I am having some problems with my ESQ-1.

[dudefinal]

When my Filter "FREQ" parameter is high enough every eighth key I play will skip or just not play. Sometimes it will fizz in or bubble in or there will be a bump sound before or during the note plays or sometimes the eighth note won't play at all. Turning down the Filter "FREQ" parameter usually gets rid of the problem but I don't like knowing that there are some sounds I can't get too. Any ideas on what might be causing this? I have done Filter tuning and everything checked out. (Values were between 146-153.) I have played eight keys with the filter "FREQ" turned down and all the voices seem to be function as in when I press down nine keys the first key cuts out as it should. I have done all the tests that I could from the outside of the synth, everything passed, and have not opened it up yet. Could this be a software problem? The software version is 3.40. I did do a factory reset and it did not help or atleast I don't think it did. I will be updating that in the future and I do plan to open it up later today or tommorow. I do have a vintage synth repair place near to me and was wondering if any of you could point me toward the problem or even a possible solution. I have been asking around on forums and noone seems to know whats wrong... well actually noone seems to care as I have gotten no replies. The guy I bought it from does except thirty day returns but I would rather not go that route unless repairs seem too expensive. I really like this synth and really want to get it working! Any help would be greatly appreciated! Thank you.

Here's a video that demonstrates my problem that I took. https://www.youtube.com/watch?v=HgbGoGjwuSI

[Enzo]

Hi,

First, if you have a vintage synth place and they have a competent shop, they don;t need suggestions. If they hit a snag, invite them here, but what a shop needs is a clear reporting of the symptoms.

Software? if the software was buggy, it would have ALWAYS done this. Did it used to work? Has this problem arisen lately? I used to be an Ensoniq authorized service center, and I don't recall ever seeing that particular symptom, so I suspect it wasn't a systematic error in the software.

I actually have a working ESQ1 main board in my storage unit.

Rather than accuse folks of not caring, perhaps no one has anything useful to reply with? This forum for example is mainly about guitar amps. Ensoniq never released schematics even to the service centers, until late in the game they SOLD us sets of the early model schematics. We never had access to the prints for any current or recent models. So there is a very limited pool of people who can even speak knowledgeably about the circuitry.

I suspect you may have a failing Curtis chip, and turning down the filter just takes the signal out of the range of the fault. generally this sort of symptom I expect a re-initialization to cure, but if you did that, it must be in the system.

[dudefinal]

I just bought the synth a few weeks ago and the problem was there when I received it. The person I bought it from said that he tested it and didn't see anything wrong with it. Maybe something knocked loose while shipping?

Sorry if I came off a little rude :/ just a bit desperate to get this synth working. Been posting on many different forums recently and will see if anyone replies. Thanks for the info!

Edit: I also have another question. Do I have to buy a Curtis chip custom for the Esq-1 or can i just buy a new CEM3379 and throw it down in the synth and have it work. I have noticed, according to this site https://en.wikipedia.org/wiki/CEM_an...n_synthesizers, the ESQ-1 has other Curtis chips. Any idea on which ones failing and how could I tell which one of the many chips were failing?

...For example can I buy this... http://www.ebay.com/itm/CEM-3379-IC-...3D182371060961... or do I have to buy one custom tailored for the ESQ-1. Thanks!

[Enzo]

I don't KNOW it is a bad Curtis chip, it just comes to mind as one place I'd be looking. I don;t recall the inner circuit well at all, I haven;t worked on one for 15-20 years. But there is also an SSM chip along with each Curtis chip.

No the Curtis chips were not custom. There was a series of CEM chips for the synth trade. I don't remember the one in the ESQ1, look on the ICs. I don;t recall there being two types in there.

There are eight voices, and one is affected. If I recall, the CEMs are in sockets, but none of the others, except like the ROMs. So one voice as it cycles through has the filter problem. One thing I might try is going down the row of CEMs, and then down the SSMs is to grip each IC with your fingers, so you have as much finger flesh on the IC pins. They run on 5 volts, so there is no danger. But while teh voice is acting funny, see if gripping any of the ICs makes it change in ANY way. the impedance of your finger and the capacitance of your body can change the resonance or frequency or whatever. If grasping the IC changes things it might be bad. Also, once you think you have identified a bad CEM, pull it from the socket (yes power down for that) and see if now the eighth voice is now silent. If one of the seven remaining voices still does the thing, then we pulled the wrong IC.

