Re: Help! I bricked a perfectly functioning 2467B!
Don, and for those interested if you go to YouTube to Ben Eater's video's he shows how to make an EEPROM breadboard programmer using an Arduino to enter the program. He also sells the breadboard kit and the Arduino too, and shows how to assemble and use it.
Jim O.
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Try reseating all the ICs. If they are in the faulty TI type, a warmup problem as you see is a classic TI socket symptom.
As to the "fit" problem -- different types of plug-ins have different slot patterns in their edge connectors. This was done so custom wiring on the backplane could interconnect plug-ins and the correct plugin would be constrained to the correct slot.
Look for barriers on the mainframe slots other than the one common one.
--
Bob Haas
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If the single digit is much brighter than normal, the display scanning is likely not working.
If the digits are otherwise fine, then it's either drivers to the LEDS, or the decoding is bad.? IIRC, the sign may be driven separately and not multiplexed.
If the display is still scanning (look for positive going pulses on U1701, they may not go to ground, but should go to 5 volts, signals D1 inverted to D5 inverted)? then the problem is in the decoding, all of which is in the digital section U1603).? Look for a clock on pin 8, and activity on the other pins.
Best I can do, since I haven't looked at any of mine for this problem.
Harvey
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On 4/6/2024 12:59 PM, Bob W8RMV wrote: Hi Members,
I've had this TM504 for 10 years maybe, and it has right to left: DM501A, DC503A, AM502 & PS503A.
All has been good until recently. The DM501A has a start up issue.
When it is started from cold, all that is displayed is a - (minus sign). It will not respond to any buttons pushes except the minus sign will disappear if I activate AC from DC.
Then after about 5 or 10 minutes it will suddenly start working on all functions.
I took the 501 out & checked all the electrolytic around the regulators. I was surprised to find they were all 85°C caps but they all tested good & do not show any distress. I looked for cracked solder connections & did not see any. I have not remelted the regulator pins, yet. I started to reseat the IC's but halted that.
The DM501 only seems to "fit" the left slot so I cannot power it on the other 3 slots. Maybe the left slot has an issue?
So I thought I'd ask for guidance here. I do not have a single port "TM504" for testing, but I wonder if there is anything I should look for in the DM504?
Thanx - Bob
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Re: Help! I bricked a perfectly functioning 2467B!
Hi Don,
I bought from this listing; it's a set of four. Only one is needed for our cal data experiment. I picked these because they have markings like the datasheet and don't look like they've been black-topped. Until I actually have them in hand and test them, I have no idea if they're genuine or even work for that matter. Counterfeit chips are rampant on ebay for anything that's out of production. I got burned on that (again) two weeks ago. Some of they fakes can be quite convincing. (Maybe someone will point out I've already bought a fake...)
Usual disclaimer - I don't know, or have any affiliation with this seller.
The programmer will verify if they can be successfully programmed, but I will also try them in a real scope. I don't have a 2467B, but I do have a 2445A which uses 27512 EPROMs and has the same processor and memory architecture as the 2467B.
-mark
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On Sat, Apr 6, 2024 at 03:06 PM, Don wrote:
On Sat, Apr 6, 2024 at 09:54 AM, Mark Litwack wrote:
Hi Don,
I've ordered some Winbond W27C512 electrically erasable EPROMs from ebay
where
the markings at least look like the datasheet. There's plenty out there that
don't. We'll see what I get.
For years it's been advised for people to take a video of EXER 02 to capture
the cal data, but the restoration of that data on some model scopes, like
yours with the separate RAM and battery and no GPIB, has been left unsaid.
If you have the opportunity to get a fresh cal compatible with your budget, go
for it. That's clearly the best path in the end, and I don't want to imply
otherwise.
I'm going to pursue this restoration method in any case, since it does come up
and may be the only option for some people (assuming I can make it work).
Since you already lost your cal, there's no further risk if you still want to
try it, and if you don't mind the extra time.
