Test Equipment Anonymous (TEA) group therapy thread

[AVGresponding]

Update on the AD7461A DMM.
Iasked ADCMT for a manual using theironline form. Inital response was fast and seemed hopeful. I carried on investigating in the meantime.
Close visual inspection revealed no internal damage other tha the broken plastic around the bezel. The plastic is very brittle. The tabs holding the display / keyboard PCB in place snapped off as soon as I tried to move them. I stuck them back on with "plastic-weld" aka methylene chloride.. When I tried to put the PCB back in the tabs broke again but not at the weld.. I welded the tabs in a different position while holding the PCB in place.

Having ruled out physical damage my prime suspect was the relays. Some power off measurements and circuit tracing indicated the relays were powered from a 5V "digital" supply with open collector low-side drivers. Thus I felt happy to operate them with power on by connecting the low side of the coil to ground via a 10 ohm resistor. This soon revealed that one of the relays (281) was not reliably switching to one position. I "excercised" it a few times and that was enough to get the unit through self test about 50% of the time. This allowed me to confirm that the meter was otherwise OK.
I've ordered a full set of replacement relays. They are only a couple of pounds each from Digikey. Only trouble is getting down between them to solder the L shaped leads on these SMD versions.
Calibration is about 600uV off at 10V.
ADCMT got back to me today saying the meter was over 10 years old so they won't repair it and suggest I buy a new one 

Robert.

Translation issues? From what I've seen, getting service information for Japanese TE is difficult at best. Doesn't stop me from lusting after anything with a dot matrix VFD though

[Robert763]

No, messages were clear and descriptive. Perfect english.

Robert.

[PascalNE]

Just collected my new unexpected low ball acceptance. The 34970A, everything seems to work perfectly
  but I have already discovered two irritating things about it.
- noisy fan (something I find completely intolerable so it'll have to be replaced)
- soldered battery for the clock that requires disassembly to replace 

Apart from these it all seems quite nice of course I can't do a full test but it passes all the self tests and all seems ok so really not bad for what I paid.
And luckily a forum member has offered to sell me a 34901A which would allow me to use all the functions.

Update on the AD7461A DMM.
Iasked ADCMT for a manual using theironline form. Inital response was fast and seemed hopeful. I carried on investigating in the meantime.
Close visual inspection revealed no internal damage other tha the broken plastic around the bezel. The plastic is very brittle. The tabs holding the display / keyboard PCB in place snapped off as soon as I tried to move them. I stuck them back on with "plastic-weld" aka methylene chloride.. When I tried to put the PCB back in the tabs broke again but not at the weld.. I welded the tabs in a different position while holding the PCB in place.

Having ruled out physical damage my prime suspect was the relays. Some power off measurements and circuit tracing indicated the relays were powered from a 5V "digital" supply with open collector low-side drivers. Thus I felt happy to operate them with power on by connecting the low side of the coil to ground via a 10 ohm resistor. This soon revealed that one of the relays (281) was not reliably switching to one position. I "excercised" it a few times and that was enough to get the unit through self test about 50% of the time. This allowed me to confirm that the meter was otherwise OK.
I've ordered a full set of replacement relays. They are only a couple of pounds each from Digikey. Only trouble is getting down between them to solder the L shaped leads on these SMD versions.
Calibration is about 600uV off at 10V.
ADCMT got back to me today saying the meter was over 10 years old so they won't repair it and suggest I buy a new one 
EDIT: The operating manual says rhe relays are a standard "wear-out" service item.
Robert.

Glad to see the 7461A working, mine has been pretty solid although I do have constant "range anxiety" knowing that if something does go wrong it's on me to find out how to fix it.
The 7461A is still in production by ADCMT as far as I can tell so it's pretty rubbish that they can't even provide proper support to something they still produce.

[Robert763]

Yes still in production. They were more than happy to sell me a new one...
I distell them it was a personal item. Another supplire to think twice about buying from. What most suppliers don't realise is that my treatment as a hobbyist affect where my employer spends their (somewhat larger) budget....

[PascalNE]

Yes still in production. They were more than happy to sell me a new one...
I distell them it was a personal item. Another supplire to think twice about buying from. What most suppliers don't realise is that my treatment as a hobbyist affect where my employer spends their (somewhat larger) budget....

I do wonder if the schematics are available to anyone even larger clients or do they just insist you buy a new one or maybe let them fix it for a high price 

[factory]

There doesn't seem to be much on the forum about the 7461A, this is especially strange for something they claim is over 10 years old, can't even find a single internal picture, or am I missing something with the forum search?

David

[Robert763]

They seem to be fairly rare on the used market. Like a lot of kit from that part of the world there is minimal repair information available. Anything other than a simple fault and it's a throw away item.

[TERRA Operative]

Yeah, Advantest can be a downright pain to even get a single manual from if it's not already online somewhere, or they saw fit to bestow their holy generosity upon us by having it on their website already. They are worse than how Keysight (don't) support their recently obsolete gear....
Even when I contact them in Japanese I usually get stonewalled.

