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The Status of my Autotune & DAC Tests was Re: Re: It's official- my Xpander is sick
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Voice 1 seems to be bad, so I've turned it off.
With Voice 1 Off, This is the status of Autotune VCOs- PASS PW - PASS RES- PASS VCF- PASS VCA- FAIL (With VCO1 on, all the above tests FAIL.) On Master Page, Page 2, Voices On.OFF, All Voices show FAIL DAC Tests DAC Mono- Page 2 LED blinks about 2 times per second (Is this good or bad? Nothing in the service manual about the blink Rate. I hear a Buzz in the audio- which sounds like a sawtooth going about 5 times per second. DAC OFFSET- Page 2 LED blinks about 2 times per second. Good or bad? All other tests on the Service Page are OK Out of tune Points to the DAC, pray it's is not failed because it's Can you tell if the filter still sweeps well? Or - Turn off the VCOSelf resonating? Yes. Once we know if it's the DAC orAlso- after hitting untune on the DAC page, then doing auto tune, my VCOs sound much better. In tune, that is. So- it only looks like Voice 1 is fialing, and the VCA test. Now what ? |
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Hi Tony,
Power Supply: If you have a buzz in the audio output Then the power supply may be going. An easy way to tell is to get a new large capacitor of the same value and voltage . And use jumper leads to jump it across the suspect cap. If the buzz goes away then Replace Em. You will probobly not be able to find exact matches. So some retrofitting may be in order. You probobly know this Tony, but these caps have a polarity to them. So you have to notice where + is and put the new one in the same way. + to +. Also you can go higher in capacitance and voltage ratings but not lower. Voice 1 Problem: I suspect a bypass capacitor located at the output of each voice. I keep seeing this part failing in more and more M12/Xpanders.( mine included) So get a new 2.2uF 50 volt electrolytic cap. and replace C749 (for Voice 1). It is toward the front of the board. This same value part is all over the voice circuits. So.. It would not be a bad Idea to get a bunch of em, and replace all Cx49s. Again you gotta observe polarity. I don't know about the DAC mono test, but if you can get the voices to tune, then the DAC's probobly good. Good Luck Karl --- In xpantastic@..., "Tony Cappellini" <cappy2112@...> wrote: or bad? Nothing in the service manual about the blink Rate.about 5 times per second.it's VCOeven harder to find than the CEMs.Can you tell if the filter still sweeps well? Or - Turn off the waywaves and turn the resonace all the way up,and the cutoff all the voice.down, Mod by keyboard to see if you can play the filter like a
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Power Supply:Perhaps I should upload a short mp3 of it and let the court decide. Would someone upload (or just email me) an mp3 of what I should be hearing during the Dac test- just so I know what to expect in the future? I will try your suggestions Karl, thanks for the tips. BTW My Xpander came to life after I pressed Untune, then ran Autotune. The output level is much higher, and has more presence. Before- when I posted the message about looking for someone local to do a side by side audio comparsion- my XPander had a weak output and sounded dull. |
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Hey Tony,
I was looking in the Xpander Service Manual. I Have a PDF copy, but I don't remember were I got it. Anyway, It says that When you do the DAC mono test you should hear none or very seldom beep on the audio. But thats it, nothing on what to do if you hear lots of beeps (page 35) The next page describes a software reset - Hold down clear (at the end of the MOD row) And turn Power On. The M12 service manual has none of this. --- In xpantastic@..., "Tony Cappellini" <cappy2112@...> wrote:You know, I have done really bizzare mod stuff with mine (every mod routed to itself etc..) I have sometimes locked it up. Maybe you created a ghost in the machine and the untuning / retuning fixed it. The manual says untuning clears all the software clibration registers. Karl |
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I will.
I hope to take a look inside this weekend. During the week is difficult Karl- my car is making a noise that also sounds like my Xpander.He fixed my Xpander in no time across the atlantic Any idea what is wrong ;-) On Fri, Sep 5, 2008 at 8:23 AM, philipperyckman <caractere@...> wrote: All of you, |
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¿ªÔÆÌåÓýThere?s nothing wrong with it,- use it as a synth ...Try to create?a wovel sounding selfplaying patch which sings the song "Rolling Home" ... :-D
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Karl,
I went through all the DC voltmeter measurements in the service manuel. Everything looks good (to me) except for Step 3, +5M text. On the right side of D4 (as I am facing the Processor Board, sometimes I measured 6.6 v, other times I measured 3.9 to 4.9 volts. I suspect there is a bad solder joing on D4, so I will reflow this. Power Supply:I looked at C3 and there is some dry dusty residue on the negative side of C3. There is less residue on the negative side of C1. These caps are old, so I might as well just replace them all at the same time. There are 4 more electrolytic caps on the PS board, but their leads are right up against the PCB, so I can't see if they are leaking. Voice 1 Problem:I dont want to trust my baby Xpander to my shaky hands that haven't used a soldering iron regularly since 1985, so I will have a pro do this for me. It will be worth the money to have all the voices re-capped. In a previous email you referred to a RARE DAC. The service manual references several whose part numbers look like easy to find components to me. Which rare DAC are you referring to? Thanks Tony |
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Hi Tony,