-mark
Mark,
I would like to try it. As you said, there is no further risk since I have
already lost the cal and I think it will be an interesting exercise (my
interest in EPROMS has been piqued) and could help others who may find
themselves in a similar situation. Could you give me the link to the Winbond
EEPROM? I'll see if I can order some.
Don
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Hi Members,
I've had this TM504 for 10 years maybe, and it has right to left: DM501A, DC503A, AM502 & PS503A.
All has been good until recently. The DM501A has a start up issue.
When it is started from cold, all that is displayed is a - (minus sign). It will not respond to any buttons pushes except the minus sign will disappear if I activate AC from DC.
Then after about 5 or 10 minutes it will suddenly start working on all functions.
I took the 501 out & checked all the electrolytic around the regulators. I was surprised to find they were all 85°C caps but they all tested good & do not show any distress. I looked for cracked solder connections & did not see any. I have not remelted the regulator pins, yet. I started to reseat the IC's but halted that.
The DM501 only seems to "fit" the left slot so I cannot power it on the other 3 slots. Maybe the left slot has an issue?
So I thought I'd ask for guidance here. I do not have a single port "TM504" for testing, but I wonder if there is anything I should look for in the DM504?
Thanx - Bob
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Re: Help! I bricked a perfectly functioning 2467B!
Menahem,
Thank you for your generosity in offering to loan your EEPROM programmer. I am currently toying with the idea of acquiring one since it may come in handy for other uses in the future. I might take you up on your offer if I don't find a suitable one. BTW, what is the brand and model of the EEPROM programmer that you are offering to loan?
Don
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Re: Help! I bricked a perfectly functioning 2467B!
On Sat, Apr 6, 2024 at 09:54 AM, Mark Litwack wrote:
Hi Don,
I've ordered some Winbond W27C512 electrically erasable EPROMs from ebay where
the markings at least look like the datasheet. There's plenty out there that
don't. We'll see what I get.
For years it's been advised for people to take a video of EXER 02 to capture
the cal data, but the restoration of that data on some model scopes, like
yours with the separate RAM and battery and no GPIB, has been left unsaid.
If you have the opportunity to get a fresh cal compatible with your budget, go
for it. That's clearly the best path in the end, and I don't want to imply
otherwise.
I'm going to pursue this restoration method in any case, since it does come up
and may be the only option for some people (assuming I can make it work).
Since you already lost your cal, there's no further risk if you still want to
try it, and if you don't mind the extra time.
-mark
Mark, I would like to try it. As you said, there is no further risk since I have already lost the cal and I think it will be an interesting exercise (my interest in EPROMS has been piqued) and could help others who may find themselves in a similar situation. Could you give me the link to the Winbond EEPROM? I'll see if I can order some. Don
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Re: Help! I bricked a perfectly functioning 2467B!
On Sat, Apr 6, 2024 at 09:20 AM, Craig Cramb wrote:
In retrospect, I should have followed the adage "if it ain't broke...."
Don,
At this point I recommend carefully package the instrument and sending the
scope to me in Wichita,Ks 67212 for recalibration, or if Chuck has
availability send it to him. The other paths you are trying to do could
possibly send you further down the rabbit hole. Chip desoldering, soldering,
eprom erase and flash chips on the A5 could end up being something else you
wish you hadn’t done. This issue you are having is just like if the battery
had naturally lost its charge, recalibration is the way to go.
Craig
Craig, I totally understand your perspective on this. However, I am a hobbyist and an avid DIYer. I have two other scopes including a modern digital scope, therefore, I cannot justify the expense of a formal calibration (not to mention shipping back and forth which in and of itself will be prohibitively expensive). Moreover, my EPROM chip is socketed and does not need desoldering. I will be temporarily substituting a custom programmed EPROM chip to load the cal constants (the original EPROM chip will be untouched other than to remove it temporarily). Therefore, I believe the risk of causing irreparable damage is small and worthwhile taking. Thank you for your input Don
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Re: Help! I bricked a perfectly functioning 2467B!
I have a spare EEPROM programmer that I could let you have for a few weeks, as long as you cover the postage out and back
Menahem Yachad
CondorAudio
Israel
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Re: Help! I bricked a perfectly functioning 2467B!
