ESQ-1 Sound Issues

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JHatzia
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ESQ-1 Sound Issues

Post by JHatzia » Mon Jul 31, 2017 6:09 am

I have a mint ESQ-1 that had its battery replaced with a AA pack from the previous owner. Apparently after this the synth lost nearly all it's sound and only makes a squawk every 8th voice. Otherwise it operates as should, all the buttons and faders work, I can save patches, I can even hear the metronome. Even though the AA pack was reading 3V fine, I replaced it with a battery from Syntaur, confirmed it was reading 3V.

Here's the catch, while the battery reads fine after a reset it still reads as "BATT-000" when pressing Record+Compare.

All keys confirmed via MIDI. The schematics are so hard to read I can't find the battery on it anywhere. This synth is so minty and this seems like an easy fix. Any tips would be great!

Description from Seller: "I'm heartbroken. I was getting my beloved classic Ensoniq ESQ-1 ready to post on OfferUp, had just replaced the internal lithium battery for the sequence memory (got the Low Battery message on booting), and no sound would come out! Well, a buzzy ghost of one of the Ensoniq wavetables was making an intermittent appearance. I did all the usual things - soft reboot, hard reboot, filter reset. No change. I even reseated all the main chips, memory, and connectors. I googled, and it sounds like a bad chip somewhere."
Last edited by JHatzia on Wed Aug 02, 2017 4:10 pm, edited 1 time in total.

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Re: ESQ-1 Sound Issues

Post by meatballfulton » Mon Jul 31, 2017 3:41 pm

The first step with many ESQ-1 problem is to go through all the ribbon connectors and make sure they are properly connected. If that is of no help, then I would start looking at the circuit board in the area of the battery modification looking for problems there.

Good luck.
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JHatzia
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Re: ESQ-1 Sound Issues

Post by JHatzia » Mon Jul 31, 2017 3:47 pm

All ribbons seem to be fine. Like I said, I can hear the metronome as should- just all the voices barely make a sound except a single voice makes the same sound regardless of which patch. I'm just trying to figure out where the battery feeds to, to see if I can measure where the voltage drops off.

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Re: ESQ-1 Sound Issues

Post by Rasputin » Mon Jul 31, 2017 4:23 pm

JHatzia wrote:I'm just trying to figure out where the battery feeds to, to see if I can measure where the voltage drops off.
There's a battery whose (-) goes to ground and whose (+) goes to a resistor. The resistor goes to +VBAT (which isn't a part, but a trace which carries power) and also the anode side of a diode. In turn, the cathode of the diode goes to a capacitor which goes to +VB (which, again, isn't a part, but a trace which carries power to various sections of the board).

Check that the polarity of the battery is correct and that the diode only allows flow one way.

On metal ESQ-1 models this is CR1 (diode) and C1 (I think) for the capacitor.
On plastic ESQ-1 models this is CR3 (diode) and C18 (I think) for the capacitor.

The voltage drop across the diode should be about 400m VDC. The voltage at the RAM chips should be close to the battery voltage minus the measured diode voltage drop, so if the battery is 3.2v then 2.8v (and so forth) should be as low as the battery measures at the RAM chips.

If you're referencing the Buchty based schematics then they're not going to help you, really, unless you already know what you're looking for. They're on "esq1_digit3.gif" though (upper-right corner), if you're curious.

You want to look at U19/U20 (metal) or U14/U18 (plastic) as far as the RAM chips go. They should say 6264 somewhere, I believe. VDD (pin 28) is where +VB should end up, I'm pretty sure.

That said, I think you may have a misconception about what it means when the battery test reads "000". You should try a soft reset and retune the filters. Hit Record + Soft Button #1 and then "YES". Now hit Record + Filter.
Last edited by Rasputin on Mon Jul 31, 2017 5:06 pm, edited 6 times in total.

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Re: ESQ-1 Sound Issues

Post by JHatzia » Mon Jul 31, 2017 4:27 pm

The polarity of the battery is correct. There were two solder tabs underneath the + lead of the battery that looked like a component may have went there- but I'm pretty sure it's for batteries that have two leads on one side. Do you know the specific resistor name, +VBAT (is this part of an IC?) and diode locations? I can't find this on schematic anywhere. Thanks!

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Re: ESQ-1 Sound Issues

Post by madtheory » Mon Jul 31, 2017 4:39 pm

You already got great advice on Vintage Synth Repair group on Facebook, and you've posted on Ensoniq Users group as well.

That was perfect advice you got there.

Follow what Rutger Vlek said, and he has offered to help you trace through the circuit too. And it really does look like the battery was not soldered in properly, you need to trace that voltage and make sure it's getting past the horribly burnt pad next to the resistor. That would explain why the diagnostic is reading 0V from it.

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Re: ESQ-1 Sound Issues

Post by Rasputin » Mon Jul 31, 2017 4:42 pm

JHatzia wrote:The polarity of the battery is correct. There were two solder tabs underneath the + lead of the battery that looked like a component may have went there- but I'm pretty sure it's for batteries that have two leads on one side. Do you know the specific resistor name, +VBAT (is this part of an IC?) and diode locations? I can't find this on schematic anywhere. Thanks!
I just updated my post with extra info, but it's pretty apparent if you just follow the traces.

