Lathe digital readout

[crosswinds]

Hello!

Im trying to help a friend with a digital readout "headunit".

It reads scales from two axis and displays on LED segments.

One of the axis, gets a "error" message at random times (getting worse).

So the first thought is that it is the scale, but we have shifted the scales, and it still gets on the same axis on the DRO.

So i opened up the unit, to have a Quick look.

I pulled out my ESR-meter, and started to check the caps on the small PSU-board inside the unit..

I did find Three that is a bit off from specs in the datasheet(total of 7 on the psu-card):

Chemi-con SXE
35v 220uF 0.51 ohm
35v 220uF 1.1 ohm
10v 470uf 1.2 ohm.

These are placed on the secondary side of the PSU..

My question is, are these ESR values "bad enough" to be able to cause any interference with the Circuits after it? I seem to remember ESR-values in the datasheet for the SXE to be esr at around 0.18.

The DRO is probably very very picky with its signal from the scales, to make sure of no faults in the Readings. and the scales seem to be directly fed from the psu.

The problem occurance Changes with the units temperature. Cold seem to make it worse.

[junktv]

Re: Lathe digital readout

Pics model of the dro? Glass or mag?

[crosswinds]

Re: Lathe digital readout

Thanks for your reply

Sorry, no pics at hand right now.

Its a Sony LH 32 and its magnetic

[junktv]

Re: Lathe digital readout

I was looking into this as a hobby/start if i found a smaller vmc cheap and planned to go glass and mach3 instead of a dro. That isn't a hobby level dro you have but may check wires and connectors also. Scales and limit switches needed to be shielded from what i remember. If the cables are older you may try replacing those and see if it goes away. It's cheap and if older they are more than likely broken down. A machine shop is a rather harsh environment.

The fact you have a esr meter tells me you know more than i do on the board level stuff. I didn't know if it was diy shumatech? dro or something. Although i doubt they are used much any more. These nerds are getting fancy in the home cnc world.

[stj]

Re: Lathe digital readout

just replace every cap with low esr like panasonic FR,

you need better than average caps in these type of applications because of the electrical noise when the motors are driven.

[rievax_60]

Re: Lathe digital readout

Look for a backup battery that might be leaking.

[crosswinds]

Re: Lathe digital readout

just replace every cap with low esr like panasonic FR,

you need better than average caps in these type of applications because of the electrical noise when the motors are driven.

Thanks for your reply!

My regular supplier does have the FR series.

This is the list for all of the unit:

400V 68uF TSNH 1x


35v 220uF SXE 2x


25v 47uF Nichicon PL(M) 2x


10v 1000uF SXE 2x


10v 470uF SXE 4x


50v 4.7uF H9401 Nichicon 1x


16v 120uF Nichicon PF(M) 6x


10v 470uF Nichicon PF(M) 1x


10v 82uF SXE 1x

Do you think everyone of these are safe to be replaced with Panasonic FR?

Look for a backup battery that might be leaking.

The unit does not seem to have a backup battery.

[stj]

Re: Lathe digital readout

SXE sounds seriously old!

btw, you need to include diameter & height (unless height is not an issue)

[crosswinds]

Re: Lathe digital readout

SXE sounds seriously old!

btw, you need to include diameter & height (unless height is not an issue)

Hehe yes! The unit is from the first half of 1990´s

The height and diameter is about right on those i can find.
But can i replace them all with the FR series? (some they reffer to FM)

What do you Think about the measured ESR and the problem at hand? Might we be on to something?

[stj]

Re: Lathe digital readout

well the 400v one you can leave - that's a panasonic part and a good one.

the others i would go for - nothing to lose.

[crosswinds]

Re: Lathe digital readout

well the 400v one you can leave - that's a panasonic part and a good one.

the others i would go for - nothing to lose.

Alright! And the nichicon ones is compatible with FR/FM series?

[stj]

Re: Lathe digital readout

probably.

no better answer without a schematic

[crosswinds]

Re: Lathe digital readout

No schematic available, sorry.


Well all Panasonic FR is on order, so i hope Everything goes well

: Nichicon PF seem to be low impedence, and PL is "extremely low impedance" ..

According to the datasheet the Panasonic ones is of impedence, but hopefully thats a good thing?

[delaware74b]

Re: Lathe digital readout

50v 4.7uF H9401 Nichicon 1x

First week of 1994, H9401 is the plant(H), 94=1994 01= first week

Definitely a '94 build, time for a recap....

[kc8adu]

Re: Lathe digital readout

yes replace ALL lytics.these units are often left on 24/7 and the caps are done.
have not seen further glitches after a total recap.and thats after servicing hundreds of these.

[crosswinds]

Re: Lathe digital readout

Hello everyone.

Thanks for your input.

I have now replaced them all(except one that im still waiting on, ofcourse)

And ALL of the Nichicon 16v 120uF on the "sensor board" have leaked from the bottom. Very small amounts, so not visible Before i lifted them.. One of them directly connected with the problematic axis, actually have leaked bad and eaten the traces. So that was probably the cause of the failure. So i had to bridge that trace. thats never fun, but had to be done.

Some of the SXE on the PSU also had leaked from the bottom, but no traces on that side..

Will let you know how it works after i recieve the last one!

[kc8adu]

Re: Lathe digital readout

it will.
the 2 in my boneyard are lightning kills.

[Per Hansson]

Re: Lathe digital readout

Nice work crosswinds! Do post pictures if possible, always fun to see the object in question

[crosswinds]

Re: Lathe digital readout

Hello again!

Success! The unit is now working great again.

Thank you all for your help and input.

Sorry, i do not have any picture of the unit.