Hi Don,
I've ordered some Winbond W27C512 electrically erasable EPROMs from ebay where the markings at least look like the datasheet. There's plenty out there that don't. We'll see what I get.
For years it's been advised for people to take a video of EXER 02 to capture the cal data, but the restoration of that data on some model scopes, like yours with the separate RAM and battery and no GPIB, has been left unsaid.
If you have the opportunity to get a fresh cal compatible with your budget, go for it. That's clearly the best path in the end, and I don't want to imply otherwise.
I'm going to pursue this restoration method in any case, since it does come up and may be the only option for some people (assuming I can make it work). Since you already lost your cal, there's no further risk if you still want to try it, and if you don't mind the extra time.
-mark
|
Re: Help! I bricked a perfectly functioning 2467B!
In retrospect, I should have followed the adage "if it ain't broke...."
Don,
At this point I recommend carefully package the instrument and sending the scope to me in Wichita,Ks 67212 for recalibration, or if Chuck has availability send it to him. The other paths you are trying to do could possibly send you further down the rabbit hole. Chip desoldering, soldering, eprom erase and flash chips on the A5 could end up being something else you wish you hadn’t done. This issue you are having is just like if the battery had naturally lost its charge, recalibration is the way to go.
Craig
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Re: Help! I bricked a perfectly functioning 2467B!
In retrospect, I should have followed the adage "if it ain't broke...."
The ironic thing is, I tested the 35+ year components that I removed from the A5 board (the LTC-7P battery and the four electrolytic caps) and found them to be better than the new ones I replaced them with.
The old battery (from 1989) had a 3.705 voltage while the new battery had a 3.678 voltage (I know that a lithium battery discharge curve makes it impossible to predict when they will fail and the old battery may have been on the verge of failing). The old electrolytic caps (47uF 25V) measured almost exactly 47uF and had an ESR of 0.9 ohms whereas the new caps were between 48 and 49uF and had an ESR of around 2 ohms! (these are not some el cheapo caps from ebay, but are Panasonic ones from Mouser). Given that the old caps tested so good, I am having second thoughts about replacing the electrolytic caps in the power supply boards and on the main board (I had ordered caps for all the boards in the scope)
Don
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Re: Help! I bricked a perfectly functioning 2467B!
On Sat, Apr 6, 2024 at 08:44 AM, N1IXF wrote:
Don,
You might also look at using a one time programmable EPROM that you could
purchase from Mouser.
I had a similar issue, though not Tek related, where I didn't have a UV eraser
and bought a few of these chips just in case I messed one up. They are cheap
enough.
Of course you'll still need the programmer.
Rich
Thanks, Rich! I will look into it. Don
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Re: Help! I bricked a perfectly functioning 2467B!
Don,
You might also look at using a one time programmable EPROM that you could purchase from Mouser.
I had a similar issue, though not Tek related, where I didn't have a UV eraser and bought a few of these chips just in case I messed one up. They are cheap enough.
Of course you'll still need the programmer.
Rich
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Re: Help! I bricked a perfectly functioning 2467B!
On Fri, Apr 5, 2024 at 11:06?PM Don via groups.io <donald_s_58103= [email protected]> wrote: I agree that a fresh calibration would be best. However, I don't have the
equipment to do a half-decent job. The manual lists about 23 different
pieces of equipment for the calibration process. Of these, I only have a
couple of signal generators (an HP 8640B and an HP 3325B). The synthesized
signal generator that I have (the HP 3325B) only goes up to 21 MHz (not
sure if that is enough). Also, I have reviewed the calibration steps in the
service manual and I find it quite daunting. So, at this point, all I am
looking to do is to get the scope back to where it was before I started
tinkering with it. Thank you for your offer to do an informal cal. I wish I
could take you up on it, but I am not local to you (I am in North Dakota).
I hear you, to each his own. My 2467 was well out, though I'd also fiddled with the CRT calibration during repairs. Good luck!
