|
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. Not so easy on the 7854, since there are a bunch of boards crammed into a backplane - so to check you would have to pull the boards, and risk static damage to unobtainium devices. And then what would you learn anyway? Craig
|
What do you guys consider a fair price for a keyboard? I've seen prices all over the landscape. I paid $109 for mine from eBay back in March '13, plus shipping to the UK. These guys have got one for $120 . Good luck! Craig
|
On 1/19/2014 11:06 AM, Craig Sawyers wrote: What do you guys consider a fair price for a keyboard? I've seen prices all
over the landscape. I paid $109 for mine from eBay back in March '13, plus shipping to the UK.
These guys have got one for $120 .
Good luck!
Craig
Craig, Thanks! I'll keep my eyes peeled for one around that price range. Mark
|
On Sat, Jan 18, 2014 at 7:36 PM, <sbell@...> wrote:
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.
I did repair one board with Motorola ROMs, but I don't know if it was the ROMs or the FPLA that had failed. Should I replace all these ROMs or are there other likely causes for the checksum error? The ROMs & FPLA are the most likely cause.
|
On Sun, 19 Jan 2014 10:25:21 -0700, you wrote: On Sat, Jan 18, 2014 at 7:36 PM, <sbell@...> wrote:
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.
I did repair one board with Motorola ROMs, but I don't know if it was
the ROMs or the FPLA that had failed.
Should I replace all these ROMs or are there other likely causes for the checksum error? The ROMs & FPLA are the most likely cause. I left the discussion of the FPLA (FPRP?) to others since I am not sure what it could be replaced with and I believe with the right firmware image, the board can be modified to not use it. My understanding is that it was used to patch the mask ROMs with code stored in the 2716 EPROMs. Since the FPLA uses NiCr fuse PROM technology which is very different from the mask programmed Mostek ROMs, I have assumed it is more reliable. Incidentally, Signetics called the 82S107 a Field Programmable ROM Patch. It is obviously based on their 82S100 Field Programmable Logic Array but among other differences, the -CE input is replaced with a -Flag output so instead of responding to chip enable, it generates its own chip enable which is used to drive other chip enables.
|
The firmware image I used doesn't use the FPLA, as it was captured by
reading out the contents of the board at board (rather than chip) level -
BUT you stil lneed the patch ROMs as there is code in them that's used that
isn't patches to the base ROMS.
The ROM images are here: <>
I just removed the FPLA and connected a jumper between two pins of the FPLA
socket (no I can't remember which and the 7854 is inaccessible right now).
Regards,
David Partridge
toggle quoted message
Show quoted text
-----Original Message----- From: TekScopes@... [mailto:TekScopes@...] On Behalf Of David Sent: 19 January 2014 18:38 To: TekScopes@... Subject: Re: [TekScopes] RE: New (to me) 7854 scope On Sun, 19 Jan 2014 10:25:21 -0700, you wrote: On Sat, Jan 18, 2014 at 7:36 PM, <sbell@...> wrote:
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.
I did repair one board with Motorola ROMs, but I don't know if it was
the ROMs or the FPLA that had failed.
Should I replace all these ROMs or are there other likely causes for the
checksum error?
The ROMs & FPLA are the most likely cause.
I left the discussion of the FPLA (FPRP?) to others since I am not sure what it could be replaced with and I believe with the right firmware image, the board can be modified to not use it. My understanding is that it was used to patch the mask ROMs with code stored in the 2716 EPROMs. Since the FPLA uses NiCr fuse PROM technology which is very different from the mask programmed Mostek ROMs, I have assumed it is more reliable. Incidentally, Signetics called the 82S107 a Field Programmable ROM Patch. It is obviously based on their 82S100 Field Programmable Logic Array but among other differences, the -CE input is replaced with a -Flag output so instead of responding to chip enable, it generates its own chip enable which is used to drive other chip enables. ------------------------------------ Yahoo Groups Links
|
Yes, that's why I don't know if it was the Motorola ROMs or the FPLA that failed on that one board. I am pretty suspicious of fuse programmed parts though... some of them suffered from growback. I'm not sure what you mean about the jumper - you shouldn't have to do that. Also, slack.com URLs will stop working eventually... the new, permanent (?) URL is: On Mon, Jan 20, 2014 at 2:44 AM, David C. Partridge <david.partridge@...> wrote: The firmware image I used doesn't use the FPLA, as it was captured by
reading out the contents of the board at board (rather than chip) level -
BUT you stil lneed the patch ROMs as there is code in them that's used that
isn't patches to the base ROMS.
