[sdiy] strange strange SAJ110 divider issue? ARP Solina CONCLUSION..?

[Bob Weigel]

Ok here's the deal.  First I lowered voltage to -8.5V with no problem.  
Going much lower would cause others not to work right it appears.  But I 
managed out of 20 chips or whatever to BARELY find 6 to fill in for the 
bad chips.   Or..chips that wouldn't work in those locations anyway.  
One of the 'bad' chips even worked fine in another location.

Anyway as usual I just hit defeat after defeat at the front end of my 
trials of chips and was convinced it had to be something in the power 
supply or something that I just wasn't seeing.  Bringing the supply down 
some DID help some of the chips to work that otherwise would not 
though.  But it was NOT out of spec at all. ..had .7V below max I think 
when we started on it or more.

THE TUNING THOUGH is the current dilemma.  It's sharp. The coil appears 
good.  It tunes down down down w/tuning pot in center on panel.  Then 
finally starts tuning up as the ferrite passes the center.  It gets 
within half a step of being in tune.

The transistor in the oscillator was a NTE128 but the replacement for 
the original reads an NTE199.  Of course..mine has different 
TOS...someone or the factory cut traces and hard wired an M50240 onto 
this thing.  And it uses SAJ110 instead of the SAA1004 int he diagram 
which probably like I say explains why the diagram says -12V for it's 
supply.

Anyway does anyone know if that was a factory do on the TOS?  And I've 
measured resistances and they area ll in spec that relate to the tuning 
save..the pot itself I guess.  I wonder if a cap has drifted then since 
the transistor didn't help.  I also notice though that there is a lot of 
voltage dependency on these oscillators.  Back in the 70's voltages were 
a little lower on average I think.  Can't recall when they changed but 
it doesn't seem to make much difference from 122V or whatever we have 
here to 117V which they had some places I think back then. -Bob

Bob Weigel wrote:

> Just an adendum to this.  I see that on the variac I can cause the 
> chattering dividers to work/not work by lowering voltage to 110 or 
> 100v zone.  What the heck is going on here?  They *are* supposed to 
> work...these chips..at 10 or 11 v...right? How come they all fail on 
> the same divider?  What a nightmare.  As I was trying to get a couple 
> keys to work that had bad contact busbar alignment I managed to twak 
> something and knocked out the op amp, transistor and burned the 47 ohm 
> resistor.  hehe..so now I have to get that stuff in there and try to 
> even get it making sounds again.
>
> Bob Weigel wrote:
>
>> I tested a whole bunch of SAJ110's in the crumar organ we just did.  
>> They work perfectly in there.  So ...I finally pulled the old solina 
>> string ensemble back out.  Put a tested chip in a socket I'd 
>> installed that was on a problem chip location (number 4).  The...same 
>> divider on pin 11 is still garbled.
>> I can unhook the whole trace!  Still..the..same garbled sound.  I 
>> have -10V instead of the -12V the diagram says should be there. 
>> However the DOCS on the chip say absolute max rating is -11V there!  
>> It's smooth.  No ripple or fuzz visible on the scope.
>>
>> All the other outputs seem to be working fine on that chip.  Though 
>> other dividers are also having problems.  Very puzzling.  Has anyone 
>> ever seen a phenomena like this? I mean it's clearly dividers that 
>> work in another machine so something about the power supply would 
>> seem the logical first guess but is it possible there's something I'm 
>> not seeing just causing one line to do that on every chip I put in 
>> there?? Cap esr's seem fine.  I even paralelled another cap just to 
>> be sure...-Bob
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