lulu_joe

OK. Guys and gals. Reseated chip. I socketed it when I replaced. Turned synth back on while pressing p. All better! Didn't put all the case screws back in yet though just in case. TX. Again. JoeF.

Doh! Solved one and another problem just showed. Oh well, going to catch my breath before I attack this again. Turned off and on a bunch then sealed it up, programmed a patch and when I came back and turned it on it powers up and all the lights come on, the display remains blank and no sound or controls work. I tried repowering with P button pressed but nothing changes. JoeF.

Hello and thanks to all. IanB you got it! Put in a new 4011 and we are playing again. Cool sounds already. I love this synth. JoeF.

Hello all. I rechecked K and it is low when the power supply is plugged in and low when the unit is switched on, then high when switched off. It does not fall. It just stays high until the unit is switched on again. K and pin 13 and 12 are in the same state always. And pin 14 is sitting at right around 5V. Pin 7 is 0V. I am ordering a couple 4011s. JoeF.

I will recheck K and all I reported today though I am confident of today’s readings. But, if I probe the pins of the 4011, pin 11 is not always the opposite of 12 and 13. And it should be if it is a NAND. Correct? Also, not to be too big a nudge. But, if I need to find replacement transistors where can I find a cross reference. And, is 2sc17400 the same as 2sc1740? Tx. JoeF.

Hey there, I am reprobed some things because as I said originally I had never used an oscilloscope as a test instrument before, merely entertainment when looking at audio signals. But, I think I have made a breakthrough for this problem thanks to all your help but particularly you IanB. If I short 4011 pin 11 with 10 the unit shuts OFF! Pin 10 is low. But, as you said the 4011 is suspect. Pin 11 and 12 both go high and low as the on off button is pressed. High when off, low when on. Pin 11 never changes. K goes low when plugged in. High when the unit is turned on and low when turned off. L is low when plugged in. Goes high when turned on and stays high when turned off. I know I shouldn't be complaining when I still have a job to go to, since most of my friends got shutout Mon., but I just want to stay home and solve this puzzle and make killer bass sounds with this synth again! Thanks again. JoeF

OK. More probing. M went high when powered on but never came down or produced the downward pulse. D never comes down after unit is turned on E goes down but never back up Again, thanks for looking. Any suggestions? JoeF.

I did try the APO switched on and the CZ stays on. I will try those other tests once ASAP. To. JoeF.

Where do you see this? Quadrant F,4 on card MA2M. I can’t find it or the zener diode? JoeF.

Hello. So I probed the additional points that folks suggested. A works as expected. B did not pass. Plug in and turn on it is Low. Press off and it goes High. Turn on again goes Low. F Goes High when switched on and stays high until unit is unplugged. G Plug unit in and turn it on, this goes High and stays high until unplugged. Thanks for looking. Any clues? JoeF.

All, thanks again for the input. I will look at the schematic a little tonight. Too late and too tired to test. I will report back ASAP, though. JoeF.

To answer the question about the audio relay. It was faulty. Not completely open or closed. The volume would fade in and out as you played the keyboard. If you knocked the pcb you’d here crunching distortion. The new relay fixed all that. I think it’s a component around T6 or T7. It’s the signal from the 4011 pin 11 that is not going low. The logic from input pin 12 and 13 is not right. I don’t understand how the transistor logic works well enough to know exactly whether it’s a diode or rc cell. JoeF.

Hi all. Thanks so much for the advice. Workday so I only had a bit of time to look at my synth. But, I checked the switch using continuity and it is fine. It is not the switch. I will carefully read everyone’s comments and make the checks at points A and B. Then report back as soon as I can. Is there any ez check for caps in circuit or do I have to remove them to check them? Diodes? JoeF.

Hello all, I have been making progress in that I am learning how to trace and test with my Oscope. I have found that at test point “L” the state never goes low once high. So, I traced back to location J which passes the test. But, at test point K the voltage goes high as it should when the unit is switched off but it never falls back down. I am thinking I should remove caps in this vicinity and check them? Thanks. JoeF.

OK. Unfortunately, on the CZ-1000 these old ribbons are soldered. I did check the continuity on the pins. All is good. I am looking at the schematics and next to the amp/power board are alphabetical test points(?). I have an oscilloscope but have never used it to troubleshoot. I have only played with it to look at audio signals for fun. One test point, “L” is NMI which looks like a shutdown signal on pin 8 of the ribbon. I am going to probe that and see if I can see it occur. The guest bed room is getting pretty cluttered as the tools get moved from my smallish workbench. Ha! Thanks again. JoeF.

Thanks for the response. I have puhed the reset. I will check the switch function I see there are several switches made on the switch board. Then look into tracing the connections from the switch to the board. I have replaced the relay because it was bad. I couldn't find the actual component and used a recommended replacement. But as far as I can tell it only handles audio. I am concerned that I have burned something out from using a too powerful Wallwart(9v regulated but 2A). I have a 9V, 850ma one now. But, the symptom is actually as you describe. The main board isn't getting the signal to shut down and is running on memory backup power or something? I can change settings as if the unit was still on. JoeF.

Hello, my CZ-1000 lights and display stay on after power is switched off, but the sound stops. When I unplug the power supply or remove the batteries the lights and display and on-off indicator light go out and stay out until the on button is pressed. Then the unit powers on and functions normally, and again when I press the button to turn the unit off, all the lights stay on. Any idea where to start troubleshooting? Thanks. JoeF.