My Tektronix®  SCOPE rebuild page.                                                             
Model Tek 2430A . (the ALPHA version only.
I am Not affiliated with Tektronix but old logo's used with permission!

For scope theory (of operations) go back to this page and for free manuals.

My non A, is similar.





I will only cover 1 newer feature  of the ALPHA version scope, and that is the HIDDEN BATTERY.  and removing shorts.

NVRAM:   NON volatile Random Access Memory. (the battery makes this RAM, not forget data at power off time)
The ram never fails ever, just the battery inside it. 
The bad things about using the DALLAS NVRAM, my list: (legacy points of view only )  Bad now, but not back in 1986.
  1. That it has hidden batteries inside. (deep, too deep)
  2. That can not be measured by you directly.
  3. The 3rd bad is that the whole 28 pin chip must be unsoldered, (a very hard job that, for sure pin 14 ground and pin 28 power) {tool limits sure}
  4. The 4th bad thing is that the only warning the batteries died, (both) is all loss of data and huge bill to do a base calibration is now needed.
  5. You get to throw away a good NVRAM just for the loss of  a simple battery.
  6. Best practice in this PUPPY is replace the DALLAS every 15 years, or buy a crying towel later.
  7. A standard DIP clip will no work on this huge chip, to suck the data out  of it. (forcing you to use  28 wires, hand soldered or removing the chip first)
The good thing is that it has 2 batteries that can last combined for 20 years. 10+10. (reports of many failing at 17 years) at least 10 years before the KEEPER-II(tm) on the NON ALPHA.
The Dallas is cheaper, (combined prices ram+battery) The maker says 10 years, even with 2 batteries. (odd fact)
Read the date code first before buying,  Today is 1805 (2018 work week 05)
All pins on a new chip in hand from pin 14 read 0v. so there is no way to test the battery inside.


The below are my theories on how to backup this data.

NV RAM HELL:?
Error code 4720 is low battery , below 2.4vdc. (time to get busy get a new battery now) NON "A" only warning.
Error code 6000 is NV CRC failure  , almost always caused by dead battery. (mostly doom this point on) Legacy points of view here, not 1987 .
Error code 6100 is CAL constants in NV lost, same deal, battery dead. (doomed)
 

The NVRAM never goes bad only the hidden batteries do. (and Cap.s on all PCB, love to  shorts sure)
The cure with the DALLAS chip is to back up data first. In a nut shell this.
One precaution I'd take is buy a 28HC256 chip and burn it with a huge block of text full.  Then read it back proving that  it works.
Then burn a spare DALLAS chip with the same data.  (looks good?  this text, say  book of test huge  6000 words book? of text?
Now doing this gains you huge confidence things can work. (all done off line, (scoped parked on shelf safe)  Then Danger looms next . Hihi (ham for LOL)
ATMEL is now
Microchip (2016 buy out) The chip is now hard to find, if you avoid scalpers at $130 each.(or fake clones from china)
The Atmel chip uses 12vdc to erase the chip using OE pin (and a 6 byte code),  do avoid this action , or damage to any Dallas chip is assured. Max voltage to Dallas is 6v !
The Atmel chip has charge pump inside I guess, that that lets you program it all below 5.25vdc on any pin, using only old TTL rules. 0.8vil max to 2.2vih min.
I have no idea how Atmel charges any of the floating gates (secrets?)
Fowler-Nordheim tunneling(and charge trapping,etc) . I'm told its charge pump or boost converter there.
The magic fast erase mode overloads the pump so 12vdc is needs at  the 6 byte Erase command. (ok I get it) if paranoid put 6v Zenor diode on the OE pin. (no 2 programmers are the same)
Of if your programmer promises a fast erase, bingo 12vdc.

