Test Equipment Anonymous (TEA) group therapy thread

[factory]

(Robert was too sophisticated)

So lower power settings are using newer LDOs, but higher part is closer to what have been.

I suspect that the Siglent linear PSUs are switching the transformer secondary for the lower voltage ranges to reduce dissipation.

robert.

Yep, you can hear the relay click. The TTi doesn't, so the poor thing has to dump a lot of heat at low voltages, hence they are prone to crispy-board syndrome

The PL330QMD has six transistors per channel, if I've read the service manual correctly, the excess heat will be dumped by each trio of heatsinks. The overheated resistor in another thread was due to a wiring error, which didn't seem to stop it functioning.



The service data is one of the manuals in this thread (PL series service); https://www.eevblog.com/forum/repair/programmable-version-of-the-tti-pl-series-power-supply/msg3966785/#msg3966785

David

[TERRA Operative]

So, I made a beautiful replacement Eveready 765 Eveready 763 (Stupid typo!) battery using AA cells for my HP 427A voltmeter, and it doesn't fit...   

I made it to the dimensions in the Eveready datasheet as I didn't have an original to compare to, but somehow the bracket in the 427A is expecting a battery that is 4mm shorter in length and 2mm narrower in width.

Time to spin a second revision of PCB's....   



Does anyone have a genuine Eveready 765 Eveready 763 battery they can measure the dimensions for me? 

[vk6zgo]

So, I made a beautiful replacement Eveready 765 battery using AA cells for my HP 427A voltmeter, and it doesn't fit...   

I made it to the dimensions in the Eveready datasheet as I didn't have an original to compare to, but somehow the bracket in the 427A is expecting a battery that is 4mm shorter in length and 2mm narrower in width.

Time to spin a second revision of PCB's....   



Does anyone have a genuine Eveready 765 battery they can measure the dimensions for me? 

Eveready & its "kissing cousin" "Ever Ready" in the UK tend to use the same part number for almost (but not quite) identical batteries.
The UK 276 (with press studs on top) was just slightly different in dimensions to 276p's from Australia, (with the 2 pin socket) & probably both are different to the US version.

[TERRA Operative]

Looks like something like that may be the case....

I found the 763 in a databook just now, with different dimensions.... 

First attachment below is the datasheet I worked from found on the Farnell website, second is from an old Union Carbide battery databook.

[Peter_O]

(Robert was too sophisticated)

So lower power settings are using newer LDOs, but higher part is closer to what have been.

I suspect that the Siglent linear PSUs are switching the transformer secondary for the lower voltage ranges to reduce dissipation.

robert.

Yep, you can hear the relay click. The TTi doesn't, so the poor thing has to dump a lot of heat at low voltages, hence they are prone to crispy-board syndrome

The PL330QMD has six transistors per channel, if I've read the service manual correctly, the excess heat will be dumped by each trio of heatsinks. The overheated resistor in another thread was due to a wiring error, which didn't seem to stop it functioning.



The service data is one of the manuals in this thread (PL series service); https://www.eevblog.com/forum/repair/programmable-version-of-the-tti-pl-series-power-supply/msg3966785/#msg3966785

David

Yes, the Siglent is tapping the transformer, as David showed in the teardown.
https://youtu.be/mdOauVzY9OU?t=1167

The hottest component in the TTI 330D is the Diode D16, it's an 1N5401 which runs at its limit of 3A at 3A output current of the PSU and reaches over 90°C.
I do not quite understand, what this diode is for, having a bridge rectifier already. It's the same layout and diode as with the 1A and 2A versions of the PL PSUs, where a 3A 1N5401 should be perfectly fine. I wonder, if I should replace the diode with a - say - 5A one, like a 6A10, which I have at hand.

   

   



Edit: added some pics.

[m k]

Maybe against wrong series connection.

[Gertjan]

Without looking at the schematic, I think it is to create a (-0,7V) negative supply rail -V2.

regards, Gertjan.

[Martin.M]

FSH --> Fluke Philips PM9080 optical RS232 interface cable --> GPD µPC 

[Robert763]

Without looking at the schematic, I think it is to create a (-0,7V) negative supply rail -V2.

regards, Gertjan.

Gertjan beat me to it.
It is to provide a "common" rail that is 0.7V above the 0V of the power transformer/bridge rectifier/filter capacitor. Thus making the 0V effectively -0.7 volt and allowing the "commmon" to come down to 0V with the electronics still operating with a bit of headroom. Putting a higher current diode in would improve reliability. Maybe half of, or paralleled pair in a TO-120 package. Just make sure it's not  schottky type.

Robert.

[Robert763]

FSH --> Fluke Philips PM9080 optical RS232 interface cable --> GPD µPC 

I can confirm that the older Fluke optical to serial (RS232 or USB) interfaces work with a R&S FSH series analyser.
I normally run FSHView on a PC with a bigger screen than the FSH though

Robert.

