1972 Marshall 1987 pics - How does this look?

Mikeyboyeee

Well-known member
1972 Marshall 1987.

Supposedly mostly to all original. Irons too.

Miantened by Trace at Voodoo.

Thoughts? If good I'm pulling trigger.

Birth year holy grail amp for me.

Looks good to my untrained eye.
 

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glpg80

Well-known member
Tons of Iskra resistors, lemco dog bone 47pF capacitor off the phase inverter for stability and another dog bone 470pF (they’re rare af and getting hard to find), sprague orange drops all around, no Phier resistors, and a few carbon composition components for bias.

The original phase inverter coupling caps have been replaced with orange drops which is murderous given the vintage of the other components - the originals must have been leaky. Sozo would have been a better modern replacement.

A few of the bias resistors have been changed along with the bias caps. The original screen resistors are gone for metal films.

The bias diode should be replaced with a modern 1N4007, and the caps on the right to the bridge rectifier disconnected or at least verified not to be electrically leaky.

It does look freshly recapped B+/screen wise.

It’s mostly original, but would need to see a tech to get a few poorly chosen components changed out for proper vintage sound and also preventative maintenance.
 

harddriver

Well-known member
I'll just recap what glpg80 already pointed out. The original .68uf Mustard has been replaced with some type of polypropylene cap from the looks of it. The 100K plate resistors on V1A V1B have been replaced with modern CF resistors. In 1972 the V1B coupling cap usually was a strange long pencil like metal electrolytic at least it was on my 72 50 watter but the NOS Mustard there is an upgrade. The V1A 330uf cap looks like it might still be an original Erie it might be fine or ready to leak electrolyte just check it out mine was bad so I changed it out for new.

The Bias filter caps are newer that's good, the PI couple caps are some type or orange drop could be either polyester or polypropylene 715 and they look like .047uf which is actually good for a 50 watter on the low end. I installed .1uf in mine and it's fine.

The Yellow rectangular plastic looking chicklet caps were common in the 1972 year, mine has them as well.

The green electolytics of the far right of the board a just there to make sure there is no loud click when coming off of standy, if they are original you might want to upgrade them with two .22uf 1000VDC polyester or polpropylene caps. If the amps been played regularly then they might be fine.

OH... I forgot the mention the bright channel ceramic caps looks like a 500pf cap judging from the diameter of it. It came stock with a 5000pf Lemco ceramic cap which I feel really give the Marshall SL it's crunch and grind but everyone'e ears are different. Good luck with the purchase.

The amp looks nice and clean with up to date maintenence, it probably sounds great the way it is. :2thumbsup:
 
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Exo-metal

Well-known member
All we need from the OP is that it's a done deal now, well a few more pics wouldn't hurt lol
 

glpg80

Well-known member
I'll just recap what glpg80 already pointed out. The original .68uf Mustard has been replaced with some type of polypropylene cap from the looks of it. The 100K plate resistors on V1A V1B have been replaced with modern CF resistors. In 1972 the V1B coupling cap usually was a strange long pencil like metal electrolytic at least it was on my 72 50 watter but the NOS Mustard there is an upgrade. The V1A 330uf cap looks like it might still be an original Erie it might be fine or ready to leak electrolyte just check it out mine was bad so I changed it out for new.

The Bias filter caps are newer that's good, the PI couple caps are some type or orange drop could be either polyester or polypropylene 715 and they look like .047uf which is actually good for a 50 watter on the low end. I installed .1uf in mine and it's fine.

The Yellow rectangular plastic looking chicklet caps were common in the 1972 year, mine has them as well.

The green electolytics of the far right of the board a just there to make sure there is no loud click when coming off of standy, if they are original you might want to upgrade them with two .22uf 1000VDC polyester or polpropylene caps. If the amps been played regularly then they might be fine.

The amp looks nice a clean with up to date maintenence, it probably sounds great the way it is. :2thumbsup:
I missed those carbon film resistors on the plates of V1A and V1B. Those will affect the sound of the amp a lot even if they’re the correct value. I assume the originals had drifted too much.

I agree there’s a polypropylene cap on the left that isn’t original but there’s also a carbon composition resistor under it that isn’t original either.

To the OP those yellow chicklet caps are also rare AF and shouldn’t be changed out unless needed, most of the time they are fine.
 
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