  • Backup the chip any way you can now,before the battery dies, never after.
  • Then remove the DALLAS chip. (unsolder 28 pins do no damage, sure) or remove it first then backup data. Never use a grounded tip soldering iron or risk data loss. (ESD resistors ok)
  • Install a ZIF socket now into the PCB 28 pin pad holes, solder it down, (this should have been done new, for $3 cost,and was not)
  • Load the above data onto the new DALLAS chip using your programmer,(write mode)
  • Insert the new programmed chip into the ZIF.
  •  (in each step above, with the chip removed for reading or writing, clean the pins spotless of all flux using alcohol, (non rubbing type with oil in the mix) a bit of water in the mix is ok.)
One other idea is to convert to FRAM /PRAM or MRAM chips. (I will show links to that in the link sections below)
Reading data 101:   DS1230Y  (any speed is ok today) 32k x 8  {256k/bits}  (16 times larger than the NON "A" scope.)
A Programmer for $30 TL866CS from China? (ebay searched)   13,137 IC's supported.(2018)
Must be USB with software to run it.( to get lowest price with USB and  no PLCC adapters even cheaper.)
The best programmer has  universal skinny/wide DIP ZIF socket, as below has. (just for our job)

You then tell the progrmmer to  save data to a file.  (read and save, do not use the program or burn features until later !)
This DALLAS works, more like the base operations of  old 27C256 (HV chips bad) or the vastly  better 28HC256? (pops to my mind) the last is bingo.
The pinouts  can be different  on other chips, but not the below. (if not  a match?, adapters must be constructed)
Here is good matchup  Dallas on the left and a FLASH EEPROM on the right from ATMEL 28HC256. Has the same pinout.   But hark the DS1230ab/y are directly supported .

The pins match perfectly as do the Address lines and controls seen above clearly.
Next is a programmer that can do this , ATMEL chip. (connect up and save the binary to a file in binary  or hex format)
Most newer burner scan, so can this.  (the word burn comes from fuse burned, PROMs (1970s), then EPROM then EEROMS later) In truth is CMOS gate charging.




  See the full list of chips supported are here , dated and supports our chip directly.

2430A   battery:  A horse of a different color, no external battery! "Dang !"
The 2340A (alpha version)  may (3 decades old ,almost) commonly will have the Dallas (Maxim now) NVram failure (battery inside dead).
 

 

The 2340a does a CRC check (@boot) on the NVram, if that fails, it is corrupted, if corrupted the battery maybe DOA. 
The Dallas chip, has  a battery inside it , in fact 2 batteries  (and auto-fail-over for battery failure #1 to 2)  Maxim and STmicro both make this device. 
The Dallas chip, has deep buried batteries, that can not be physically  meter probe tested  and checked.
For proof of that see Figure 2 here. (no DC level warning pins, in the design, oops? that sux ! swamp gas)
These inside SRAM's chips are very special, in that they are hand picked for less than 1uA off line current or less.  and a 10year life span with dual batteries inside.
(one batteru fails? , it drops to the spare, inside)
I believe HP liked this newer design due to lower cost and has 2 batteries to fail.  (my wild guess and guess #2,  if bad in 20 years, you get a bill for $1000 PCB with new DALLAS on it.....ouch)

The DS1235 is obsolete now (it subs to, DS1230Y-120 or faster even 100nS is good ) all faster Dallas work here, 100ns is the speed, access time, the cost of fast is free, Moores law.Intel.



TEDIOUS Extreme steps: (pure theory on this scope)  due to the fear of unsoldering it first,(valid)
(scope unplugged from wall power)
High RISK but after 30 years,? It has no future this old.
In circuit reading to files might work (not tested by me, scared, but have done it on other systems and it worked 1/2 the time , expected that I did)
  1. Solder 28 kynar wires (wirewarp #30 guage) to each of the 28 pins.  A cool trick2 is buy 28pin dip header. See below that.
  2.   (use a soldering pencil that is not grounded tip )  do not ground any pins or bad can happen for sure pin 27 !!!!
  3. Tediously wire each kynar end to the programmer below. using the correct matching pin patterns 1 to 1. 2 to 2, ect.
  4. Connect the USB cable. (windows ding dongs it) PnP run the Programmers APP.
  5. Pick 28HC256 device. (in the software App) Or used the direct way.
  6. Back  up the NVram, by doing a  read and save. with the app.
  7. Examine the data,. does it look real, or full of FF's (use hexeditor free to read it)
  8. Buy a new fresh DS1230Y-120 or faster even DASH -100 chips are faster,and good, (seen today)
  9. Program the fresh new Dallas  NVRAM with the above saved file data you created, using the same programmer  tool. 
  10. Remove the old chip from the main board. (it's junk now) but if wise backup one more time directly removed, do the file MD5 match?
  11. Install a new socket to  the main scope PCB board,  I like this type a ZIF socket (zero insertion force) seen HERE.  0.6" wide fat DIP
  12. Plug in your new programmed NVRAM, to the ZIF.  Reassemble your SCOPE. to the normal state.
  13. Boot up the scope (power button on). and run all diagnostics and let it do the self CAL. It will pass because the factory CAL was not lost.
  14. The rumor is, that you can use a logic analyzer (yes if done it on other gear) to back it up  this data .  (a $35 programmer is way cheaper by 10 fold)
  15.  if lucky all is good. "CHEERS"
DALLAS NVRAM. Is not easy to remove.
 
