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Silverfish
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10th February 2013
Old 10th February 2013
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ESQ-1 help

Hey! It's another ESQ-1 repair thread!

I got an ESQ-1 tonight for a very good price, and I totally expected it to have a few issues. And it's got them.

1. Internal battery needs to be replaced. No biggie. I can do that. But is that causing....

2. All patches cut off the tail end of the notes, so any release seems to be cut off.

3. The filters aren't working. I can move that slider all I like, but nothing happens. I've done a soft reset and a filter tuning, and all eight of the filter values were between 40 and 60. Which makes me think....

IT'S A POWER SUPPLY ISSUE.

I haven't measured the voltages across the supply yet, or reseated the molex connectors, but that's the direction I'm headed.

Am I right? Am I wrong? Am I screwed?

Thanks for your help!
Silverfish
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10th February 2013
Old 10th February 2013
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I forgot to mention...

It's a metal-case ESQ-1, with OS 3.5.
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10th February 2013
Old 10th February 2013
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First of all...AWESOME description of what's going on with your board. That makes is a lot easier for people like me to help people like you.

Second...good call on the power supply. While it could be something else, the PS is a good place to start. The question is...which power supply ?

The volume, filters, panning, and resonance are fed by a small power supply circuit toward the right side on the main board; it's next to one of those Molex connectors you were looking at. Yet that little bugger is fed by the main power supply board on the left side. So if it's a power supply issue, it could be the main supply, the little on-board supply, or somewhere in between.

Let's start with the in between. Remember that Molex connector on the main board ? There's another one just like it on the main power supply board. A bundle of nine wires goes between the two.

You know what's coming...unplug and plug in the connector on each side. The metal parts of the connectors are known to oxidize - especially if the 'board was stored unused in a basement. Over time, it may be enough to break the connection. A few plug-unplug cycles will "clean" them.

A few things to know before you do this...

- I actually own an SQ-80, so the advice I give is based on that.
- Save any patches or sequences.
- Shut off your ESQ-1 and unplug it.
- Move it to an uncarpeted room. Your "workbench" should NOT have a roller chair. All this sounds silly, but is to protect your keyboard's innards from static electricity. When working on the board, occasionally discharge yourself by touching a large metal item.
- Open the ESQ-1. Several hex screws on top then firmly lift up on the front. The back-end has a piano hinge.

Yeah...I'm sure you knew all that...except the part about me not owning an ESQ-1.

If the simple "fix" doesn't work, we will have to dig deeper. Just get your multimeter and soldering iron ready !

Good luck !

EDIT: Check out "Ensoniq Heaven", the Rainer Buchty site. He has lots of ESQ-1 and SQ-80 goodies - including schematics.
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11th February 2013
Old 11th February 2013
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Thanks for your help, Waveform:blue. So here's where I'm at:

I reseated all chips. Nada.

I tested the Power Supply. All voltages are within the acceptable range.

I ran the filter tuning. The results are approximately half of the value they should be, for all chips.

I also realized that none of the envelopes are working, which is why the notes just cut off- they just stop.


You mentioned the analog power supply, but I'm pretty sure all power to the Main Board comes across one molex connector line. The other line next to it is the pitch and mod wheel inputs.

So, that's where I'm at. Any suggestions on the next step?

Thanks again!
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11th February 2013
Old 11th February 2013
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SQ-80/plastic ESQ-1 filter supply checks

+/-12V from the power supply board also feeds a smaller dual supply on the main board. This unbalanced supply reduces the voltage to +7/-5. On an SQ-80, the circuit is on the main board about an inch away from the Molex at 4 o'clock...

- A MJE-182 transistor, 7.5V Zener, and 300 Ohm resistor form the positive half (+12V in, +7V out).

- A 7905 regulator is the negative half (-12V in, -5V out).

One of these supplies has failed. Let's find out which !

For the +7 Volt supply, look for the MJE-182 transistor. It's a grey, blue, or green plastic rectangle with three leads out the bottom and a hole near the middle. Measure the voltage on each of the three leads with reference to analogue ground. From left to right there should be 7V on the emitter, 12V on the collector, and 7.5V on the base. BE CAREFUL ! SHORTING ADJACENT TRANSISTOR LEADS WITH A METER PROBE CAN KILL THE FILTER ICs !

