开云体育

Look at the data sheet for the LM1881. With only a little care you can use it on a bread-board.

Thanks Jon, I have a DS1225 on order from Mouser. When you say 'use EEPROM programming to load default CAL' what do you mean - is there some default binary for the NVRAM?

As regards the triggering issue, I have already replaced all PSU caps and verified the voltages. The A5 board SMU caps aren't leaky and measure OK too. I'm wondering if it could be an issue with U500? I may be able to lay my hands on one of those.

cheers

Keith

Keith,

I just notice this statement in your first post: "It's a 1996 model but no surface mount caps."
Are you saying the A5 controller is not using surface mount parts?

--Victor

Keith

The error message indicate dead NVRAM battery

Needs ver careful removing, place low profile machine pin 28 pin socket, get new genuine Dallas Semi replacement, use EEPROM programming to load default CAL


Perform a complete CAL according to the service manual.

All other faults....check PS and HV for failed caps, check A5 control board for leaks of SMD lyrics.

See both Tektronix forums on groups.io and EEVblog 2465 teardown thread.

Also Condor Audio and hams for 2465 rebuild notes

Bon chance


Jon

Here is a link to the service manual:? is one for the diagrams only:?
I believe you are referring to Fuse F558 which is a 0.25 Amp fuse. If so, there is a good possibility that the U550 HV multiplier is shorting. These are very old now and are prone to failure very easily. One way to check this is to disconnect Pin 10 of the HV transformer T550 or Pin 11 of the multiplier and switch it on with a new fuse. If it does not blow, then you know that the unit is faulty.
I have a 465M and some parts somewhere. Let us know.
Ananda

Hi Gurus>
I have a badly behaving analogue RGBHV video signal.
Whilst VSync pulses repeat steadily every 49.99 Hz, HSync is all over the place Both H & V pulses are negative going from 5v to 1v).
I have developed an HSync substitute, which mimics the 4.7us HSync pulses and starts on the tail end of each VSync pulse (210us).
These are 271 lines to a frame, thus 271 HSync pulses per frame.
Unfortunately because only the front end of the HSync train of 271 pulses is tethered to the VSync pulse the last video line is not necessarily complete before the HSync pulse starts.
The attached display knows its got an incoming signal but cannot display it because the frame/line rate is not stable.
I have several ideas on how to solve it, but to do so I need to see the last line of the frame, before the VSync pulse starts.
I can use a 7854 or 7844 or 7904 and have the usual timebases to work with them. So either I need to trigger on the 270th HSync pulse or extend the display to show all 271 lines at a display rate of 500ps per sec and trigger on any HSync pulse. HSync counting is in binary.
I realise I can extract the relevant HSync pulse, but to do so I will have to make up new PCBs, AND that will only get me the one pulse out.
Anyone got any ideas ?

So I finally received the capacitors I ordered from DigiKey on 1st Jan, apparently there was an IT issue that caused the order to be delayed, then the weather affected shipping... Anyhow, I replaced all the electrolytics on the A2A1 and A3 boards, plus the rifa's on the A3 inverter board.

Made up a load board with a 2.2ohm 20W for the +5VD, and 100ohm 5W resistors for the +5V, -5V, +15V, -15V, -8V. But 8.2K for the 84V and 4.3K for 42V rails as it seemed the current draw would be a bit OTT for those rails with 100ohms.

Anyhow testing the board with that load looked good, voltages were what they should be, so I fitted the PSU back. Measured J119 pins are now:

pin1 (-15v) = -14.957
pin 2 (+5V digital) = 5.006
pin 3 = (-15v unreg) -18.855
pin 4 (10v ref) = 10.004
pin 5 (-5v) = -4.985
pin 6 (+15v) = 15.014
pin 7 (gnd) = -0.001
pin 8 (87v) = 87.02
pin 9 (42v) = 42.46
pin10 (unused) = 0.004
pin 11 (-8v) = -8.032
pin 12 (5v analog) = 4.971
pin 13 = -1.3705
pin 14 = -1.3692

On power up, I got a test fail: 'Test 04 Fail 12 TV<6400>'. From what I read this is the Dallas Semi NVRAM cal. The datecode on that chip is '96 so I guess it needs changing?

