Re: Tek 492 Y axis failure?
James,
I do not know if the 494XX type is the same or not in its guts. This site may help: . Page 9 may be of help. The resistors he mentions should be increased to 2W (15mm length or longer). A 1 or 2% tolerance would be even better than original. Keep looking for bad tantalums, you may fine more.
Mark
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Re: Like to say hello and ask a question about my Tektronix 465 ocsilloscope
Wilfred:
All of the capacitors that you mention are part of the power supply, and
their ripple is not specified, as they are part of pre-regulator
circuitry.? Can you check the regulated DC voltages and determine if the
ripple on the DC voltage buses are within limits?? These limits should
be specified somewhere in the service manual(s) (refer to w140.com).? If
the service-manual-specified limits for ripple on the various regulated
DC buses are within limits, you should be fine.
If I am missing something here, that others are aware of, please let
me/us know!
Mike N4MWP
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On 3/12/25 15:36, Wilfred via groups.io wrote: Hello again,
It's been a while since I wrote and had to say goodbye to my 465 oscilloscope, but I managed to find another one and luckily without any issues.
The serial number is 109003, which is I understood one of the latest. (Not sure though)
Anyway, I did a check on the power supply voltages and the big capacitor's ripples between the plus and minus on the Elco itself:
C1512 (550uF) 79V and 300mV ripple,
C1513 (1200uF) 74V and 1V ripple,
C1542 (5500uF) 23V and 1.5V ripple,
C1552 (50009uF) .2V and 700mV ripple,
C1562 (3000uF) 12V and 1V ripple.
Any idea if this is acceptable ?
It might be wise to replace them in the future, but for now I just leave it as it is and use the oscilloscope it was made for.
Thanks again and have a lovely evening,
Wilfred
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Re: Like to say hello and ask a question about my Tektronix 465 ocsilloscope
Hello again,
It's been a while since I wrote and had to say goodbye to my 465 oscilloscope, but I managed to find another one and luckily without any issues.
The serial number is 109003, which is I understood one of the latest. (Not sure though)
Anyway, I did a check on the power supply voltages and the big capacitor's ripples between the plus and minus on the Elco itself:
C1512 (550uF) 79V and 300mV ripple,
C1513 (1200uF) 74V and 1V ripple,
C1542 (5500uF) 23V and 1.5V ripple,
C1552 (50009uF) .2V and 700mV ripple,
C1562 (3000uF) 12V and 1V ripple.
Any idea if this is acceptable ?
It might be wise to replace them in the future, but for now I just leave it as it is and use the oscilloscope it was made for.
Thanks again and have a lovely evening,
Wilfred
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Re: Salvage yard rescue: Tektronix TU-50. Some questions from a non-tech
ricky covell
<hypomnnqn@...?subject=Re:%20Salvage%20yard%20rescue%3A%20Tektronix%20TU-50.%20Some%20questions%20from%20a%20non-tech>
wrote:
Date: Tue, 11 Mar 2025 21:29:54 PDT
(The leveler) seems quite do-able, just a handful of resistors, a cap, and
a 6110.
You do not need the 6110 tube. While not totally unobtanium it may be
easier to replicate the sine wave leveler with the 190B leveler which uses
a pair of 1N97A germanium diodes and a different resistor network. It will
work equally well as the tube version used with the 190A. The TU-50 is a
combination of three production instruments housed in one large cabinet.
The three instruments are a 190 constant amplitude signal generator, a 180
time-mark generator, and a 105 square wave generator. Schematics available
on Tekwiki. - Ferrous
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Hi.
I have this 492 which was working.
Last week a friend donated a largely stripped 492 whose remaining parts I thought could be tested in the working unit.
First thing to test was the crt.
Unfortunately, nothing appeared on the display and the distinct smell of toasted component filled the air so quickly turned the 492 off.
Following my nose, led me to the video amplifier board, where a shorted tantalum was quickly found.
With that replaced, the 492 came back to life, all the lights, traces, display readings etc. However, there appears to be no vertical readings.
Before I dive into the manual when I next get time, does anyone have any idea as to where to look? For example, could the video board have damaged an adjacent board?
I've seen people replacing the diode and tantalum in the Yig filter, so I should just check there first...
Once this is fixed, I'll give it a miss testing the remaining parts and just sell them 'as is - for parts'
James
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Re: Identify TDS640A 'hackable' options via serial number?
HI Bill,
You said " but it quickly turned back to monochrome within a few seconds."
Was that with the LCD screen fed from the VGA signals from the rear panel as I assumed (foolishly) that an external VGA monitor would be in colour ?
