Cgs synth

What manufacturer were the chips?

Ken

>One thing of interest, I bought the LM3900s and they say LM3900 on the

chips but the package they came in said LM339. But I just figured they used
containers they had on hand. I'll pick up some other LM3900s and give it a
shot and I'll do a little research on PN4250s I used.

>
>Thanks, Sean
>
>--- In cgs_synth@yahoogroups.com, sasami@... wrote:
>>
>> Looked it all over. Compared it with mine. Can't see anything obviously

amiss.

>> My thoughts:
>> 1) check that the PN4250 are in the correct way. I can see you have them
>> according to the overlay, but perhaps the transistors are reversed int he
>> package. (all the same, I don't see how this would have any effect on your
>> problem.
>> 2) I guess it is possible that it is the LM3900 chips themselves that are no
>> good. If someone has relabeled CA3401 and sold them as LM3900, you would
>> expect trouble, as the CA3401 is only good to 15V, unlike the LM3900 that
>> can go up to 30V. They aren't NTE or something like that, are they?
>> 3)I can't read the 1n caps, so I can't say they are the right part.
>> (0.001uF, 1n, 1000pF).
>>
>> Ken
>>
>> >Maybe, slightly better pic of back...
>> >https://sphotos-a.xx.fbcdn.net/hphotos-ash4/317422_10151631973766807_174487
>> 4777_n.jpg
>> >
>> >
>> >--- In cgs_synth@yahoogroups.com, "Sean" <solidratestudios@> wrote:
>> >>
>> >> Hopefully this works? btw, I also had to use two larger 2.2M resistors
>> in the build. One is pulled in the pic (for troubleshooting)
>> >>
>> >> Thanks -Sean
>> >>
>> >>
>> http://groups.yahoo.com/group/cgs_synth/photos/album/1219515935/pic/list?mod
>> e=tn&order=ordinal&start=1&dir=asc
>> >>
>> >> --- In cgs_synth@yahoogroups.com, sasami@ wrote:
>> >> >
>> >> > Take some high res photos - IN FOCUS - of both sides so we can look

at it.

>> >> > Ken
>> >> > >Yup, only connected to 1n cap and not using pad T. No shorting

when chip

>> >> > is out. Burn mark on pin 9 appeared from first LM3900 going poof. I've
>> >> > checked solder joints and traces many times over. I can't help but

think

>> >> > it's something else.. maybe a weird transistor or cap or mislabel

resistor

>> >> > here? btw, same behavior on both LM3900s... extreme heat. Ouch.
>> >> > >
>> >> > >--- In cgs_synth@yahoogroups.com, "cg_synth" <sasami@> wrote:
>> >> > >>
>> >> > >> pin 9 should be connected only to a 1n capacitor. Pad T is not used.
>> >> > There should be no current flow through it. Find out what pin 9 of the
>> >> > socket is short circuited to.
>> >> > >>
>> >> > >> --- In cgs_synth@yahoogroups.com, "Sean" <solidratestudios@> wrote:
>> >> > >> >
>> >> > >> > Been testing my voltages (with blown LM3900s removed) btw, pin

9 is

>> >> > getting burns on IC socket.
>> >> > >> >
>> >> > >> > 1) +7.50
>> >> > >> > 2) 0
>> >> > >> > 3) -7.41
>> >> > >> > 4) -14.01
>> >> > >> > 5) +3.59
>> >> > >> > 6) -0.06
>> >> > >> > 7) -14.87
>> >> > >> > 8) -0.01
>> >> > >> > 9) 0
>> >> > >> > 10) -0.10
>> >> > >> > 11) -0.06
>> >> > >> > 12) +8.06
>> >> > >> > 13) -3.34 (stepped), +5.82 (smooth)
>> >> > >> > 14) +14.86
>> >> > >> >
>> >> > >> > Strange voltages I'm getting.
>> >> > >> > -Sean
>> >> > >> >
>> >> > >> > --- In cgs_synth@yahoogroups.com, "adematteo" <adematteo@> wrote:
>> >> > >> > >
>> >> > >> > > Sorry, that came out as a big garbled mess.
>> >> > >> > >
>> >> > >> > >
>> >> > >> > > 1) +13.54
>> >> > >> > > 2) 0
>> >> > >> > > 3) -9.23
>> >> > >> > > 4) -14.35
>> >> > >> > > 5) +11.13
>> >> > >> > > 6) -0.113
>> >> > >> > > 7) -15
>> >> > >> > > 8) -.010
>> >> > >> > > 9) 0
>> >> > >> > > 10) -.112
>> >> > >> > > 11) -.115
>> >> > >> > > 12) +13
>> >> > >> > > 13) -4.92 (Stepped U5) +12.64 (Smoothed U2)
>> >> > >> > > 14) +15
>> >> > >> > >
>> >> > >> > > --- In cgs_synth@yahoogroups.com, "adematteo" <adematteo@> wrote:
>> >> > >> > > >
>> >> > >> > > > So all the voltages read the same on both chips except for

