I've just won one of these on eBay and was wondering if anyone knew anything about them. I understand that Custom Sound (in Pudsey in Yorkshire) was taken over by FAL (Futuristic Aids Ltd) but nothing else.
It is SS with 2 2N3773s in the output and is supposed to be 65watts. It has a 15" speaker which is like new, but has no markings on it. It has had the back stove in but sounds OK. No idea when it was made.
Does anyone know anything about these and where I can get a circuit for it, although it probably wouldn't be too difficult to trace it out.
Tony.
Don't know anything about them myself, pictures would be immensely helpful.
This is the one.
Just dismantled it and trimmed back panel with Jigsaw. Removed the power amp from the bottom of the cabinet - oh dear what a mess underneath. Looks like a few repairs have been done. Power transistors mounted on a 2mm Aluminium bracket to the STEEL chassis. Not a lot of heat transfer there. Looks like I may have to make a new PCB and I will then fit a proper heatsink. Not surprising there have been so many repairs, I expect the original output transistors were 2N3055s not the 2N3773s in now.
Managed to trace out the power amp circuit - attached. Note no thermal compensation. :'( Circuit common arrangement for the time. Must have been thousands built of similar design used in disco amps etc. I've repaired a few.
Also photographed the front and rear of the power stage PCB. Repairs appear to be consistent with overheating failures Probably more than once - tracks lifted etc.
Found final examination sticker on Preamp board - March 1984.
Will trace out Preamp next.
Tony
I'm in a dilemma now. Do I rebuild this as is with its inherent thermal problem, or do I add thermal compensation and a proper Heatsink? This would make it more reliable but wouldn't be original any more.
BTW the Power supply gives out 63 volts unloaded
I would rebuild it with a proper heatsink etc. It's the "right" way to do it in my book. But I personally would want it to work properly rather than be in "original" build quality - some may not agree there.
I belive these amps date to early 1980's. I was not aware of FAL acquiring Custom Sound, as far as I know Custom Sound was still running as is about the same time when FAL went down under, which would have been app. mid 1980's. I'd be interested to learn more about this if you have some further info.
I wouldn't really worry about originality, unless that is what you're after. I think its a quite long stretch of those things ever becoming collectable or museum pieces revered for original condition. Rather just make it a tool that can take the abuse it's supposed to withstand.
Quote from: tonyharker on August 23, 2011, 06:45:06 AM
Managed to trace out the power amp circuit - attached. Note no thermal compensation. :'( Circuit common arrangement for the time. Must have been thousands built of similar design used in disco amps etc. I've repaired a few.
Also photographed the front and rear of the power stage PCB. Repairs appear to be consistent with overheating failures Probably more than once - tracks lifted etc.
Found final examination sticker on Preamp board - March 1984.
Will trace out Preamp next.
Tony
the power transitors are indeed 2N3055's as I have one myself and just checked them :)
A long shot, but worth a punt
I just picked up a 4 Channel Custom Sound Trucker amp.
just wondered if any one here happed to have repaired one of these? ..have a traced out circuit diagram for them
Not even opened it up yet ..so it maybe a sinmple fix..but just getting prepared
I cant post a picture at the moment,
Start by describing what real problem does yours have ;)
I have not powered it on yet myself, but previous owner says that not even neon power switch comes on. Also some vague reference to it 'not sounding right before it died'
He assured me basics like fuses have been checked.
The 'not sounding right comment' made me think possibly something in output stages died, then perhaps taking power supply with it.
As I said, not even got around to opening it up yet. I was killing time yesterday at work, waiting for a job to come at my day job ( standby for air ambulance) so I started searching around for info /schematics for this amp.
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That reasoning is flawed. Not sounding right could be ANYTHING, after all everything in the amp is part of it making sound. It could have an output problem or a preamp problem or a power amp problem, or most anything.
I agree with Juan, FIND OUT what the amp does wrong, then we can form a good troubleshooting plan. if the power light doesn't even come on, it still can be many things. If the switch has a neon lamp in it, then likely your main power is interrupted somehow. if it is an LED, then we know it is going to be powered from secondary side voltages.
And we can never rule out coincidence. It could have died at the same time it was sounding bad, though the two things are unrelated.
And any experienced tech knows, you NEVER take the customer at his word. Find out on your own what it does wrong. He assured you all the basics have been covered. But we have no idea how accurate that is. He may THINK he covered all the basics, but that doesn't make it so. Fuses have to come out and get measured with an ohm meter. Fuse holders (with fuse in place)and power switches have to be checked with ohm meters for function. Continuity through the power cord must be checked, as well as checking the power transformer primary for opens. None of this requires a schematic so far. With any luck we never get as far as needing a schematic.
Thanks for taking time to reply.
I do know all of the above.
Is it so wrong to wonder if anyone has a schematic ?
I'd still be looking for one even if it worked 100 %
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The bigger picture is that you have some work to do by tracing the circuit out if you want one. But hey at the same time you get to learn something so it's a win win. In the meantime if you want it fixed the Gents here will be more than happy to help someone who is willing to learn.
My thoughts would be a Dimbulb tester then if the preamp and power amp are separable by a connector halfing the amp to narrow down.
nosaj
Tracing myself is not the issue, I am sure this unit will not be covered in SMD's .
I usually do a rough paper sketch first then transfer to... umm damn... the Mac App I use has skipped my mind, but I transfer to a computer based schematic.
The sound 'changed' over a short period of time, while the rest of the kit was unchanged, so he says.
Still not got home yet to open it up and take a look.
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Farther up the thread that you attached to show someone else's work, best to verify before using it. But if yours is identical to the pics (power board), then it shouldn't be too inherently hard for you to do.
Start with disconnecting the Power transformer from the board and see if you are getting any voltage from there. All this figuring you have checked the fuse.
i used to want to have a schematic for everything sort of a roadmap of sorts, but sometimes you have to forgo one and trudge on with research or help. Pictures help best, and you can use skitch to anotate.
nosaj
Welcome to the forum.
No, it is not wrong to ask for a schematic.
Since we do not know you yet, we cannot assume any particular level of skill and experience. One thing a lot of people do is stall in the absence of a schematic. My point was aimed at suggesting there is a lot that one can do without schematics in most cases.
And the secondary point was that it makes more sense to plan the operation after determining just what the thing needs in the first place.