AC1 component layout

[James Bailey]

Hello and Happy New Year to all after a long time away.

Haven't actually gone anywhere, just not had the time to participate in the goings-on here.

Anyway, unfortunately the gear had to go back in for repair recently as one channel was off. Wiggling the cable between AC! and AP3 would cause some response but never permanent, and with lots of hum. I tried contact cleaner and reseating the cable a few times to no avail.

The shop, after some investigation, says it may be something internal but aren't sure of the component layout on the board. I seem to remember some mention of this being available somewhere so was wondering if I could obtain some sort of copy for them. Any help would be greatly appreciated.

Thanks folks.

James Bailey

[John Mayberry]

Go to www.lecsonaudio.com.

 

Should be there.

 

 

Happy New Year as well,

 

John

 

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[Spiny]

there is a service manual for the AC1 on the site with a full circuit
diagram

alan

On Jan 8, 3:16 pm, "John Mayberry" <emm...@emmaco.com> wrote:
> Go towww.lecsonaudio.com<http://www.lecsonaudio.com/> .

>
> Should be there.
>
> Happy New Year as well,
>
> John
>
>   _____
>

[Spiny]

here is the link
http://lecsonaudio.com/wp-content/uploads/2011/10/Lecson-Technical-Service-Manual-AC1-and-AP1.pdf
I'd right click the link and save the PDF

spiny

[Stephen]

Hopefully it is something simple such as a cold solder joint.

On 8 jan, 12:30, Spiny <t...@allthingsspiny.co.uk> wrote:
> here is the linkhttp://lecsonaudio.com/wp-content/uploads/2011/10/Lecson-Technical-Se...

[Gordon Campbell]

Hi James (from another lurker…)

 

My AC1 has been languishing for months at a repairer for what seems like the same reason as yours. I wonder if it’s the same place as he told me he had 2 others in a similar position. Its Armstrong Hi-Fi on Blackhorse Lane.

 

The guy there told me last month that he had a circuit diagram but not a board layout and that he needed the latter and was gradually creating one by cross referencing photos of both sides of the board with the circuit diagram.

 

I have no idea about these things so the above might not be quite what he said…

 

Does the above make sense? If so is there anyone that can help?

 

Cheers,

Gordon

 

From: lecson...@googlegroups.com [mailto:lecson...@googlegroups.com] On Behalf Of James Bailey
Sent: 08 January 2012 14:01
To: lecson...@googlegroups.com
Subject: AC1 component layout

 

Hello and Happy New Year to all after a long time away.

--

[Spiny]

hi
There never was a board layout in the Official service manual. As far
as I know no one has created one either I'm afraid.
There may have been some in the factory for stuffing the boards, Stan
would know. Don't think they escaped though :(

I'm afraid you just have to look, compare, measure and use the service
manual and your experience

alan


On Jan 9, 9:02 am, "Gordon Campbell" <gor...@tslmail.com> wrote:
> Hi James (from another lurker.)

>
> My AC1 has been languishing for months at a repairer for what seems like the
> same reason as yours. I wonder if it's the same place as he told me he had 2
> others in a similar position. Its Armstrong Hi-Fi on Blackhorse Lane.
>
> The guy there told me last month that he had a circuit diagram but not a
> board layout and that he needed the latter and was gradually creating one by
> cross referencing photos of both sides of the board with the circuit
> diagram.
>
> I have no idea about these things so the above might not be quite what he

> said.

[Gordon Campbell]

Thanks Alan.
My AC1 has been there since May last year and I still have no idea whether
it will ever get fixed, but I don't know of any other option, so there it
stays....

[Spiny]

:(

[Spiny]

the AC1 was innovative in its day using fet switches - and these cause
grief to repair shops as they are rarely come across.
and then there is the magnets, anyone who has had these fall off knows
the problems getting them back in the right place - wrong and switches
can open/close in the wrong place.

the fets (2N3819's mainly but others will do) run on a -19 volt line
for cut off, this needs checking. Untoward noises hiss etc can often
be traced to a leaky fet (I replaced a couple in mine a decade or so
ago (maybe 2, time passes) the effect was a strong hiss and
distortion. The rest of the circuit is actually fairly simple. A
signal generator and a Scope will usually spot the problem tracing the
signal in until it stops at a FET usually.

Depends on the symptoms but from the description - check all the FET's
first - or even blanket replace them, they are cheap CPC do them at 6
to 8 pence each in small quantities for example.

Alan

[organstan]

On Jan 9, 6:55 pm, Spiny <t...@allthingsspiny.co.uk> wrote:
> There never was a board layout in the Official service manual. As far
> as I know no one has created one either I'm afraid.
> There may have been some in the factory for stuffing the boards, Stan
> would know. Don't think they escaped though :(
>

There was indeed a board layout drawing. An A3 photocopied sheet
taped onto a piece of cardboard. There were 3 or 4 drifting around
the factory.

I don't recall the layout ever being copied or sent out; nobody ever
asked for one to my knowledge. Most service technicians of that era
could trace the circuit pretty quickly

Stan