Jerome,
The 10meg resistors I got from Mouser are 1/2W Xicon 273 series. You may want to get extras in this value for other items. The 1% types have a low temperature coefficient which is better in low level circuits. The 5W I mentioned I got from ebay from China. You can get the 1% types now which I prefer. If you want to add inrush limiting, add a 527-CL70 NTC from the mains to the power transformer. The dual 15mfd in the B+ supply can be a single 33mfd ULD type. R403 can be increased in resistance, e.g. 3300 or 3500 ohms. This reduces the current through the VR tube and keeps the lower B+ stable.
I got my 130LC last year after looking for some time. I am glad I got mine and restored it. It is great to use when needed. I am sure you will be happy with yours when you get it going. I am glad to see one of these being brought back to life and used.
Mark
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Thank you Mark, that is information I can use, along with all the other info I have received from the members here. I really do need to replace the electrolytics. They won't last forever. All the paper types are gone and have film types in their stead.
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On 2/17/22 21:12, Mark Vincent wrote: Jerome,
I have a 130LC I restored. I used 1% resistors except, for now, the 33,000 ohm 5W 5% (I plan to make it a 1% type soon) replacement of R95. It is a bit larger in power than necessary. A 3W would work. It works fine now.
I did use Nichicon ULD types for the electrolytics. I did replace the old wax in plastic case with 5% types. The pots for the three ranges may need to be adjusted when the .0047mfd and larger values are replaced on the switch.
Mark
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Jerome,
I have a 130LC I restored. I used 1% resistors except, for now, the 33,000 ohm 5W 5% (I plan to make it a 1% type soon) replacement of R95. It is a bit larger in power than necessary. A 3W would work. It works fine now.
I did use Nichicon ULD types for the electrolytics. I did replace the old wax in plastic case with 5% types. The pots for the three ranges may need to be adjusted when the .0047mfd and larger values are replaced on the switch.
Mark
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Re: Tek TDS-3000 V3.41 Firmware
There were some floppies that did 2.88 MB, but they were very rare.
CD's do 470 mb or so, DVD's do 4.7 GB.? If at all possible, use an SD card or microSD card for cheapest storage.
Putting a file on a disk uses up N clusters, where n (typically) is 512 bytes.? If your file is 1 byte over a limit, then it takes another 512 bytes, even though it really doesn't.
It occupies that last sector, (or cluster in an HD), but doesn't use all of it.
Harvey
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On 2/17/2022 8:47 PM, Jim Ford wrote: Bruce, IIRC, a 3.5 inch floppy holds 1.44 MB.? So, yeah, 1.5 MB plus a bit more would probably push it over the edge.? ? ? ? ? ? ?Jim Ford?Sent from my T-Mobile 4G LTE Device
-------- Original message --------From: "ebrucehunter via groups.io" <Brucekareen@...> Date: 2/17/22 5:11 PM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] Tek TDS-3000 V3.41 Firmware To follow up on my previous message, I just noticed that when I copied the V3.41 files from my computer to a memory stick, for carrying to my old laptop in the shop, each file was swelled by 20 to 30 kB.? This might have been just enough to put the third group of files beyond the capacity of the disk.Tomorrow I'll try downloading them directly to the old laptop with a 3-1/2-inch drive.Bruce, KG6OJI
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Re: Tek TDS-3000 V3.41 Firmware
Bruce, IIRC, a 3.5 inch floppy holds 1.44 MB.? So, yeah, 1.5 MB plus a bit more would probably push it over the edge.? ? ? ? ? ? ?Jim Ford?Sent from my T-Mobile 4G LTE Device
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-------- Original message --------From: "ebrucehunter via groups.io" <Brucekareen@...> Date: 2/17/22 5:11 PM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] Tek TDS-3000 V3.41 Firmware To follow up on my previous message, I just noticed that when I copied the V3.41 files from my computer to a memory stick, for carrying to my old laptop in the shop, each file was swelled by 20 to 30 kB.? This might have been just enough to put the third group of files beyond the capacity of the disk.Tomorrow I'll try downloading them directly to the old laptop with a 3-1/2-inch drive.Bruce, KG6OJI
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Thank you Bob. I am fortunate in that my 130, unlike about all my other Tek gear, is very clean. Possibly came out of a clean room, who knows. No evidence of tobacco tar or even much dust.
