KevinE

I have a disco-style subwoofer here with a faulty amp module. It's been to another dealer - who have removed the SOIC14 PWM ic before giving up.

I wonder if anyone knows what it should be? The possibilities are endless......

Quote

I've seen (heard) that problem when the Vcc supply cap for the IC was dried out

I'd have hoped the engineer who repaired the board had changed this routinely. 🧐

2 minutes ago, KevinE said:

Crikey, does sound loud. 

Have a look at this one, see if it will go in. It is nominally 27V and will crank up past 28V on the main output. It also has a 12V 0.5A 'fan supply'. 

rs meanwell smpsu

PS..take the RS specs with a pinch of salt - they're up to standard as usual. The datasheet says it is a 120W version as suggests the part number, and although it is described as having a 'single output' the datasheet also says the 120W version has a supplementary 12V fan supply

Crikey, does sound loud. 

Have a look at this one, see if it will go in. It is nominally 27V and will crank up past 28V on the main output. It also has a 12V 0.5A 'fan supply'. 

rs meanwell smpsu

from memory, these Kam bars do whistle loudly when all the lamps are faded up to max. If you do a chase, the power supply sounds a bit musical. Unless you think it's excessive, and the 28V stays fairly steady throughout, I'd say it was ok. 

If you'd rather change the board I'm sure a 24V psu with adjustable output would go up to nearly 28V as they are sometimes used to trickle charge lead-acid batteries at 27.6V. You could piggy back a 1A 3-leg switching regulator off the main output for the 12V if they share a common 0V.

If all else fails you might be able to use a bolt-on flange adapter mounted to the rear of the horn maybe.

ebay link

A very earnest video but I'd be worried as the importer about liability, particularly with regard to the electrical safety of the design (let alone the quality control) , which may not necessarily be apparent until something major has already happened. Western branded chinese lights will have spent considerable time at testing labs in the UK or Europe before being put onto the market. Things like creepage & clearance, high-pot testing of the SMPSU transformers, flammability of the plastics used - you're only going to discover these little gotchas when the thing catches fire or shoves 230V up your DMX chain. 

I know a batch of chinese lights (I dont know the supplier) where they were all sent out with the earth wire not connected at the fixture end. I've personally seen all-steel enclosures with an IEC inlet with only 2 wires coming out of the back, that sort of thing. 

I haven't heard of anything recently but if a brand owner decides your lights could accidentally be mistaken for some of theirs, you're going to get a letter from their solicitor. 

Quote

, is it worthwhile trying to release and re-crimp the IDC?

they're a 1-shot thing, recrimping might make it worse. ISTR the headers are proper pcb-mounted receptacles with latches. Some Mackies also have cable-mounted receptacles in addition though I dont know if that applies to yours.

If you dont have any luck cleaning your noisy gain pots I might have some on a scrap panel, I think they're probably specials knowing Mackie. 

you may be lucky rearranging the cables but the fault is usually the connection between the cable and the IDC portion of the connector that goes intermittent. And that's quite a few pins!  

I've just ran the 'download to 2510' program from Martin to load a 2510 with 20 sequences. No problem there.

I've saved it as a .b25 file in the default Martin folder on my C drive, it appears in the file list in the martin program and I can use it and it works. 

However I want to save a backup in my 'D' drive which is my files store. But, I can't navigate to it in W10 File Explorer. It does not appear. 

It is there in my 'recently used' section, and I can right-click and 'copy' it, but when I try to 'paste' it in my D-drive, I get an error 'file not found'.

It also won't appear in a windows search.

Is there a work-around or is it just an older file that (yet again) W10 can't cope with?

😃Well, I sorted it this morning. 

Probing the PFL multiplexer IC7 on the faulty module showed the output that feeds  the left channel was not sitting at zero but about 0.5v.   Selecting PFL caused the IC rails to offset by a corresponding amount which then slowly drifted back to 0. Changing the multiplexer IC7 effected a cure. 

