Jump to content

posty07

Regular Members
  • Posts

    65
  • Joined

  • Last visited

Previous Fields

  • Member Status
    Working in the industry
  • Current Employment or place of study
    Mobile Disco and Teesside University
  • Full Name
    Adam Postgate

Contact Methods

  • Website URL
    http://sldisco.webs.com

Profile Information

  • Location
    Durham

Recent Profile Visitors

The recent visitors block is disabled and is not being shown to other users.

posty07's Achievements

Full-timer

Full-timer (6/14)

  • Dedicated Rare
  • First Post
  • Collaborator
  • Conversation Starter
  • Week One Done

Recent Badges

  1. Hi all, Trying to identify the attached damper part - I see them on a few different scanners but have never managed to find any replacements other than direct from the manufacturer. Anyone know what these are called/where to buy in the UK? TIA Adam
  2. Hi all, Probably unlikely.. but I'm trying to source an entire top half of an inno scan LED. Does anyone have maybe a broken one lying around that I could purchase? Thanks!
  3. For the LED? It's 5v 18a The main board uses 12v 8a
  4. Hi All, I've bought replacement barrel mirror strips for a barrel lighting effect, but they don't come pre-assembled in any way. They will be rolled around the metal disc at one end but they are just held by tape or glue at the other end.. My question is, does anyone have any experience with this and what did you use as the "tape/glue"? The Chauvet rep I spoke to suggested carpet tape but I've no experience and don't fancy buying it if it's not going to work Cheers!
  5. Ah that makes perfect sense, thanks! In that case they're all working as they should after mosfet (and thermal pad) replacement surgery. Thanks again for your help on this!
  6. Hi @DrV I've now replaced with the new exact replacements and it's working perfectly. Both sets of current sense resistors are getting ~100mv. One thing I'm a little concerned about is the MOSFET driving voltage is different for each one and my thought is maybe the LM358 is damaged and not outputting the full voltage.. is this likely? So measuring the LM358 we have: Vcc: ~5v In1+: ~0.9mv In1-: ~0.9mv Out1: ~4.8v In2+: ~0.9mv In2-: ~0.9mv Out2: ~3.6v Am I wrong to assume there should be a much lower voltage drop?
  7. So, I was doing a bit more measuring now I'm familiar with the proper operation of those 2 chips and turns out even the "working" one had a problem. Dry joint on the drain of one of the MOSFETs was causing it to dim slightly too because the current sense resisters weren't getting anything. Fixed that and I can now see that those replacement MOSFETs are just not letting through enough current at all. I'll update once the new ones are in! Thanks for all your help so far
  8. Yep that worked perfectly, the dim one is only getting 23.5mv whereas a good one is showing 100mv. However the dimmer one is the one that I've replaced the MOSFETs with the wrong or at least different ones. Is this likely the issue? I'd guess this will happen if the gate doesn't get enough voltage to turn on enough?
  9. I finally get it! Thank you for your excellent explanation, that's genuinely really helped me. So to test this I'm going to need a scope aren't I..?
  10. AHH I think I get it. So when the 393 is 'off' it is floating but when on, the output shorts to ground..? Because of this, the current sense should be low, so the 358 turns off? Have I understood that correctly?
  11. So if the 393 is outputting high, then the 358 also outputs a voltage to drive the MOSFET? I really need to do some more research on these circuits as they're confusing me slightly!
  12. There is a Shunt regulator.. not sure if that's the same thing - but no ramp generator. As far as I can tell this isn't using pwm to dim the LED. Seems to be current limiting instead, perhaps to ensure flicker free? I'm no expert so I'm not exactly sure but that's how I've understood the circuit.
  13. Yes I think it is, I've checked the pot and it's working well. The 3 pin connector comes from a control board which gives it a 5v power, ground and a control PIN which seems to change voltage to control the brightness - which I'm guessing is what the comparator circuit is for
  14. Thanks I will - to be fair most of that burn was there already as these appear to get very very hot.. The IC on the right is an LM393 and left is LM358. Both double op amps which appear to be working. Though I'm having trouble working out how the output is calculated using the 2 inputs.
  15. A few photos of the board. I've swapped the MOSFETs on this one for a similar spec but I've since realised that their fully 'on' voltage is a little higher. To me this circuit seems to not use pwm to dim the LED and actually seems to use current limiting using the MOSFETs.. of course I could be very wrong. I'm waiting on exact replacements so hopefully they will do the trick as the led is now brighter, but not completely full, with these replacements. P.S. ignore the missing pad underneath.. too much heat applied - it doesn't connect to anything as it's the pad on the top that connects to its trace
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.