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problems with Dick Sniff's cheap 10Mhz CRO

B

Bob Parker

Would not surprise me if the original unit came out of the factory like
that. QA on such low cost units is almost non-existent, it's a lucky
dip. Same deal with those el-cheapo multimeters, many of them have
faults out of the box.

Dave :)

Not just cheap instruments either. Back when I was servicing audio
gear, it wasn't uncommon to have a brand-new CD player with an up-market
brand name not function straight out of the box.... because a ribbon
cable hadn't been plugged in.
I recently bought a generic 512MB USB flash drive. Completely
erratic operation which often made Windoze Explorer freeze.
Final testing? What final testing? Let the customer see if it works.

Bob
 
B

Bob Parker

It may certainly well have been, do you know for sure it was working
before DSE sent it?

Of course I can't say for certain that it wasn't already damaged,
because I wasn't there. If I was there, I'd have brought it home in my
car and none of this would have happened. But...

(1) The bloke who sent it me has been a mate for longer than you've
been alive. He'd never do anything like that. He's willing to sign a
Statutory Declaration that the CRO was working and was not damaged in
any way before he posted it.

(2) The side the CRT was shattered on was facing the top of the
case. To me it looked like that's the side the impact was on.

(3) There was absolutely no evidence that the CRO's metal case had
impacted onto anything while outside its carton. No dents, deformation
or anything, top or bottom (or anywhere else).


What was the packing like in the orginal CRO box?

Standard moulded styrofoam, more than adequate to protect against
*reasonable* transportation shocks, I'd have thought.

The photo to me shows a rather small original box, and not what I would
call teriffic packaging outside it.

In the light of what happened, obviously the packing wasn't
sufficient to protect against what it was subjected to. The sender
wasn't anticipating the kind of rough handling the carton received.


I recon you simply ran out of luck Bob, or perhaps this scope
construction has a particular weak point, shock or vibration wise?.

Yep, I sure ran out of luck. As you can see in the photos, the CRT
has protective rubber mounting rings around it. Maybe the impact
"waveform" which broke it was right at the glass's resonant frequency?


As I have said before I have shipped many fragile items including CROs by
Australia Post without any problem what so ever. But then again I am
*really* paranoid about packing.

After this, I'm going to be too!! I'll only use Aust Post as an
absolute last resort in future. I saw a posting on a newsgroup from
someone who packed up some china plates really carefully, with each one
wrapped in cloth.
After Australia Post had transported them, most of the plates were
broken. That person was as amazed as I was, at AP's ability to break
things.
I bet you didn't write "Fragile" on anything you sent, which seems
to be an invitation to them to drop the article from as high above the
floor as possible.


Aust Post are no worse than the likes
of other courier companies in my experience.

What annoys me more than the damage is the many-weeks-long
beaurocratic run-around I got afterwards, and Aust Post's attitude of
"No care and no responsibility taken".
As a last resort, a couple of months ago I wrote to AP's NSW Manager
about all this, as their website suggests. Never got a reply. Maybe the
letter got broken in transit? :)


Bob
 
P

Phil Allison

"Simple Simon the Congenital MORON "
Hit the nail on the head.


** Simon is an absolute fuckwit.

Nails driven into his pointy head cause no pain.


Wish I had hours to troll newsgroups :)


** You have just convincingly proved that you do - fuckwit.

Piss off to hell !!




.......... Phil
 
S

Simon

Some poeple don't have the time to pop into a DSE store, could easily
waste an hour of your time, and to some people that's valuable. Often
easier and cheaper to get something posted.

Hit the nail on the head. Wish I had hours to troll newsgroups :)
 
S

swanny

Bob said:
Not just cheap instruments either. Back when I was servicing audio
gear, it wasn't uncommon to have a brand-new CD player with an up-market
brand name not function straight out of the box.... because a ribbon
cable hadn't been plugged in.
I recently bought a generic 512MB USB flash drive. Completely erratic
operation which often made Windoze Explorer freeze.
Final testing? What final testing? Let the customer see if it works.