- If the emitter voltage is low but the other two are OK, replace the MJE-182.
- If the base and emitter voltages are near zero but the collector is OK, the Zener has shorted. It's silver with a black band on one end just below the transistor. The 300 Ohm resistor next to it may have also burned out.
- If all three voltages are low, recheck the +12V supply and the Molex connectors.

The -5 Volt supply is easier. The regulator IC is a bit larger than the transistor you just tested. It's black with a metal tab at the top; there's a hole in the tab. On an SQ-80, its all covered with an inch of heat-shrink tubing. Measure the three leads from left to right, ground is 0V, input is -12V, output is -5V. As before...SHORTING ADJACENT PINS CAN KILL THE FILTER ICs !

- If the output is low but the input is OK, replace the 7905 IC.
- If both input and output are low, recheck the -12V supply and Molex connectors.

I'm at work...so this is all I can offer for now.

Good luck !
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#6
11th February 2013
Old 11th February 2013
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waveform:blue - these are some incredible and easy to follow answers you're giving here! Ever consider starting a synth-repair blog/journal? You should. I mean, I'm sure you have tonnes of free time and the willingness to share your knowledge for free. Right?

Seriously though, I'm saving this thread in case I need it for future reference. Thank you!
#7
12th February 2013
Old 12th February 2013
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Quote:
Originally Posted by silent5 View Post
waveform:blue - these are some incredible and easy to follow answers you're giving here! Ever consider starting a synth-repair blog/journal? You should. I mean, I'm sure you have tonnes of free time and the willingness to share your knowledge for free. Right?

Seriously though, I'm saving this thread in case I need it for future reference. Thank you!
Wow...thanks for that. However, I'm afraid you spoke too soon...

I just found some ESQ-1 PC board photos and schematics online. While the images are poor, I can make out enough to see that my SQ-80 advice will not apply directly to his metal ESQ-1.

Yo Silver ! If you're still tuned into this ratscrew, give me a little time to put together a plan you can actually use.
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#8
12th February 2013
Old 12th February 2013
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Waveform:blue, I'm still following along, and Silent5 is spot on regarding your help- excellent! .

I appreciate you taking the time to help me figure out what's going on with this beast. Someone from another forum mentioned that if all eight voices are functioning, then at least the CEM3379s are still good. I was worried about that one.

He also mentioned that if those voices are working, then the issue is BEFORE those chips. I haven't had a chance to dig into any schematics yet, but I'll have a look and see what I can dig up.

Thanks again for your help!
#9
12th February 2013
Old 12th February 2013
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Quote:
Originally Posted by waveform:blue View Post
Wow...thanks for that. However, I'm afraid you spoke too soon...

I just found some ESQ-1 PC board photos and schematics online. While the images are poor, I can make out enough to see that my SQ-80 advice will not apply directly to his metal ESQ-1.
Well, it's a good thing I subscribed to this thread. SQ-80 tips as well.
#10
12th February 2013
Old 12th February 2013
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Quote:
Originally Posted by Silverfish View Post
Waveform:blue, I'm still following along, and Silent5 is spot on regarding your help- excellent! .

I appreciate you taking the time to help me figure out what's going on with this beast. Someone from another forum mentioned that if all eight voices are functioning, then at least the CEM3379s are still good. I was worried about that one.

He also mentioned that if those voices are working, then the issue is BEFORE those chips. I haven't had a chance to dig into any schematics yet, but I'll have a look and see what I can dig up.

Thanks again for your help!
No prob, Silver. We 8-bit Ensoniq users need to stick together

BTW...I agree that the CEM3379s are fine. All eight of them would have to fail for the symptoms you describe.

Anyhoo...I found a real dodgy photo of your metal ESQ-1 from the Syntaur site. Combined with some blurry schematics from Ensoniq Heaven, I've almost enough to help you out. Yet you need to help me first...

About two inches to the right of that infamous Molex connector you should see two transistors arranged like this...

| <-- black
| <-- green

This is the +7V/-5V main board analogue supply - I think. Each one of these transistors has a metal tab with a hole. First make sure the tabs are not touching. Now measure the voltage on each tab with respect to analogue ground. One should be +12 Volts, the other is -12 Volts. Tell me which is which so we can fix this thing.
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12th February 2013
Old 12th February 2013
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Results:

Black: +11.84V
Green: -12.00V
#12
13th February 2013
Old 13th February 2013
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Waveform, I sent you a PM (hope that's ok). I managed to corrupt my ESQ-1 with some sysex mere hours after receiving it (yay me!). I have to do a hard-reset and need a few pointers.
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13th February 2013
Old 13th February 2013
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Metal ESQ-1 filter supply checks

Quote:
Originally Posted by Silverfish View Post
Results:

Black: +11.84V
Green: -12.00V
Here we go...