I'm ok on that score thanks! I'm working over tonight and have made progress. I've pulled out all the I/p modules and just used one as a tester - (a mono/mic channel) and it still did it. So, desultorily, I took the the test channel out and put the next one to hand in instead, and that did not cause a pop! So then I fitted the other channels, a mix of mono and stereo line back in, until I had every module PFL'ing without a pop. As you can imagine, when I fitted the one channel I'd been using for testing - it made all the other PFL switches 'pop'.

It's this one mic channel causing the problem.

It has been worked on before. Most of the fusible resistors have been changed; usually a sign of op-amp trouble; however all the op-amps are original. I'm beginning to wonder if an op-amp had failed, maybe gone DC and taken the fusible resistors out. They've been changed by A.N.Other - but the faulty chip is still there.

Mass chip probing and probably changing will come on the Monday, had enough for today. I'll report back for anyone interested!

I'm trying to track down a slightly obscure fault on a Soundcraft Series 10 broadcast desk.

When any PFL button is pressed, the PFL works fine but there's a POP through the left headphone and also the left PPM meter kicks hard over for an instant. It's only the left channel.

The fault can be seen on the PFL 'L' bus that serves the modules. 

AFAIK, pressing a PFL button does 2 things: it sends a  logic signal to the master section which controls the audio routing to whatever's selected to monitor the PFL (pres phones, studio phones, studio monitors, control room monitors,  etc).  And then it places the pre-fade channel signal onto the PFL L&R buses.

The PFL action is working fine, everything is routed to the proper places and L&R audio finds its way through where it should. 

Just a POP !

Anyone had experience on these? I havent....

I don#t want to sound too northern but the closest I've got to onsite catering has been receiving vague directions to the nearest chip shop

I've had a go in the past fitting a capsule into the original plug-in module but it did not sound acceptable. I'll ring Showcomms but I think if its no longer on their stock list then it means it's no longer available.

I need a replacement capsule for an SKM100 handheld. It's discontinued by Sennheiser. Does anyone have any soruce for aftermarket ones, or a lead on any uk stock? It's the sort with the long body and plugs in. Be a shame to scrap an other wise good transmitter. It's for a pub singer.

are the ballasts from the same fixture manufacturer or did you source generic ones from aliexpress etc? The ones with fewer chokes might have omitted the PFC correction maybe.

I think the ispot150 was a genuine coemar product made in Italy. These are getting a bit old nowadays!

I've had a few mains RFI filters go bang in Robe fixtures, replacing them effects a cure. I think they probably use metallised paper capacitors inside which can fail short circuit if they've lain for any length of time without power.

not sure if this is overkill but the Showtec TR512 is ideal. It can also be remote mounted and controlled from a wall plate button panel.

https://www.showtec.co.uk/onlineshop/index.php?route=product/product&product_id=997&search=tr-512

I'm insured through a broker, Marsh Commercial, who have supplied me with both Axa and Zurich policies. Marsh are pretty flexible with what they will and wont include on a policy.

probably varistors, (MOV's). Their job is not to go short but to 'absorb' transient overvoltage spikes, however they have their limits and will split or go short if they do fail due to such overload. Hopefully that will be the only problem and they can be replaced (typically a 230VAC fixture will use 275VAC rated varistors) but do make sure that's what they are and not something like an X or Y class suppression capacitor. Replace like for like!

The last time I had some little roundish blue things fail in a Martin was in a MAC and they were capacitors in the electronic ballast. The IGBTs in the PFC circuit had also failed.

if the pump's giving grief I'd bung a new one in, about a tenner aren't they? I think the valve sticking is due to degradation of the rubber o-ring which causes the ball to stick to it.

Just wondering if anyone knows the going rate for renting an ongoing parking space/operating centre  for a single 25ton curtain sider> UK Midlands rural. 

Crickey, I didn't know they'd gone into liquidation. (jan, 2021 apparently). I ordered a replacement neutron star heater off them last month (sept) which arrived, as per usual, next day.

I think the G300 is a smoke machine BTW rather than a hazer?