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Rebonjour cher Jason and Luca:

1/ The issues of U800 are discussed at length in many threads, see especially the fine notes of Chuck Harris.
use TEKscopes2 as he was banned from Tekscopes at groups.io.

2/ In U800, The original TEK designers used NO heatsink, the dissipation is via the mounting screws and PCB.
The tension on the IC presses it to the PCB. Set by special washers and torque spec on nuts.

DO NOT attempt to tightne the nuts, or remove them or add any HS.

If you already made such useless mods DO NOT touch as further fiddling may kill the custim TEK IC

3/ Later SN 2465B used a substutue U800 as TEK stopped cistom Hybrid prodction.
Those IC are more pronee to fail

4/ BOTH mgt screws on U800 are NOT at ground but -80 (?) V.

If any hardware, nuts, or HS on the screws touches the housing, instant short of the PSU and possible kill of U800.

5/ The need for HS is a myth, them is fine and within rating IF you JUST LEAVE IT ALONE!!

Some use an external fan blowing at U800 if running 2465B with case removed.

Internal fan gives sufficient air with case properly in plave and NO HS or mods to U800.

6/ I have measured the U800 temo at the screws and center of IC, very normal Trise, no HS.

I have many 2465/B/7 that have run for decades with no U800 failure and no HS.

Just the experience of an old retired EE (1968).

Bon Chance !

HAVE AN ABSOLUTELY FANTASTIC DAY!

Jon

Jean-Paul

Thanks for sharing your experiences. In this case I will leave the IC alone and just lubricate the fan to ensure proper cooling.

My question still remains: What do I replace the Keeper II LTC-7P with? I cannot have the originals shipped here in Europe.

There are some China alternatives: EVE EF651625, otherwise I will just solder in a regular Li-SOCl2 in parallel

question still remains: What do I replace the Keeper II LTC-7P

Lost that in the long thread and long replies.

Suggest you start a new thread/topic. Use a photo of the battery



Jon

If the OP has not already done so, it might be useful to post the question on the TekScopes2 forum as well as this forum.

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All spelling mistakes are the responsibilty of the reader (Rick Renz, STK, ca. 1994)
DaveD
KC0WJN
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We alwasys use BOTH Tekscopes and Tekscopes2, as they are different.

The batteries mentioned are at Mouser, DK but not shipped to EU.

I am sure epay in EU/France/etc has Chinese clones or vendors that do not care about Li battery regulations.....

Jon

Hi Luca,

Indeed Mouser doesn't deliver these Timekeeper Batteries to Europe, but Conrad has the same Battery (LTC-7PN). Same Pin-Out. This time without its casing.



Egge Siert

Hi,

I found this already and it seems to be a Chinese company EVE with not too positive feedbacks on the internet. I think I'll stick to bodging in a Saft LS-14250 or Tadiran SL-850/S unless someone recommends against it

Hi Luca,

Maybe you have another WWW? I am not aware of this reviews, more the contrary. I replaced in the past 4 of these batteries with the "suspect" EVE's. No problem with them so far (the originals were also still good). Besides Conrad also Farnell have them on stock. When you order from them I don't think you are at risk.

Egge Siert

Hello Egge

It was on Amazon, but for some other type of battery. If you had good experiences with them I'll try it and buy from Conrad.

The original still has its charge, but if you check the datasheet it just sharply drops off once it's done. My guess is this can be anytime now since the original is over 30 years old.

If you had experience with four of them already, how did you bridge it during the swap? Any tips on the procedure to avoid data losses?

I don't understand what you mean by "working underground". Would you clarify that, please?

DaveD
KC0WJN

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All spelling mistakes are the responsibilty of the reader (Rick Renz, STK, ca. 1994)
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Hi Luca,

I used a cotton towel as a surface, a Weller Magnastat (floating not grounded) and a Low Cost (ZD8915) Desolder Station. First I made a Back-Up with one of the new Batteries. Later I replaced it with one of originals (still good). I soldered the connections. I didn't take the disconnect risk with using Alligator Clips during handling of the Board. I also included a 10K Resistor in series with the Negative Pole. This to minimize the risk of shorting the leads accidentely.

On eevblog there are similar tips on this.

Egge Siert

Hi Dave,

Thank you. I edited the Message.

Egge Siert

Egge,

Thank you. So you put down a cotton towel on your bench and did the work with that as an anti-static surface?

Forgive me, but that is so far out of my experience as an engineer as to be difficult to understand. But it sounds as if it is a unique and effective solution.

DaveD
KC0WJN

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All spelling mistakes are the responsibilty of the reader (Rick Renz, STK, ca. 1994)
==============================

Hi

Before proceeding with the battery swap I thought I'd check the recapped PSU first. Unfortunately the scope is now comatose with all voltages being wrong. Is it possible that a recap throws off the reference voltage by that much? J119-4 is at around 5V.

Can I try to adjust it or should I try to find out if something else is fundamentally wrong?

One of the caps is getting hot. I think I made an oopsie

(similar to here )

Doesn't help to take notes when they're wrong. I hope it's just those caps

Success! I put in the correct caps and also managed to swap the battery as suggested. I'll let the scope run for a bit to see if everything went well.

On Mon, Feb 5, 2024 at 07:48 AM, Ozan wrote:

FM18W08

I have also with success replaced DS1230 Dallas chips in HP scopes with FM18W08 and a SOIC to 28DIP board from CPC Farnel + IC socket = 5$/GBP and works well.