The ROM images are here: <>
I just removed the FPLA and connected a jumper between two pins of the FPLA
socket (no I can't remember which and the 7854 is inaccessible right now).
Regards,
David Partridge
-----Original Message-----
From: TekScopes@... [mailto:TekScopes@...] On Behalf
Of David
Sent: 19 January 2014 18:38
To: TekScopes@...
Subject: Re: [TekScopes] RE: New (to me) 7854 scope
On Sun, 19 Jan 2014 10:25:21 -0700, you wrote:
On Sat, Jan 18, 2014 at 7:36 PM, <sbell@...> wrote:
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.
I did repair one board with Motorola ROMs, but I don't know if it was
the ROMs or the FPLA that had failed.
Should I replace all these ROMs or are there other likely causes for the
checksum error?
The ROMs & FPLA are the most likely cause.
I left the discussion of the FPLA (FPRP?) to others since I am not sure what
it could be replaced with and I believe with the right firmware image, the
board can be modified to not use it. My understanding is that it was used
to patch the mask ROMs with code stored in the 2716 EPROMs.
Since the FPLA uses NiCr fuse PROM technology which is very different from
the mask programmed Mostek ROMs, I have assumed it is more reliable.
Incidentally, Signetics called the 82S107 a Field Programmable ROM Patch.
It is obviously based on their 82S100 Field Programmable Logic Array but
among other differences, the -CE input is replaced with a -Flag output so
instead of responding to chip enable, it generates its own chip enable which
is used to drive other chip enables.
------------------------------------
Yahoo Groups Links
------------------------------------
Yahoo Groups Links
|
Oh, I agree with you. The FPRP jams (in the technical sense) the ROM outputs
with its own data and does not participate in address decoding so when reading
out the ROMs with the FPRP patch data, the 2716 address space need to be
included in one way or another as well. I would assume that the 2716s were not
patched by the FPRP as well so they can be copied directly but they could have
been.
On the uprated memory board, all of the firmware fit within a pair of 27128s so
I assume that after removing the dead code in the original ROMs and applying the
patches, it all fit in 16k x 16.
Incidentally, there is an interesting discussion here about the history of these
chips where one of the designers says that as far as he knows, nobody actually
used the FPRP and none were sold:
Cavlan: . . . The FPRP, which is the ROM patch, I don¡¯t believe we ever sold any
of them.
Cline: It was a perfect product for narrow applications. Remember what I was
talking about before?
Cavlan: Right. Yeah it was just a security blanket for someone to know that
they could use it if they needed to but, in fact, <turning to Cline> if I
remember correctly, wasn¡¯t there one manufacturer that bought some and put on
their shelves for inventory, and then they returned them to us?
toggle quoted message
Show quoted text
On Mon, 20 Jan 2014 09:44:35 -0000, you wrote: The firmware image I used doesn't use the FPLA, as it was captured by
reading out the contents of the board at board (rather than chip) level -
BUT you stil lneed the patch ROMs as there is code in them that's used that
isn't patches to the base ROMS.
The ROM images are here: <>
I just removed the FPLA and connected a jumper between two pins of the FPLA
socket (no I can't remember which and the 7854 is inaccessible right now).