[Martin.M]

the µPC is actually the only one here what have the 9pin RS232.
I have to look to get a adaptor for the adaptor..

[Robert763]

That is a problem with mdern PC's I' wasn't aware of the uPC. Seeing how it's marketed, to IT professionals, I guess they include the RS232 to allow it to be a local terminal for servers and switches. It's a cute little thing.
I have an old Panasonic CF19 ruggedised PC fro when I need a real RS232 built in.

I made up 232 to USB adaptor lead for the FSH-3 interface using a (genuine) FTDI lead.

[Addicted2AnalogTek]

It's a good weekend to be shacked up inside, away from the cold, sorting through and repairing my gear so I can make my workbench more functional. I've been neglecting it for most of the year and only set up and used what I needed to in order to repair a few boards, which was really just my desoldering/soldering tools, a multimeter, and a power supply. Although I clearly didn't NEED any more gear, that didn't stop me from deal surfing and buying some HP and Tek gear!!
Added to the stash: HP 8904A 006/H16, HP3457A (MINT!!), HP 3478A (MINT!!), a couple Tek 577's, and a stack of Tek 7k series plugins and TM500 calibration plugins, and a couple universal programmers that are forcing me into a Windows XP i7 3770K PC build.

Today's mission: Repair and verify this golden nugget or hit the parts wall. Surprisingly, for a 1975 build unit, I'm not finding many out of spec components. In addition to two bad electrolytic capacitors, I'll be replacing all of the dipped tantalum "fruit stripe" caps and any that are not properly derated, such as the 6.8uf 35V tants on the -30V and +30V supplies. I will NOT be fully recapping this unit as it's unnecessary and would be rather expensive for replacements that are up to the "30D" grade or better, or for my typical EPCOS can re-stuffing capacitors.

C716, the Step Amplifier Low Volt power supply bulk filter capacitor is supposed to be 9600uF.

I just looked, and that's my parts wall for this unit. Bummer.

-Brian

[m k]

I made up 232 to USB adaptor lead for the FSH-3 interface using a (genuine) FTDI lead.

Buying these adapters from ebay is safe.
RS232 has +/- voltages, lowest is 0.2V for both sides, so CH340 alone is not enough.
If bought adapter doesn't have a level shifter you'll get your money back.

For PC an RS-port is a chipset thing, even if not present outside it's possibly still present inside.
It's also possible that backplate includes a blind 9pin socket position.

OT,
macro enhancement.
Other thing is how one certain butterfingered is going to change that 511, it should be 510.
(maybe original brainiac thought that the other value is close enough)

[d-el]

Kikusui PLZ1003W, swapped OTP by EEPROM, upgraded to last firmware.

[m k]

Does anyone have a genuine Eveready 765 battery they can measure the dimensions for me? 

Old Union Carbide manual has no battery of 765, but museum has a picture, it's 9V.

My 763 width and depth are ok, but height is 61 and something mm, so fraction more like 13/32, as Farnell states.

So the old manual has old measurements, but new posts, if it's even the same actual product.

[TERRA Operative]

Yep, 763 is what I'm interested in. 765 is a typo. derp, I should type slower, especially while on my phone on the train....

What are the actual dimensions you measure from your 763 (Including position of the studs) in millimeters?

[m k]

Nominal dimensions from the wide side of Exell 763A(NEDA 710) are (WHD) 92.1 x 77.8 x 51.6 mm.
Height includes a contact screw and its plastic cap nut.
NSN has same dimensions as 3.5 x 3.0 x 2.0 inches.
Pretty stupid that the box height is not mentioned.

My machine has a plastic leak protection trough, with molded number 4040-0040.
Its short side is very tight, but it's not straight, so machine has some extra space.

Old battery dimensions from above are 88.1 x 71.8 x 51.2 mm.
Screw is 7 and plastic cap nut 10 mm tall.
Box height is 62.2 mm, some bumps included.
Positive screw is 17.6 mm from the side, like old manual.
Between screws is 42.1 mm, also like the old manual.
So much from old manual, excluding that height.

[d-el]

Honeywell 1000000 Ohms

[m k]

How are 4-wire results?

[KrudyZ]

How are 4-wire results?

Do you think he's hiding 50 m of wire under the table?

[m k]

No.

Do you know how much is last digit?

[Peter_O]

No.

Do you know how much is last digit?

Just the 2 ct of a metrology rooky, correct me: 
Acc. to spec the error of the Keithley 2001 is +110ppm in the 2MOhm range, which explains the 70 Ohm mismatch perfectly fine.
In case the 2001 would be the perfect instrument: It's not about the last digit of 100mOhm, it's about 70 Ohm, which no cable effect would explain, 2 or 4 wire.

[m k]

It's not how good or bad is the measurement, or absolute value, it's a difference between measurements.

[d-el]

How are 4-wire results?

Do you think he's hiding 50 m of wire under the table?

K2001 4W mode support max 200kOhm.
I can measure the difference in K2010.