Re: [Kawai-Teisco] Digest Number 441[1 Attachment]
2016-03-19 by ipc.de@web.de
Hi, I just wanted to let you know, that you are not alone. This is very common problem on the SX210. I have two models here which both show this envelope hanging sporadically and on different voices. Since the envelope circuit is somewhat a feedback loop, it hangs itself, not easy to track down the faulty circuit with the oscilloscope. I once did find, however, two defective 4066. I replaced them and I replaced ALL CMOS on one voice, which was not so easy to do, since the PCBs in this machine are not well laminated and the traces come off easily upon soldering. But the full replacement had no lasting effect: Still all the voices hang sporadically, including the fully re-fitted one. Some voices are mor prone to hanging others hang only very rearely, in particular when other voices are already hanging. Both my SX210 machines have the same problem with each having individual "preferences" which voices hang. I swapped the voice boards and found that the preferences stay with the voice board. Therefore I exclucde the CPU board as the major source of this mysterious problem. BTW, the hanging is a prominent problem of the VCA envelope. The VCF envelope has similar problems, but there I found faults in the D and S sections of the ADSR envelope. I have the impression, that this is a fgeneral fault of the circuit design, which comes apparent after some chips run out of specs or something. I also thought it was a grounding issue. On the other hand, I found that a hanging voice sometimes reacts to temperature (heating or cool spray). I found that after keeping the SX210 running for one hour, the problem fully dissapeared and never came back on this session. The other day the problem persists all day. Thus, there might be broken traces, particularly the ones that go under the chips on the top side of the PCB, where you cannot reach them for tracing, ARGHH. In a similar type of PCB of the same vintage I once found cracks exactly where the linear traces meet the circular TTH solder pads. I also tried to track down the comparator circuit with the OP-amp. But I did not quite get it how this works. The signal produced by the CMOS circuit on the input of the OP-amp seems to be quite ok. But the output looked uncanny... Good luck, and thank you for some more insight. Mondo Am 19.03.2016 um 09:36 schrieb Kawai-Teisco@yahoogroups.com:
Show quoted textHide quoted text
> Yahoo! Groups > <https://groups.yahoo.com/neo;_ylc=X3oDMTJldXU4ZWw2BF9TAzk3MzU5NzE1BGdycElkAzEyMzE2NTQ2BGdycHNwSWQDMTcwNTAzMjE0NARzZWMDZnRyBHNsawNnZnAEc3RpbWUDMTQ1ODM3NjU2MA--> > > The Kawai & Teisco Analog Synths Group Group > <https://groups.yahoo.com/neo/groups/Kawai-Teisco/info;_ylc=X3oDMTJlZWUzcHMwBF9TAzk3MzU5NzE1BGdycElkAzEyMzE2NTQ2BGdycHNwSWQDMTcwNTAzMjE0NARzZWMDaGRyBHNsawNocGgEc3RpbWUDMTQ1ODM3NjU2MA--> > > > > 2 Messages > > Digest #441 > 1a > SX210 Envelope Issue <#1a> by xorsister > 1b > Re: SX210 Envelope Issue <#1b> by xorsister > > > Messages > > > 1a > > > SX210 Envelope Issue > <https://groups.yahoo.com/neo/groups/Kawai-Teisco/conversations/topics/887;_ylc=X3oDMTJxOWJsZTd1BF9TAzk3MzU5NzE1BGdycElkAzEyMzE2NTQ2BGdycHNwSWQDMTcwNTAzMjE0NARtc2dJZAM4ODcEc2VjA2Rtc2cEc2xrA3Ztc2cEc3RpbWUDMTQ1ODM3NjU2MA--> > > > > Fri Mar 18, 2016 10:35 am (PDT) . Posted by: > > > xorsister > <mailto:aliendelon@...?subject=Re%3A%20SX210%20Envelope%20Issue> > > > Hey guys! Still