Sencore LC102 & LC103 Capacitor & Inductor Analyzer

[coromonadalix]

Managed to get the Sencore IB78 RS232 interface  for a premium price

Gonna try to make a schematic for it,  the eeproms dump now exists,  will compare to mine when i'll have it ...

A member here pigrew is trying to simplify the design for his usage, dont know if it'l get public

I'll try to do the same on slightly older tech ??  5v i/o fpga / cpld ...  but i'm rusty

Tested my lc102 so far, i had the supply cord from an leader ac xformer,  made a new dc supply for it,   works fine, lc102 seems pretty spot on,  cant find any calibration service near me to do a cal of this unit

[HighVoltage]

You should probably ask the sysop move this topic to test equipment or start a fresh thread....

Requested, may be an admin will notice.

[mr.fabe]

Tested my lc102 so far, i had the supply cord from an leader ac xformer,  made a new dc supply for it,   works fine, lc102 seems pretty spot on,  cant find any calibration service near me to do a cal of this unit

If the readings are pretty close, I wouldn't adjust it unless you absolutely have to.  You have a LC102 and can perform the calibration yourself since the unit has variable pots.  Much similar to the LC53, LC75, LC101 type units.  I wish the LC103 had that option since calibration was quoted at $500-$600 USD.  Pretty ridiculous pricing for a non-Lab type piece of equipment...

[coromonadalix]

The lc102 need a few  parts for calibrating it myself

I have a hard time to find 0.25% precision caps and some coils values in Canada

You need:

caps
1500pf
1.2uf
500uf

coils
20uh
80uh
800uh
8mh
60mh
80mh
800mh
2 henry
8 henry

res  not wire wounded type   not too difficult to find
1 ohm
15 ohms
20 ohms
150 ohms
250 ohms
1,5K ohms
50k ohms

[mr.fabe]

Here's a pic of the battery and clip..  I think I paid around $24 USD  for the battery and $5 for the clip.

(Attachment Link)

Sorry about the delay on the battery clip information...

The battery clip I purchased was from DigiKey.

https://www.digikey.com/product-detail/en/mpd-memory-protection-devices/ZA5350-B/ZA5350-B-ND/124921

[HighVoltage]

The lc102 need a few  parts for calibrating it myself

I have a hard time to find 0.25% precision caps and some coils values in Canada

The caps and inductors should also be easy to get.
Let me see what I can find in my bins.

I will use my Philips / Fluke PM6306 to select the values of caps and inductors.

[Xenawise]

@HighVoltage:

Hello, looks like you have a first production version of you PCB's (Version "B"). I recently repaired this version LC103 (it would fail the "OPEN" test but complete the "SHORT" test - turns out it was one of the SOT-23 2N3906 - Q13 - transistors in the low current source circuit. The transistor is completely open, all leads! Not sure what happened to it, there are no physical signs of failure either like too much current blew a chunk out of the case or something. It looks "normal" just like it's sister (it is connected in a darlington pair). Took quite a while to find this as well, I would say I have over a week into troubleshooting alone and since I have two LC103's now I could do some part swapping to help with the process.

In any case, I see that your EPROM is version 1.53! I have a Version "C" LC103 as well (I have two of them and actually three LC102's, one of them I need the LCD displays for as they got cracked during some shipping damage) and it has version 1.41 of firmware. Perhaps you could pull the EPROM and read it and post up the resulting BIN file? I would love to update to the latest firmware, although I wonder if the calibration of the unit is somehow tied the version of firmware (highly likely) so it might just be better to stick with whatever EPROM shipping in the unit to maintain the calibration. My Version "B" LC103 has firmware version 1.31. I have swapped the 1.41 firmware chip into the Version "B" and it does work, and your pictures show you have a Version "B" unit with version 1.53 firmware. Maybe it was sent in for repair or calibration and Sencore updated the firmware during the repair. As for Version "A" models, I don't think they were sold and were probably the last of the pre-production units. I believe Version "B" PCB's were the first production runs. My Version "C" unit does not have any of the bodges that the Version "B" PCB's have, and the power supply unit has some significant changes as well.

In any case, have fun with your LC103! They will only rise in value as time goes on I predict, unless some manufacturer comes up with something that can replace it which I doubt will ever happen.

Regards,

Xenawise

[coromonadalix]

A 20 farad or 20 henry lcr seems improbable, with an 1kv leak test ?? more improbable ?  seen tons of models up to  100,000uf  seen nothing in recent models higher or equal to the lc102, lc103  can offer ??

I can be wrong

[HighVoltage]

@Xenawise
Very interesting, thanks.

OK, I will get the EPROM version 1.53 read out.

Based on your facts, it really seems that my unit was repaired at a later time and the new FW installed.

[syau]

Scored a LC102, unable to zero on short, other capacitor measurement work except the ESR which give -ve 

Managed to open up the cover on the big white relay, cleaned the contact with deoxit, also did so with the adjacent one. Still fail when I do zero on short. Surprising, it show short when I shorted the lead during capacitor measurement.

Need to do some trouble shooting on the ESR circuit.

[coromonadalix]

@syau   does it says  error 7 ??  do you have an original test cable ? 


With a cable i had for years :  i've made the open short tests, they are okay, but if i add some tests clips to complete the cable  it doesn't pass the open test, but pass the short test  ... i have to get the correct impedance vs the cable capacitance ...

You have explications in the user manual for the errors test(s)

[syau]

It show error 4 during short cal. I did bypassed the input coax and directly shorting the input to the pcb (the one has 1 thin white wire and 3 thick red) with the same result. (the white go to the shield, center red go the the coaxial center, the right red go to the coaxial center after the fuse)

Tried to remove the fuse (by turning bnc anti-clockwise) but unable to do so, looks like the previous owner turn it too hard in order the secure a good contact 

No error 7 during esr measurement, only give -ve which keep changing

Note: The test lead I am using is not original.