The best way to remove it is to use profession grade ESD rated,  solder /unsoldering stations with a vacuum pump.(electric)
Know that this PCB uses no low temp solders back in 1984, 700f only.
How to make a DIP header,  solder the SIPS to the board, the solder the kynar wire to the header, plug the header in to the programmer ZIF socket.

To desolder any pad?  on the main  PCB chip of the scope (DALLAS PADS)
 Best is to wet it first with solder pencil with ADDED low temp solder and flux.
This mixes the solder down to a lower melting point in about 1 second.  From 700f solder to vastly lower,  and makes desoldering vastly more easy.  ( a very magical trick this is once learned)
Then with a cheap (or expensive vacuum pump system) suck the hole out. do not heat any pad over 3 seconds.
Use solder wick with water soluble flux. if above fails .
The key success is work fast, use flux. (flux cleans up later easy no worries)

This tool is $7 connect the small wire to 1meg ohm resistor and to bench ESD ground.  Do not ground it directly to ground or risk data in the chip.




The never do section:
Avoid touching jumper J156.  (until you) Read the SM.  read page PDF 179 on it's proper usage.
This jumper prevents the External CAL from activating  (doing so by accident destroys the NBS ( now called NIST) NVRAM calibration) pg 182.
SM = Service manual.

After a loss of all data in the above NVram
Read SCOPE PDF page 254.  For  COLDSTART, + SELF CAL + EXTENDED CAL. See manuals below.

Links: (good)

Hacking ++  (I'd not do this to the NVRAM , but if compelled by demons... or? )

Dr. H. Holden (see how he captures the data on DALLAS NVRAM)

See here for free  manuals.

Link to above  programmer device list (text)


Secrets :
Dallas Semi:
Date codes,  YYWW  is the code.  (year and work week) I read like 10 QA failure reports and learn this by deduction. My spare is 1451a    2014 , week 51. (Christmas)
The suffix "A" not sure, plant code. Philippines
Okay one data sheet of many shows.
"Each DS1220Y is marked with a 4-digit date code AABB. AA designates the year of manufacture.
BB designates the week of manufacture. "



The 2430A End Zone :    Most of the below is moot , if the RAM is already, Dumped (lost all its data, offsets, gains, etc)




Example 1:  (the failure is super easy , a shorted cap. but finding it is much harder.)
Of a dead short to any  power bus .
See this page, click shorted CAPS.

I use  these same Scopes, to calibrate and or align  my HAM RADIO GEAR.
I use my scope to set RF signal generators, to exact output levels, as seen HERE.
This saves me a fortune in expensive other gear, that  I don't want to own, fix, or overhaul, nor find parts not sold for them.

I hope my page helps others fix their scope.
Buy a scope that has automatic calibration built in to it, this is your first buy.
Do not buy or own any Tube scopes. IMO.


rev 16++++ 8-27-2013  (last edit, 9-6-2016) revised again Jan,29-2018 (battery swaps) I split all pages.

I'm on Eham.net,  K5JXH.




Warning , This page (nor any others) is not affiliated to the company Tektronix, in any way, shape or form, nor to any other company.
This page is only commentary on their very fine products. The best of the best ! 
The Tek logo is the property of Tektronix.  I use it, only to show their old cool logo. 

Long live TEK !