Author Archive

Kramer VP-725DSA Repair – Part 1

January 2nd, 2013 No comments

I’ve acquired another bit of hardware that was heading towards the skip – a Kramer VP-725DSA Presentation Switcher/Scaler. Its problem is that it no longer responds to any of the buttons on the front control panel, and is permanently stuck on DVI 1. When controlling it via its network control application, it does respond to the virtual button presses, but then almost immediately jumps back to its previous state, and intermittently does a factory reset.

First up I whipped out the front control panel PCB and checked out the DVI 1 button. The button checks out as I had suspected, and I turned my attention to the switch mode power supply (SMPS).

The four voltage rails (+5, -5, +15 and -15) all tested fine, but on further inspection the resistor R3 looked rather crispy. Even with no load attached to the output of the SMPS, the resistor gets pretty hot. I’ve tested the resistor out of the circuit and it reads 75K, which is what I guess it should be. The colour bands are rather cooked – currently purple, black, brown, gold, but they may have originally been violet, green, orange, gold.

For now I’m going to focus my attention on the SMPS, as I suspect there’s some issue with its output which is upsetting the rest of the unit – excess ripple, noise, etc. I’ve just got to track down what is pulling excess current through R3. I’ve emailed Kramer to see if there’s a service manual available before I start poking around further. I guess that one of the electrolytic capacitors is out of spec, but there’s no visible problem with any of them.

To be continued…

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Theatre Rigging Refit – Part 3

August 7th, 2012 No comments

The first stage of my rigging improvement program is complete – i.e. raising the upstage roll-drop support framework.

It took a lot longer than I expected to complete this stage, as a lot of time was spent tweaking and re-tweaking the alignment of the three support struts. I’ve also redone the hanging points for the existing ‘hemp’ line-set above the framework, and installed a new additional line-set. Lastly I’ve installed a length of Unistrut on the end wall, which will replace the timber rail that is still there at the moment.

Next the ropes and pulleys on the roll-drops themselves need to be replaced, and new cloth fitted, as there’s far too many layers of paint on the existing ones. After all that the roll-drops can be reattached to the support framework.

A lot to do before production begins on panto in another couple of weeks!

Categories: Projects, Theatre Tags:

Theatre Rigging Refit – Part 2

July 31st, 2012 No comments

I’ve made a reasonable amount of progress so far. The roll-drops are down, the fan heater is gone,  the cyc is now supported independently, and the Unistrut has been removed.

Tomorrow I’m hoping to get the Unistrut refitted in its new position, and at the weekend I hope to get some new Unistrut bolted above the pin rail.

I need to try and get the place tidied up for a free hire that we’re giving on Tuesday, so I want to get as much completed as possible in the next five days.

Categories: Projects, Theatre Tags:

Theatre Rigging Refit – Part 1

July 23rd, 2012 No comments

This month’s project is to sort out some of the rigging above the upstage area of The Little Theatre’s stage.

The existing upstage rigging consists of three pieces of Unistrut at 4m above the stage, from which are attached five roll-drops (also known as oleo or olio drops) which are used for back-drops.

I have a few issues with the current installation:

  • Firstly the tops of the roll-drops are below the level of the lighting bars, which means the border that is used to hide the rolled up drops casts a very noticeable shadow.
  • Secondly, and more importantly, the rope and pulleys that have been used up until now are far from appropriate.
  • Thirdly a number of the fixings used to suspend the Unistrut are less than ideal, i.e. Coach screws and M8 set screws, some of which are loose or just look rough because M10 nuts have been used as washers.

The ultimate goals of the project are to raise the Unistrut supports by 0.6m, taking them to about 0.5m above the lighting bars, and secondly to replace all the rope and pulleys on the roll-drops. The roll-drops already need new cloths, so we’ll be fitting larger ones anyway.