Regards,
David Partridge
-----Original Message-----
From: TekScopes@... [mailto:TekScopes@...] On Behalf
Of David
Sent: 19 January 2014 18:38
To: TekScopes@...
Subject: Re: [TekScopes] RE: New (to me) 7854 scope
On Sun, 19 Jan 2014 10:25:21 -0700, you wrote:
On Sat, Jan 18, 2014 at 7:36 PM, <sbell@...> wrote:
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.
I did repair one board with Motorola ROMs, but I don't know if it was
the ROMs or the FPLA that had failed.
Should I replace all these ROMs or are there other likely causes for the
checksum error?
The ROMs & FPLA are the most likely cause.
I left the discussion of the FPLA (FPRP?) to others since I am not sure what
it could be replaced with and I believe with the right firmware image, the
board can be modified to not use it. My understanding is that it was used
to patch the mask ROMs with code stored in the 2716 EPROMs.
Since the FPLA uses NiCr fuse PROM technology which is very different from
the mask programmed Mostek ROMs, I have assumed it is more reliable.
Incidentally, Signetics called the 82S107 a Field Programmable ROM Patch.
It is obviously based on their 82S100 Field Programmable Logic Array but
among other differences, the -CE input is replaced with a -Flag output so
instead of responding to chip enable, it generates its own chip enable which
is used to drive other chip enables.
------------------------------------
Yahoo Groups Links
|
The FPRP is different from the original FPLA in that the chip enable input which
enables the outputs is replaced with a flag output which is used to disable the
ROMs when an FPRP address is decoded. If the FPRP is removed, then the flag
output has to be set to not disable the ROMs which is just one jumper.
Normally the flag output, pin 19, would be tied to ground, pin 9, but in this
case Tektronix did something a little more complicated because the flag output
disables 13 bits of addresses which the FPRP replaces, disables the main ROMs,
and allows the patch ROMs to be enabled so it may need to be tied to another
spot to get the address decoding correct.
toggle quoted message
Show quoted text
On Mon, 20 Jan 2014 09:11:40 -0700, you wrote: Yes, that's why I don't know if it was the Motorola ROMs or the FPLA
that failed on that one board. I am pretty suspicious of fuse
programmed parts though... some of them suffered from growback.
I'm not sure what you mean about the jumper - you shouldn't have to do that.
Also, slack.com URLs will stop working eventually... the new,
permanent (?) URL is:
I left the discussion of the FPLA (FPRP?) to others since I am not sure what
it could be replaced with and I believe with the right firmware image, the
board can be modified to not use it. My understanding is that it was used
to patch the mask ROMs with code stored in the 2716 EPROMs.
Since the FPLA uses NiCr fuse PROM technology which is very different from
the mask programmed Mostek ROMs, I have assumed it is more reliable.
Incidentally, Signetics called the 82S107 a Field Programmable ROM Patch.
It is obviously based on their 82S100 Field Programmable Logic Array but
among other differences, the -CE input is replaced with a -Flag output so
instead of responding to chip enable, it generates its own chip enable which
is used to drive other chip enables.
|
No, you do not need to do anything like that if you use the Pentti
Haka ROM images from my site. Just pull out the FPLA/FPRP.
toggle quoted message
Show quoted text
On Mon, Jan 20, 2014 at 10:37 AM, David <davidwhess@...> wrote: The FPRP is different from the original FPLA in that the chip enable input which
enables the outputs is replaced with a flag output which is used to disable the
ROMs when an FPRP address is decoded. If the FPRP is removed, then the flag
output has to be set to not disable the ROMs which is just one jumper.
Normally the flag output, pin 19, would be tied to ground, pin 9, but in this
case Tektronix did something a little more complicated because the flag output
disables 13 bits of addresses which the FPRP replaces, disables the main ROMs,
and allows the patch ROMs to be enabled so it may need to be tied to another
spot to get the address decoding correct.
