Mechanical problems that need sorting before the electrics or will recur.

Each channel has 2 "daughter " board output arrays with power rails via the
aluminium hex bar standoffs. One end has the screws nicely soldered on to
the main board conductor traces, but these standoff boards just screwed
against polyester pcb board, no star washers, contact (in theory) is on the
other side of the board, but not with loose screws. This amp is used in
alternately both damp and dusty environment so inside looks more like 20
yearold, aluminium corrosion etc.
Any mod better than cleaning faces and adding star washers ?

Also the clinch nuts that hold the pa boards away from the top and bottom
covers are just clinched into pcb polyester so easily turn and work loose,
any mod for that ?
are they called clinch nuts in USA ?


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

Meat Plow wrote in message
...
On Fri, 10 Jul 2009 17:12:08 +0100, "N_Cook" wrote:

Mechanical problems that need sorting before the electrics or will
recur.

Each channel has 2 "daughter " board output arrays with power rails via
the
aluminium hex bar standoffs. One end has the screws nicely soldered on to
the main board conductor traces, but these standoff boards just screwed
against polyester pcb board, no star washers, contact (in theory) is on
the
other side of the board, but not with loose screws. This amp is used in
alternately both damp and dusty environment so inside looks more like 20
yearold, aluminium corrosion etc.
Any mod better than cleaning faces and adding star washers ?

Also the clinch nuts that hold the pa boards away from the top and bottom
covers are just clinched into pcb polyester so easily turn and work
loose,
any mod for that ?
are they called clinch nuts in USA ?

Would be nice to see some pictures of what you are describing. Appears
though that it's a more modernized and moderately redesigned
incarnation of the old CS series amps. Your mods sound reasonable.
Don't know quite what you mean by clinch nuts.


This amp is 30Kg in weight and because the clinch nuts are so small and
flexible top panel, so close to the pcb, someone has post-factory lined the
panel with sticky thick plastic sheet. You cannot extend the "nuts" without
modifying the single internal bracing metal (full-on engineering).

Clinch nut
http://imgs.tootoo.com/1c/30/1c301bb...6ca0f5266b.jpg
fine if the bolt is pulling the clinch into the polyester but here, with
movement (not used in racking) and flexing can pull these clinches
out/loosen them.

I'm thinking anvil , flat-head steel screw threaded-in to protect the
aluminium and then ground down tip old cross-head screw driver hex-bit
hammered on the internal aluminium ring to deform 4 points out into the
polyester, on all the clinch nut/standoffs.

For the daughter boards, longer screws and star washer under the heads. And
non-ferrous star washer on the electrical side between aluminium pillar and
lead'tin/copper, but stainless steel or chromed brass for this position ?

schematic is at eeserviceinfo

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

Anyone familiar with the diac+triac circuit in each cnannel? that eeservice
schematic is not clear enough on interboard links.
The cut-out is just a thermo-electric self-conained mains overload cutout

looks as though the diac/triac is for crowbar protection of the speakers
from DC fault developement in the amp. On the assumption the mains trip will
trip.
Anyone know how to test these ? disconnect the output and put some DC there
and see what happens, who much DC for a 1KW, 2 ohm speaker bank rating ?

I've now taken this amp apart. There was one zinc plated nut with captive
star washer , loose inside, causing trouble. Now I've found another one,
lodged safely, in the base. Can I find where these 2 have come from ? -
anyone been here before?. They are loose fitting ,32 TPI , on the other
0.128 inch screws used inside , so presumably 6UNC. As this is in the UK,
unlikely 2 would have fallen in the fan access , in a metric-screw UK.
Exactly these style nuts are used elsewhere in the amp , but the next size
smaller. Most screws in there are tapped clinch nuts or chassis steel.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

1 of the 2 nuts holding the IEC socket was off. I wondered why the owner did
not hand me the "lump of metal" that he discovered wedged in an active area,
he probably dropped it trying to retrieve it, from a visible but awkward
place. The screw was in place , with a tight fit , not threaded, through the
IEC. Owner out of contact for a few days, so stymied , in case I'm inferring
too much, ie 1 nut only.

The found nut had no sputter or smoke marks unlike the pcb.
Re-clinching with a ground down cross point driver bit and anvil etc, worked
well, retapping with 4UNC , because of the corrossion rather than any
deformation by my action.

More accidents waiting to happen, presumably because this amp is used
outdoors at full 2KW whack. Not only the screws holding the daughterboards
to the pillars but the pillars to the soldered-in-heads mainboard screws
undid in the range of 0.1 to 0.2 N-m , presumably due to creep of the pcb
polyester. So presumably a generic problem for all these sort of Peavey
amps. So 3 stainless steel star washers each on these active pillars, longer
screws and laquer over the exposed screw heads.

The hex pillars have been cut with star patterns on the ends which just
grind into the polyester on tightening. So I've changed my mind to abraid
the pillar ends , 3 st/st crinkle washers , longer screws and laquered heads

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/