Glancing over the 'user' configurable 'hacks' I don't see one to enable colour on the display?
Dave
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Hii all,
the PSU is now ok. After adjusting the DIP Switches the SA is starting and I can see the 100 MHz signal I injected.
But I think the Signal is not locked. Down to 100 kHz ResBW the signal is stable (not exact 100MHz) , but from 30 kHz ResBW the signal is out of screen and the sweep is very slow.
Horizontal Frequency Self-Correction gives Error: 129 MHz Tuning Range Unknown, sometimes 129 MHz Tuning Correction Terminated, or 129 MHz Timed Out.
All stored Data is lost, because the LI- batteries have been for several years at Null Volt.
Is it possible to fix the problem without the Extender card?
Regards
闯ü谤驳别苍
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Re: Tek 2235 Q944 Equivalent-squished horizontal
On Fri, Feb 21, 2025 at 09:40 AM, Eng Heads wrote: The squished horizontal is due to low voltage on the 8.6V--in fact all the DC
voltages are low by about 15%. In the 22xx scope's power supply the 8.6V rail acts as a reference for all other voltages, so if 8.6V is low, all other rails will also be dragged down.
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Re: Identify TDS640A 'hackable' options via serial number?
The possible options are only the ones which are listed in the datasheet! For example the number of sampling points can not be increased in a TDS6xx because of the other sampling technology of the whole family.
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Re: Identify TDS640A 'hackable' options via serial number?
Yes, color Proc boards are different from monochrome. Thay have additional color video schematics. Regarding 1M and 2M, If we look inside the oscilloscope, we can see which type of memory is being used: 64K or 1M (on the Acq. board) Jared, and how i can disable 1F option? (All the 640 have a floppy. I don't have a floppy and tried to disable it in EEPROM. But, no way: with both possible values i have an error regarding 1F) Peter ср, 12 мар. 2025?г. в 01:48, Jared Cabot via groups.io <jaredcabot= [email protected]>:
As far as I know, the VGA output provides exactly the same image as on the
CRT. So a monochrome scope will output a monochrome image via VGA.
As for enabling options, the link provided above by walkerru3 to the info
I posted on eevblog forum is everything you need to know.
According to the user manual here (page A-1):
You have the following options available:
1F - Floppy Disk Drive (Requires the floppy drive to be installed)
13 - RS-232/Centronics Hardcopy Interface (Requires the serial interface
to be installed)
05 - Video Trigger (Requires the Video Trigger board to be installed)
2F - Advanced DSP Math (No prerequisites, can be software enables with no
additional parts)
You can also try enabling option 2M and see if it works. Just reboot the
scope and see if it shows up on the boot splash screen. If not, then
disable it and try 1M instead, rinse and repeat.
Jared.
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Re: Salvage yard rescue: Tektronix TU-50. Some questions from a non-tech
Yeah, shame about the probe for sure. I had the same schematic up and it seems quite do-able, just a handful of resistors, a cap, and a 6110. I'm not familiar with the plug type so maybe that's another story. And yes, I'd rather keep it to heat my apartment than it wind up being picked apart by ebay detritivores. Here's a few quick shots if anyone was curious: /g/TekScopes/album?id=301236I'll have to carry it somewhere with better lighting this week haha Re: Eric You're more than welcome to send me a direct reply if you want to make an offer. I'll be thinking on it for a couple more days, but I'll keep a note and get back to you if I'd like to pass it on to someone. Appreciate it
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Re: Identify TDS640A 'hackable' options via serial number?
As far as I know, the VGA output provides exactly the same image as on the CRT. So a monochrome scope will output a monochrome image via VGA.
As for enabling options, the link provided above by walkerru3 to the info I posted on eevblog forum is everything you need to know.
According to the user manual here (page A-1):
You have the following options available:
1F - Floppy Disk Drive (Requires the floppy drive to be installed)
13 - RS-232/Centronics Hardcopy Interface (Requires the serial interface to be installed)
05 - Video Trigger (Requires the Video Trigger board to be installed)
2F - Advanced DSP Math (No prerequisites, can be software enables with no additional parts)
You can also try enabling option 2M and see if it works. Just reboot the scope and see if it shows up on the boot splash screen. If not, then disable it and try 1M instead, rinse and repeat.
Jared.
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Re: 5B44 Dual Timebase parts - knobs wanted!
Speedy reply from VintageTek Museum, unfortunately it's:
"We no longer have the volunteers who had the time to look for parts and ship worldwide. Sorry we can’t assist in these kinds of parts searches."
Oh bother! The hunt continues.
