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IanB

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About IanB

  • Birthday 02/06/1966

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    Northampton, UK

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  1. Small "further to" what @pianokeyjoe just said, the CT can operate as 4 synths in one (same number of voices, divided into 2 poly and 2 mono synths) and you can write to the edit buffer on all of them so repatch them all using their separate MIDI channels. The rhythm section also operates on a separate MIDI channel. So the CZ schematics offer help, but there are various differences as we already have seen.
  2. Hello everyone I'm just having a read of this thread (haven't paid attention as my day job is intense hours wise at the moment). Nothing to add but all most interesting!
  3. People still love the CZ synth engine, and I've also been baffled since 1982 or whatever as to why they never developed the VL-1 (VL-Tone) further. It was like they never realised what they had.
  4. I've submitted version 1.12 to the Microsoft Store which fixes this bug and it should become available for download shortly once they've validated it. You should get an update popup when you launch the app once the certification is complete🙂 This is one of those bugs that has me wondering why nobody ever noticed/reported it before! Thanks for your helpful feedback @Bay Mud😃
  5. @Bay Mud Thanks for pointing it out, it's amazing how one can spend ages writing an app and miss obvious things until somebody points them out. Then you wonder why nobody else has🙂 This appears to be that bad habit of programmers counting from zero, so you go 0, 16, 32, 48 but when you're counting from 1, as with patch numbers here so it's 1, 17, 33, 49... I'll sort this out and post an update to the Microsoft Store over the next few days.
  6. Hi @Bay MudI'll have a look at this and get back to you. First impressions here is that it's a goof on my part! 1+32 is 33, not 32, oops!
  7. Excellent comments from Chas above. The RIFA looks ok (they normally fail apocalyptically) and aren't required for circuit function anyway (you can just remove it if you want tbh, it's there to comply with regulations basically). It certainly won't work with missing fuses!
  8. So here is what I'd likely do: connect your meter, measuring voltage, securely to the output of the 7815 voltage regulator- you may have or may need to obtain crocodile clips that slip onto the multimeter probes. Starting with the main board disconnected, turn the power on. You should be reading -15V. Now plug the main board in and see if the voltage drops straight away to zero.
  9. Hi @Rookierafa are those resistance readings? This isn't something I'd really be checking at this stage. I'm speculating at the moment that there is a short circuit somewhere on the main board causing the negative regulator to shut down. Likely culprits would be either a physical solder "bridge" somewhere (have you soldered anything on the main board?) or a capacitor or possibly transistor which is short circuited. Try doing a continuity test on the main board, while it is unplugged, between the incoming regulated voltage rails and ground. If either is shorted (it "beeps") that will be useful although it probably won't be that simple. It's a bit strange that this all started with the PSU suppression cap blowing but that might be a red herring; possibly blew open circuit years ago.
  10. A good Easter to you also @Rookierafa and I'm sure we'll get this sorted. Will post more thoroughly later (just got home from work, rather tired) but two types of transistor are "ordinary" bipolar ones with the base etc and FETs with drain etc. The power amp has its own supply that doesn't run through the 7815/7915 regulators. It's the outputs at the top of the PSU diagram on the right labelled +VA and -VB on the diagram (but apparently +VA and -VA on the actual PCB.
  11. OK so that's progress. As I said previously, the 7815 will shut down if it sees an overload/short on its output (they are well designed to avoid blowing up). So likely there is a short on the main board somewhere. This might be a physical short circuit, or may be a failed capacitor, transistor or some other component. I'm about to head out to work but I'll take another look at the circuit diagram this evening when I get home. The power readings on the main board will be doing strange things because the negative is basically disconnected when the 7815 is in shutdown.
  12. Hmm. The output of the fuse, the capacitor and the input of the 7915 are all directly connected on the circuit diagram so should all be at the same voltage, it's the -VCC fuse. You said you have measured the voltage at the fuse but didn't mention checking the fuse itself. Is this voltage at both ends (i.e. is the fuse good or blown)? If you have your 27V at the fuse out terminal, then either the PCB track is damaged or the 7815 has a dry solder joint. Take out the fuse and check its continuity with your meter. With power off check you have continuity from the fuse terminal to the 7915 input (centre pin) and also to the capacitor's -ve terminal (I assume it's the capacitor nearest the 7815). Can't think of anything else to suggest right now...
  13. Ok, so it looks like you have no output from the 7915 you replaced (it's a voltage regulator not a transistor btw). Check what voltage you have on its 3 pins. The input is the centre one (2) the output is the right one (3). Is it bolted to the case or a heatsink? Its metal tab is connected to its input so if the heatsink is not isolated or it's bolted to common metalwork it should have an insulating washer. If it has no input, check the fuse before it and the bridge rectifier before that (feel free to post a photo of it). You probably have +15V on both pins of the op amps etc because there's not voltage supply on the negative supply pins at all so the +15 is just backfeeding through them. Also note that the 7915 has internal short circuit protection so it may be fine, but is shutting itself off due to a short circuit on its output, so it may not be the culprit but we will start there. If you can disconnnect the PSU outputs from the other board(s) to check the voltages that would be useful to do for that reason. If there's -15V on 19/brown when it's not connected to anything else, the problem is further down the circuit...
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