A look inside an Iwatsu SS-8740 (LeCroy LA314) 400MHz Analog 'scope

[perdrix]

I just got a new to me Iwatsu SS-7840 (aka LeCroy LA314) from an auction here in UK.   It seems a nicely put together 'scope designed to compete with the Tektronix 2456B.



As they say don't turn it on, take it apart!

Power supply, HV, Horizontal and Z-Axis



Detail of conformal coated sub-board in PSU



Vertical board plus detail of CRT termination - can anyone give me any idea what the wire stub on one side of the termination is for - my guess is that it has something to do with the bandwidth variant that goes to 470MHz?



CPU board (lower left) and main board with delay line (lower right)



I was amazed to find that the CR2354 backup battery soldered to the CPU board in 1997 still has a good charge on it!

Now if only I can find an IE-1066 Adjustment Jig (calibration fixture) to go with it!

Dave

[shakalnokturn]

Neat! So Japanese... Thanks for sharing.
Did you get that blue CRT filter off in the end?

[BravoV]

Really nice Dave, what a score ! 

Thanks for sharing the teardown photos, loved how you picked few detail close up spots. 

It seems a nicely put together 'scope designed to compete with the Tektronix 2456B.

Honestly, even though I own a Tek 2465B  , this SS-7840 is one of my dream scope too, I guess I'm too greedy. 

[nctnico]

I used to own one of these. Very nice analog scopes but I wish it had a full set of attenuators on all channels.

[guido]

I have a 7810. The manual contains the schematic for the IE 1066 (electrotanya has the manual). It is just some logic, opamps and a very early audio DAC with parallel inputs, a PCM55.
You can also use a PCM54, which is what i did 

Works great, apart from the buzzer. Never got round to figure out what is wrong there 

[dzseki]

Very nice! The V amplifier looks rather effortless for 400MHz performance, at least compared to my HP 1720A's.
The brochure I saw mentioned 470MHz only in certain V/div setting for the SS-8740H, for the rest "only" 440MHz, so it might be more like an input related thing, or cherry picking some key components.

[perdrix]

Hi Guido

I'm assuming that you built that yourself?  If so do you have any spare boards?  Or would you share the Gerber files?

Thanks
David

[guido]

Hi,

Yes. No. Yes. Contact me offline