1973 Super Lead problem

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Lefty Lou
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Re: 1973 Super Lead problem

Post by Lefty Lou » Mon Nov 25, 2013 4:58 am

Aren't the 73' Super Lead heads the last of the turret board era? I have a 74' Super Lead converted to a 68' Super Lead spec, and 74' was the year that Marshall switched to the etched circuit board.

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mightymike
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Re: 1973 Super Lead problem

Post by mightymike » Mon Nov 25, 2013 6:26 am

73 was the transition year. There are some 73's that are PTP, others that are PCB..
Sometimes old parts are used on newer models. For example: I once saw a 72 with laydown pt and Self lead ot..

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Re: 1973 Super Lead problem

Post by 54strat » Mon Nov 25, 2013 9:32 am

"Officially" Marshall transitioned to circuit boards in August 1973, with the exception being Major's which were still part of the range through 74 with turret boards.
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Re: 1973 Super Lead problem

Post by Dries » Sun Feb 02, 2014 9:19 am

Amp's doing really well after a while now. Sounds great ! But the PT gets fairly hot after playing a hour or so. Much hotter than my 78 super lead or my '79 2203. Bias is the same...

http://oi41.tinypic.com/k9h5s.jpg

http://oi40.tinypic.com/33z7ibs.jpg

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Re: 1973 Super Lead problem

Post by demonufo » Sun Feb 02, 2014 10:15 am

Also the Super PA (and 50W Super PA's) were still turretboard build often well into 1975.
So I like purple, okay!!!!!!

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Re: 1973 Super Lead problem

Post by demonufo » Sun Feb 02, 2014 10:17 am

Dries wrote:Amp's doing really well after a while now. Sounds great ! But the PT gets fairly hot after playing a hour or so. Much hotter than my 78 super lead or my '79 2203. Bias is the same...

http://oi41.tinypic.com/k9h5s.jpg

http://oi40.tinypic.com/33z7ibs.jpg
Too hot to touch? Or just hot?
So I like purple, okay!!!!!!

83.7% of all statistics are made up on the spot!

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Re: 1973 Super Lead problem

Post by Dries » Sun Feb 02, 2014 3:21 pm

After a couple hours of band rehearsal, you can't hold it longer than 5 secs.

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Re: 1973 Super Lead problem

Post by demonufo » Sun Feb 02, 2014 4:24 pm

Hmmm, that's not ideal. I'd be tempted to monitor what the current draw is.
So I like purple, okay!!!!!!

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Re: 1973 Super Lead problem

Post by Dries » Sun Feb 02, 2014 5:42 pm

Damn, will measure it tomorrow. The filtercaps are new ones, with new bleed resistors. Bias caps too, and all tubes ( mullard RI power tubes ). I think it comes comes from the heaters though, because it gets hot too when it's played with the ppimv turned down, no much difference on full blast with a attenuator.

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Re: 1973 Super Lead problem

Post by demonufo » Mon Feb 03, 2014 10:53 am

What voltage is your heater string sitting at?
So I like purple, okay!!!!!!

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Re: 1973 Super Lead problem

Post by Dries » Mon Feb 03, 2014 12:38 pm

Last time I measured it , it was around 6.2V on the 240V tap (european here). So that's good ant doesn't point on a short in the circuit..

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Re: 1973 Super Lead problem

Post by Dries » Wed Feb 05, 2014 1:57 pm

Measured some things today. Heaters are 6v, B+ 440v. The mains current in standby is 250mA and 660mA on.
That looks good, I remember the heaters were a bit too high with the 220v tap, and it got even hotter.

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Re: 1973 Super Lead problem

Post by neikeel » Wed Feb 05, 2014 3:33 pm

Dries wrote:Measured some things today. Heaters are 6v, B+ 440v. The mains current in standby is 250mA and 660mA on.
That looks good, I remember the heaters were a bit too high with the 220v tap, and it got even hotter.
I am intrgued, do you have a clip on ammeter or did you interrupt the HT line?
Neil

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Re: 1973 Super Lead problem

Post by Dries » Wed Feb 05, 2014 4:26 pm

neikeel wrote:
Dries wrote:Measured some things today. Heaters are 6v, B+ 440v. The mains current in standby is 250mA and 660mA on.
That looks good, I remember the heaters were a bit too high with the 220v tap, and it got even hotter.
I am intrgued, do you have a clip on ammeter or did you interrupt the HT line?
I took out the fuse of the mains. Did no HT measurements.

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Re: 1973 Super Lead problem

Post by TheVibratory » Fri Feb 08, 2019 9:00 pm

Hi Dries, I have your old amp now. Instead of the 47nF I put in a 22nF mustard cap and restored bright cap to 5K. While looking for info I find myself looking at pictures of my OWN amp! lol. Did you own the amp a long time? Thanks for any info you may have.

Cheers,
Pat

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