Sound City 100 Mk3 - Master volume

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Re: Sound City 100 Mk3 - Master volume

Postby Papa Dog on Thu Sep 01, 2016 6:00 pm

Dean Jr. wrote:IT is interesting to compare the schematics for the LB-100 and the 120, which has reverb. I do not see that pin 7 is part of the reverb circuit in the 120. Pin 2 is. I would suggest tracing things out there before making a move. YMMV.

http://schematicheaven.net/bargainbin/s ... y_100b.pdf

http://schematicheaven.net/bargainbin/s ... 20_miv.pdf

Dude, try The Sound City site schematics
I cannot vouch for the schematics on other sites, and I try to stay up on the ones on our site.
From what I have been told many of my schematics have been ripped to other sites.
The Sound City Site is not a product of the new Sound City amp builders.
Nor are we, by any means, ome "official" site, but have been around for a fairly long time and our information is generally reliable.

The schematic for the Mk4 120 and the Mk3 100 are totally different animals.
However, on the 120 the reverb lines do not connect to any pin3 on either v3 or v4.
It can be daunting, but I just looked at a couple of schematics to confirm.
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Re: Sound City 100 Mk3 - Master volume

Postby Papa Dog on Thu Sep 01, 2016 6:18 pm

The Hiwatts wrote:Thank you Papa Dog!! Appreciate you taking the time to help!!!

We have established remove 1M Resistor
Wiper of 1M pot onto Pin 7

I need to know where other side of pot is wired

and then Ground the pot on the 3rd leg of Pot!!!


looking at the pot from the back (shaft pointing away from you)
tabs on the top
the wire from the reverb jack (socket) will go on the left.
wiper (middle) to pin 7
tab on the right will go where you are showing the "ground" symbol on the marked up pic.
that should effectively replace the 1 meg resistor, if that pot is turned fully clockwise.
I hope that works for ya.
I will not be liable for any damages which might result from taking my advice in these matters.
proceed at your own risk.
There Ain't No Such Thing As A Free Lunch.

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"To talk of many things:
Of shoes--and ships--and sealing-wax--
Of cabbages--and kings--"
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Re: Sound City 100 Mk3 - Master volume

Postby Dean Jr. on Thu Sep 01, 2016 7:17 pm

MY apologies for the intrusion. I stand corrected.
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Re: Sound City 100 Mk3 - Master volume

Postby Papa Dog on Thu Sep 01, 2016 7:22 pm

Dean Jr. wrote:MY apologies for the intrusion. I stand corrected.

it was not an intrusion.
and it is ok.
I do not know much, but if I can help out I try to do so.
and I have spent hundreds of hours studying these schematics.
I still miss things.
There Ain't No Such Thing As A Free Lunch.

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"To talk of many things:
Of shoes--and ships--and sealing-wax--
Of cabbages--and kings--"
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Re: Sound City 100 Mk3 - Master volume

Postby The Hiwatts on Thu Sep 01, 2016 9:02 pm

Thing is I need the amp to gig with so I haven't got time to dwell on this!!


I just need to know where the Master volume pot will go so I can get the amp back together

So any info is appreciated - thank you

Justin
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Re: Sound City 100 Mk3 - Master volume

Postby Papa Dog on Thu Sep 01, 2016 9:33 pm

The Hiwatts wrote:Thing is I need the amp to gig with so I haven't got time to dwell on this!!


I just need to know where the Master volume pot will go so I can get the amp back together

So any info is appreciated - thank you

Justin


looking at the pot from the back (shaft pointing away from you)
tabs on the top
the wire from the reverb jack (socket) will go on the left.
wiper (middle) to pin 7
tab on the right will go where you are showing the "ground" symbol on the marked up pic.
that should effectively replace the 1 meg resistor, if that pot is turned fully clockwise.
I hope that works for ya.
I will not be liable for any damages which might result from taking my advice in these matters.
proceed at your own risk.
There Ain't No Such Thing As A Free Lunch.

"The time has come," the Walrus said,
"To talk of many things:
Of shoes--and ships--and sealing-wax--
Of cabbages--and kings--"
Papa Dog
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Posts: 1337
Joined: Mon Mar 15, 2010 6:48 pm
Location: Narly Ampwerks

Re: Sound City 100 Mk3 - Master volume

Postby The Hiwatts on Thu Sep 01, 2016 10:07 pm

Ok

1. remove 1M ohm resistor?
2. Disconnect pin7 on V3
3. Connect 1M potentiometer wiper to Pin 7

This I need the answer too!!! 4. Connect other side of pot where does this go? Connect to which reverb wire? There are 2 reverb wires

5. Connect pot to ground

Thank you
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Re: Sound City 100 Mk3 - Master volume

Postby The Hiwatts on Thu Sep 01, 2016 10:23 pm

Like this??

X means remove

Is this what you mean papa??

Image
Last edited by The Hiwatts on Thu Sep 01, 2016 10:28 pm, edited 1 time in total.
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Re: Sound City 100 Mk3 - Master volume

Postby Papa Dog on Thu Sep 01, 2016 10:24 pm

The Hiwatts wrote:Ok

1. remove 1M ohm resistor?
2. Disconnect pin7 on V3
3. Connect 1M potentiometer wiper to Pin 7

This I need the answer too!!! 4. Connect other side of pot where does this go? Connect to which reverb wire? There are 2 reverb wires

5. Connect pot to ground

Thank you

the wire that connects to the junction of the 1 meg resistor and the wire that runs from it to pin 7
There Ain't No Such Thing As A Free Lunch.

"The time has come," the Walrus said,
"To talk of many things:
Of shoes--and ships--and sealing-wax--
Of cabbages--and kings--"
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Re: Sound City 100 Mk3 - Master volume

Postby Papa Dog on Thu Sep 01, 2016 10:27 pm

wow...you posted while I was typing.
did what I said make sense?
There Ain't No Such Thing As A Free Lunch.

"The time has come," the Walrus said,
"To talk of many things:
Of shoes--and ships--and sealing-wax--
Of cabbages--and kings--"
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Re: Sound City 100 Mk3 - Master volume

Postby The Hiwatts on Thu Sep 01, 2016 10:30 pm

Just posted a picture Papa - think this is what you mean

Image
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Re: Sound City 100 Mk3 - Master volume

Postby The Hiwatts on Thu Sep 01, 2016 10:32 pm

Leaving the green reverb wires attached :cheers:
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Re: Sound City 100 Mk3 - Master volume

Postby Papa Dog on Thu Sep 01, 2016 10:46 pm

that isn;t exactly how I would do it, but yeah, that would work
There Ain't No Such Thing As A Free Lunch.

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Re: Sound City 100 Mk3 - Master volume

Postby The Hiwatts on Thu Sep 01, 2016 10:57 pm

Thank you Papa,

Just out of curiosity what way would you do it?

Thanks :not_worthy:
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Re: Sound City 100 Mk3 - Master volume

Postby Papa Dog on Thu Sep 01, 2016 11:06 pm

The Hiwatts wrote:Thank you Papa,

Just out of curiosity what way would you do it?

Thanks :not_worthy:

the way you have it lined out will work fine.
in fact it will likely work better than what I was thinking of.
There Ain't No Such Thing As A Free Lunch.

"The time has come," the Walrus said,
"To talk of many things:
Of shoes--and ships--and sealing-wax--
Of cabbages--and kings--"
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