Test Equipment Anonymous (TEA) group therapy thread

[Vgkid]

Ooh nice. I got one of those Flukes waiting to finally get working (replaced all caps and carbon comp resistors with 50/100ppm metal films so far), also got a 335A to bash into shape too one day.

Nice. I need to tear mine apart to do some preventive work on it. I does appear to be working correctly, as all ranges work. Either it or, my 34420 is drifting. About 15ppm pk-pk over a few hours.

[med6753]

Trying to track down very intermittent sweep length issue on the Type 547. It's nice when your TE can also function as a "bench" for your other TE. Unfortunately as soon as I started probing around it starting working. Figures.  But I'll eventually track it down.   

[Saskia]

computer for daughter is finished, tested, and works. Received a Demolition Man pinball cpu board, some vias eaten away, but should be fixable. Also, finally back at size 18 and 30 kg weight shed.

[med6753]

computer for daughter is finished, tested, and works. Received a Demolition Man pinball cpu board, some vias eaten away, but should be fixable. Also, finally back at size 18 and 30 kg weight shed.

Good deal all around, especially the weight loss. 

[mansaxel]

It's not just AVO that made meters without a range switch, here's one from Weston;

I own an AC Volt meter from Weston, marked "PROPERTY OF IBM" that has 6 binding posts along the top of the case; one for 0V, and then 5 ranges up to 250V. It works. I hardly ever use it. Not useless, just "limited applicability".

[Specmaster]

computer for daughter is finished, tested, and works. Received a Demolition Man pinball cpu board, some vias eaten away, but should be fixable. Also, finally back at size 18 and 30 kg weight shed.

Good job, are you still going for a size 14?

[med6753]

Is there some kind of screening mesh in front of the CRT?

Yes, X-Ray emission screen. Was an optional item for most portable Tek scopes. I have one which will fit a 465/475. My Type 535A also had one that has since been removed.

Nope,
A wire mesh you can see through wont stop x-rays.
The part number is 378-0237-00 NSN 5915012124417

FILTER,RADIO FREQUENCY INTERFERENCE
NSN: 5915012124417
MFG: TEKTRONIX INC. DBA TEKTRONIX
Description: FILTER,RADIO FREQUENCY INTERFERENCE

You are correct. RFI shield not X-Ray. D'OH. 

[tautech]

Yes Mr Gates how may I serve you better now I have had my second chip installed 

Our 2nd dose on Nano particles has not improved 5G reception. 
Maybe it needs time for them to multiply. 

[mnementh]

computer for daughter is finished, tested, and works. Received a Demolition Man pinball cpu board, some vias eaten away, but should be fixable. Also, finally back at size 18 and 30 kg weight shed.

mnem
*toddles off to have a little rotisserie roasted chicken Thanksgiving Dinner with the fam*

[Vince]

30V unloaded is not unusual; LED backlights are driven by a CC converter that will provide a fixed drive current no matter what the actual VFd of a LED string, as long as it is within a given operating voltage. The LED strip and converter are chosen to match vs voltage and desired drive current.

That 9V regulator output, if it is not to power the LCD, may be to power the BU Camera. This is why I suggested you check for continuity from the 9V Reg Vout to the LCD ribbon first. It may also run to the LCD as a signal to switch inputs to the analog camera line.

mnem
 

Again... I have already dug enough into the 9V rabbit hole... not saying this isn't it, just that it's now time to go chase other much more obvious leads = the FREAKING BACKLIGHT !!   

How could I have 30V to it and it not working ! It's such an obvious problem, blatant, so why waste time down the 9V rabbit hole instead ?! 

So I took the front panel assy apart to get at the LCD backlight. Unfortunately as you implied... it's built into the panel assembly itself, so no access.
So tried to test it, to light it up with my lab power supply. As you said it's most likely an LED not CCFL, so I can try to light it up with my lab power supply in series with a beefy current limiting resistor.. .as my power supply current limiting pot can't go lower than 50 or 70mA minimum or so, so was afraid it might fry the LED backlight...

