20th June 2012
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#1 | | Gear interested
Joined: Jun 2009
Posts: 16
Thread Starter | Soundcraft series 1s-refurb help/advice
Hi,
I'm attempting to refurb this thing. It used to work quite well-few channels had a couple of problems, intermittencies but generally ok and sounded nice, hence my refurb attempt. (I also have a series 1 not a 1s btw, which is a bit different) This post is for the 1s.
yesterday I turned it on and no audio was passing on any output though lighting functions worked ...and yes i tried changing cables, other chanels, insert etc..
All signs seem to point to it being a prob in power supply-according to some research. What to do?-I'm sort of a novice with electronics (ive changed caps, ic's, repaired a few things, modified some pedals etc here and there but still have trouble with some things- however with some advice I'm confident enough.
Oh- the p/s caps appear to be original and don't have any visible signs of cap wear but if they were bad would this affect the entire unit in not passing any audio at all? I know that bad, leaky caps in p/s would be humming and noisy but no sound at all? I know in a past situation changing an electrolytic on one of the channels brought said chanel back to life. I know people are going to tell me to replace all the caps, which I might eventually do but first I'd like to get it all working. It was almost all good before this episode.
please excuse my ignorance
Cheers and many thanks.
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20th June 2012
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#2 | | Lives for gear
Joined: Oct 2006 Location: Toronto, Canada
Posts: 811
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Yes, probably the power supply. I haven't seen one of these since the 80's so I can't remember if the supply is internal or external. To fix this, at the very least you are going to need a DMM (digital multi-meter) to measure voltages and check parts. Speaking of voltages, there are POTENTIALLY LETHAL VOLTAGES IN THE POWER SUPPLY, so be careful, and / or get some help from a tech.
Best,
Ike
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Ike Zimbel,
Zimbel Audio Productions Ltd.
Toronto
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"Studio House Calls". Authorized Warranty service for Allen & Heath, Clear-Com, Drawmer, Soundcraft, SPL and Yamaha. Repairs and upgrades to analog audio equipment including: AMEK, dbx, Neve, Neotek, MCI, Soundcraft and more. Ask about our RF frequency co-ordination services! www.zimbelaudio.com | |
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20th June 2012
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#3 | | Gear interested
Joined: Jun 2009
Posts: 16
Thread Starter |
yes it's an internal p/s. I'll add a schematic for the hell of it. I'll also add some pics later on- just because. This is supposed to be an ongoing learning experience for me and I'm quite sure about the ongoing part of it.
I have a multimeter, an old oscilloscope (though I'm still learning how to use it) and a signal generator.
Cheers
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15th November 2012
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#4 | | useless frog
Joined: Jun 2010 Location: Alsace, France
Posts: 183
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Hey, too bad I just noticed your post I have been refurbing my 1s at the same time you posted. It wasnt working at all when I got it, a huge buzz in the headphones, VU's peaking all the time. No apparent wear from the caps. 
First I killed every elco or so cables in there to see clearly, I don't need the elco connector in my studio use. I changed every electrolytic cap including the ones in the power supply (total approx 150 caps), and cleaned every switch, pot and fader with F-gas and then lubed with a mix of deoxit and mineral oil with the help of a syringe and a needle. I then changed the pad resistors to have 40db of attenuation instead of 20 so I can now use tham as line inputs. (This is the transformer input version). I soldered direct outs in place of the inserts from the pre-fader solder points on the PCB. Finally, I fit carnhill output transformers to the octal-base output transformer slots. The mixer now works fully, the pre's are great and have enough juice to use a SM7 for vocals, and the line summing is just as you would expect with LOTS of headroom (this beast seems to never clip). The overall noisefloor is very low (pre's and summing). If you want the manual and schemo's with transformer octal base layout drop me a pm !
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"Lots of units are more flexible than the PCM70. An Alesis Quadraverb has quad raverbs: that's 4 times as many raverbs as other leading raverbs . It sounds like 4X crap. " - Eganmedia
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15th November 2012
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#5 | | Lives for gear
Joined: Mar 2010 Location: Brooklyn, NY
Posts: 538
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If possible, disconnect the power supply from the rest of the board. Check internal fuses (if any), then turn it on and measure voltages. I don't know about the 1S, but the Series 1 has a single voltage rail IIRC. If you have schematics the voltages should be on there, perhaps even some test points with voltage readings. No voltage or wrong voltage means the PSU needs work. Be sure to check for AC on the DC lines as well. If the PSU tests OK disconnected, reconnect and see if the board works (might have been a bad connector). If not, then the board is pulling the power supply down and you will have to try disconnecting each channel until you find the culprit.
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21st November 2012
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#6 | | Gear interested
Joined: Jun 2009
Posts: 16
Thread Starter |
got the p/s working again...turned out the fuse holder just needed to be cleaned! Now to fix some channels and other things
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