Racking Spectra Sonics 101

[frob]

just a sugestion, but this should be in the meta.

 

[frob]

has anyone tryed the make before break switch with a cap yet. and does it solve the problem of the pops?

 

[cannikin]

Joe mentioned a cap before the switch - page 6 of the thread.

I got a make before you break switch in addition to the cap fixed the "pop" issue for me.

 

[frob]

good it does work then. also did you just use the four possition switch or did you figure what the values would be for more stages? i just got two and so i am kind of excited.

 

[hejsan]

Hi, I'm starting racking up of a pair of channels.

On the 101 cards, are there only 2 caps that need to be replaced, or are some of the small capacitors also electrolyte?

What capacitors have you guys used?

Thanks,
hejsan

 

[3nity]

i'm trying to gather all the info i need to finally rack mines...but i have a question if i usae a rotary switch for steped gain is there anyway i should be able to install an output trimmer?? or should i use a 50K rev Log instead?
thanks.

 

[Animatic]

Used to have a studio rack FILLED with these things.
3 dozen or more SS 101's, and sad to say, without consulting me,
the whole rack went to a landfill decades ago.
I was sad then and sadder now...

It was out of a rebuilt Flickenger console.
Or maybe the SS were the rebuild new parts.

As to the feedback gain question a simple 25k linear pot
would easily replace the resister choices I think.
Personally I would use a 50K.
put it in and run it with a scope
and mark your DB points on a scale.
Nothing really says it needs to be fixed.

 

[3nity]

How old are those boards? Do you think they could something wrong? with them given the age on them?

Like resistors or non electro caps ( i already replaced the electros)

Thanks by the way.

 

[Animatic]

Likely pre 1970...
The're cool,
but the same thing is smaller than your fingernail these days.
And likely cleaner. But they are still interesting
and should have a defined sound.
Only listening will decide if this is a good sound for you.
IMHO.

I find it interesting that so many are looking to the tech of the past,
to create the sounds for tomorrow. I still love tubes.

 

[3nity]

The reason why i asked that...its cuz theres a 10R just after the 24 volts pad...burning every time i powered the cards!

What can be wrong?

 

[raysolinski]

Bad transistor? these guys are pretty simple...do you have the schematic? I know I have one around here somewhere.....

Ray

 

[Animatic]

I'd say try a much lower voltage like 5v and see what's happening around
the circuit WITHOUT smoking it. Gradually bring it up and check voltages/current etc.

 

[3nity]

I'm gonna try that...(lower voltage)...
I'm pretty sure its a bad transistor but hey where can i find this oldies?

I'm thinking of lift some parts, where power flow trough and see if the 10R still burns untill i identify the bad part.

Thanks guys.

 

[Animatic]

Post a parts list.
I am sure there are close approximations still available.

If I still have a schematic for these,
it is 10 boxes down, in a storage box 12,000 miles away.

But they shouldn't be hard to draw out.
Might be a useful thing to do anyway.

 

[3nity]

heres the schematic:
http://www.technicalaudio.com/a2z/S/SpectraSonics/SpectraSonics_101sch1.pdf

 

[3nity]

before going on with the trouble shooting i wanna make sure that wiring is right...

heres a pic of how i did it...

I;m sorry for not getting it guys...

 

[Animatic]

Man! is THAT nostalgic.

Talon has the 2N4248, 2N3566, transistors in stock

http://www.talonix.com/shop/item.aspx?itemid=3292

TheCS1711 is discontinued but here's the data sheet

http://www.datasheetarchive.com/pdf-datasheets/DataBooks/52-68.html


One stupid question.
Were you using the feedback gain pot turned low?

At this age caps are the 1st choice for things gone bad.
Resisters might change value a bit, but not quite die off yet.

 

[clintrubber]

IIRC the circuit in the patent featured a few Ge-transistor types, yet most/all implementations here use all-Si. Anybody knows more ? Maybe most of the real-world boards had Si perhaps ?
Hah, maybe they had already switched to all-Si by the time the patent was granted (1968) :wink:

From the patent I get the impression that at the time of writing (1965) the choice for Ge or Si was partly influenced by the cost of the one over the other, who knows that might have been the main reason... ?

http://www.pat2pdf.org/patents/pat3376515.pdf

 

[3nity]

I used a 10K resistor as a fixed gain.

 

[3nity]

bump?