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Re: ESQ-1 Sound Issues

Post by Rasputin » Mon Jul 31, 2017 5:11 pm

I'm going to go out on a limb and say that the ESQ-1 isn't giving you a "Low Battery" warning when you turn it on. That would indicate that the problem isn't what you think it is.

Revisit my first post in this thread, especially the part about re-initializing, and think about how things might sound if the filters lost their calibration due to the battery change. And also, if all the patches are lost/reset when the battery is changed then it would also make sense, in the scheme of things, right?

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Re: ESQ-1 Sound Issues

Post by JHatzia » Mon Jul 31, 2017 6:27 pm

Thank you! I have tried the Soft Reset and Filter calibration before after reading in the manual to do so if BATT reads 000. The Soft Reset seems to work fine, the patches revert to the original and I can save. However BATT is still 000. Filter Tunings are within 140-160 as expected. I will review your first post once I have a chance.

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Re: ESQ-1 Sound Issues

Post by Rasputin » Mon Jul 31, 2017 7:14 pm

JHatzia wrote:Thank you! I have tried the Soft Reset and Filter calibration before after reading in the manual to do so if BATT reads 000. The Soft Reset seems to work fine, the patches revert to the original and I can save. However BATT is still 000. Filter Tunings are within 140-160 as expected. I will review your first post once I have a chance.
What are you expecting the battery readout to report? That's pretty much a rhetorical question, but one I want you to think about to prompt your troubleshooting theories.

What I mean is: Why do you think it's not supposed to be 000? What is it "supposed to be" as far as you're concerned, and why? What is it indicating and what is it trying to tell you?

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Re: ESQ-1 Sound Issues

Post by madtheory » Mon Jul 31, 2017 10:37 pm

:D

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Re: ESQ-1 Sound Issues

Post by JHatzia » Tue Aug 01, 2017 3:33 am

I agree looking towards the battery was a loose theory and probably not the source of the issue. However the previous owner did a suspect job of replacing the battery, so I desoldered his AA pack replacement, cleaned up the flux (not a burnt pad) and replaced it with a proper battery from Syntaur.

After doing this I wrongly assumed this "BATT-000" reading had something to do with it. After checking out page 9 on the SM I see that 000 means it's fine. The default patches are there, I can't hear them but I can save a patch and it retains after power cycle. This section of the synth appears to be working fine. You're right there is no Low Battery Message. Total wrong assumption on my part. I've just heard that these units can do strange things with battery issues.

I've followed your guidance to the best of my ability. Here's what I've got (it's the plastic version).

From the battery: 3.092VDC
CR3: 3.080V (Anode)
CR3: 3.020V (Cathode)
U14: 3.020V
U18: 3.020V

I see where you're coming from after referring to SM page 9. The SM mentioned that the Sequencer Expander Cartridge can drain the battery. It may be worth noting that this unit does have a SQX-20 installed.

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Re: ESQ-1 Sound Issues

Post by Rasputin » Tue Aug 01, 2017 4:59 am

JHatzia wrote:You're right there is no Low Battery Message. Total wrong assumption on my part. I've just heard that these units can do strange things with battery issues.
It's a reasonable assumption considering the apparent cause -> effect thing and so forth. So now we just have to figure out why you're not getting any sound.

What do we know?

If the metronome works then the entire output stage works, so that rules out any jacks, op-amps, volume sliders, etc. Since you've tested both the MIDI and keyboard and it at least makes a "peep" on occasion then we know it's responding to note data. We know the filters respond to auto-calibration properly.

What does that leave us with? Well, I'm not there, so I can't say, but the patch data is one wildcard that I can't rule out, and I'm not sure there's enough in this thread to deduce yet.

I would try restoring some new patches from either Tape In or SysEx and see if ANY of the patches get any semblance of working voices, above and beyond what you're getting now.

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Re: ESQ-1 Sound Issues

Post by JHatzia » Tue Aug 01, 2017 6:45 am

I have successfully sent patches from the unit to Sysex Librarian via USB to MIDI. But when trying to load patches from Sysex Librarian the ESQ-1 immediately says "Target System Not Responding." So instead I loaded sounds off the ESQ Voice 80 cart. I should mention that when I can get a note to trigger a sound, it's always an off tune D#. The only patch that seemed to sound like it somewhat worked was "Icepops" but I think this is mostly the keyboard tracking the resonating filter. It seems like from this behavior the filter is working. So progress?

Adjusting the cutoff, resonance and all Filter parameters affect the sound. The envelopes do as well (I can adjust release time for example) but when adjusting the OSC and DCA section don't seem to do much.

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Re: ESQ-1 Sound Issues

Post by madtheory » Tue Aug 01, 2017 11:58 am

LOL I was misleading myself too.

RE- SysEx: does the ESQ-1 default to MIDI handshaking? Can that be disabled? Does SyEx librarian have anything about that?

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