Bob
Connect the output of the manufacturing line straight to the input of the
plastic packaging line ...
 
J

jasen

Yup, this shows the issue (excuse the quality)

http://www.chrome64.org/CRO.jpg

Im a complete noob with a CRO btw, so excuse me if its something really
dumb :D

Look in the instructions for the bit on adjusting the compensation...
there's a small screw near the plug end of the probe cable.
(it's on page 7, if you've lost it you can download a pdf from DSE)

The artwork shows vertical lines on the display, in real life there won't be
any because the electron beam is being re-targeted too fast for enough
electrons to hit the part between the upper and lower lines and light it up.

(aside to phil)
The drawings in this manual are the same as the
ones in the "digimess" 10Mhz scope manual on farnell's site,
the schematic is similar to the one DSE sent me too.

Did they send you a bearly readable one, mine looks
like it was a fax that was scanned by a monkey.

Bye.
Jasen
 
J

jasen

No, thank you!


I played with the compensation, but without a decent sine to adjust
against its a waste of time.

nah adjust on a square wave, even a badly malajusted probe will produce a
perfect sine on the display if you feed one in at the tip. so testing with a
sine is pointless.

Bye.
Jasen
 
J

jasen

Of course I can't say for certain that it wasn't already damaged,
because I wasn't there. If I was there, I'd have brought it home in my
car and none of this would have happened. But...

If you try to post anything that rattles (I did that once) Aussie post
have you sign a special ticket that basically says it was laready like that.
In the light of what happened, obviously the packing wasn't
sufficient to protect against what it was subjected to. The sender
wasn't anticipating the kind of rough handling the carton received.

DSE NZ don't use NZ post for shipping their scopes, IIRC they use DX
or possibly UPS.

Bye.
Jasen
 
B

Brian Goldsmith.

What annoys me more than the damage is the many-weeks-long
beaurocratic run-around I got afterwards, and Aust Post's attitude of
"No care and no responsibility taken".
As a last resort, a couple of months ago I wrote to AP's NSW Manager
about all this, as their website suggests. Never got a reply. Maybe the
letter got broken in transit? :)


Bob


***Er,why didn't you take out the $2.50 option and register the thing for an
agreed value?

Brian g.
 
P

Phil Allison

"jasen"

(aside to phil)

** Said in a theatrical whisper ???

The drawings in this manual are the same as the
ones in the "digimess" 10Mhz scope manual on farnell's site,
the schematic is similar to the one DSE sent me too.


** DSE emailed me some schems that appear identical to the Caltek and
Digimess ones.

However, the input stage of the vertical amp is not accurately represented
on any of them.

Did they send you a bearly readable one, mine looks
like it was a fax that was scanned by a monkey.


** DSE do actually employ monkeys - AFAIK.

That is just an ugly rumour.





....... Phil
 
B

Bob Parker

***Er,why didn't you take out the $2.50 option and register the thing for an
agreed value?

Brian g.


Because this was sent by Registered Post which supposedly includes
insurance of $100.

Bob
 
P

Phil Allison

"Brian Goldsmith."
***Er,why didn't you take out the $2.50 option and register the thing for
an
agreed value?


** Would make no difference.

To claim on the insurance, the item must either become lost in the post or
suffer visible damage though apparently appropriately packed.




....... Phil
 
P

Phil Allison

"Phil Allison"

Correction:


** DSE do NOT actually employ monkeys - AFAIK.

That is just an ugly rumour.




....... Phil
 
B

Bob Parker

To claim on the insurance, the item must either become lost in the post or
suffer visible damage though apparently appropriately packed.



...... Phil

Yep. It doesn't matter if they smashed a carton full of
carefully-packed china or the CRT in an oscilloscope by dropping the box
flat onto the floor from 6 metres up in the air, if there's no obvious
external damage then clearly the contents were already smashed when
posted and you're making a false claim. That's their attitude anyway.
 
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