pin 13

>> >> > which i make a note of :
>> >> > >> > > >
>> >> > >> > > > 1) +13.54 14) +15
>> >> > >> > > > 2) 0 13) -4.92 (U5 Stepped) +12.64 (U2 Smooth)
>> >> > >> > > > 3) -9.23 12) +13
>> >> > >> > > > 4) -14.35 11) -.115
>> >> > >> > > > 5) +11.13 10) -.112
>> >> > >> > > > 6) -0.113 9) 0
>> >> > >> > > > 7) -15 8)-.010
>> >> > >> > > >
>> >> > >> > > > --- In cgs_synth@yahoogroups.com, sasami@ wrote:
>> >> > >> > > > >
>> >> > >> > > > > Seriously, chip frying is indication of serious power
>> routing issues.
>> >> > >> > > > >
>> >> > >> > > > > With the chips OUT, read the voltages on each pin of the

socket,

>> >> > then list
>> >> > >> > > > > them here.
>> >> > >> > > > >
>> >> > >> > > > > Ken
>> >> > >> > > > >
>> >> > >> > > > > >Thanks again Ken, and Rich for all the helpful suggestions.
>> >> > >> > > > > >I've triple checked component values at this point,replaced
>> >> > >> > > > > trannies,ic's,gone over continuity testing and visually
>> inspected
>> >> > the board
>> >> > >> > > > > under a magnifying lens with no luck.
>> >> > >> > > > > >
>> >> > >> > > > > >There has to be a short or something that i am just not

seeing

>> >> > because i'm
>> >> > >> > > > > getting inconsistent results when i plug it in every time

i make

>> >> > a change.I
>> >> > >> > > > > fried another lm3900 in the smooth section only this time it
>> took
>> >> > a few
>> >> > >> > > > > minutes.I've been able to get a slewed/smoothed signal to
>> pass but no
>> >> > >> > > > > control over the hold or rate, i've gotten a steady tone from
>> >> > plugging the
>> >> > >> > > > > cycle into the in of the smooth section but again no

control to

>> >> > change the
>> >> > >> > > > > pitch and now i'm back to were i started with no effect and
>> a strong
>> >> > >> > > > > negative voltage on the outputs ?
>> >> > >> > > > > >
>> >> > >> > > > > >I'm gonna take a little break but at this point i'm

seriously

>> >> > considering a
>> >> > >> > > > > do over.
>> >> > >> > > > > >
>> >> > >> > > > > >Thanks again guys i really appreciate you taking the time to
>> >> > offer your
>> >> > >> > > > > time and experience !
>> >> > >> > > > > >
>> >> > >> > > > > >--- In cgs_synth@yahoogroups.com, sasami@ wrote:
>> >> > >> > > > > >>
>> >> > >> > > > > >> Been thinkng about this - The problem may also be

caused by

>> >> > putting a
>> >> > >> > > > > >> voltage on the input pins, which are designed for
>> current, not
>> >> > voltage.
>> >> > >> > > > > >> Check nothing is shorted to them. Check your resistor

values.