That "+12V" looks a bit low. Yeah...I know it's in spec - still bugs me though. Could you do me a favour and carefully check if the tab on that black transistor is hot ? If so, both the transistor and the related Zener could be toast.

Also, check ALL five fuses on the main power supply board. A single open one will turn one of the full-wave rectifier bridge into a half-wave. This will introduce some hum into the output, You probably would have noticed that, though.

Before we go on, here's a little background on the circuit...

The metal ESQ-1 main board power supply is similar in function to the SQ-80 supply I described earlier. Regulated +/-12V is reduced to a regulated +5.2V/-6.8V. However, the execution is just a little different. Each half of the unbalanced main board supply is made up of a transistor, Zener diode, resistor, and capacitor. No regulator IC is used.

I found two metal ESQ-1 schematics online. However, the image quality is meh and they contradict each other. So I drew my own schematic - it's attached. Use it as a reference for the troubleshooting that follows.

So lets start with the positive supply...

Look for the black transistor you tested before. The leads from back to front are emitter, collector, and base. With reference to analogue ground, the emitter is +6.8V, while the base is +7.5V. Please don't measure the collector; a meter probe can easily short it to the base or emitter. This would pump 12 Volts straight to the CEM3379s - not good. Besides, the collector is internally connected to the metal tab; you already measured 11.84V there.

- If the emitter and base voltage is near zero, the 7.5V Zener diode has shorted; replace it. Make sure the 300 Ohm resistor hasn't failed, as well.
- If the emitter and base voltage is near zero AND the transistor is hot, both the Zener and transistor have shorted; replace both. Also replace the 300 Ohm resistor if it looks burnt.
- If the emitter voltage is low, AND the base voltage is OK, the transistor has failed; replace it.

For the negative supply, look for the green transistor just below the black one you just tested. The leads from back to front are emitter, collector, and base. With reference to analogue ground, the emitter is -5.2V, while the base is -6.0V. As before, don't risk measuring the collector lead in these tight quarters; replacement CEM3379s are hard to find. Collector and tab are internally connected; you already measured 12V there.

- If the emitter and base voltage is near zero, the 6.0V Zener diode has shorted; replace it. Make sure the 300 Ohm resistor hasn't failed, as well.
- If the emitter and base voltage is near zero AND the transistor is hot, both the Zener and transistor have shorted; replace both. Also replace the 300 Ohm resistor if it looks burnt.
- If the emitter voltage is low, AND the base voltage is OK, the transistor has failed; replace it.

I've included part numbers and designations for nearly all the components on the schematic. These are ones that I'm pretty sure are correct. I was not able to confirm the transistor part numbers so I did not include them. One of the schematics I found online call out MJE-172 and MJE-182 for the transistors. However, that can't be right as neither part has heatsink tabs like the ones on your board. So if one of your transistors has failed, you will need to look for the number on the device itself.

Good luck !
Attached Thumbnails
ESQ-1 help-ps.png  
#14
13th February 2013
Old 13th February 2013
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Is anyone out there familiar with hard-resetting the Esq-1? I need to do this to mine. It says to jump CR1 to C1 on the metal cased version. I can see a C1 and CR1 on the left side of the board near the power supply, but I'm not sure if they are the only C1 and CR1 inside this thing and I really don't want to screw something up here.

I sent some nasty sysex to it last night in error and though it boots and displays the OS version, after that screen all functionality is gone and the patches are all messed up. It's not the battery as it was just changed and this happened immediately after transferring the sysex to it.

I appreciate any help, kinda ticked off right now. This is the 2nd time my presonus interface has sent garbled sysex to something.
#15
13th February 2013
Old 13th February 2013
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Hey chem...

I can help you after work. However, I can tell you this much right now...

- In the procedure you mentioned, hold the shorting jumper in place only for a second or so. Just leaving it there will probably drain the battery.

- If you have the oldest version of firmware, a reset will revert all of the internal patches to "BRASS1".