I use my experience to work on these in the absence of good documentation. Even with the schematic, it is not for the novice. I use my scope in this. other than pulling ICs from sockets, there is little else you can do that is not technical. Even without the unit schematic, we can look up the data sheet for the ICs and explore their functions. A control voltage pin is a control voltage pin, wherever that voltage comes from.

And that brings up a point - nothing acts on its own, this is all about the CIRCUIT. SO the Curtis chip might be getting a control voltage from another IC, and THAt IC cannot run the control voltage all the way up...for example.

[dudefinal]

I don't KNOW it is a bad Curtis chip, it just comes to mind as one place I'd be looking. I don;t recall the inner circuit well at all, I haven;t worked on one for 15-20 years. But there is also an SSM chip along with each Curtis chip.

No the Curtis chips were not custom. There was a series of CEM chips for the synth trade. I don't remember the one in the ESQ1, look on the ICs. I don;t recall there being two types in there.

There are eight voices, and one is affected. If I recall, the CEMs are in sockets, but none of the others, except like the ROMs. So one voice as it cycles through has the filter problem. One thing I might try is going down the row of CEMs, and then down the SSMs is to grip each IC with your fingers, so you have as much finger flesh on the IC pins. They run on 5 volts, so there is no danger. But while teh voice is acting funny, see if gripping any of the ICs makes it change in ANY way. the impedance of your finger and the capacitance of your body can change the resonance or frequency or whatever. If grasping the IC changes things it might be bad. Also, once you think you have identified a bad CEM, pull it from the socket (yes power down for that) and see if now the eighth voice is now silent. If one of the seven remaining voices still does the thing, then we pulled the wrong IC.

I use my experience to work on these in the absence of good documentation. Even with the schematic, it is not for the novice. I use my scope in this. other than pulling ICs from sockets, there is little else you can do that is not technical. Even without the unit schematic, we can look up the data sheet for the ICs and explore their functions. A control voltage pin is a control voltage pin, wherever that voltage comes from.

And that brings up a point - nothing acts on its own, this is all about the CIRCUIT. SO the Curtis chip might be getting a control voltage from another IC, and THAt IC cannot run the control voltage all the way up...for example.

Thank you so much for the reply! I will be re-seating the chips and isolating the faulty one if there is a faulty one. If there is a faulty one and I isolate it I will replace it. If I don't see any change I will check out the SSMs. If all else fails I will take it to a professional vintage synth repair place near to me. I have the official ESQ-1 service manual printed out and I will be sure to print any other documentation that could help. I do want to check all the voltages from DCA4 all the way down to power supply. I assume the board and its components are in a way that reflects the diagram on the from of the ESQ-1. Thanks for your reply!

[Enzo]

If you look at the official "service manual" I think you will find it is very simplistic, and doesn't get much past taking a few voltage readings on the power supply. In fact, they don't usually say check the 5v power supply, they say check between point X and point Y and get 5v more or less some amount.

Their entire service philosophy was based on board swaps. The manual got you to identify which board had the issue, then you were to order a replacement. Under warranty, we got an hour labor and the board swap was free. They charged our account $500 for the board, and gave us a $500 credit when we returned the bad one. After warranty, they still expected a board swap, expect they charged us the $500, but only gave a $400 credit for the dud. Our cost was then $100, and we were expected to charge the customer $150. So we made $50 on the whole deal. Even if we knew what it needed, like a Curtis chip or even just a SCSI connector, they wouldn't sell us parts. Problems arose when they ran out of good boards, and we had to wait for a bad board to return so they could fix it and send it back out to us. And more than once I received a bad board from them. I recall one time I fixed their bad board and billed them. Then when they folded into EMU, the whole support structure disappeared, leaving zero support for the products. As far as I know one guy bought up the assets eventually, and now holds the entire Ensoniq market hostage for inflated repair prices. Or you find someone willing to tackle it like we used to do before retirement.

Checking voltages takes just a minute or two. They come into the board on a 5-6 pin molex connector.