>> >> > Maye sure you
>> >> > >> > > > > >> haven't installed 15 ohms instead of 1M.
>> >> > >> > > > > >>
>> >> > >> > > > > >> Ken
>> >> > >> > > > > >>
>> >> > >> > > > > >> >Will do.Thanks guys!
>> >> > >> > > > > >> >I'll report back when i get this working.
>> >> > >> > > > > >> >
>> >> > >> > > > > >> >--- In cgs_synth@yahoogroups.com, Richarius Molindarius
>> >> > >> > > > > >> <richmolindarius@> wrote:
>> >> > >> > > > > >> >>
>> >> > >> > > > > >> >> Use a well lit magnified lamp. Especially for that

board.

>> >> > Hard to find
>> >> > >> > > > > >> >> small trace breaks and bad solder joints.
>> >> > >> > > > > >> >>
>> >> > >> > > > > >> >>
>> >> > >> > > > > >> >> [Non-text portions of this message have been removed]
>> >> > >> > > > > >> >>
>> >> > >> > > > > >> >
>> >> > >> > > > > >> >
>> >> > >> > > > > >> >
>> >> > >> > > > > >> >
>> >> > >> > > > > >> >------------------------------------
>> >> > >> > > > > >> >
>> >> > >> > > > > >> >The CGS Modular Synth home page:

http://www.cgs.synth.net/

>> >> > >> > > > > >> >Yahoo! Groups Links
>> >> > >> > > > > >> >
>> >> > >> > > > > >> >
>> >> > >> > > > > >> >
>> >> > >> > > > > >> >
>> >> > >> > > > > >>
>> >> > _______________________________________________________________________
>> >> > >> > > > > >> Ken Stone sasami@ otherunicorn@
>> >> > >> > > > > >> Modular Synth PCBs for sale <http://www.cgs.synth.net/>
>> >> > >> > > > > >> Australian Miniature Horses & Ponies
>> >> > <http://www.blaze.net.au/~sasami/>
>> >> > >> > > > > >>
>> >> > >> > > > > >
>> >> > >> > > > > >
>> >> > >> > > > > >
>> >> > >> > > > > >
>> >> > >> > > > > >------------------------------------
>> >> > >> > > > > >
>> >> > >> > > > > >The CGS Modular Synth home page: http://www.cgs.synth.net/
>> >> > >> > > > > >Yahoo! Groups Links
>> >> > >> > > > > >
>> >> > >> > > > > >
>> >> > >> > > > > >
>> >> > >> > > > > >
>> >> > >> > > > >
>> >> > _______________________________________________________________________
>> >> > >> > > > > Ken Stone sasami@ otherunicorn@
>> >> > >> > > > > Modular Synth PCBs for sale <http://www.cgs.synth.net/>
>> >> > >> > > > > Australian Miniature Horses & Ponies
>> >> > <http://www.blaze.net.au/~sasami/>
>> >> > >> > > > >
>> >> > >> > > >
>> >> > >> > >
>> >> > >> >
>> >> > >>
>> >> > >
>> >> > >
>> >> > >
>> >> > >
>> >> > >------------------------------------
>> >> > >
>> >> > >The CGS Modular Synth home page: http://www.cgs.synth.net/
>> >> > >Yahoo! Groups Links
>> >> > >
>> >> > >
>> >> > >
>> >> > >
>> >> > _______________________________________________________________________
>> >> > Ken Stone sasami@ otherunicorn@
>> >> > Modular Synth PCBs for sale <http://www.cgs.synth.net/>
>> >> >
>> >>
>> >
>> >
>> >
>> >
>> >------------------------------------
>> >
>> >The CGS Modular Synth home page: http://www.cgs.synth.net/
>> >Yahoo! Groups Links
>> >
>> >
>> >
>> >
>> _______________________________________________________________________
>> Ken Stone sasami@... otherunicorn@...
>> Modular Synth PCBs for sale <http://www.cgs.synth.net/>
>>
>
>
>
>
>------------------------------------
>
>The CGS Modular Synth home page: http://www.cgs.synth.net/
>Yahoo! Groups Links
>
>
>
>

_______________________________________________________________________
Ken Stone sasami@... otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>