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Hey all, I picked up a RM15 (rackmount 515) a few weeks ago and aside from missing most of its tubes it is in impeccable condition. What's peculiar is next to the s/n is a plate that says MOD 801C. Any and all information I can find on the 515/515A goes up to MOD 760C, and associated engineering documentation. I cant find a thing on MOD801C. Anyone hear of such a thing?
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Re: Identify TDS640A 'hackable' options via serial number?
I replaced the crt on my 640 w/ an LCD. I smiled for a brief second when i saw colored text on boot, but it quickly turned back to monochrome within a few seconds. I'm guessing this is exactly what we're talking about, the firmware/settings get bootloaded and it turns off functionalities. thats all i can offer, but figured i'd mention --Bill WW1H On Tue, Mar 11, 2025 at 4:54?AM Dave B via groups.io <davebullockmbe= [email protected]> wrote: Hi Teksperts,
Is it possible to identify which options are locked within a Tektronix
TDS640A from the serial number?
I understand that many options are present but 'locked' from access on
lower spec models and are unlockable with a hardware/software 'hack'? I am
particularly interested in the FFT math function...
I am aware that there is often an extra 'sticker' on the rear of the
instrument declaring enabled options like (1F floppy drive) etc but is
there a database that explains what hidden options are available?
Secondly:-
Does anyone know if the VGA output displays in colour even if the
oscilloscope is shipped with a monochrome screen (and if VGA colour), can
the screen be substituted for a colour LCD like the "CRT and shutter" swap
previously described in this forum?
Thanks
Dave
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Re: Identify TDS640A 'hackable' options via serial number?
Dave, Yes, for 2F no any hw changes needed, only unlock by EEPROM modifying (don't forget to unlock EEPROM when modifying EEPROM ;). The color TDS with NuColor using non-VGA signals on the connector attached to color CRT board. I have a TDS544 Proc board, but w/o color CRT & CRT board, only monochrome from TDS540. I tried to convert the video signals to connect the monochrome set, but it didn't work out. Then I connected VGA pins. It works. As i remember, the problem in clock frequencies. But keep in mind that with this connection, you will not be able to directly connect both the internal LCD and the monitor. You will need some kind of VGA splitter. Peter вт, 11 мар. 2025?г. в 16:16, Dave B via groups.io <davebullockmbe= [email protected]>:
HI,
Thanks for your swift reply.
So what you are saying is that :-
1). The FFT math function will already be installed and just needs
'unlocking' via one of the two methods you describe (2F Advanced DSP
math)
so I don't need any additional hardware fitting? (like would be needed to
increase recording capacity)
2). It's easiest to fit a new backlit LCD display and just drive it from
the VGA output that is available on the rear panel?
I had seen the article on removing the degrading gel/'shutter' and CRT and
this inspired me to wonder if a monochrome TDS640A could be modified to
colour simply with a screen 'transplant'.
Looks very interesting.
Many thanks for the information, it is greatly appreciated.
Dave
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Re: Salvage yard rescue: Tektronix TU-50. Some questions from a non-tech
On Tue, Mar 11, 2025 at 01:55 AM, ricky covell wrote:
Are they still relevant for current day technicians who restore vintage
scopes?
You are missing the attenuator probe... so you can't generate the various calibration voltages. (So, how will you use it?) I've never seen one of those probes for sale. The plug is a Cannon plug, I think. I don't think they are relevant, except to individuals like Eric. Maybe if you are really into 'tube type' boat anchor test gear. AFAIK 75 year old 500 series scopes, don't need 75 year old test gear to calibrate. I couldn't scrap it. Cause it's good for holding down the basement floor, ... and taking up space... at least...until some villain re-scraps it. If you don't want to do that... maybe give it to someone who values it... and won't destroy it. Not sure how you would ship it though. (It's heavy, and bulky... going to cost a lot.) -- Roy Thistle
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hi brian i am interested in model 2465b with serial b0655.... regards saroj On Mon, Mar 10, 2025 at 2:07?PM Brian Symons via groups.io <symons391= [email protected]> wrote: While looking for some manuals I found the bitsavers.computerhistory.org
site.
It has some very high quality manuals including TEK ones.
Regards,
Brian
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Re: Tek 2235 Q944 Equivalent-squished horizontal
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Re: Salvage yard rescue: Tektronix TU-50. Some questions from a non-tech
If you decide to sell it, I’m highly interested in it. I’ve been working on collecting Tektronix in house test equipment. It will have a good home.
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Mike Dinolfo
Wilfred
James55
Jared Cabot
rivet_head
Eric Boyle