Will also download the reworked manual. My manual is copyright 1960, and is rather bare bones. It is an original Tek, but the circuit description section is about a third of the size of the one in a later manual that I printed out last night. Got the link for that manual at W140.com. The manual I have is rather odd in that some of the print is blue. Only Tek manual I have that is like that.
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On 2/17/22 20:13, Bob Albert via groups.io wrote: On my 130, the variable oscillator won't oscillate.
On Thursday, February 17, 2022, 05:08:34 PM PST, Tom Lee <tomlee@...> wrote:
Hi Dave,
The docs at VintageTek are great. The gentleman who wrote the three-part
article did a remarkable job of documenting his restoration of his 130.
He even restored the manual (he did more than photoshop an existing
manual -- he rewrote it!). After you've read his docs, you'll understand
how that unit works at a deep level.
If the signal that drives the Schmitt looks good (both amplitude- and
dc-wise), the number of possible faults goes way down. A few component
checks/substitutions should get your unit functioning again. Then
perform a cal, and it should be as good as new.
Good luck hunting!
--Cheers
Tom
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After replacing the CRT with an apparently new part (the anode lead was unbent and had no soot on it, and was strapped to the neck with a latched rubber belt) I now have absolutely no traces on the CRT. I replaced R4124 (which had drifted high by 25%) with a 22M metal film resistor, but still no traces, so I started taking measurements:
* the heater on the new CRT measures 13¦¸, which is the same as the old CRT (which produced a trace, even if it was distorted).
* the Z-axis test point responds to the INTENSITY control, ranging from 14 V to 88 V.
* the HV test point reads only -1220 V, which is about half what it should read. I double checked the HV probe and meter using the +55 V and +110 V rail test points, and they read close enough to assure me that the meter and HV probe were measuring correctly (~60 V and ~120 V, respectively).
So it looks like I have something wrong in the HV section. I¡¯ve had something similar happen on a 475 (or was it a 475A) that was working on, and was not able to get the grid bias adjusted. It turned out to be something wrong with the precision thick-film resistor that feeds the cathode voltage back to the regulator circuitry. I¡¯m chasing that down now.
I¡¯m just trying to get to a point where I can verify that the new CRT isn¡¯t faulty too, but the scope is not cooperating.
¡ª Jeff Dutky
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On my 130, the variable oscillator won't oscillate. On Thursday, February 17, 2022, 05:08:34 PM PST, Tom Lee <tomlee@...> wrote: Hi Dave, The docs at VintageTek are great. The gentleman who wrote the three-part article did a remarkable job of documenting his restoration of his 130. He even restored the manual (he did more than photoshop an existing manual -- he rewrote it!). After you've read his docs, you'll understand how that unit works at a deep level. If the signal that drives the Schmitt looks good (both amplitude- and dc-wise), the number of possible faults goes way down. A few component checks/substitutions should get your unit functioning again. Then perform a cal, and it should be as good as new. Good luck hunting! --Cheers Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 2/17/2022 16:54, Jerome D Leach wrote: Thank you Tom, will take a closer look at the resistors in that
circuit, and will then report back.
Dave (yeah, go by Dave, never much cared for Jerome)
On 2/16/22 23:21, Tom Lee wrote:
Hi Jerome,
That's a nice unit and definitely worth fixing.
V70 is a straightforward Schmitt trigger, and there's not a lot that
can go wrong. Measure voltages on the tube pins. Measure resistances
(R72 and R73 in particular). If they've drifted far upward (including
going open-circuit altogether), that would certainly kill the
Schmitt. You'll find something quite obvious from those measurements.