The readout of e.g. ch1, ch2, timebase seems correct but has '?' in all the spaces... does this happen because the cal is invalid?

Lastly, there seems to be a triggering problem. On slow X axis speeds e.g. 200mS/cm I can get a correctly triggerred trace, but on faster ones the triggering either is intermittent or fails completely. It's not clear if this is an intermittent connection or something else. Any thoughts?

cheers,

Keith

The code I used on TDS7104 was in the earlier message:
=======
tempBuf=malloc(0x800)
nvMem_read(0,tempBuf,0x800)
fdescriptor=open("dbfs:c:/vxBoot/eepromdump.bin",0x0202,0777)
bytesWritten=write(fdescriptor,tempBuf,0x800)
close(fdescriptor)
=======

I have tested the code on TDS7104. I didn't compare with an EEPROM programmer but extensively looked at the contents and I convinced myself it is correct.

The code you copied is from user Wevie for TDS8000 and it differs from TDS7104.
Ozan

Bonjour, we recieved a fine TEK 492 SA, circa 1980s..1990s, fine condition CAL in 2007. SN B055xxxx
Will post photo album.

Q: Do these have the notorius SMD lytics on some PCB that leak and corrode ?
Which PCBs are suseptible?

WTB: For nonprofit museum , restoration to original condition:
Original TEK front cover
small knob (intnesity, etc)
complete service manual (2 vol, binders) original printed version
MANY THANKS !!

Have an absolutely fantastic day!

Jon

Thank Benjamin for answering....
There is a 1000mfd/75wdc cap in the circuit, so there is a filtering (regulation) on this power supply, as I look with a scope at the waveform of the 32 v unreg, it is really 56 volts... in that case, the value of the cap should be much higher than 75volts... Well, I guess that I will have to dig on that !!
Best reguard's, By the way I usually speak french, so forgive my writing ...

When you look at the diagram, you observe that there is a regulation by the addition of a 1000 mfd/75wdc cap..and if it is really 56 volts, the value of the cap should be much higher..

Hi John:
Thank you for your kind offer.
I have a great 555 scope, which I intend to keep working.
I also have types CA, D, W, 1A7, and 1A5 plugins.
Would your parts stash include those from scavenged plugins?
In particular, my W plugin likely needs some part(s) for repair of the
large reference voltage selector rotary switch. Possibly a switch wafer,
although it has been a few years since I tried a repair.

Thanks for reading!

Randy
Tek 555, 7934, 7633, 7623, and HP, Fluke, and others.

On Mon, Jan 13, 2025 at 12:37?AM Nick Bergan via groups.io <nbergan13=
[email protected]> wrote:

Hi John,
Thanks for offering to share.
Do you have many 7000-series knobs and potentiometers?
I'm also looking for a correct graticule, light filter and CRT bezel for
my model 511 and model 422, which aren't exactly in the 500-series. If
nothing else, I might have to make my own or use parts from similar models.
I think I own or have seen just about all of the Tektronix analog scopes
in a 60-mile radius, lol.
I sure have made a lot of eBay purchases for how recent I got into the
restoration hobby. I'd hate to know how much I've paid in just shipping for
parts and tubes.

hers the scriptblock part i talk about:

tempBuf=malloc(0x20000)
acqLibReadNVRAM(0,tempBuf,0x20000)
fdescriptor=open("c:/eepromdump.bin",0x0202,0777)
bytesWritten=write(fdescriptor,tempBuf,0x20000)
close(fdescriptor)
‐----------------------------------------------------

This script block is a sequence of VxWorks commands designed to read data from non-volatile memory (NVRAM) and save it to a file. Here's a breakdown of each command:

tempBuf=malloc(0x20000)

Allocates a block of memory of size 0x20000 (131,072 bytes) and assigns the pointer to the tempBuf variable.
This memory is used to temporarily store the data read from NVRAM.
acqLibReadNVRAM(0, tempBuf, 0x20000)

Reads data from the NVRAM (Non-Volatile Random Access Memory).
The first parameter (0) likely represents the starting address or identifier for the NVRAM.
The second parameter (tempBuf) is the destination where the data will be stored.
The third parameter (0x20000) specifies the number of bytes to read.
fdescriptor=open("c:/eepromdump.bin", 0x0202, 0777)

