Just purchased a 7854 off the Bay of E yesterday. Obviously, haven't received it yet. Pictures from the auction do not show it powered up, but the description says used but signs ofcosmetic wear, but according to the seller it is operational.

Not ever having had a scope of such complexity before, anything I need to look out for when powering it up?

Doesn't come with a keyboard, so I'll be looking for one of those. Preferably one that isn't more thanI paid for the scope. ;-)

Comes with a 7D15 counter/timer and what looks like a 7B71 time base (hard to tell exactly, picture is kinda fuzzy).

Mark

Mark,

On Sat, Jan 18, 2014 at 12:59 PM, Mark Wendt (Contractor)
<mark.wendt@...> wrote:

Just purchased a 7854 off the Bay of E yesterday. Obviously, haven't
received it yet. Pictures from the auction do not show it powered up,
but the description says used but signs ofcosmetic wear, but according
to the seller it is operational.

Not ever having had a scope of such complexity before, anything I need
to look out for when powering it up?

Doesn't come with a keyboard, so I'll be looking for one of those.
Preferably one that isn't more thanI paid for the scope. ;-)

Comes with a 7D15 counter/timer and what looks like a 7B71 time base
(hard to tell exactly, picture is kinda fuzzy).

Mark

The usual applies. When first powering it up, disconnect the PSU and
run it with loads. At first don't turn on the HV section. Once the LV
seems to work, get the HV working (everything should still be running
on loads)

Cheers,
D.

On Sat, Jan 18, 2014 at 5:51 AM, cheater00 . <cheater00@...> wrote:

The usual applies. When first powering it up, disconnect the PSU and
run it with loads. At first don't turn on the HV section. Once the LV
seems to work, get the HV working (everything should still be running
on loads)

Wow. I would have to say... don't do that. Too much work and too
much risk of messing something up, for no gain.

I have actually found 7854s to have very little power supply trouble
compared to say 7904s... but I only have 4 of them :)

On 01/18/2014 09:47 AM, David DiGiacomo wrote:

I have actually found 7854s to have very little power supply trouble
compared to say 7904s... but I only have 4 of them :)

Dang! I only have one. :-)

I disagree, it either works or it doesn't. Just check the line voltage
setting is correct (you really don't want to put 240V into a 'sope
configured for 110V), and then switch it on.

Most likely fault on these is ROM rot. Power up and nothing on the display
:(

Regards,
David Partridge

I agree too - just turn it on. At most I'd pull the covers and do a visual
inspection to make sure there is nothing clearly wrong, boards missing etc.
Like my 7104 as I collected it - the power supply was disconnected, and
there were paperclips on top of some of the boards (an attempt at
sabotage?). But that was unusual - generally a 7000 series mainframe fires
up with a few slight oddities, or the power supply goes into self-protect
tick mode.

Craig

开云体育

I count myself lucky to have one and a keyboard that works!

DaveD

Howdy,

? ?I saw the posts on this topic earlier this past week and they didn't register in my head. ?But how concerned should I be about this "ROM rot"? ?What is the cause? ?What is the cure? ?I have an old-school PROM burner. ?Can I just copy the chips?

? Do we have some statistics on how frequently it occurs? ?Chip date code ranges for bad chips, etc...?

? Dan

On Sat, 18 Jan 2014 08:47:38 -0700, you wrote:

On Sat, Jan 18, 2014 at 5:51 AM, cheater00 . <cheater00@...> wrote:

The usual applies. When first powering it up, disconnect the PSU and
run it with loads. At first don't turn on the HV section. Once the LV
seems to work, get the HV working (everything should still be running
on loads)

Wow. I would have to say... don't do that. Too much work and too
much risk of messing something up, for no gain.

I have actually found 7854s to have very little power supply trouble
compared to say 7904s... but I only have 4 of them :)

I agree about not pulling anything apart just for power supply tests especially
given that the seller says it works and just suffers from the usual cosmetic
wear. I would probably start it up though with no plug-ins installed. The
digital part of the 7854 should do its normal power on self test routines.

Is the 7904 power supply that much worse? I though it was the same basic design
and I would expect more problems with them simply because they are older.

The original mask ROMs (Mostek? Motorola?) have poor long term reliability and
not just in the 7854. Assuming you can find some 2364 pinout EPROMs, the
easiest option is to copy the ROMs to them or burn directly from the available
firmware images.

Originally I planned on using a couple of 2364 pinout to 2764 pinout converters
and 2764 or 27C64 EPROMs but my 7854 is a later version which does not use the
2364 style parts.

On Sat, Jan 18, 2014 at 6:42 PM, David <davidwhess@...> wrote:

Is the 7904 power supply that much worse? I though it was the same basic design
and I would expect more problems with them simply because they are older.

My experience is yes, since all of mine are currently broken :(

You do not need the keyboard to use the 7854 for routine storage and waveform
measurements. When it boots up, its basic functions work like any other 78xx or
79xx series mainframe.

If you want the complete experience to go with the keyboard, it may be worth
picking up a 7B87 timebase which replaces the 7B80 and allows pretrigger
acquisitions up to the admittedly slow maximum sample rate of the 7854.

The 7D15 should work fine in a 7854. I know mine does. The 7B71 timebase works
in the 7854 with some minor exceptions that you are unlikely to encounter which
are discussed on page 2-24 and 2-25 of the operating manual.

As I said in my other post, I would start by powering the mainframe up without
any plug-ins. It should execute a power on self test and report any errors. As
others mentioned, checking the line voltage setting and fuses and doing a basic
visual inspection with the two covers removed is worth doing as well.