Anyway, experimented a bit. At first even with 60Volts (the two floating output wired in series) I could not light it up, zero light, zero current flowing, nada, dead. So I thought OK see, the LED string in there is open circuit, it's dead that's all. Then as I wasfiddling with the panel, suddenly I saw a very brief flash of white light !  Hmmm.... dodgy connection is it ?! I tried tapping the panel, twisting it a bit, eventually light came back up, and stayed ! 
So I experimented with voltagE/current... turns out with a voltage as low as 8Volts is enought to light it up, and it draws less than 10mA... because the ammeter on the power supply has 10mA resolution, and it was showing 0.00A ...

So I kept playnig with it.. then eventually found out the problem is a dodgy connection where the black an dred LED wires exit the panel assembly !
So I would need to open it up to see if I can do something about it, oh no !!!!! 

If it's like a TV set, the wires are just soldered to thin PCB holding all the white LEDs. So might be as simple as reflowing a couple joints ! ... IF I can open the panel assembly AND put it back together again properly...  unlikely I guess !!!! 

So... I reconnected the front panel PCB and LCD panel to the main board, just the bare boards not the front panel assemby/plastic... so that I can pwoer up the unit while style have access to the backlight wires / panel, so I can wiggle the wires at will.*

Power the unit up... no picture. 30V at the backlight driver output.
Wiggle wires and tap the screen.. LIGHT !! We have PICTURE !!!!!!  This thing is WORKING !!!!! 
With the backlight working, voltage goes down from 30V (which must the max/unloaded voltage then) to 8+ Volts.

Played with the thing for 30 minutes... backlight still working. So it's fixed... but no really ! Of course the moment I put everything back together again, OBVISOULY the backlight will stop working !
So... what to do ! If works for now... but can fail anytime. But fixing it required taking the LCD panel assy apart which could be fatal to the panel !
Granted, all it would do is bring it back to where it was when my friend gave it to me : "No picture".
So maybe we could just consider than I have nothing to lose so might as well give it a go ??
If soeone here did it before and can give advise, now is the time ! 

Will contact my friend to see what he wants to do.

I tried looking the LCD panel up on the web to see if one could buy a new panel, and for what money... but the part number I see at the back of the panel yields no result...   

[mnementh]

Hmmm... it's weird they use that connector to the LED strip; that kind is usually used on CCFL tubes for the HV.

Yeah, since you've determined that wiggling the wire brings light, I'm afraid you're going to have to brave taking the panel apart and live with the consequences. Do your due diligence; find the cleanest corner you can, far away from fans or HVAC vent to bring dust. If you can, make a pseudo-clean-room from new trash bags taped around a piece of glass or an old storm window (clean it extra carefully) propped up on the bench and work under that.

I've done this job... it's not easy but it can be done with a minimum of dust intrusion.

Good luck!

mnem
 

[xrunner]

GPSDO Display Progress

Back panel designed and printed. Openings for USB, PWR, RS-232, and 1 PPS LED.

Shouldn't need more explanation, but I could be wrong. 

[beanflying]

Yes Mr Gates how may I serve you better now I have had my second chip installed 

Our 2nd dose on Nano particles has not improved 5G reception. 
Maybe it needs time for them to multiply. 

Might be your more rural setting needs a better antenna 

[Cerebus]

Hmmm... it's weird they use that connector to the LED strip; that kind is usually used on CCFL tubes for the HV.

Yeah, since you've determined that wiggling the wire brings light, I'm afraid you're going to have to brave taking the panel apart and live with the consequences. Do your due diligence; find the cleanest corner you can, far away from fans or HVAC vent to bring dust. If you can, make a pseudo-clean-room from new trash bags taped around a piece of glass or an old storm window (clean it extra carefully) propped up on the bench and work under that.

I've done this job... it's not easy but it can be done with a minimum of dust intrusion.

Good luck!

mnem
 

Why do I now have a mental image of Mnem entangled in bin bags and masking tape, like a kitten tangled in string?

