **gnugear** » Thu Aug 11, 2005 9:35 pm

Is that 68k in parallel with the 10uf normal?

7string · Post by **7string** » Fri Aug 12, 2005 12:32 am

Thank You for the layout George.
Thats gonna help me bigtime.

Pat

bmf5150 · Post by **bmf5150** » Fri Aug 12, 2005 12:33 am

thats for biasing correct?
stan

5150loveeddie · Post by **5150loveeddie** » Fri Aug 12, 2005 12:35 am

I though the mix resistors were 270K in 67?

Post by **VelvetGeorge** » Fri Aug 12, 2005 12:40 am

The 68k is for biasing.

My late '67 has 470k mix resistors, but they should be 270k earlier in '67.

George

mightymike · Post by **mightymike** » Fri Aug 12, 2005 2:51 pm

Thanks George.

Ralle 500 · Post by **Ralle 500** » Fri Aug 12, 2005 6:14 pm

5150loveeddie wrote:I though the mix resistors were 270K in 67?

Those were in the JTM's
Ralle

Guest · Post by **Guest** » Fri Aug 12, 2005 8:45 pm

George,

You sure you don't have a 10k/1watt resistor in series with that 8k2/1watt resistor on the H.T. line? I know the earlier '67 amps had just the one 8k2 resistor, but I thought your amp was a slighly later '67 amp.

5150loveeddie · Post by **5150loveeddie** » Sat Aug 13, 2005 1:20 am

Ralle 500 wrote:
5150loveeddie wrote:I though the mix resistors were 270K in 67?
Those were in the JTM's
Ralle

Yeah?

Billy Batz · Post by **Billy Batz** » Sat Aug 13, 2005 3:55 pm

I read an article somewhere specifically about those mixer resistors. It said you can date marshalls by the presence of 470k mixers because they started in early 67. If the amp has 270k that doesnt mean its pre 67 because they still showed up in amps after the 470k's but the 470k's started being used at a specific ttime.

Flames1950 · Post by **Flames1950** » Sat Aug 13, 2005 3:58 pm

I remember that too but I don't remember where I read it.

5150loveeddie · Post by **5150loveeddie** » Sat Aug 13, 2005 4:20 pm

What would be the differences between the 270ks and the 470ks? Anyone knows, more gain with the 270Ks mix resistors??

Billy Batz · Post by **Billy Batz** » Sat Aug 13, 2005 4:24 pm

no. More high end less gain. 270k has less resistance between the mixer and the unused/opposite channels volume pot ground. In other words the volume controls are more interactive with each other.