Good luck!
-- Cheers,
Tom
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Dave, Stephen and Albert,
My unit is serial 90XX (forgot already), and as was noted, has a 6DJ8 for V70, although the chassis panel lists the 6BQ7 as well.
Not sure if I am going to the dungeon tonight, pretty beat after work today, but will take the pointers thus so graciously given and look at it tomorrow. When I prodded it with the 'scope probe, didn't get the voltages, so will check those along with the frequency and report back. Been given a lot of information and after a good nights rest, will put fresher eyeballs on it.
As for the calibration, I am fortunate to have snagged an S-30 Delta standard somewhere a few years ago. Have only given it a cursory inspection, but it appears to have never been tampered with. In fact, it looks almost new.
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On 2/17/22 14:45, Dave Wise wrote: No big deal, I just wanted to ensure the archive doesn¡¯t mislead the next guy.
Once the OP has the multivibrator sorted out, there¡¯s a home-grown calibration technique that doesn¡¯t require the S-30 Delta Standard, just one precise capacitor and a frequency counter. (The latter wasn¡¯t commonly available when the 130 was created.) See ¡°/g/TekScopes/topic/tpe_130_l_c_meter_calibration/7656928¡±.
If you see nonlinearity on the 3, 10, or 30 ranges, look at C94, C93, and C92. Even if they are not leaky, the paper or paper-plastic caps Tek used are prone to Dielectric Absorption and this application is sensitive to it. But take care not to over-correct ¨C those caps weren¡¯t particularly good even new, and Tek printed the meter scales to match them. I installed polypropylene caps only to find that I was (slightly) off in the opposite direction! Use polyester instead.
Dave Wise
From: [email protected] <[email protected]> On Behalf Of SCMenasian via groups.io
Sent: Thursday, February 17, 2022 11:21 AM
To: [email protected]
Subject: Re: [TekScopes] Type 130 L-C Meter
You're right. Sorry for the confusion.
Stephen Menasian
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Re: Tek TDS-3000 V3.41 Firmware
To follow up on my previous message, I just noticed that when I copied the V3.41 files from my computer to a memory stick, for carrying to my old laptop in the shop, each file was swelled by 20 to 30 kB. This might have been just enough to put the third group of files beyond the capacity of the disk.
Tomorrow I'll try downloading them directly to the old laptop with a 3-1/2-inch drive.
Bruce, KG6OJI
|
Hi Dave,
The docs at VintageTek are great. The gentleman who wrote the three-part article did a remarkable job of documenting his restoration of his 130. He even restored the manual (he did more than photoshop an existing manual -- he rewrote it!). After you've read his docs, you'll understand how that unit works at a deep level.
If the signal that drives the Schmitt looks good (both amplitude- and dc-wise), the number of possible faults goes way down. A few component checks/substitutions should get your unit functioning again. Then perform a cal, and it should be as good as new.
Good luck hunting!
--Cheers
Tom
--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
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On 2/17/2022 16:54, Jerome D Leach wrote: Thank you Tom, will take a closer look at the resistors in that circuit, and will then report back.
Dave (yeah, go by Dave, never much cared for Jerome)
On 2/16/22 23:21, Tom Lee wrote:
Hi Jerome,
That's a nice unit and definitely worth fixing.
V70 is a straightforward Schmitt trigger, and there's not a lot that can go wrong. Measure voltages on the tube pins. Measure resistances (R72 and R73 in particular). If they've drifted far upward (including going open-circuit altogether), that would certainly kill the Schmitt. You'll find something quite obvious from those measurements.
Good luck!
-- Cheers,
Tom
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Jean-Paul,
Given my state of electronics expertise, ALL notes help, and I read them closely. Thank you.
