[sdiy] advice please -- aging chips and caps

[Czech Martin]

I've read that some very old 4000's designs were not continued,
when the enhanced (buffered, dimensioned, etc.) 4000 series came out.
A couple of the very first 4000 designs have problems, like latch up,
or unsymmetrical (weak) drive etc. Some of the 4000 numbers
do not appear any more because of this.
I guess this was 30 years ago.

m.c.

-----Original Message-----
From: Tim Ressel [mailto:madhun2001 at yahoo.com]
Sent: Samstag, 9. August 2003 19:25
To: john mahoney; synth-diy at dropmix.xs4all.nl
Subject: Re: [sdiy] advice please -- aging chips and caps


John,

I'd replace all the electrolytics. 

Replace the 4000's??? I've never heard of that. The
only thing I can think of is if the ICs were stressed
by ESD hits. I'd leave them until something fails.

--tr


--- john mahoney <jmahoney at gate.net> wrote:
> Having read Scott Rider's article "Things to Know
> When Repairing Vintage
> Synthesizers" 
> (http://www.oldcrows.net/~oldcrow/synth/tips.txt), I
> am now a
> little concerned about my Korg Mono/Poly, which has
> reached adulthood
> (assuming that synth years = human years).
> Basically, Scott says to replace
> all old 4000 series CMOS chips as well as certain
> types of caps.
> 
> My questions for you folks:
> (1) Many of you have years of experience. Have you
> seen signs of CMOS
> senility or caps with Alzheimer's?
> (2) Should I replace the "at risk" components now,
> even though the synth is
> working perfectly? Or, wait and see, but *if*
> something goes bad then
> replace everything as he suggests. I'd like to add a
> few extra
> inputs/outputs/patchpoints to the Korg, so I have
> reason to do surgery.
> (See? This is a DIY question!)
> (3) Given the parts list below, do you see any parts
> that I should try to
> obtain now, just in case? For example, if the SSM
> chips are available,
> should I stock some? (I don't even know if the SSM
> chips are available
> anymore!)
> (4) Oh, yeah: What's the difference between the
> HD14000 series and the
> normal 4000 series, if any?
> 
> ICs in the Mono/Poly (thanks to the excellent Zen
> Mono/Poly website):
>     SSM2044 4-pole voltage controlled filter
>     SSM2033 Voltage controlled oscillator (Qty: 4)
>     MM5837 Digital noise source
>     Intel 8049 8mhz CPU
>     HD14007UBP Dual complementary pair + inverter
>     HD14013BP Dual D flip-flop
>     HD14042BP Quad latch
>     HD14066BP Analog CMOS switch
>     HD14069UBP Hex inverter
>     HD14071 Quad "or" gate
>     HD14174BP Hex flip-flop
>     MC14504 Hex level shifter
>     NJM4556 Dual high-current op-amp
>     NJM4558DV Dual op-amp
>     M5230L Variable output voltage regulator
>     TL072 Dual J-FET operational amplifier
> 
> Thanks to everyone for any and all insight you can
> offer.
> --
> john
> 


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