LeCroy 9450 with bad 1M inputs, need help

[Martin.M]

hello friends,

I have a cute 9450 Dual 350MHz LeCroy with defect Input modules HHZ, on both channels,
have buyed the scope in this condition.

It works on both channels at 50 ohms, with calibration error (small offset comming from the HHZ?)
1M inputs are dead. The clock timer forget the time date when turning off the scope  (battery empty?), this is not fine but I can accept it.

So I need this input modules, its impossible to repair them bec. the IC there is directly coated on the print.

So I need please:

* 2pcs of this hhz, or a aquisition board from a scrapped one, ore 2 pcs. rebuild HHZ: I have the gerber data and instruction how to make that.

of coarse full payed, this instrument is to cute to put it in the junk ! the CRT is without any burn in, in perfect condition.

thank you

greetings from germany
Martin

[SiliconWizard]

I love those older Lecroy scopes! I own a 9354AL, fantastic tool!

Anyway, you should take a look at the Lecroy Yahoo group (LeCroy_Owners_Group). They have info on the HHZ module AFAIK (schematic and other):

https://groups.yahoo.com/neo/groups/LeCroy_Owners_Group/files/HHZ406_HHZ606/

Those modules seem very hard to find, but I'm guessing they should not be too hard to repair.

[Martin.M]

thank you.
The instruction how to bebuild that HHZ is taken from the group, including application and gerber files.
But I am not familiar with smd solding, so need Help 
greetings
Martin

[SiliconWizard]

Obviously you should check whether they can be repaired...

For all the passive and discrete components, replacing them is easy. Now there are also 2 COBs on the PCB (chip on board, the ICs that are under a small blob of black resin). If those are toast, there is no way to repair the modules AFAIK.

So checking all the components except the ICs would be a good start. If you can spot some that are defective, there is a chance this is fixable (although one of the ICs could still be toast as well), but if none seem defective, your chances of fixing the modules are probably zero.

As I really like those scopes, I can offer to *try* and repair the modules if they are fixable. PM me if interested.

[tautech]

But I am not familiar with smd solding, so need Help 
greetings
Martin

It is not hard but you will need:
Practice before actual rework on old SMD PCB's.
Jewelers magnifying headset.
Fine stainless tweezers (non-magnetic)
Some type of fine and soft hot air heat source.
Liquid or paste flux.
Some fine tips, 2.4mm max. Hoof and chisel work fine. Do NOT use conical, they have insufficient thermal mass !

Helpful hints/advice:
Use only leaded solder so to not need too much heat.
Wet/dilute existing solder with fresh solder and then sucker/braid.
Hakko K style knife/skew tips will bridge both pads of most SMD passives so removal is easy; sweep off or pull with tweezers.
Really only IC's need hot air for removal.
Most rework won't need solder paste.
Be careful with SMD electrolytics, it's easy to lift a pad.

[Martin.M]

here are informations and data I have collected.

www.wellenkino.de/lecroy/hhz.zip   (this are the rebuild instructions from the lecroy group)

www.wellenkino.de/lecroy/service.pdf  ( the book for the scope)

greetings
Martin