Although there was one time I managed to get in contact with a fellow enthusiast there when asking about some Takeda Riken gear (what Advantest was originally called when they first started out), he managed to find an original copy of the manual in their archives, with schematics! (so they DO have archives!) and he personally took the manual home that night and scanned it for me, just as a personal favour. That is certainly NOT company policy though.


Now Kikusui on the other hand, they are the opposite. They have a huge amount of manuals available, stretching back multiple decades. (To be fair, like Keysight does have the archive of older gear, besides those archives that caught on fire seven years ago...)

[PascalNE]

Yes the only place I’ve really seen talking about the 7461A/7451A is on Chinese forums like here  https://www.mydigit.cn/thread-101755-1-1.htmlfrom what I can tell they are much more common  and much cheaper over there so maybe if I look a bit harder I can find something useful 

[Rubo]

What exactly are you trying to find out?

Recently I bought a 7461A as a restoration project (the price was too good to pass up).
Functionally it's working perfectly, cosmetically - is a different story.

So I can try and take pictures/measure stuff if you need it.

[m k]

Yeah, Advantest can be a downright pain to even get a single manual from

Since they most likely are not dumb, there must be a rational reason.
Maybe quality is too good for the size of the market.

If so then the other firm still around with the opposite policy must do something special, sort of.
Larger market maybe.

Maybe there's a grudge, Shingen lost.

[PascalNE]

What exactly are you trying to find out?

Recently I bought a 7461A as a restoration project (the price was too good to pass up).
Functionally it's working perfectly, cosmetically - is a different story.

So I can try and take pictures/measure stuff if you need it.

Thanks for the offer, if you are responding to me I don’t need any info right now just want to try and collect anything that would be useful in case of failure.
My ADCMT is working fine but since in such nice condition I haven’t wanted to open it. 

[Rubo]

Thanks for the offer, if you are responding to me I don’t need any info right now just want to try and collect anything that would be useful in case of failure.
My ADCMT is working fine but since in such nice condition I haven’t wanted to open it. 

Indeed I was 

Mine will need A LOT of cleaning and some of the plastic is cracked/broken.
I want to try and find replacement plastic pieces (either from ADCMT directly or salvaged) and make it look nice again.

Inside it has a pretty clean layout and since it has no fan, there's not much dust.
Right now i've been running it 24/7 to make sure no surprisez crop up and to try and figure out if it has any drift.
Tempco is right around 1ppm/C, so it's not as good as 34410A or 34465A, but is very predictable.

[Zoli]

After reading and understanding(mostly) the service manual,  I've managed to spend some quality with the HP 5245L.
First, internal evaluation: main revision - 716; previously repaired, mix-and-match modules from multiple revision(544, 648, 716 etc.); most of the boards have "Tested Feb 1968" stamp.
IC infected, since the OCXO had been replaced with a newer generation one, and it has 3 IC's; the fan had been replaced with a 120X38mm/1500rpm one.
Troubleshooting:
 - OCXO: works, in spec.
 - 10MHz: works, stable.
 - Dividers: all works, stable.
 - Control signals: Gate is OK, rest later.
 - Signal path: amp, freq. trigger, main gate - all good. 50MHz counter - no signal out.
Dig in the 50 MHz counter: Q9(2N2635) BC interrupted; replaced with 2N2907 - still no signal out. Monitoring the BCD outputs - Houston, we have a problem(or two);
see scope capture(channel 3 for is wrongly 1X, is 10X in reality, so multiply the voltages with 10) and schematics with the corresponding colours.
Since the 2N709 is unobtanium, unless you want to try the fleabay lottery(I won't), the chance to repair is to replace them with 50C02(have, SOT-623) on PCB adapters(don't have);
as result, packed back together for a later time. Next on the list: caps replacement. Once the counting is fixed, I will deal with the decimal points and the rebel display boards.
Stay tuned for the next episode...

[madao]

Although there was one time I managed to get in contact with a fellow enthusiast there when asking about some Takeda Riken gear (what Advantest was originally called when they first started out), he managed to find an original copy of the manual in their archives, with schematics! (so they DO have archives!) and he personally took the manual home that night and scanned it for me, just as a personal favour. That is c

Ouch...good, i have scanned  yesterday takeda riden spectrum analyzer manual.
https://elektrotanya.com/showresult?what=tr1422b&kategoria=All&kat2=All

huge book !