On Mon, 20 Jan 2014 09:11:40 -0700, you wrote:
Yes, that's why I don't know if it was the Motorola ROMs or the FPLA
that failed on that one board. I am pretty suspicious of fuse
programmed parts though... some of them suffered from growback.
I'm not sure what you mean about the jumper - you shouldn't have to do that.
Also, slack.com URLs will stop working eventually... the new,
permanent (?) URL is:
I left the discussion of the FPLA (FPRP?) to others since I am not sure what
it could be replaced with and I believe with the right firmware image, the
board can be modified to not use it. My understanding is that it was used
to patch the mask ROMs with code stored in the 2716 EPROMs.
Since the FPLA uses NiCr fuse PROM technology which is very different from
the mask programmed Mostek ROMs, I have assumed it is more reliable.
Incidentally, Signetics called the 82S107 a Field Programmable ROM Patch.
It is obviously based on their 82S100 Field Programmable Logic Array but
among other differences, the -CE input is replaced with a -Flag output so
instead of responding to chip enable, it generates its own chip enable which
is used to drive other chip enables.
------------------------------------
Yahoo Groups Links
|
See all the fun I missed by buying the wrong 7854 version!
So then the flag pin would be pulled high by the pullup. I traced the address
decoding out once but did not keep any notes. I initially assumed the flag
signal needs to be set either high or low but now having looked at it again I
was not sure.
toggle quoted message
Show quoted text
On Mon, 20 Jan 2014 11:43:25 -0700, you wrote: No, you do not need to do anything like that if you use the Pentti
Haka ROM images from my site. Just pull out the FPLA/FPRP.
On Mon, Jan 20, 2014 at 10:37 AM, David <davidwhess@...> wrote:
The FPRP is different from the original FPLA in that the chip enable input which
enables the outputs is replaced with a flag output which is used to disable the
ROMs when an FPRP address is decoded. If the FPRP is removed, then the flag
output has to be set to not disable the ROMs which is just one jumper.
Normally the flag output, pin 19, would be tied to ground, pin 9, but in this
case Tektronix did something a little more complicated because the flag output
disables 13 bits of addresses which the FPRP replaces, disables the main ROMs,
and allows the patch ROMs to be enabled so it may need to be tied to another
spot to get the address decoding correct.
|
Well, the 7854 arrived in yesterday in a BIG brown box delivered by a big brown truck. No visible damage to the BIG brown box, so I excitedly slit open the packing tape. Scope was packed well with decent styrofoam, and was shrink-wrapped before being put in the packing.
Got it out of the box, blew off the little styro balls from the packing, opened the scope case and saw the inside of the scope was really, really clean. This scope, both from the outside and from the inside of the case looks like it was just taken off the shelf at Tektronix.
Pulled the 7603 off the cart, placed the 7854 in it's place. Pulled the 7D15 and 7B71 out of the plugin slots and fired it up. Guess it hadn't been run in a while as the fan was quite noisy when I first turned it on, but the fan eventually settled down into a nice murmur.
Self test completed successfully, and I proceeded to start fiddling with the front panel controls. Shut it down and popped in a couple of known working 7B53's, a 7A18 in the left vertical slot and a 7A22 in the right vertical slot. Powered it back up, and fiddled some more with the front panel controls to get a feel for the switchology.
I hooked a short BNC cable to the CAL port and to the 7A18. Very, very nice trace. Same for the 7A22.
Shut it down, pulled one of the 7B53's and popped in the 7B71 that came with it. Got to do some reading on this time base, but it too worked sweet!
Now for the real gloat...
I bought the 7854, which came with the 7D15 and 7B71 for... $110.
I just purchased the waveform calculator from the Bay of E this morning - $45 ;-)
I'm a terribly happy proud new owner of a working 7854! Woo hoo!!!!!!!
Mark
|
I bought the 7854, which came with the 7D15 and 7B71 for... $110.
