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However, the 453 MOD703H I have uses solid state diodes. It is the original style in terms of CRT and controls, but has many board changes internally.

Of the ones I have, it is a bit more mysterious
Like the others I have, it came from the USAF.

On 2 May 2025 5:40 pm, Ray M wrote:

Looking at docs, it appears the the tubes were used in the later (20,000+) 453's as well.

The pencil rectifiers were used in the later (serial 20,000+) 453s. Only the Nuvistors were replaced (with FETs) in those 'scopes.
--
Dale H. Cook, GR/HP/Tek Collector, Roanoke/Lynchburg, VA

Mark,
Not sure if I understand this correctly: when I measure 3.6V on a 3.5V battery (and 3.45V on both of the SONY SRAMs) can I not safely conclude that the battery is still OK?

Gerdy,

Even though the battery shows the correct voltage, its age is another matter. Mouser has 667-TL5903P as a replacement that is heavier in capacity. I had the 7000 fail in my 2440. This battery fixed that. Calibrating it was easy. I did totally recap the piece with Nichicon ULD, UHE and LGR for the main filter condenser. It is best to keep a gap between the bottom of the condenser and board to allow for air flow and making sure you can add solder to the top to ensure a complete connection from bottom to top. Make sure to replace all RIFAs! You can use X1 and Y1 types at a higher voltage than original.

You can add good compound between the CCDs and their heatsinks. Make sure to do what Bob K. says about using an external fan when the case is off. Oil the original fan while you are working on yours.

Mark

Looks like it's from a TM5000-series plugin. Probably something like the
DC5010; certainly from something that had a non-GPIB variant.

Dave Casey

On Fri, May 2, 2025 at 6:18?PM bill K7WXW via groups.io <K7WXW=
[email protected]> wrote:

While going through another crate of Tektronix gear I came across this
board, which has the legends "GPIB", "TEK T1", and "R-0291-XB". My google
fu might be weak but I can't find any hint to the board's use or origin.

Anyone recognize it?

Here's a link to the photo:


Thanks - Bill

While going through another crate of Tektronix gear I came across this board, which has the legends "GPIB", "TEK T1", and "R-0291-XB". My google fu might be weak but I can't find any hint to the board's use or origin.

Anyone recognize it?

Here's a link to the photo:

Thanks - Bill

Yes, solid state

By "diodes" do you mean solid state diodes (vs. tube diodes)?

Thanks,
Barry - N4BUQ

no the idea was to move them to a new location......hopefully they will be put to good use.
搁别苍é别

A few other variants.

Product Mod Description
453 120H Sawtooth out.
453 l27C Internal Sync Separator for TV applications.
453 l52J Special panel with "Property of Friden, Inc." lettering to be added to panel in standard 453 type
453 165M Watertight combination case; EMI to MIL-I-61810.
452 172Z External graticule.
453 208A Deeper panel cover and handle (Mod 147A); P6019 and 3 9 1 P6010, vibration test (Mod 799H).
453 208B Deeper panel cover and handle (Mod 147A); vibration test; probes changed to P60l9, 9' P6006 and two 9' 1 P6007.
453 210H IBM package. P6010.
453 221T Probes changed to one 9-foot P6019 w/passive termination, and two 9-foot P6010, w/511 probe tip cables.
RM453 127C Internal Sync Separator for TV applications.
RM453 l53F Oversize rack panel, special handles, MS power connector, tracks with extra travel.

Guess I priced them too cheap!! That's GOOD. Cheap is GOOD!! They have been bought. Thanks!!
--
Kim Herron
W8ZV
w8zv at goldenradioservice dot com
www.goldenradioservice.com

Looking closer at the MOD703K doc, it shows diodes and not tubes. It appears the the MOD703H also has diodes on the HV assembly.

Thanks. I noticed the -A after I posted and could not correct it. CTR instead of CRT as well ;-)

Looking at docs, it appears the the tubes were used in the later (20,000+) 453's as well.
Now I am curious if the MOD703K share the HV board with the 753A-5.

