Teardown - Hitachi V1065

[grumpydoc]

From what I can see in the circuit description, it depends on the trigger circuit, not the CPU. I am a decent amount off, not just a few digits.

I've just had a look, not really paid attention to that part of the circuit before.

The trigger circuit is the logical place to start as you obviously want to clean up the input signal to a pulse train to count.

If you look the trigger pulses are fed from the top of R655 (waveform 4 top right of sheet 4 of the circuit diagram) to IC2170 which is an 74AS74 configured to give a /4 frequency division (bottom left of sheet 5). From there it is passed to IC2171, a 74LS393 dual 4-bit counter where a further /32 frequency division takes place. After that it is fed to the PC5 input of the CPU via input selector IC2161 (bottom left of sheet 8 now).

If your frequency counter is off I'd check the CPU clock frequency first - there isn't really much to go wrong, just a crystal, two caps and a resistor straight to the CPU but the CPU clock is the only reference for the frequency counter that I can see.

[Flump]

thanks for the look inside grumpydock
lots of good info here.

I wonder if anyone knows if the scope test point on the front of it
can be adjusted as mine reads 1043 measured by the scope  and not 1k,
my multimeter reads 1042 so it is the test point reading high.

[true]

thanks for the look inside grumpydock
lots of good info here.

I wonder if anyone knows if the scope test point on the front of it
can be adjusted as mine reads 1043 measured by the scope  and not 1k,
my multimeter reads 1042 so it is the test point reading high.

It's not meant to be that accurate. If you want it to be, I'm sure you could solder something in to correct it...

[rbm]

I hope that I can ask a question about the sister scope to the 1065, the V-695 (60MHz model).  They share a great deal in common.

I recently purchased one and just received it in the post.  The owner didn't disclose the broken selector switch (S1603 on the schematic); I assume it is broken because it does not select any of the functions reliably. 

My selector switch has no centre detent position (only up and down), and the up / down positions are not-momentary in operation (the switch remains).  From the above text "fairly normal centre biased toggle" and from the schematics, S1603 looks to be a DPDT centre detent, possibly momentary action.  Is this correct or should the up-down positions be non-momentary?

I'll have to tear into the scope to take a look at the front panel circuit.  However, from the pictures posted above, it appears that S1603 is not able to be serviced.  Will I need to desolder and replace this switch completely or can it be salvaged?

Thanks in advance for helping.

[grumpydoc]

My selector switch has no centre detent position (only up and down), and the up / down positions are not-momentary in operation (the switch remains).  From the above text "fairly normal centre biased toggle" and from the schematics, S1603 looks to be a DPDT centre detent, possibly momentary action.  Is this correct or should the up-down positions be non-momentary?

It's a centre-biased DPDT, open contacts in the centre position and not momentary action. From memory it has a mounting for the grey paddle switch which is the one feature that might be difficult if you try to replace it.

However, it is likely that the switch can be salvaged as it sounds exactly like the switch on the scope I took apart. You do need to remove the front panel switch and LED board which means taking out the PSU/HV board and the CPU board - after that there is enough room to wriggle it out. Take the grey plastic paddle off squirt some contact cleaner or IPA into the top of the switch, then work the switch a bit. It will probably start to come free and work correctly. Repeat if necessary and if the contacts are not working try to get some contact cleaner or deoxit or equivalent into the switch itself. Finish with some light oil into the top of the switch (especially if you used IPA to clean - many commercial contact cleaners have a light lubricating oil in them anyway).

[old gregg]

Seems that the switches end up with issues. I've a Hitachi VC-6023 and its push/pull buttons are a gamble everytime I want to use one. I can't pull the button otherwise it doesn't go back to its orginal position, which give an odd reading.

I thought about changing the part (but not references) but maybe a good cleaning could do the trick.

[rbm]

MINE HAVE THAT CHIP TOO Only on the right side. Wonder why that is.

I've got a theory for this.  Mine also have both top corners chipped.  When I took my scope apart for servicing, I noted that the metal cover is captured by the bezel along the top edge and the two sides.  It needs to be slid into place carefully when removing and replacing.