Dave
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On 2/17/22 05:27, Jean-Paul wrote: bonjour ¨¤ tous
Have 130 LC since 1980s, from LLNL salvage was $0.30/lb,
Still working fine, uniquely wide,capacity compensation 75,pF.
generally the problems in older valve equipment is often leaky or open electrolytics, carbon composition resistors that drift higher, or were overloaded, and defective paper, oil or plastic capacitors.
hope this note,helps you
Jon
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Kerry and Tom, thank you both for the link to the Tek Museum's video on the 130, will try to watch it tonight. Have poked around the Museum's website, but haven't availed my self of all the resources.
Dave
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On 2/17/22 03:47, Tom Lee wrote: VintageTek received permission to post the three-part article. See
There's also a beautifully restored manual as well.
--Cheers,
Tom
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Thank you Tom, will take a closer look at the resistors in that circuit, and will then report back.
Dave (yeah, go by Dave, never much cared for Jerome)
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On 2/16/22 23:21, Tom Lee wrote: Hi Jerome,
That's a nice unit and definitely worth fixing.
V70 is a straightforward Schmitt trigger, and there's not a lot that can go wrong. Measure voltages on the tube pins. Measure resistances (R72 and R73 in particular). If they've drifted far upward (including going open-circuit altogether), that would certainly kill the Schmitt. You'll find something quite obvious from those measurements.
Good luck!
-- Cheers,
Tom
|
Tek 2715 75 to 50 ohms conversion
Hi,
I want to change my Tek 2715 75 ohms input to 50 ohms. From what I read in the service manual, its just the input connector that has a 25 ohms resistor, internals of the 2715 is all 50 ohms.
Has anyone done this modification? Do I to buy a new conector or its a question of moding the installed conector?
Any help is greatly apreciated.
Alfredo
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Tek TDS-3000 V3.41 Firmware
In preparing to update the firmware on my TDS3052 scope to V3.41, I downloaded the file from the Tektronix website and began transferring it to four 3-1/2-inch disks as instructed. The first two disks wrote fine, but with the the third I began getting a message "insufficient space on disk." After trying several discs and getting the same result, I checked the file lengths. To my surprise they were:
#1 - 532kB on disk for 3 items
#2 - 397kB on disk for 4 items
#3 - 1.5 MB on disk for 3 items
#4 - 815kB on disc for 3 items
Something seemed incorrect so I downloaded the file again, but with the same results. Have others experienced this?
Bruce, KG6OJI
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Thanks Harvey for your reply. Yes, the 468 does not support remote operation. However it does support a remote WF request from the GPIB controller.
Replacing the CPU with a more modern microcontroller is the ultimate goal. That would replace all the ROMs as well as the System/Scratch RAM. However, the Acquisition RAM (512 bytes) and Display RAM (1K) are still needed since the 468 hardware autonomously accesses those. I' m more into AVRs then ARM myself.
At the same time, I have been able to change the address decoding logic so that I can now use the full 32KB ROM space, using an AT28C256 Eeprom, as well as added Serial I/O (with the existing 8085 CPU). I have decoded the Service ROM code and relocated it to run in the address space above the standard 16KB ROM range.
-Jan-
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Some things to consider on this scope:
1) it is send only, IIRC, and was never designed for remote operation.
2) you set it up with the front panel controls, I don't think that any of the scope settings can be remoted.
3) IIRC, this was a "get waveform, press button, get printed copy" concept.
I did look at replacing the CPU, but that was going to be a plugin module of some sort, either just replacing the CPU or CPU/ROM etc.
Although, the original system RAM and ROM become more or less irrelevant once you put in an ARM processor.
Harvey
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On 2/17/2022 2:50 PM, jrseattle wrote: Hi, David.
I'm mostly interested in the DIGITAL internals of the 468: how does the 8085 CPU accomplish its tasks. Making the GPIB work is part of that.
As I mentioned, John (Twilight-Logic) created this AR488 GPIB controller which can be made for less than $20.00 (I made the pro-micro version, see for more info).