Are the Motorola ROMs subject to the same ROM rot problems as the notorious Mostek parts?

I have recently acquired a 7854 and it has a checksum error on power-up. I opened it up expecting to find Mostek parts but found it used Motorola parts instead. The Tek part numbers (with Motorola part numbers in brackets) are 160-0408-01 (SCM92210P), 160-0409-01 (SCM92211P), 160-0410-01 (SCM92212P) and 160-0411-01 (SCM92213P). The date codes are all mid '83.

Should I replace all these ROMs or are there other likely causes for the checksum error?

Stephen

The MCM68766 EPROMs are the ones I used. The ROM images are at
and
ftp://ftp.bluefeathertech.com

HtH
Dave

I did some sleuthing online and apparently it is just the Mostek mask ROMs which
are the problem. For a 7854 it may not be a big deal because firmware images
are available but if I had an old piece of test equipment, I might pull the ROMs
anyway and back them up just in case.

Good Day,

I would never, ever power-up any used electronic equipment without performing at least a basic check. Takes only a few minutes, time well spent!

I want to make sure that all connectors are in place and there is no obvious problem, i.a. a failed capacitor or other component or board failure...
This seems only a reasonable thing to do with a 7854, given the complexity of the design and those many connectors.

And, yes, the initial power-up always goes without any plug-in.

Good Luck,

Magnus

On 1/18/2014 5:02 PM, David C. Partridge wrote:

I disagree, it either works or it doesn't. Just check the line voltage
setting is correct (you really don't want to put 240V into a 'sope
configured for 110V), and then switch it on.

Most likely fault on these is ROM rot. Power up and nothing on the display
:(

Regards,
David Partridge

Yeah, the line voltage setting is the first thing I check on everything electric I bring into the home/shop. Learned that lesson once, long ago.

The ROM rot was my biggest worry. When I started watching this particular 7854 on the Bay of E, and thought I might stand a good chance of getting it, it prompted my question the other day about chip programmers, since I don't as of yet have a programmer in my arsenal.

Thanks,
Mark

On 1/18/2014 6:18 PM, Craig Sawyers wrote:

I agree too - just turn it on. At most I'd pull the covers and do a visual
inspection to make sure there is nothing clearly wrong, boards missing etc.
Like my 7104 as I collected it - the power supply was disconnected, and
there were paperclips on top of some of the boards (an attempt at
sabotage?). But that was unusual - generally a 7000 series mainframe fires
up with a few slight oddities, or the power supply goes into self-protect
tick mode.

Craig

Craig,

Good. Sounds like my usual first-look inspection. Open it up, clean out the mouse (mice?) nests, blow it out with dry air, check the fuses, that sort of thing.

Kinda excited. After listening to youse guys go on about this scope, I've been drooling over getting one. Right place, right time, right price, and one is on it's way to me. ;-)

What do you guys consider a fair price for a keyboard? I've seen prices all over the landscape.

Mark

On 1/19/2014 7:48 AM, Toelle, Magnus wrote:

Good Day,

I would never, ever power-up any used electronic equipment without
performing at least a basic check. Takes only a few minutes, time well
spent!

I want to make sure that all connectors are in place and there is no
obvious problem, i.a. a failed capacitor or other component or board
failure...
This seems only a reasonable thing to do with a 7854, given the
complexity of the design and those many connectors.

And, yes, the initial power-up always goes without any plug-in.

Good Luck,

Magnus

Magnus,

You betcha. As I mentioned in a previous post, that's my modus operandi for any piece of equipment with an unknown operating condition that arrives on my doorstep.

We've had a good lot of discussion recently on the ROM rot, as David calls it, and this scope is pretty complex, I was wondering if there was anything else I might need to worry about under the hood.

Thanks,
Mark

On 1/18/2014 9:05 PM, David wrote:

You do not need the keyboard to use the 7854 for routine storage and waveform
measurements. When it boots up, its basic functions work like any other 78xx or
79xx series mainframe.

If you want the complete experience to go with the keyboard, it may be worth
picking up a 7B87 timebase which replaces the 7B80 and allows pretrigger
acquisitions up to the admittedly slow maximum sample rate of the 7854.

The 7D15 should work fine in a 7854. I know mine does. The 7B71 timebase works
in the 7854 with some minor exceptions that you are unlikely to encounter which
are discussed on page 2-24 and 2-25 of the operating manual.

As I said in my other post, I would start by powering the mainframe up without
any plug-ins. It should execute a power on self test and report any errors. As
others mentioned, checking the line voltage setting and fuses and doing a basic
visual inspection with the two covers removed is worth doing as well.

On Sat, 18 Jan 2014 06:59:46 -0500, you wrote:

Just purchased a 7854 off the Bay of E yesterday. Obviously, haven't
received it yet. Pictures from the auction do not show it powered up,
but the description says used but signs ofcosmetic wear, but according
to the seller it is operational.

Not ever having had a scope of such complexity before, anything I need
to look out for when powering it up?

Doesn't come with a keyboard, so I'll be looking for one of those.
Preferably one that isn't more thanI paid for the scope. ;-)

Comes with a 7D15 counter/timer and what looks like a 7B71 time base
(hard to tell exactly, picture is kinda fuzzy).

Mark

David and everybody that's contributed,

Thanks for all the hints and tips. Can't wait to get this thing up on the bench. ;-)

Hard part is getting it past my wife to the bench.

Mark