Have been out of pocket for a few days ( building a parade float). Back now. --- In xpantastic@..., "Tony Cappellini" <cappy2112@...> wrote: I went through all the DC voltmeter measurements in the service6.6 V seems very strange for the memory power supply. The battary might need changing. If you are re-flowing the + side of this circuit ( M+5V) you better make sure you have an un-grounded soldering Iron. If not the +Mem supply will be shorted to ground and then the MEM will be lost. Hope I caught you in time. I notice in the Xpander schematics D4 exsists twice. One is a diode at the top edge of the board the other is an LED for the LFO. Now I am sure you know the difference between a diode and an LED but I thought I would mention it. This was changed in the M12 schems. I looked at C3 and there is some dry dusty residue on the negativeIf this is shiny brown, this may be soldering flux. This should always be cleaned off the circuit board. After about 5 - 10 years this will eat the solder and cause problems These caps are old, so I might as well just replace them all at theI have not seen this in Oberheims, but many times in old Korgs / Rolands. It will be worth the money to have all the voices re-capped.Good Idea, I am thinking off doing this myself. When I change my battary. In a previous email you referred to a RARE DAC. The service manualWell, I be talkin about U811 the main DAC which feeds the voice board. The MP7614C-4 was mad by EXAR and is obsolete per their web site, and the HS3140C-4 was made by SIPEX and is also obsolete. I suppose with digging you can find this part out there somewhere (repair shop or part house which specializes in obsolete parts but you will pay quite a bit). Good Luck Karl |
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Thanks Phillipe,
You are too kind. Truth is, You fixed it by doing all the heavy lifting(real work). I just made some suggestions. Glad I Could Help Karl --- In xpantastic@..., "philipperyckman" <caractere@...> wrote:
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6.6 V seems very strange for the memory power supply. The battaryThe Service manual reads that this should be 4.4 V with power on, and 2.xV with power off. With power off, the voltage reading is correct. I will probably change the battery too, since it's been about 10 years after it was changed last. If you are re-flowing the + side of this circuit ( M+5V) you betterI will have the solder tech where I work do all of this for me since he does soldering all day long. I dont trust myself soldering on pcbs. He has a nice temperature controlled iron with many removable tips. Hope I caught you in time.I havne't heard of an ungrounded soldering iron before, but I assume you mean that the iron should not have the ground prong of the power cord connected. This is easily done with an adapter. I notice in the Xpander schematics D4 exsists twice. One is a diodeThe D4 I'm referring to is on the Processor board-not the voice or pot board. This is how the service manual refers to it. If this is shiny brown, this may be soldering flux. This shouldIt doesn't look like flux too me, and is far enough away from where the solder flux would have been when it was soldered. Well, I be talkin about U811 the main DAC which feeds the voiceI googled for this part, and many hits were found on websites that specialize in getting rare parts. They want orders of $100 or more. It might not be a bad idea for us to do a group purchase of these, if we could find a supplier who would sell us a small order. I suppose with digging you can find this part out there somewhereI wish there was a cross reference online that would tell you which commercial devices also used these components It would be much easier looking for an appliance than a chip. |
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--- On Sun, 9/7/08, Tony Cappellini wrote: From: Tony Cappellini |
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Hi Tony, > > Well, I be talkin about U811 the main DAC which feeds the voice --- In xpantastic@..., "Tony Cappellini" >wrote:
> I googled for this part, and many hits were found on websites that > specialize in getting rare parts. > They want orders of $100 or more. ? What was the cost per part? I have a problem every once in a while (well, more and more lately)?when a part for a current product goes obsolete. What is not so clear on a web search is a lot?of these "rare part" companies are working from the same stock of parts. They trade and post each other's part lists. So although you may get dozens or even hundreds of hits there are usually only a few parts out there. Last year I went looking for a very recently obsoleted part. When it was all said and done. The parts I was looking for were in Italy, there were only 25 of them, and I would have had to Pay $85.00 USA a piece + shipping. All for a part that a few months ago I was only paying $7.00 for. It was cheaper at that point to redesign. Most of the generic logic chips in the Xpander/M12 are still > I wish there was a cross reference online that would tell you >which Tony, you may already know this but has a nice list of analog synthesizers and what CEM parts are used. It's not everything but it's a start Best Regards |
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Hello Randy,
Sounds right to me. I was thinking of the times I have seen techs leave the synth plugged in and powered up to avoid dumping the memory. It takes guts but some guys do it. Best Regards Karl --- In xpantastic@..., William Cason <randycason102@...> wrote: unsoldering the battery, I it shouldn't matter if the iron is grounded or not because there will be no >circuit to complete! Just make sure your xpander's not plugged in, and its chassis isn't touching the same ground that the iron's grounded to (like the chassis of another plugged-in device) and you should be OK.[xpantastic] Re: It's official- my Xpander is sick To: xpantastic@... |
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Nothing is ever posted on these sites, you have to call and tell themThey want orders of $100 or more.What was the cost per part? how many you want to buy. Even at $50-$100 a piece, it's better than letting a $1600 (or more) synth lay useless, if the part ever failed. How are you going to resdesign and manufacture an IC unless you have athat a few months ago I was only paying $7.00 for. It was cheaper at that point to redesign. semiconductor fab & mfg + experience doing it? yes- many of the CEMs he has listed are alreayd sold out. I got the last 3372 and a 3340, and still have some others from many years ago. I don't have any 3374's though, but I heard these dont go bad on the XP/M12 very often. When I first moved to San Jose, I went to the company here that was still selling these chips for $15, and bought a handfull. |
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--- On Tue, 9/9/08, Karl wrote: From: Karl |
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