[Cerebus]

I have just now emerged from about three hours getting the Nexperia spice model of an 74HC4053 into something like usable shape in LTSpice. Do Nexperia provide a spice model that's helpful? No, they provide parts of transistor level models that you have to splice together into something like the original. So what I've just basically done is make a whole transistor level spice model of an IC. Actually only one half of one of the three switches in a 74HC4053, so I have more left to do, but at least it's more "cut and paste" than proper modelling work. Urgh!

I feel a little bit ... dazed.

[mnementh]

Hmmm... it's weird they use that connector to the LED strip; that kind is usually used on CCFL tubes for the HV.

Yeah, since you've determined that wiggling the wire brings light, I'm afraid you're going to have to brave taking the panel apart and live with the consequences. Do your due diligence; find the cleanest corner you can, far away from fans or HVAC vent to bring dust. If you can, make a pseudo-clean-room from new trash bags taped around a piece of glass or an old storm window (clean it extra carefully) propped up on the bench and work under that.

I've done this job... it's not easy but it can be done with a minimum of dust intrusion.

Good luck!

mnem
 

Why do I now have a mental image of Mnem entangled in bin bags and masking tape, like a kitten tangled in string?

aaaaaaaaccccck! Get out of my head!!!!

mnem
Awww, dammit... claws shredding everything...

[mnementh]

https://monster6502.com/

This is just for you, C. 

mnem
may the Hertz be with you...

[0culus]

Here's a real boat anchor for you folks: https://www.ebay.com/itm/131480542091


AN/UPM-137A radar test set. Shipping weight is only 200 lbs... 

[Saskia]

computer for daughter is finished, tested, and works. Received a Demolition Man pinball cpu board, some vias eaten away, but should be fixable. Also, finally back at size 18 and 30 kg weight shed.

Good job, are you still going for a size 14?

Yes. will take me another 20 - 30 kg. Just about 5 cm belly away from a size 16 Levi 550. Working on it. New clothes will deplete my TEA budget significantly ...

[Ice-Tea]

computer for daughter is finished, tested, and works. Received a Demolition Man pinball cpu board, some vias eaten away, but should be fixable. Also, finally back at size 18 and 30 kg weight shed.

Now, that's an honnest days work 

[psykok]

Heads up for all German members...

The German Institute for Broadcast Technology (IRT) in Munich is being disbanded which in itself is a shame and a sin but there's nothing we can do about it. They're currently auctioning off all of its assets, mostly office furniture and computer/network equipment but also various electronics and TE. The list includes things like Rohde & Schwarz ADS with a starting bid of 200 euros, HP Universal Counter, Modell 5314 A, various decoders, encoders and analyzers, a Tektronixs (sic!) 2430 scope starting at 50 euros, Weller WECP 20, 3D printers, Rohde 6 Schwarz FSQ8, CMW500, Tektronix TDS 724A, Audio Precision System One +DSP, Rhode & Schwarz SAF... over 1800 items.

https://www.reich-bayern.de/de/objekte/au-116/liquidationsversteigerung_der_irt_institut_fuer_rundfunktechnik_gmbh_teil_2_-_ha?Lstatus=1

Do note: +18% fee, +19% VAT, no shipping, bidder collects.

they have a lot of interesting Equipment but with the taxes and fees it gets  expensive

[med6753]

Here's a real boat anchor for you folks: https://www.ebay.com/itm/131480542091


AN/UPM-137A radar test set. Shipping weight is only 200 lbs... 

My hernia came back just by looking at it. 

[Saskia]

hmm, wait, was that the piss in a sack or the ouch, can't lift nutting ...

just taking the piss out of you

[med6753]

hmm, wait, was that the piss in a sack or the ouch, can't lift nutting ...

just taking the piss out of you

The hernia was the can't lift nuthin but also contributed, but wasn't total cause, for piss in the sack. It's complicated but happy to report that everything in that department is normal now. 

[Brumby]

... and he has the rope to prove it!