BTW...I don't own an ESQ-1 - just two SQ-80s and two ESQ-ms. So I need to dig a bit before I can give you much useful metal ESQ-1 info.
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13th February 2013
Old 13th February 2013
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Hey waveform:blue,
I got a hold of Rainer Buchty and he said that with a few different board revisions out there, I could seriously screw over my ESQ-1 by doing the jump and he suggested the only way to do this safely is to just disconnect the battery for a second. Luckily my battery was recently replaced with one that has solder tabs, so I should be able to handle it. I have the latest OS. I'll give it a go when I get off work. Fingers crossed, I just got this synth yesterday and it's minty mint. I won't be using that interface for sysex transfers anymore.

Edit: Noob question, does it matter which side of the battery I disconnect or should I disconnect both sides?
#17
13th February 2013
Old 13th February 2013
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Doesn't matter which side.

Good call from Rainer, BTW.
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13th February 2013
Old 13th February 2013
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Success

Desoldering one side of the battery and connecting it again reset the

yAy

Thanks for the assistance.
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#19
14th February 2013
Old 14th February 2013
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Okay. I had a chance to measure the voltages. Here are the results.

Black Emitter: +6.89V
Black Base: +7.47V

Green Emitter: -5.59V
Green Base: -6.16V

I'm a little bit baffled. Your move, Waveform:blue.
#20
15th February 2013
Old 15th February 2013
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My esq-1 has also been flipping out lately kinda. Froze a couple times, and last night the lcd display went out, with the board still functional. It worked after turning off and back on though.
#21
15th February 2013
Old 15th February 2013
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GODAMMIT ! Gearslutz ate my post TWICE ! Work sucked too. I'm gonna get pissed early tonight. Here are some thoughts before I'm blotto...

You found good power on the main board supply. Time to look elsewhere.

Toward that end, how about a hard reset. As mentioned before, the safest method is to briefly disconnect one side of the battery. Warm up that soldering iron !

Did you say ALL the envelopes don't work ? I ask because envelopes 1 - 3 are in the sound chip, whereas envelope 4 is with the panning and resonant filter in the SSM3379. Please check envelopes 1 - 3 by assigning obnoxious values that can easily be heard.

Don't worry if this doesn't pan out. I've a few moves yet to play. We are going to troubleshoot a TL081 op-amp, AD5724 ADC, and 74LS377 next.

But now...alcohol.
#22
15th February 2013
Old 15th February 2013
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For the non-working envelopes, may be obvious, but have you set them to a modulator with the values up?

Asking because you've just recently got it so maybe you didn't know.. but then what do i know about your knowledge
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#23
19th February 2013
Old 19th February 2013
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Reporting back after being away:

It seems just Envelope 4 is bad. The others are working fine.

I'm going to do a hard reset via battery removal tonight, so we'll see where this takes us.
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#24
19th February 2013
Old 19th February 2013
  #24
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Hard reset has no effect. :(
#25
4th March 2013
Old 4th March 2013
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Heeey Silver. My turn to report in...

Apologies for the late response. I’ve been underground for a while - about a mile underground, actually. I work with mining vehicles. There have been some bugs in the design I’ve had to work out. I’m going back under next week. Wireless coverage is notoriously bad in a coal mine, so I’d better help you out now before you buy a new keyboard.

Take a look at the attached photos. One of them is a PC board for the metal-case ESQ-1. Please verify that I’ve correctly called out those three ICs. If I got that right then we can get started.

The other photo is a partial schematic of an SQ-80 I originally got from the Rainer Buchty site. I’ve combined the important bits from two pages. It’s not an ESQ-1, but close enough. Just ignore the part designations, although the part numbers will be correct.

Now here’s a little background so you won’t be testing in the dark…

The SSM3379 filter/VCA chips are completely analogue. As such, they also require analogue control voltages for the filter, resonance, volume, and L-R panning. Problem is, just about everything else in the ESQ-1 is digital. Ensoniq designers bridged this gap by using several circuits to convert digital signals to analogue control voltages. One of these circuits has failed in your ESQ-1.

The AD7524 is a digital-to-analogue converter IC. It takes the digital control signals from the ESQ-1 data bus and converts them to the corresponding analogue control voltages. The output is “conditioned” by a TL081 Op-Amp IC. From there, the signal is multiplexed by a bank of SSM2300 ICs. These route the control voltage to the filter, resonance, volume, and panning inputs on all eight SSM3379 ICs.