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7B87 max acquisition speed in single-shot
Hi all,
I have a 7B87 that I use together with my 7854 when I need to take single-shot measurements.
One thing that has always puzzled me is the clock rate the 7B87 can output itself.
For example, according to the table on page 1-7 of the manual, it can reach 10.24 MHz for a sweep rate of 10us/div.
If the 7854 is set with 512 points-waveform the maximum possible acquisition speed is 0.2 ms-div. At 1ms-div if you try to acquire a single'shot the 7854 stops reporting AQS ERROR.
After careful consideration and also reading the "Specifications and ordering information" datasheet I found that it actually works like this:
Fastest sweep rate -> points/wfm:
50us -> 128
100us -> 256
200 us -> 512
500 us -> 1024
20 and 10 us of seep rate do not seem reachable in any case because the 7854 stops with AQS ERROR.
The question is: why does the 7B87 provide unusable clock rates? Perhaps for a future improvement of the 7854?
Another question is: why do faster sweep rates correspond to lower pts/wfm?
On the "Specifications and ordering information" datasheet I also found "EXT CLOCK 2us/pt maximum" written.
Which undoubtedly corresponds to a maximum sweep of 0.2 ms/div using 1024 points/wfm. Using 128 pts/wfm the 7B87 manual states that 8 clock cycles are required to acquire one point.
Confused...
Max
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Re: Slightly off topic, but I'm getting desperate. Looking for the Adjustment Program for the HP/Agilent 4263B
I unlocked a few options on my unit with a script I made, which were probably not calibrated from the start.
Also it would be nice if we could get the adjustment software out there to keep these instruments running as long as possible, especially after repairs, they are a nice instrument to use.
It's a shame that they can no longer be calibrated properly for the want of a small BASIC program. Even some of the cal houses that responded to me said that they were unable to perform adjustments on these units..
Jared
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Re: trigger problem with 7B70
On Apr 5, 2024, at 21:53 , Tom Lee via groups.io <tomlee@...> wrote:
The 2N5771 is an 850MHz ft, 15V PNP. Ordered. I was hoping you'd be able to correct me off the top of your head :). Pretty cheap, too. The language of my people. Thanks! Adam
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Re: trigger problem with 7B70
The 2N5771 is an 850MHz ft, 15V PNP. Pretty cheap, too.
-- Cheers,
Tom
--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
420 Via Palou Mall
Stanford University
Stanford, CA 94305-4070
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On 4/5/2024 2:24 PM, Adam R. Maxwell via groups.io wrote: On Fri, Apr 5, 2024 at 11:14 AM, Mark Vincent wrote:
The high speed transistors could be replaced with KSP10BU. The pinout is BEC. I need a PNP transistor, though. Pretty sure KSP10BU is NPN, as I have some and
checked everything in my limited stash as a potential replacement. Finding a PNP
over 500 MHz looks unlikely, especially in the 2 GHz range of the 151-0271.
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Hi everyone, this is my first post here. I'm Max from Wellington, New Zealand. I recently acquired a 465, which I think is in pretty good shape for a piece of electronics as old as me!
It is an "option 5" which is interesting, designed to troubleshoot TV signals (the scope originally belonged to a local broadcasting facility).
I have already identified a few issues with it though. The first one was that the "x10" CH2 volts/div indicator lamp was busted, which, because of the interesting commutation logic happening around there, meant that the "x1" lamp on the same channel was also not operating. Since I didn't have a replacement lamp (anyone knows where I could find one, by the way?) I substituted a resistor instead and voilà, x1 lamp working again. My first ever electronic repair! Now I'm hooked!
Don't tell my wife: I just ordered another oscilloscope to debug my oscilloscope (a cheap Fnirsi TC3, which also does wave generator and component tester - that should be handy).
I am now in the process of reading everything I can find on the 465, including on this Group, which is quite a lot. I have a few more gremlins to troubleshoot, so I'll probably come back here for help at some stage...
Anyway, nice meeting you all!
Max
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Bob Haas
Bob W8RMV
Craig Cramb
Jared Cabot