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
e=tn&order=ordinal&start=1&dir=asc
Ken Stone sasami@... otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>
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...4777_n.jpg
>https://sphotos-a.xx.fbcdn.net/hphotos-ash4/317422_10151631973766807_174487
>in the build. One is pulled in the pic (for troubleshooting)
>
>--- In cgs_synth@yahoogroups.com, "Sean" <solidratestudios@...> wrote:
>>
>> Hopefully this works? btw, I also had to use two larger 2.2M resistors
>>http://groups.yahoo.com/group/cgs_synth/photos/album/1219515935/pic/list?mod
>> Thanks -Sean
>>
>>
e=tn&order=ordinal&start=1&dir=asc
>>routing issues.
>> --- 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
>> > >> > > > >inspected
>> > >> > > > > 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
>> > the boardtook
>> > >> > > > > 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
>> > a fewpass but no
>> > >> > > > > minutes.I've been able to get a slewed/smoothed signal to
>> > >> > > > > control over the hold or rate, i've gotten a steady tone froma strong
>> > 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
>> > >> > > > > negative voltage on the outputs ?current, not
>> > >> > > > > >
>> > >> > > > > >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
>> > 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/>