Looking at the HV section, it has the 120-0471-00 transformer, same as what is listed for the 453A.
The MOD703H has the 120-0360-00 HV tranformer, same as what is listed in the 453 manual. Not clear where I would find the tubes

On 2 May 2025 4:56 pm, Ray M via groups.io wrote:

453-A Larger CTR, 60 mHZ

All of the 453A (note that there is no hyphen in the model number) examples that I know of have solid state HV rectifiers in place of the pencil tube rectifiers, leaving the CRT as the only vacuum tube.
--
Dale H. Cook, GR/HP/Tek Collector, Roanoke/Lynchburg, VA

Ray M <raymond.muno@...> added folder */Tek 453 variants*

I added the type study spreadsheet in the Files section.

/g/TekScopes/files/Tek%20453%20variants/Tek%20453%20Type%20Study.xlsx

I the three Tek 453 scopes. Two are MOD703K, one is 703H.

I find the docs that show some differences, along with changes.

In the family, I find these variants

453 SN < 20,000
453 SN 20,000+ Major change seems to be nuVistors are changed out for FET's
453 MOD703H (see below)
453 MOD703K (see below)

453-A Larger CTR, 60 mHZ
453-A Later SN, many changes
453A-1 Uncalibrated delay of the delayed sweep
453A-2 Calibrated delay time
435A-3 Calibrated sweep delay and mixed sweep
454A-4 Single time base
453A-5 No documentation found, X-Y mode

The 453 MOD703K seems to have more in common with the 453A-5. They share most of the same boards, larger CRT.

The docs I have show MOD703K includes:

1. SAWTOOTH OUT facility has been added to the rear panel via BNC connector.
2. CH 1 OUT connector has been moved on the front panel, Amplitude is 200 mV for each division of CH 1 deflection,
3. A GATE and B GATE facilities have been added to the rear panel,
4, The Calibrator Current Loop has been added to the front Panel, and the 1 V CAL connector has been moved
5. A TRACE FINDER control has been added to the front panel.
6. The HORIZ DISPLAY switch has an added position providing XY.
7. The light on the RESET control has been deleted.
8. TRIGGERING (DELAYED SWEEP); COUPLING and SOURCE functions, have been added including an EXT TRIG INPUT or EXT HORIZ connector,
9. Special accessories in lieu of standard are provided, See parts list.

Mod 703H includes:

1. A SAWTOOTH OUT facility is added with its BNC connector mounted on the side panel.
2. Amplitude of CH 1 OUT signal is increased to 200 mV for each division of vertical deflection.
3. The CRT is replaced with a CRT having a special internal rise~time graticule.
4. Two. probe tip adapters, two banana plug tips, and a 13.5" BNC to BNC 50 Ohm coaxial cable are added to the standard accessories.

I have compiled a type study showing the board part number designations that were used in all the variants, compiled from docs and compared to the ones I own. The doc I find for changes to the 703H and 703K shows changes for 703H after serial number 60777. They do not agree with the one I have that is 60794. The board numbers listed for the 703K agree with what I find in the two scopes I have. The 703H has a couple of boards that have 703H silk-screened on them, and there is a small daughter board (670-704-00) attached to the A Sweep board, missing on the 703K's

I think that means a checksum failure. In other words, it’s detected that the data has corrupted in the non-volatile RAM. That’s typical of battery failure causing lost settings, but may happen if the RAM itself is failing or — possibly — power supply or other issues causing it to be unreliable.

Indeed, I found the SRAM datasheet, data retention is min. 2V. So I think with my Li battery still at 3.6V I am still OK.
I checked the PS, especially the caps, none of them look bad, I will try to remove the PS board (tried already but no luck so far) and measure them.
I do see 2 (X2?) caps that are bulged as well as a 1 W resistor looking burnt, all on the PS board near the mains entrance. These will have to be replaced but not sure this is the reason of the fail codes.
This is what I originally posted:
" Fail codes 7000 & 9000 at startup, drilling a bit deeper: 9210,9220 & 7210,7220,7230,7240.
The scope had already shown a few times CKSUM-NVRAM FAIL but then a restart fixed this every time, now besides the FAIL messages for the above, it shows PASS for this particular check although there is an asterisk markerd like this CKSUM-NVRAM* "

Not sure what the * means in the CKSUM-NVRAM* ??

Look to see what the lowest voltage is for data retention.? The 4.5 volts is the minimum for successful writing and reading. Data may be retained, but not manipulated, at lower voltages.? You see this for some battery backed up RAM chips.


Harvey