I just purchased the waveform calculator from the Bay of E this morning
- $45 ;-) That sir is a real bargain! Almost as good as my AA501 for $14 or 7L5 with tracking gen in a scope for ?70 (say $100) :-) Craig
|
On 01/24/2014 07:54 AM, Craig Sawyers wrote: I bought the 7854, which came with the 7D15 and 7B71 for... $110.
I just purchased the waveform calculator from the Bay of E this morning
- $45 ;-) That sir is a real bargain!
Almost as good as my AA501 for $14 or 7L5 with tracking gen in a scope for
???70 (say $100) :-)
Craig
Heck yeah! I'll take them kinda bargains every day of the week! You stole both that AA501 and that 7L5. ;-) I'm on a metal working forum where when someone posts his gloats like that, it's obligatory for the rest of the forum population to post in reply - "YOU SUCK!" ;-) Mark
|
You know sometimes you go off people :)
Me - jealous? Yes, you bet! That's an amazing bargain.
Regards,
David Partridge
toggle quoted message
Show quoted text
-----Original Message----- From: TekScopes@... [mailto:TekScopes@...] On Behalf Of Mark Wendt Sent: 24 January 2014 10:55 To: TekScopes@... Subject: Re: [TekScopes] RE: New (to me) 7854 scope I bought the 7854, which came with the 7D15 and 7B71 for... $110. I just purchased the waveform calculator from the Bay of E this morning - $45 ;-) Mark
|
One thing I always found odd is that the 400 MHz 78xx series existed when the
500 MHz 7904 predates them by a couple years. There is a difference in the
trigger channel switch chain which might explain this but I suspect it was for
yield or because of grading.
You definitely got a great deal. I think the best I have done is a K212
instrument cart for $0.99. I got my 7904 with a full set of plug-ins including
a 7CT1N for about what you paid.
I think you can use the 7B71 to delay the 7B53A which will give you the
alternate sweep mode of operation that the 7B53A by itself lacks. I think the
7B71 will also work with the 7B87 so you do not need a 7B85 if you want to
capture pretrigger events.
toggle quoted message
Show quoted text
On Fri, 24 Jan 2014 05:55:08 -0500, you wrote: Well, the 7854 arrived in yesterday in a BIG brown box delivered by a
big brown truck. No visible damage to the BIG brown box, so I excitedly
slit open the packing tape. Scope was packed well with decent
styrofoam, and was shrink-wrapped before being put in the packing.
Got it out of the box, blew off the little styro balls from the packing,
opened the scope case and saw the inside of the scope was really, really
clean. This scope, both from the outside and from the inside of the
case looks like it was just taken off the shelf at Tektronix.
Pulled the 7603 off the cart, placed the 7854 in it's place. Pulled the
7D15 and 7B71 out of the plugin slots and fired it up. Guess it hadn't
been run in a while as the fan was quite noisy when I first turned it
on, but the fan eventually settled down into a nice murmur.
Self test completed successfully, and I proceeded to start fiddling with
the front panel controls. Shut it down and popped in a couple of known
working 7B53's, a 7A18 in the left vertical slot and a 7A22 in the right
vertical slot. Powered it back up, and fiddled some more with the front
panel controls to get a feel for the switchology.
I hooked a short BNC cable to the CAL port and to the 7A18. Very, very
nice trace. Same for the 7A22.
Shut it down, pulled one of the 7B53's and popped in the 7B71 that came
with it. Got to do some reading on this time base, but it too worked sweet!
Now for the real gloat...
I bought the 7854, which came with the 7D15 and 7B71 for... $110.
I just purchased the waveform calculator from the Bay of E this morning
- $45 ;-)
I'm a terribly happy proud new owner of a working 7854! Woo hoo!!!!!!!
Mark
|
ROFL! I love it when any of us get a great deal on this equipment we just gotta have around. I just figgered it was about time I got in on a little of the action. ;-)
Mark
toggle quoted message
Show quoted text
On 01/24/2014 09:52 AM, David C. Partridge wrote: You know sometimes you go off people :)
Me - jealous? Yes, you bet! That's an amazing bargain.