Something has to synchronise SSM2300 multiplexers so the control voltage is sent to the correct inputs on each SSM3700 at the right time. A 74LS377 decodes this information from the address bus and forwards it on to the multiplexers.

So in short…

The AD7524 and TL081 convert digital data signals to a varying analogue control voltage.
The 74LS377 and SSM2300s route that voltage to the control inputs of the SSM3379s at the right times.

Time to troubleshoot some ICs ! All measurements reference to analogue or digital ground…

AD7524 - Pins 1 and 2 should be at or near zero. If either is high, the IC is probably bad. Otherwise it could be the TL081.

TL081 - Pin 6 will average about 2 VDC. The voltage is constantly varying, so you will also be able to measure between 0.5 and 0.8 VAC. Playing a few keys will make it change a bit. If it’s stuck low or high - or there is no AC component - either the TL081 or the AD7524 is bad. Replace the TL081 first (cheaper and easier to find).

74LS377 - Pins 2, 5, 6, 9, 12, 15, 16 will average between 2.0 and 2.5 VDC. Because these are digital pulses, you should also measure about 1.5 to 2.0 VAC. Pins 9, 12, 15, and 16 will average about 3.5 to 4.0 VDC. These are also pulsing, but you will see less than 0.5 VAC because they are high most of the time. If any of these outputs are stuck low or high - or have no AC component - the IC is probably bad.

Juuust in case you don’t know…here’s how to find IC pin numbers. Look for a notch on the chip and orient so it’s on the left side. The lower left corner is pin one. From there the pin numbers go up as you go counter-clockwise. The last pin will be in the upper left corner, right above where you started.

As always, try not to short adjacent pins. Doing so on these ICs probably won’t kill the ‘board, but it may crash it.

Good luck !
Attached Thumbnails
ESQ-1 help-esq1_metal_pcb.jpg   ESQ-1 help-schematic.png  
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#26
7th March 2013
Old 7th March 2013
  #26
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Okay! I've finally gotten around to testing the board again, armed with the information you provided. Results: I think it's a bad 74LS377. The DC results were a bit high on this chip, and the AC results were quite low, as in almost zero.

So with that in mind, I'll track down one of these chips, replace it, and see how it goes.
#27
11th March 2013
Old 11th March 2013
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Quote:
Originally Posted by Silverfish View Post
Okay! I've finally gotten around to testing the board again, armed with the information you provided. Results: I think it's a bad 74LS377. The DC results were a bit high on this chip, and the AC results were quite low, as in almost zero.

So with that in mind, I'll track down one of these chips, replace it, and see how it goes.
Hey Silver...

I'm above ground again. I just saw this post. Could you tell me which pins on the 74LS377 were "a bit high" on DC and "almost zero" on AC? What were the voltages you got? Pins 9, 12, 15, and 16 will have a low AC component - perhaps "near zero". Also the type of meter may make a difference. Mine is a "true RMS" digital meter. Just want to be sure you don't replace a good chip.

Oh...I assume measurements on the other chips are OK. Is this the case? If all chips measured out wrong, the problem is elsewhere.
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#28
14th March 2013
Old 14th March 2013
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Okay. I'm back with new results. I'll post below. As for my multimeter, it's an Extech autoranging unit, so I hope that'll work accurately for something like this.

AD7524
1. -51mV DC, 0 AC
2. -50mV DC, 0 AC

TL081
6. 2.084V DC, Average= .38V AC

74LS377
DC RESULTS
2. 2.73V DC
5. 4.7V DC
6. 4.7V DC
9. 4.67V DC
12. 4.68 DC
15. 4.7V DC
16.4.71V DC

AC RESULTS
2. .087V AC
5. .084V AC
6. .081V AC
9. .082V AC
12. .081V AC
15..081V AC
16. .081V AC

So there you have it. Any thoughts on the results?
Silverfish
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#29
14th March 2013
Old 14th March 2013
  #29
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Edit. Double post.

Last edited by Silverfish; 14th March 2013 at 05:06 AM.. Reason: double post
#30
15th March 2013
Old 15th March 2013
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OK...I think you nailed it. Just do me a favour with a couple of more checks on the '377...

The chip-select input on pin 1 should average about 4.2 Volts DC. A small AC component of maybe 100 milliVolts will be there, as as well.

Pin 11 is the write enable. I'm getting about 2.5VDC average. It's pulsing too fast to get a reliable AC reading.

If these are OK, the 74LS377 is probably toast. Replace it then start making some choons
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