The current plan for the next few week is as follows:

  1. Order additional Unistrut, fittings and fixings.
  2. Completely remove the roll-drop assemblies from the Unistrut.
  3. Remove a 4KW fan heater that’s in the way on the SR wall.
  4. Install new supports for the cyc screen, as it currently hangs from the ends of the Unistrut, but it must remain at the current level.
  5. Remove the Unistrut and all associated studding (threaded rod) and fixings.
  6. Remove the pulleys that are used to install and remove the roll-drop assemblies from the Unistrut.
  7. Refit the Unistrut at 4.6m above the stage using M10 fixings through-out, with each set screw passing completely through each supporting timber, with a hefty 50mm washer on either end, complete with spring washer.
  8. Refit the pulleys so the roll-drops assemblies can be later raised back onto the Unistrut, but this time have two different mounting positions so it’s more of a vertical lift.
  9. Install Unistrut about 4.4m up the SR wall, above the pin rail using M10 Rawlbolts, so the new head blocks (pulleys) have something more solid than a piece of timber to be attached to.
  10. Replace pulleys and rope on the roll-drop assemblies.
  11. Raise the roll-drop assemblies back into place and attach to Unistrut.
Categories: Projects, Theatre Tags:


May 6th, 2012 No comments

After getting my CCNA back in March, I decided to go with my Linux tendenacies and study for a LPIC-1 certification. Two months and two exams later I finally have the cert.

I didn’t find it too difficult, but then I have been playing with Linux for over 18 years! Nonetheless I did still learn quite a few things so it was definitely worth while doing. For the first exam (101) I scored 770 out of 800, and for the second (102) I scored 780 out of 800.

A bonus of getting LPIC-1 certification is that you qualify for a Novell Certified Linux Administrator certification as well.

I’d now like to get a LPIC-2 cert as well, but first I’m going to study for MCITP: Server Administrator on Windows Server 2008, which requires three exams – 70-640, 70-642 and 70-646. This should keep me out of trouble for a few months!

UPS Repair – Part 3

March 29th, 2012 No comments

New relays have been fitted, the unit reassembled, and powered back up. So far everything looks good, but I won’t know for sure if the problem has really been fixed until I get some under or over voltages, but I’m fairly confident of the repair.

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UPS Repair – Part 2

March 24th, 2012 No comments

I’ve stripped the UPS down and removed the main circuit board. After a quick examination I identified four likely relays and then extracted them for testing.

Relay R406 had a high resistance across a couple of contacts, so this looks to be the AVR relay. One of the other relays (I forget which) also sounded a bit tired when I was testing it.

What I plan to do next is replace all four, since I’ve already gone to the effort of removing them. The original relays are Song Chuan 793-P-1C-3. I’m going to replace them with Omron G2R-1-E 24DC from CPC. I’ll get them ordered up within the next few days, and hopefully have it back together before the end of next week.


Categories: Projects Tags: ,

UPS Repair – Part 1

March 23rd, 2012 No comments

I’ve a small project that should keep me occupied for a short while. I recently got my hands on an APC Smart-UPS X 1500VA (SMX1500RMI2U) which was heading to the skip. It had been replaced by an identical unit after it had developed a fault. Needless to say it happened not long after the warranty had expired, and it was not considered worth repairing.

The issue with this UPS is an “AVR Relay Weld” fault. Hopefully this should be an easy fix, assuming I can get a replacement relay, once I identify the exact offending component.

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My CCNA Cisco Lab

March 16th, 2012 No comments

Here’s a quick overview of the equipment that made up my Cisco CCNA lab, before I pack it away for a while.

Starting from the top:

  • Cisco 2611 with a WIC-1T
  • Cisco 2611 with a WIC-1T
  • Cisco WS-C1924C-EN
  • Cisco WS-C2950T-24
  • Cisco WS-C2950T-24
  • Cisco 2503 with Allied Telesyn 10BaseT transceiver
  • Cisco 2503 with Allied Telesyn 10BaseT transceiver

I’ve also got a Cisco 1721 with a WIC-1ADSL sitting at the back of my desk, acting as my primary ADSL router. At some point I’ll increase its memory so I can install an IOS that supports IPv6, as my ISP (Entanet) does offer this.

Hopefully I can dig this equipment out in another 4-6 months and begin working on a CCNP. Before that, however, I’ve got some other certs I want to get, starting with a LPIC-1.


March 2nd, 2012 No comments

Finally after years of not getting around to the CCNA exam, I finally did it and passed with a score of 920! Not at all bad for my first ever cert, if I do say so myself…

Now I just need to decide what to study for next. I do want to get a CCNP at some point, but I’m in no rush, so I’m currently toying with the idea of LPIC, especially since I do have Linux tendencies!

Categories: Studying Tags: , ,