I think if a ham-fisted service tech just slams the cover into place without being gentle with the corners, the corners get chipped.  Afterall its hard metal versus soft plastic.  Obvious which wins out.

[rbm]

My V695 scope has exactly the same problem as anjimoo posted above.  The selector switch is truly broken on the inside and does not function as it should.  It should have a centre resting position with momentary action either up or down.  Unfortunately, mine stays fully up or fully down and has no centre detent.

I've been doing some research to find a replacement.  Here is what I have found out so far.

The original switch is a Fujisoku ALE2S-2M4-10-Z , DPDT paddle switch with the function (ON)-OFF-(ON).  The technical data sheet for the switch can be found at:
http://copal-electronics.info/en/00134/01b64.pdf

Fujisoku was purchased by Nidec Copal Electronics in 2007 and Copal continues to build the switch.  I contacted the Canadian representative for Copal to ask about the availability of this switch.  I heard back that the switch is available through Digikey via the Copal part number above.  It is not listed on the digikey web site nor is the part number searchable.  The downside is that the minimum order  is 50 units (since the factory has to tool-up to make the switch).

Doing more research on Digikey and Newark Electronics web sites, I discovered a very good substitute for the OEM switch.  This is a NKK Switch, part number A28KB-BH-ND.  This switch has the following characteristics:  DPDT, function (ON)-OFF-(ON), snap for paddles, straight with bracket, Grey 14mm paddle X 4mm wide. The paddle is slightly narrower than the Fujisoku, as shown in the drawing below:

However, any space in the switch opening can be taken up by making a flexible sheet to fit tightly up around the handle, and slide up between the front panel and the scope case.  This switch is not stocked at Digikey or Newark. 

I placed an order with Digikey for the switch.  It was an extraordinarily long lead time to get the switch but it finally arrived.

I proceeded to remove the Horizontal control card as described in the first post of this thread.  Once removed, I desoldered the Fujisoku from the card. It was difficult to do. The reason was that the switch has a metal band that is also soldered to the board in addition to the pins.  There was a risk of damaging the board so to ease the risk to the PCB, I clipped the four tabs that fixed the metal band to the board.  I used a solder sucker to disassemble the solder joints and loosen the switch.  Once free of the board, I proceeded to clean up the pads.  I did lift a couple pads because I don't have the proper desoldering equipment; it would be best to use a desoldering station but I didn't have access to one.


You can see the switches compared side by side below.  The NKK obviously has a smaller paddle.  What is also different between the two switches is the action; the NKK is much softer in its action than the Fujisoku.  I think this softness will give the switch a longer service life.



I double checked the contact action on the NKK versus the schematic and verified the orientation of the switch.



I placed it on the board, soldered up and refitted the PCB back into the scope.  The paddle fit through the opening with no problems and doesn't look too bad.  Operation is perfect and the full functionality of the scope restored.



This is a viable, easy fix for those with a broken Hitachi scope.

[anjimoo]

Thanks Robert! Your research is most appreciated. Looking forward to hear if this component is a proper substitute. My scope is usually gathering dust b/c of the switch. Hopefully this'll revive its use

[Rmcka4004]

 :-BROKEi think I've found a replacement sw at digikey. I ordered it today and will share if it works

[mlloyd1]

Robert:

Thanks so much for your VERY informative investigation.
 
My V-665 has this exact problem and I'd like to repair it so my grandson can have this scope when he is ready for one.

However, I think the exact OEM replacement is actually the Fujisoku ALE2G-2M4-10-Z, right? Looks like the  ALE2S-2M4-10-Z is a rocker.

mlloyd1

[rbm]

Hi,

Either model can be equipped with a toggle or rocker actuator.  The difference between the G and S models is that the G has 2.54mm between contact rows and the S has 5.08mm between contact rows.  The S is the correct original designation.

[old gregg]

Hi,

I'd like to change the push/pull in my hitachi VC6023, they're all dirty and the switching isn't done properly anymore (the trigger becomes quite tricky). The service manual gives as references EVH - YK3325B14 (10K push pull). Does anyone know where I can find a replacement or a sibstitute ? (It's annoying to not being able to use the X10 mag)

I googled the refrences with no success.