[Johnny10]

Since we started repairing these Sencore units on the EEV Blog Forum the price has gone way up!

I repaired a number of these units a few years back.
I did buy parted out units etc. from this eBay seller.

https://www.ebay.com/itm/SENCORE-LC103-LC102-LC101-LC77-LC76-LC75-LC53-TEST-LEADS-SET-OF-THREE-NEW/113767939522?hash=item1a7d18fdc2:g:69QAAOSwhURZgj8w

All my units Zero, open and short, with a BNC adapter and regular clip cables.
When they don't zero it takes a while to track down the exact cause,  i.e. BNC Fuse Holder, Relays...
The relays were available on eBay also. I bought a few of the black ones from someone mismatching manufacturer name. They had 50 or so but that was a few years ago.

I should look that up again.

[coromonadalix]

As Johny10 wrote

I did all the checkups  for the mta crimp connectors, some claimed the wire cut in the connector,   unscrewed the bnc fuse, it was tighten very well, i put an bnc connector and turned slowly counterclockwise with a pair of pliers, done every checkups i could do for oxydation on the 2 big relays and the bnc test plug.

With the calibration procedures i re-checked every voltages in the lc102, they were almost perfect for its age ?   touched nothing else.

Tested the open and short tests, everything went fine.

Sencore LC-102 Cable 'zeroing' issue and 'fix'   mostly the error 7
https://www.antiqueradios.com/forums/viewtopic.php?f=8&t=286666

Normally the test leads are made with an low capacitance cable rg-62u


@syau    Your error4   Value beyond zeroing limits, see page 18 of the user manual

It simply could be your tests leads are not accepted by the lc102


Just checked my tests leads, they are slightly over 1800 pf,  damn loll         short pass,  open fail 
They are coaxial, but no specs written

[syau]

I suspect that the relay L1 failed to close during ESR and Short Zero measurement and will test it out later today. In the mean time, I ordered several 5VDC reed relay from RS (diff pin out) but better spec, which should be delivered within 3 days.

Testing has been done on the P3 connector so it ruled out the test lead issue.

By the way, any one know the source of the fused bnc jack ?

[HighVoltage]

Since we started repairing these Sencore units on the EEV Blog Forum the price has gone way up!

It is really crazy, how much they have increase since this thread is open!
For LC102 and LC103

I just got a quote from a company for a LC103 in good condition for US$ 4800 !

[Mr. Scram]

It is really crazy, how much they have increase since this thread is open!
For LC102 and LC103

I just got a quote from a company for a LC103 in good condition for US$ 4800 !

Such is the Eevblog. The prices will come down again when the initial hype blows over though.

[BU508A]

I just got a quote from a company for a LC103 in good condition for US$ 4800 !

I hope, you've showed them this:

[HighVoltage]

I hope, you've showed them this:

Yup!

I am glad I have a good working LC103, that I got for a good price. I might buy a LC102, once the prices have come down again.
No hurry! 

In regards to open and short compensation, I have tried a normal 50 Ohm BNC cable and it would not confirm the open compensation. So it seems Sencore has limited this to special cables.
I will try a few other cables soon.

[syau]

I suspect that the relay L1 failed to close during ESR and Short Zero measurement and will test it out later today. In the mean time, I ordered several 5VDC reed relay from RS (diff pin out) but better spec, which should be delivered within 3 days.

Testing has been done on the P3 connector so it ruled out the test lead issue.

By the way, any one know the source of the fused bnc jack ?

Did an in circuit testing of L1, it works but still can’t cal short nor ESR (start with -1990 displayed on the LCD and the value slowly increase up to -9.0 ohm) 

Anybody has an idea how the ESR circuit works ? One member did mentioned that it use the ESR circuit to do a cal short.

[Johnny10]

That zero issue fix on Antique Radio was a bit off in technique.
I first cut into the top of relay cover as shown in pics.
Yet afterwards, I found I could simply squeeze rectangular cover and it unlocked and whole cover came off without having cut on top that then needed to be fixed.

[mr.fabe]

In regards to open and short compensation, I have tried a normal 50 Ohm BNC cable and it would not confirm the open compensation. So it seems Sencore has limited this to special cables.
I will try a few other cables soon.

With the LC53, LC75, LC101 (units that I've owned), RG62 cables were needed to be able to zero out the meter.
With my LC103, I have no trouble with open and close compensation with any of the cables I normally use.  I use the Sencore 39G219, Fluke tweezers, mini 7" BNC to clip hook leads, and sometimes a set of needle probes for in-circuit tests.

Per the LC103 Manual for Value Beyond Zeroing Limit...

An open (greater than 20kohms) or shorted (less than 1 ohm) test lead will cause the display to show "OPEN" or "SHORT"
Possible Causes:
1. The capacitance at the TEST LEAD input is greater than 1800pF
2. The inductance at the TEST LEAD input is greater than 18uH
3. The resistance at the TEST LEAD input is greater than 5 ohms

[syau]

Replaced L1 & L9, no improvement 

Will try to replaced the 4011 & 4066 in the ESR circuitry.

[volvo_nut_v70]

Hello;

I am looking for a new or used LC102 membrane keyboard to repair the one I have. One of the "button" is worn straight through....

Thanks!

[HighVoltage]

Hello;

I am looking for a new or used LC102 membrane keyboard to repair the one I have. One of the "button" is worn straight through....

Thanks!

Every once in a while, they show up on ebay USA but right now I do not see one.
You probably have to have some patience.