trying to fix one voice on my SX210 - its stuck > infinitely - EG controls don't work, but filter envelope is - rest of > the voices works fine > I replaced TL082CP opamp, CD4066BE and 4081 chips and all caps, checked > continuity - all fine. > The thig is - that i'm getting 15v on TL082 output, and supposed to get > 0v, also 103 cap is measured 13v on the other side, and it suppose to > charge when note is played - on the other voices this point is normally > 0v and peaks to 13v when note is played > Can anyone here forward me to where to go next?)) > I'll really appreciate any help! > > > > > Attachment(s) from > 1 of 1 Photo(s) > Image > <https://groups.yahoo.com/neo/groups/Kawai-Teisco/attachments/393504725?itemid=102256761> > > Screen Shot 2016-03-18 at 20.30.45.png > <https://groups.yahoo.com/neo/groups/Kawai-Teisco/attachments/393504725?itemid=102256761> > > Reply to sender > <mailto:aliendelon@...?subject=Re%3A%20SX210%20Envelope%20Issue> . > Reply to group > <mailto:Kawai-Teisco@yahoogroups.com?subject=Re%3A%20SX210%20Envelope%20Issue> > . Reply via Web Post > <https://groups.yahoo.com/neo/groups/Kawai-Teisco/conversations/messages/887;_ylc=X3oDMTJxbjgxdW9sBF9TAzk3MzU5NzE1BGdycElkAzEyMzE2NTQ2BGdycHNwSWQDMTcwNTAzMjE0NARtc2dJZAM4ODcEc2VjA2Rtc2cEc2xrA3JwbHkEc3RpbWUDMTQ1ODM3NjU2MA--?act=reply&messageNum=887> > . All Messages (2) > <https://groups.yahoo.com/neo/groups/Kawai-Teisco/conversations/topics/887;_ylc=X3oDMTM0OWFwZjdyBF9TAzk3MzU5NzE1BGdycElkAzEyMzE2NTQ2BGdycHNwSWQDMTcwNTAzMjE0NARtc2dJZAM4ODcEc2VjA2Rtc2cEc2xrA3Z0cGMEc3RpbWUDMTQ1ODM3NjU2MAR0cGNJZAM4ODc-> > . Top ^ <#toc> > > > 1b > > > Re: SX210 Envelope Issue > <https://groups.yahoo.com/neo/groups/Kawai-Teisco/conversations/topics/888;_ylc=X3oDMTJxZmpsaDRzBF9TAzk3MzU5NzE1BGdycElkAzEyMzE2NTQ2BGdycHNwSWQDMTcwNTAzMjE0NARtc2dJZAM4ODgEc2VjA2Rtc2cEc2xrA3Ztc2cEc3RpbWUDMTQ1ODM3NjU2MA--> > > > > Fri Mar 18, 2016 11:02 am (PDT) . Posted by: > > > xorsister > <mailto:aliendelon@...?subject=Re%3A%20SX210%20Envelope%20Issue> > > > Also i don't get peak on 13v after diode on the left > Reply to sender > <mailto:aliendelon@...?subject=Re%3A%20SX210%20Envelope%20Issue> . > Reply to group > <mailto:Kawai-Teisco@yahoogroups.com?subject=Re%3A%20SX210%20Envelope%20Issue> > . Reply via Web Post > <https://groups.yahoo.com/neo/groups/Kawai-Teisco/conversations/messages/888;_ylc=X3oDMTJxYnJzaDE0BF9TAzk3MzU5NzE1BGdycElkAzEyMzE2NTQ2BGdycHNwSWQDMTcwNTAzMjE0NARtc2dJZAM4ODgEc2VjA2Rtc2cEc2xrA3JwbHkEc3RpbWUDMTQ1ODM3NjU2MA--?act=reply&messageNum=888> > . All Messages (2) > <https://groups.yahoo.com/neo/groups/Kawai-Teisco/conversations/topics/887;_ylc=X3oDMTM0ZmYybDRjBF9TAzk3MzU5NzE1BGdycElkAzEyMzE2NTQ2BGdycHNwSWQDMTcwNTAzMjE0NARtc2dJZAM4ODgEc2VjA2Rtc2cEc2xrA3Z0cGMEc3RpbWUDMTQ1ODM3NjU2MAR0cGNJZAM4ODc-> > . Top ^ <#toc> > Visit Your Group > <https://groups.yahoo.com/neo/groups/Kawai-Teisco/info;_ylc=X3oDMTJmcmJvcGtwBF9TAzk3MzU5NzE1BGdycElkAzEyMzE2NTQ2BGdycHNwSWQDMTcwNTAzMjE0NARzZWMDdnRsBHNsawN2Z2hwBHN0aW1lAzE0NTgzNzY1NjA-> > > > Yahoo! Groups > <https://groups.yahoo.com/neo;_ylc=X3oDMTJldXU4ZWw2BF9TAzk3MzU5NzE1BGdycElkAzEyMzE2NTQ2BGdycHNwSWQDMTcwNTAzMjE0NARzZWMDZnRyBHNsawNnZnAEc3RpbWUDMTQ1ODM3NjU2MA--> > > \u2022 Privacy <https://info.yahoo.com/privacy/us/yahoo/groups/details.html> > \u2022 Unsubscribe > <mailto:Kawai-Teisco-unsubscribe@yahoogroups.com?subject=Unsubscribe> \u2022 > Terms of Use <https://info.yahoo.com/legal/us/yahoo/utos/terms/>