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DYNASAW

Sirius 24 - wonky channel 13

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Hi.

(I am new here, working as a computer programmer by day, but helping our local school running their lighting installations as an amateur for the past 8 years or so, whilst an electronics engineer friend runs the sound desks and radio mikes etc. Reasonalby electronically minded and handy with soldering irons, components etc.) Have loads of analogue racks, lights, some analogue desks, but my old trusty favourite desk partially died on night 1 of school production so looked around for replacement desk)

 

As result I have recently acquired a Sirius 24 for school setup :rolleyes: , but all working except would you believe it Channel 13 :(:(

 

Sirius 24 00-480-00, serial 0284338 (mk2 ?) with memory card slot and DMX Output; Super User indicates software level 4323.

 

on PRESETS ONLY, GRANDMASTER 100%, A MASTER 100%, B MASTER 100%:-

 

All otherchannels (1 to 12, 14 to 24) output from 0v to 10V as faders moved from 0% to 100 % as expected, but channel 13 not happy.

 

I get the following as I raise either of the A or B channel 13 presets:

 

at 0% preset = 0.28V output on analogue 13

 

From about 5% to 100% gives output of around 3.55 Volts, decaying initially by 0.01 volt per second, down to around 3.49v, thereafter slowing to decay by 0.01v every 5 seconds.

 

The Green channel 13 light illuminates but never at full brightness like the other channels, so I presume this matches the approx 3.5 volt level being output.

 

From what I can work out so all other faders and parts seem to work fine, chase programming sets up OK. Have not yet checked memory programming, as would like to get the channel 13 happy again to go with our analogue racks.

 

Anybody help with an easy solution??? :unsure:

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Please have a closer look at the main pcb. For the channel 13 are following components at the output responsible:

IC 8 ( LM 324 ), Q16 (BC547), D12 (1N4148), C17 (4n7) and SIL2 (Resistor-Array 3K3). Q16 with SIL2 are the driver

for the LED. IC8 is the OPAMP for the output voltage in combination with D12 and C17.Sometimes there is also a problem

with a bad connection from the main pcb to the Socapex socket.

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Please have a closer look at the main pcb. For the channel 13 are following components at the output responsible:

IC 8 ( LM 324 ), Q16 (BC547), D12 (1N4148), C17 (4n7) and SIL2 (Resistor-Array 3K3). Q16 with SIL2 are the driver

for the LED. IC8 is the OPAMP for the output voltage in combination with D12 and C17.Sometimes there is also a problem

with a bad connection from the main pcb to the Socapex socket.

 

Swapped LM324 (overseeing Channels 13 to 16) with an adjacent LM324 running next four channels (17 to 20). Problem has duly migrated from Channel 13 to Channel 17, so suspect the LM324 is where the problem lies, so will duly sort replacement for same. :rolleyes:

 

Many thanks for your speedy reply. :D

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Swapped LM324 (overseeing Channels 13 to 16) with an adjacent LM324 running next four channels (17 to 20). Problem has duly migrated from Channel 13 to Channel 17, so suspect the LM324 is where the problem lies, so will duly sort replacement for same. :rolleyes:

 

Many thanks for your speedy reply. :D

It sounds as though you've found the problem here. I managed to repair a Sirius 24 which was, as bought on eBay, completely non-functional. Several of these LM324s had burnt out, together with two of the 4051s feeding them and a transistor and electrolytic in their power supply. Almost as though someone plugged the output into the mains! The PCB is clearly laid out in a logical way, though, which makes troubleshooting fairly straightforward.

 

You may find it worth removing and reseating all the ICs as, over the years, the contact can become intermittent.

 

Nigel

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It sounds as though you've found the problem here. I managed to repair a Sirius 24 which was, as bought on eBay, completely non-functional. Several of these LM324s had burnt out, together with two of the 4051s feeding them and a transistor and electrolytic in their power supply. Almost as though someone plugged the output into the mains! The PCB is clearly laid out in a logical way, though, which makes troubleshooting fairly straightforward.

 

You may find it worth removing and reseating all the ICs as, over the years, the contact can become intermittent.

 

Nigel

Indeed, have already reseated all IC's at time of initial investigation.

 

Replacement for dead LM324 was 74 pence courtesy Maplin, and board now seems 100% again.

 

Many thanks for your responses.

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