Opens or creates a file named eepromdump.bin in the c:/ directory.
The second parameter (0x0202) is a bitmask specifying the file open mode. 0x0202 typically means "open for writing and reading, create if it doesn't exist".
The third parameter (0777) sets the file permissions to read, write, and execute for everyone.
bytesWritten=write(fdescriptor, tempBuf, 0x20000)

Writes 0x20000 bytes (131,072 bytes) from tempBuf into the file described by fdescriptor.
The result of the write operation is stored in the bytesWritten variable, indicating how many bytes were successfully written to the file.
close(fdescriptor)

Closes the file, ensuring that any pending data is written and resources are freed.
In summary, this script allocates memory, reads a block of data from NVRAM into that memory, and then writes the data to a file on disk named eepromdump.bin.

is this tested on the 7000 series also non- B ?
and compared to the eeprom content exported with a programmer. i can believe it is but i ask this because we worked on it for a longer time. and did not succeed completely

Hi i am Charlyd on the evvblog i thought i jump in here i guess i missed this perticular part, because i am a member in groups.io here..and very interrested in exporting the eeprom content on the 7000/7000B first of all keep up the good work in exploring your equiptment.

@ozan you say and that is correct as far as i know. the cal. const. are in the eeprom.

but the script extract it from the nvram how is that.... (sorry i send my reply in parts , because this is the third time i had to start retyping all here)

Hi John,
Thanks for offering to share.
Do you have many 7000-series knobs and potentiometers?
I'm also looking for a correct graticule, light filter and CRT bezel for my model 511 and model 422, which aren't exactly in the 500-series. If nothing else, I might have to make my own or use parts from similar models.
I think I own or have seen just about all of the Tektronix analog scopes in a 60-mile radius, lol.
I sure have made a lot of eBay purchases for how recent I got into the restoration hobby. I'd hate to know how much I've paid in just shipping for parts and tubes.

On Sun, Jan 12, 2025 at 04:18 PM, richard ramacieri wrote:

Hi.. I have a 465m with HV section blowing the fuse... Found that the 32v
unreg source voltage to be 56 volts !! ..A look at the diagram show the
transfo, then a bridge and a 1000 mfd cap rated at 75 vdc...Is it normal to
have 56 vdc instead of 32v unreg...I find this very unusual !! Please let me
know..

Schematic shows 52V typical with 116V supply voltage, 56V is not excessive especially if your mains voltage is a bit above 120V.
Ozan

Unregulated voltage is higher than what us really "says". For example, the +5V unreg on my scope is around +11V, which then gets regulated to +5V. According to my service manual this is normal

For your scope, the service manual doesn't give a voltage for that, so I would recommend you check the line input settings. If those are good the 56V is probably normal.

I would also recommend checking the regulation circuit for the +32V regulated as a short there can pop the fuse. Speaking of shorts, a shirt can by anywhere on the +32V rail, so you'll have to do some power tracing.

Another question, is it blowing F558 or F736?

If it's blowing F558, it's likely a problem with the HV transformer or the transistors/diodes that drive it.

Benjamin

Hi.. I have a 465m with HV section blowing the fuse... Found that the 32v unreg source voltage to be 56 volts !! ..A look at the diagram show the transfo, then a bridge and a 1000 mfd cap rated at 75 vdc...Is it normal to have 56 vdc instead of 32v unreg...I find this very unusual !! Please let me know..

Hi... My name is Richard, I recently acquired a 465m scope in mint condition..The problem is that the fuse in the high voltage PS burn instantly when the power is applied..Check all diodes, transistors, capacitor to be ok.. Didn't check the U555 so far... Voltage are ok, 5v and -5v and 32 volts, but as I went to check the 32 volts unreg use to supply the HV, I was surprise to see a reading of 56 volts.. As I look at the disgramm, this voltage come directly out of a bridge, filtered by a 1000mfd/75volts (wich voltage value is odd compare to 56 volts)..My question, is 56 volts normal at thispoint ?

Love to have it but is it in NZ? How much do you want for it?
PM: ccdman1 at outlook dot com
thanks