pmiller056

A very long time ago I did a lot of repair work on hybrid TV sets, so I'm aware of the hazards of working with this style of circuit. There's no obvious damage to any parts on the PCB. I'll follow up Tim's suggestion later today. For my next steps, I'm inclined to trace the circuit sufficiently to work out what the various supply voltages should be. Rather than use a bench power supply, I'll use 'lump in a cord' power adapter(s) as a temporary supply(s) because the commonly found ones are double insulated and will have sufficient isolation in an all-insulated case to try using the dimmer pack as intended or off an isolation transformer reasonably safely.

Hi This is what appears to be one of the later versions of this product with an LED display and pushbuttons for configuration. There's power onto the PCB, all fuses are intact. The Triacs and power control parts are live. The display and control electronics are dead. My first line of investigation is the on-board SMPS that drives the control electronics. The SMPS 'brain' is a Power Integrations TNY274 which has the switch transistor and controller in the one package. The microcontroller driving the triacs is mains live. The DMX side of things is on an isolated supply with an optocoupler to the microcontroller. I have an isolation transformer, so I can use a 'scope if needed. In the first instance I want to know a bit about what goes where before I start work on it, but a full drawing would be ideal.

Hi. Does anyone have an internal circuit diagram for this 12 channel, 4A per channel dimmer pack to share? The PCB is marked NJD NJ942 Rev 5. They were also sold as a 'DPX 12/4' dimmer pack. It's to help a (registered charity) local community theatre repair their non-working one. Thank you.

IPA is flammable. There will be an IPA mist around the cleaner during and after use which will be easily ignited by a stray spark, such as a switch operating. IPA fumes won't do you any good. If you really have to use IPA in an Ultrasonic cleaner (I would not), then you need to use it in a really well ventilated area.

There are updated versions of the '8 pin Bulgin disco light connector' available which have much better shrouding of the socket pins. The product range now also has cable mounting plugs and sockets with much better cable clamping arrangements. Panel mounting plugs are available to stop the need for plug-plug leads (ugh!). It can be a lot of work to update these connectors, but if you have something old you wish to keep going, it is a sensible change. Unfortunately, there are still a lot of the old connectors in warehouses and in use.

Because this adapter has been widely available for a long time and is affordable as a 'first buy' for a beginner, there is chatter about these in other lighting-related online forums about them. Can you get this adapter to work with different DMX control software? There are some useful tips about getting this adapter to work on the QLC+ website (free to download and use). Use the correct USB drivers, taking into account if you are using a 32 or 64 bit version of your operating system. There appear to have been a few different versions over the years. Make sure there is sufficient power from the USB host - if necessary, use a powered external USB hub. Reliability problems may be fixed by reducing the DMX refresh rate and the DMX universe size.

The wiring loom may be faulty. In the first instance, trace the wiring back and check that the hall effect signal is getting to the relevant connector pins on the controller PCB. With any moving head fixture, after a lot of use, cores in the loom will break where it goes through and around moving parts, twisting and turning as the fixture operates. When this happens there can be many intermittent, varied and weird faults to find. If this is found to be the case, the effort and cost of repair will likely be uneconomic on such a cheap fixture. Budget fixtures tend to use internal wiring that will not survive this use for long.

The circuit diagram I have says 100k Ohm for this one. This pot is in the feedback circuit around an opamp, not (more conventionally) directly in the audio path. I don't know if it is a linear or log potentiometer.

If the venue is part of a chain of hotels, they likely to have a requirement as part of their conditions of hire that any drapery provided by the hirer must be be flame retardant. If this is not a required by their entertainment licence, then it will be required by their insurers. Drapery/curtains as well as soft furnishings used in any hotel room where people sleep should be flame retardant anyway, so the requirement will most likely apply over the whole hotel site. Unfortunately, you will need to find another supplier who has a better understanding of your requirements.

The Philips lamps linked to dim correctly from off to on, both ways. No flickering, popcorning or 'step' at low brightness. The dimming curve takes a bit of getting used to - it is noticeably 'S' shaped. The dimming curve is very flat around 'off' and 'on' and steep in the middle. They work well and correctly with an all-led load on the SCR dimmer in use. The filter inductor in the dimmer no longer buzzes like it used to! Please thank @sandall for directing me to these lamps. These lamps are less than a year old, so I've no idea how well they will age. In our case, they are in open fixtures so heat related ageing should be minimal.

The community theatre I work with has successfully swapped their tungsten GU10 houselights to LED, retaining the SCR/Triac dimmer. The following post has relevant information. https://www.blue-room.org.uk/topic/77016-small-theatre-house-lighting-update-suggestions-anyone/#comment-603906

My choice would be (my employer's) Weller W101. Big chunky tip that holds lots of heat and can heat a joint quickly before the heat 'runs away' up the wire being soldered. Much lighter and less tiring to use than a 'gun'.

In an installation with a mains electrical supply present, I would reasonably expect to find green/yellow coloured cable cores to be used as the safety earth/ground connection and never for any other purpose. If a green/yellow core in a cable is used for another purpose (even in a SELV application), it should have another colour sleeve fitted over it to show that it is not being used for an earth/ground function.

I'd be very wary about using 3d printed replacement plastic parts without understanding more about the end-use application and materials used for both the original and replacement part. Most 3d printed plastics will soften, potenetially deforming at relatively low temperatures. Plastics used in the construction of electrical/electronic equipment will have well understood and deliberately chosen flame retardant or self extinguishing properties - does the (unknown) plastic used for the replacement part have the same or better properties? For me the risks and potential liabilities of this approach for equipment used in a public place or for commercial gain are not worth it.

I'm of an age where I learned my technical drawing and design skills with a drawing board and T-Square. There is a big shift in mindset required to use modern 3d design software. My original learning was to use lines, circles, triangles, rectangles etc as the elements to construct the needed item. With 3d design software the design elements to build your 'thing' are spheres, cylinders, cones, cuboids and so on. Once I got my head past that, progress was quicker. Being able to view your design from any angle in 3d is great.