Problem with GPIB is, of course, that you need application software to process the custom GPIB commands and John provided that below - in Python which is another project :)
My cheap digital scope does all this much better, but making this 40 year old scope work the way it was intended is a goal in itself. Besides that, CRT scopes are much better at XY displays (see my Dutchtronix AVR Oscilloscope Clock). If anyone is interested in the 8085 firmware running the 468, please contact me.
What I really interested is is this: is there a way to produce "digital XY" mode on the 468? Currently, if you set the TIME/DIV knob to XY mode while the scope is in digital mode ("STORAGE" in Tek terminology), the scope gets into an undefined state.
While looking at the XY mode in Analog mode, I noticed the following: there is a separate path for Vertical Channel 1, which is the horizontal (X) signal in XY mode, but Channel 2 follows the normal path, including the delay line. This causes the Y signal to arrive later at the main amplifiers than the X signal. Is the delay so small that it doesn¡¯t matter, or is there a correction I have not found yet? For Channel 1, see J107 <1> going directly to <10>, the horizontal amplifier. For Channel 2, see <2> going to <3>, to the Delay Line, going to <5>, the vertical amplifier.
-Jan-
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Hi, David.
I'm mostly interested in the DIGITAL internals of the 468: how does the 8085 CPU accomplish its tasks. Making the GPIB work is part of that.
As I mentioned, John (Twilight-Logic) created this AR488 GPIB controller which can be made for less than $20.00 (I made the pro-micro version, see for more info).
Problem with GPIB is, of course, that you need application software to process the custom GPIB commands and John provided that below - in Python which is another project :)
My cheap digital scope does all this much better, but making this 40 year old scope work the way it was intended is a goal in itself. Besides that, CRT scopes are much better at XY displays (see my Dutchtronix AVR Oscilloscope Clock). If anyone is interested in the 8085 firmware running the 468, please contact me.
What I really interested is is this: is there a way to produce "digital XY" mode on the 468? Currently, if you set the TIME/DIV knob to XY mode while the scope is in digital mode ("STORAGE" in Tek terminology), the scope gets into an undefined state.
While looking at the XY mode in Analog mode, I noticed the following: there is a separate path for Vertical Channel 1, which is the horizontal (X) signal in XY mode, but Channel 2 follows the normal path, including the delay line. This causes the Y signal to arrive later at the main amplifiers than the X signal. Is the delay so small that it doesn¡¯t matter, or is there a correction I have not found yet? For Channel 1, see J107 <1> going directly to <10>, the horizontal amplifier. For Channel 2, see <2> going to <3>, to the Delay Line, going to <5>, the vertical amplifier.
-Jan-
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No big deal, I just wanted to ensure the archive doesn¡¯t mislead the next guy. Once the OP has the multivibrator sorted out, there¡¯s a home-grown calibration technique that doesn¡¯t require the S-30 Delta Standard, just one precise capacitor and a frequency counter. (The latter wasn¡¯t commonly available when the 130 was created.) See ¡° /g/TekScopes/topic/tpe_130_l_c_meter_calibration/7656928¡±. If you see nonlinearity on the 3, 10, or 30 ranges, look at C94, C93, and C92. Even if they are not leaky, the paper or paper-plastic caps Tek used are prone to Dielectric Absorption and this application is sensitive to it. But take care not to over-correct ¨C those caps weren¡¯t particularly good even new, and Tek printed the meter scales to match them. I installed polypropylene caps only to find that I was (slightly) off in the opposite direction! Use polyester instead. Dave Wise From: [email protected] < [email protected]> On Behalf Of SCMenasian via groups.io Sent: Thursday, February 17, 2022 11:21 AM To: [email protected]Subject: Re: [TekScopes] Type 130 L-C Meter You're right. Sorry for the confusion. Stephen Menasian
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ebrucehunter
jrseattle