Regards,
David Partridge
-----Original Message-----
From: TekScopes@... [mailto:TekScopes@...] On Behalf
Of Mark Wendt
Sent: 24 January 2014 10:55
To: TekScopes@...
Subject: Re: [TekScopes] RE: New (to me) 7854 scope
I bought the 7854, which came with the 7D15 and 7B71 for... $110. I just purchased the waveform calculator from the Bay of E this morning
- $45 ;-)
Mark
|
that, it's obligatory for the rest of the forum population to post in reply - "YOU SUCK!" ;-)
Mark <grin!>
|
David,
This is going to be a whole new experience for me, not just because of the complexity of the waveform portion of the scope. I've only had three-bay scopes up to this point, so it will be interesting to see how being able to use two time bases can be mixed into the equation.
The 7B71 is also a little different than what I'm used to using, so I really need to dig into the books. Don't have a 7B87 as of yet, though I do think I have a 7B85 in my stash of stuff.
And on the 7904 with the 7CT1N you got? Okay, "YOU SUCK!" ;-)
Mark
toggle quoted message
Show quoted text
On 01/24/2014 10:05 AM, David wrote: One thing I always found odd is that the 400 MHz 78xx series existed when the
500 MHz 7904 predates them by a couple years. There is a difference in the
trigger channel switch chain which might explain this but I suspect it was for
yield or because of grading.
You definitely got a great deal. I think the best I have done is a K212
instrument cart for $0.99. I got my 7904 with a full set of plug-ins including
a 7CT1N for about what you paid.
I think you can use the 7B71 to delay the 7B53A which will give you the
alternate sweep mode of operation that the 7B53A by itself lacks. I think the
7B71 will also work with the 7B87 so you do not need a 7B85 if you want to
capture pretrigger events.
On Fri, 24 Jan 2014 05:55:08 -0500, you wrote:
Well, the 7854 arrived in yesterday in a BIG brown box delivered by a
big brown truck. No visible damage to the BIG brown box, so I excitedly
slit open the packing tape. Scope was packed well with decent
styrofoam, and was shrink-wrapped before being put in the packing.
Got it out of the box, blew off the little styro balls from the packing,
opened the scope case and saw the inside of the scope was really, really
clean. This scope, both from the outside and from the inside of the
case looks like it was just taken off the shelf at Tektronix.
Pulled the 7603 off the cart, placed the 7854 in it's place. Pulled the
7D15 and 7B71 out of the plugin slots and fired it up. Guess it hadn't
been run in a while as the fan was quite noisy when I first turned it
on, but the fan eventually settled down into a nice murmur.
Self test completed successfully, and I proceeded to start fiddling with
the front panel controls. Shut it down and popped in a couple of known
working 7B53's, a 7A18 in the left vertical slot and a 7A22 in the right
vertical slot. Powered it back up, and fiddled some more with the front
panel controls to get a feel for the switchology.
I hooked a short BNC cable to the CAL port and to the 7A18. Very, very
nice trace. Same for the 7A22.
Shut it down, pulled one of the 7B53's and popped in the 7B71 that came
with it. Got to do some reading on this time base, but it too worked sweet!
Now for the real gloat...
I bought the 7854, which came with the 7D15 and 7B71 for... $110.
I just purchased the waveform calculator from the Bay of E this morning
- $45 ;-)
I'm a terribly happy proud new owner of a working 7854! Woo hoo!!!!!!!
Mark ------------------------------------
Yahoo Groups Links
|
Usually a delaying timebase like the 7B85 (7B71 in your case) would be used in
the left horizontal slot and a delayed timebase like the 7B80 (or 7B53A in your
case) would be used in the right horizontal slot. As far as I know, *any*
timebase can operate as a delayed timebase. The 7B87 is just a special case of
a delayed timebase intended to replace the 7B80 and operate in the 7854. It
allows capturing pretrigger events which is a typical use for digital storage
oscilloscopes and unique within the 7000 series although I have not gotten must
use out of it since I have other DSOs for that type of thing.