[Ether]

Hi, is it possible to repeat the frequency mod on a V-1560. Also, is there some way of preserving the holdoff function while getting the frequency counter?

[grumpydoc]

Hi, is it possible to repeat the frequency mod on a V-1560.

Probably - have a look at your CPU board and see if the jumpers correspond to the "no frequency counter" setting. If so swap them.

Also, is there some way of preserving the holdoff function while getting the frequency counter?

Not sure what you mean by preserve?

[Ether]

Thanks for the reply.

IT WORKED! I now have a frequency counter on the 1065 non-A. It's the 4th option of the cursor mode. Since you have a non-A, I will describe where it is:

I was referring to true's post that the frequency counter was the fourth option of the cursor selection and AFAIK, that's to adjust the holdoff.

[grumpydoc]

I was referring to true's post that the frequency counter was the fourth option of the cursor selection and AFAIK, that's to adjust the holdoff.

Ah, see what you mean.

Holdoff isn't affected - the frequency counter is the 4th measurement function - keep on pressing the selector down until you get there

[Ether]

I replaced the zero ohm resistor as according to true's post but I'm not getting the frequency counter. I did try pushing the selector all the way down though so any help would be very appreciated. 

[true]

Did you keep going down? If it doesn't work, maybe there is something else different in the 1565. I don't know. Would need to look at schematic again, and I'd be willing to, but after some serious recent trouble I am in no mindset to be able to.

[Ether]

Thanks for the reply. I did tried holding the switch down and I compared the 1060 board with the 1560. They match perfectly. Is it possible for you to check my picture against what you did and see if I screwed up the positioning? I fixed the solder joint after the picture  was taken so soldering should be fine. Also, pictures of your 1060 with the counter enabled would be nice.

[true]

Don't hold the selector down, keep pressing the selector down.

It will be a while before photos. Had a major burglary. Scope and cameras weren't stolen but other electronics things like parts and my soldering iron were, and the cameras to secure the house (to be installed the evening of the burglary) were stolen too so I am going to be delayed for a while.

[Spork Schivago]

I'm sorry to bring up a dead thread but I have one of these scopes too, Hitachi V-1065A.  The rocker switch was bad as well on mine.  It'd go up and down but no middle (S1603 AL2S-2M).  I'm pretty sure I found a replacement on Digikey, the exact replacement I mean, where you don't need to order a minimum of 50 of them.  Is this it?  http://www.digikey.com/product-detail/en/ALE1D-2M4-10-Z/563-1201-ND/1792105

Only reason I'm posting is in case other people come across this thread like I did using google looking for the exact same replacement switch.  I hope it helps someone besides me out!

[Spork Schivago]

I also believe this is the replacement plastic cover part for it:  http://www.digikey.com/product-detail/en/140000050624/563-1204-ND/1792108

[rbm]

  I'm pretty sure I found a replacement on Digikey,  ... ALE1D-2M4-10-Z/563-1201-ND/1792105

Unfortunately, the one you've pointed to is a SPDT switch.  It has the proper physical body dimensions however it doesn't replace a DPDT, centre off switch used in the scope.  The part number you supplied decomposes to:
ALE=Lever action
1=1 pole
D=ON-ON
2=PC terminal
M=standard

The NKK switch I spec'ed out in an earlier post is the correct one.  The Copal original is special order only from Digikey.

[Spork Schivago]

  I'm pretty sure I found a replacement on Digikey,  ... ALE1D-2M4-10-Z/563-1201-ND/1792105

Unfortunately, the one you've pointed to is a SPDT switch.  It has the proper physical body dimensions however it doesn't replace a DPDT, centre off switch used in the scope.  The part number you supplied decomposes to:
ALE=Lever action
1=1 pole
D=ON-ON
2=PC terminal
M=standard

The NKK switch I spec'ed out in an earlier post is the correct one.  The Copal original is special order only from Digikey.

Thank you for breaking that down for me!   I really appreciate it!   Man, I really thought that was it.  I tried going to the one you speced out earlier but I couldn't find the part number.  When I clicked the link you had up, it gave me a 404.  I went to their website and clicked on the data sheet, it gave me a 404 too (from Copal's website).