[dudefinal]

If you look at the official "service manual" I think you will find it is very simplistic, and doesn't get much past taking a few voltage readings on the power supply. In fact, they don't usually say check the 5v power supply, they say check between point X and point Y and get 5v more or less some amount.

Their entire service philosophy was based on board swaps. The manual got you to identify which board had the issue, then you were to order a replacement. Under warranty, we got an hour labor and the board swap was free. They charged our account $500 for the board, and gave us a $500 credit when we returned the bad one. After warranty, they still expected a board swap, expect they charged us the $500, but only gave a $400 credit for the dud. Our cost was then $100, and we were expected to charge the customer $150. So we made $50 on the whole deal. Even if we knew what it needed, like a Curtis chip or even just a SCSI connector, they wouldn't sell us parts. Problems arose when they ran out of good boards, and we had to wait for a bad board to return so they could fix it and send it back out to us. And more than once I received a bad board from them. I recall one time I fixed their bad board and billed them. Then when they folded into EMU, the whole support structure disappeared, leaving zero support for the products. As far as I know one guy bought up the assets eventually, and now holds the entire Ensoniq market hostage for inflated repair prices. Or you find someone willing to tackle it like we used to do before retirement.

Checking voltages takes just a minute or two. They come into the board on a 5-6 pin molex connector.

Do you maybe have any sources that would tell me voltages for any components. That would be really helpful. I am sure I could look around and find some people sharing voltages from their working ESQ-1's.

[Enzo]

Voltages? The power supplies are as expected. VOltages in digital circuits are not very useful. In the analog circuits, so many factors are involved. So if you have solid clean +5 for the logic, and clean +/-15 or 12 (I forget which) for the analog, that is the voltages I care about. Checking voltages in the works takes knowledge of the circuitry, at least from the data sheet.

[dudefinal]

Took apart my ESQ-1 but got cold feet.

I have disassembled and re-assembled the synth and everything works as it did before I opened it up. I hope I didn't mess up anything in the synth. Really should have brought it to a professional instead of opening it up myself for nothing as I do not have the proper tools to remove the CEM or SSM chips. The only thing that I got out of this was learning a lesson and possibly making the problem worse. After I reassembled it and put it back where it was before I turned it on and it held one note indefinitely and pressing other notes would do nothing except make a bump sound. I was absolutely terrified and unplugged it and tilted it on it side to move some of the dirt that dislodged when I opened it all the while praying that I didn't mess it up. I was shaking with fear that I had broken it. I plugged it back in and it worked like it did before I opened it... A stupid choice to open it but I did learn a lesson. If you don't have the technical expertise to open something... bring it to a professional or you are in for a terrifying and possibly costly ride. Thankfully for me everything seems to work fine. One of the most stressful things I've ever done. I have a question though... What is the point of the metal shield? I did not put the metal shield back in because it was a chore to get it out and it was a terrifying experience trying to get it out as the connectors were hard to disconnect. Is it normal for the connectors to be exceptionally difficult to disconnect? I was scared I'd break the main board with how hard they were to disconnect. I did do it gently by putting part of a nail clipper into the latch and slowly wiggling it out. If the shield is important to the overall functionality then I will by all means put it back in.

[Enzo]

The works are a digital system. Digital circuits are noisy, noisy to the point they can interfere with your TV reception . That shield tends to help keep such noise out of other places.

I am not sure I understand your fear here. You took it apart, and now it works exactly like it did before you took it apart? So in other words you didn't change anything? Opening the unit shouldn't hurt anything, any more than opening a car door hurts the car. Unless you took the main board out and managed to short the battery, even disassembly ought not make it forget its memory, and even that is restored with a couple button pushes.

The connectors are stiff, yes. The manual used to show using a pointed tool to wedge under than to get them off.

[Jazz P Bass]

Quote:"The connectors are stiff, yes. The manual used to show using a pointed tool to wedge under than to get them off. "

I have a feeling that techs where being a little rough on the connectors & breaking them.
That is what brought about the tool.

[Enzo]

Like thousands of linear connectors on other products, the pins grip tightly, and they use a wedge so you don't pull them up by the wires. A popinty tool like a dental explorer, or a small screwdriver, whatever.