I think the most significant difference between the 7B85 and 7B71 is that the
former displays the delay time on the readout and supports dual delayed
operation. They both have peak to peak triggering which is something I wish the
7B53A had.
I actually bought the 7904 *for* the 7CT1N but despite the UPS shipping damage,
I have grown to really like the mainframe if only because of its silent
operation (no fan) and bright and crisp CRT. The full set of plug-ins was just
icing on the cake.
It looks like the older 7854 uses the custom designed Tektronix fan found in the
other 7000 series. It should be nearly silent so if it is making noise, I would
assume that the bearings are either worn out or in need adjustment and oiling.
There was a recent discussion about this on the list.
toggle quoted message
Show quoted text
On Fri, 24 Jan 2014 10:20:27 -0500, you wrote: David,
This is going to be a whole new experience for me, not just because of
the complexity of the waveform portion of the scope. I've only had
three-bay scopes up to this point, so it will be interesting to see how
being able to use two time bases can be mixed into the equation.
The 7B71 is also a little different than what I'm used to using, so I
really need to dig into the books. Don't have a 7B87 as of yet, though
I do think I have a 7B85 in my stash of stuff.
And on the 7904 with the 7CT1N you got? Okay, "YOU SUCK!" ;-)
Mark
On 01/24/2014 10:05 AM, David wrote:
One thing I always found odd is that the 400 MHz 78xx series existed when the
500 MHz 7904 predates them by a couple years. There is a difference in the
trigger channel switch chain which might explain this but I suspect it was for
yield or because of grading.
You definitely got a great deal. I think the best I have done is a K212
instrument cart for $0.99. I got my 7904 with a full set of plug-ins including
a 7CT1N for about what you paid.
I think you can use the 7B71 to delay the 7B53A which will give you the
alternate sweep mode of operation that the 7B53A by itself lacks. I think the
7B71 will also work with the 7B87 so you do not need a 7B85 if you want to
capture pretrigger events.
On Fri, 24 Jan 2014 05:55:08 -0500, you wrote:
Well, the 7854 arrived in yesterday in a BIG brown box delivered by a
big brown truck. No visible damage to the BIG brown box, so I excitedly
slit open the packing tape. Scope was packed well with decent
styrofoam, and was shrink-wrapped before being put in the packing.
Got it out of the box, blew off the little styro balls from the packing,
opened the scope case and saw the inside of the scope was really, really
clean. This scope, both from the outside and from the inside of the
case looks like it was just taken off the shelf at Tektronix.
Pulled the 7603 off the cart, placed the 7854 in it's place. Pulled the
7D15 and 7B71 out of the plugin slots and fired it up. Guess it hadn't
been run in a while as the fan was quite noisy when I first turned it
on, but the fan eventually settled down into a nice murmur.
Self test completed successfully, and I proceeded to start fiddling with
the front panel controls. Shut it down and popped in a couple of known
working 7B53's, a 7A18 in the left vertical slot and a 7A22 in the right
vertical slot. Powered it back up, and fiddled some more with the front
panel controls to get a feel for the switchology.
I hooked a short BNC cable to the CAL port and to the 7A18. Very, very
nice trace. Same for the 7A22.
Shut it down, pulled one of the 7B53's and popped in the 7B71 that came
with it. Got to do some reading on this time base, but it too worked sweet!
Now for the real gloat...
I bought the 7854, which came with the 7D15 and 7B71 for... $110.
I just purchased the waveform calculator from the Bay of E this morning
- $45 ;-)
I'm a terribly happy proud new owner of a working 7854! Woo hoo!!!!!!!
Mark ------------------------------------
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David Hess
David C. Partridge