[factory]

After reading and understanding(mostly) the service manual,  I've managed to spend some quality with the HP 5245L.
First, internal evaluation: main revision - 716; previously repaired, mix-and-match modules from multiple revision(544, 648, 716 etc.); most of the boards have "Tested Feb 1968" stamp.
IC infected, since the OCXO had been replaced with a newer generation one, and it has 3 IC's; the fan had been replaced with a 120X38mm/1500rpm one.
Troubleshooting:
 - OCXO: works, in spec.
 - 10MHz: works, stable.
 - Dividers: all works, stable.
 - Control signals: Gate is OK, rest later.
 - Signal path: amp, freq. trigger, main gate - all good. 50MHz counter - no signal out.
Dig in the 50 MHz counter: Q9(2N2635) BC interrupted; replaced with 2N2907 - still no signal out. Monitoring the BCD outputs - Houston, we have a problem(or two);
see scope capture(channel 3 for is wrongly 1X, is 10X in reality, so multiply the voltages with 10) and schematics with the corresponding colours.
Since the 2N709 is unobtanium, unless you want to try the fleabay lottery(I won't), the chance to repair is to replace them with 50C02(have, SOT-623) on PCB adapters(don't have);
as result, packed back together for a later time. Next on the list: caps replacement. Once the counting is fixed, I will deal with the decimal points and the rebel display boards.
Stay tuned for the next episode...

Someone has really messed with those display boards, the '5MHz' 05232-6010 board is in the wrong place, it should be next to the 5245L-4B.
Also check the numbering on the chassis, as both A15 & A16 sometimes both can be 5MHz boards, this varies depending on the BCD code option. 

Those early silicon transistors are a bit fragile, they seem to give far more trouble than the Ge ones.

Not surprized to see yet another open circuit 1500uF 15V capacitor (C10), from experience this exact type often fails open in the 524xL/M counter range and the 412A voltmeter, the other types have been fine in all the counters I have.

David

[analogueAdder]

TFW you order a $450 tablet scope after a lot of deliberation and then there's a big discount on the DHO804 and DHO914S oscilloscopes and you end up questioning your life choices...

But then again, I ordered a smaller and nicer solution for what I going to do with this scope, and you can never have too much test gear so I could always get more scopes...

[Zoli]

...
Someone has really messed with those display boards, the '5MHz' 05232-6010 board is in the wrong place, it should be next to the 5245L-4B.
Also check the numbering on the chassis, as both A15 & A16 sometimes both can be 5MHz boards, this varies depending on the BCD code option. 

Those early silicon transistors are a bit fragile, they seem to give far more trouble than the Ge ones.

Not surprized to see yet another open circuit 1500uF 15V capacitor (C10), from experience this exact type often fails open in the 524xL/M counter range and the 412A voltmeter, the other types have been fine in all the counters I have.

David

Thanks for the heads-up, changing the position of the 05232-6010 board became first on the to-do list; it saves me from potential headache, beside, it acts up: stuck on 1, but resets to 0.
Situation of C10: see attached picture; it get replaced with a blue Phillips ...

[Ice-Tea]

Schlumberger SM7050 transfer standard. Clean as a whistle. Obviously well cared for.

[factory]

Three input channels, a high current input, with power/wattage buttons? Is this used for testing electric meters? Something Schlumberger were well known for making.
Strange how it has a model number containing '7050'  , the Schlumberger 7050 I'm used to seeing is much smaller.

Edit: It seems Itron took over the electric meter part of Schlumberger, as well as many others over the years.

David

[Ice-Tea]

It was indeed used for testing electricty meters. It's from the Itron closure, so whatever what was left of that branch of Schlumberger is now probably gone. Can't find a manual for it yet, though...

[Shimonu]

Not quite sure of the condition of this unit... It's working but they haven't tested it but if I'm a hobbyist it's suddenly faulty? 

[m k]

Schlumberger SM7050 transfer standard. Clean as a whistle. Obviously well cared for.

Does it have a backplane?

One module pair seems to be a double.

[EggertEnjoyer123]

Well I'm back with a Tektronix AWG610 I bought for $150 today from fleabay.

Self check passed, looks like I got lucky and everything works.

Can you post a picture of the insides?  I am curious about the output stage.  They probably didn't have an off-the-shelf opamp with enough slew rate back then.

Finally got around to backing up the two drives. I didn't need Pocket Linux to get the SSD data; I just connected my USB to IDE adapter to it directly and I used dd to copy over all the contents. I think you should be able to do it this way if you run Linux on your computer.

The amplifier appears to be an ASIC (U3500 and 3600).

[Robert763]

A package arrived from Digikey yesterday. A pack of EE2-4.5TNU relays (Dual coil latching in SMD package) and a long fine cranked tip for the Metcal.
Time to replace the relays on the Advantest / ADCMT 7461A DMM.
First issue is the correct relay is EE2-4.5TNUN. This is a "reduced footprint" version. Basically the dit of the leg in contact with the PCB is shorter. Thery re not a stock item but the EE2-4.5TNU is. Easily sorted out with a small pair of flush cutters. IT does show how tight the mounting of these relays is.
Removal of old relays was by cutting the legs with my smallest pair of lindstrom side cutters. Cleaned up the pads and soldered on the new relays.
And it works. 
However this thng is a pig to work on. The plastic parts have become brittle (date codes in IC's indicate it is no more than 20 years old) and break at the slightest touch and there is no technical information available.
I won't be buying another one.