A quick look at the Keithley 2380 DC Electronic Load

There’s plenty of information about these floating around the internet – so this is not a review, but my first impressions. Let’s unbox and take a look at this 2380-120-60:

If you’re expecting something the usual quality of a Keithley instrument, say, a Source Meter – prepare to be disappointed.  In terms of external build quality – I actually found it slightly worse than another Chinese designed & manufactured instrument I own which cost one tenth of the money.

The first issue I noticed is that the tabs on the rear bumper don’t line up with the holes in the metalwork. I’m sure they did in the CAD drawing but unfortunately due to sloppy molding the only way I could get the rear bumper to stay attached is by cutting them down to size a little. Not the kind of thing one expects when purchasing an instrument from a Tier 1 vendor.

Anyway – let’s have a look inside:

The cover isn’t very well formed either – The position of the bends wrapping down to the underside mean it has an extremely tight fit on the inner chassis, suffice to say I had quite a job getting it off. Eventually after a bit of bashing and brute force it succumbed. On my aforementioned £200 Chinese cheapie, that cover glided straight off!

Immediately we can see what the deal is here. That top PCB is 100% identical to the one found in the BK Precision 8601 which its self is designed by ITECH. I’m not going to go to the trouble of dismantling it but from what I can see that bottom PCB is looking pretty damn similar to the 8601 too.

Don’t believe me? Take a look at this:

So… this probably isn’t a Keithley instrument, but some kind of re-branded deal.

A little disappointing – but not a surprise. Given the relentless pressure of Chinese competition on these instruments, I guess western players need to cut every possible cost, and it appears that in this case, the design of the instrument has been outsourced entirely.

There is some good news – some of the gripes in this video i.e. grinding part numbers off chips, and not-particularly-well insulated mains cables – all fixed in this unit.

2380 Rear – Identical to the BK Precision 8601 minus the remote control port

Serviceability?

The uncomfortable feeling I now have – is that this is not a serviceable unit i.e. we can’t buy parts from Keithley like we can for their other products. This is a problem we often get with re-branded products – the marketer cannot provide parts because they don’t manage the life-cycle of the product.

If anyone has gone to the trouble of inquiring with Keithley on this matter I would certainly like to hear from you.

There certainly doesn’t seem to be a downloadable service manual on the Tektronix website.

The good news is perhaps – if parts aren’t obtainable from Keithley, we may be able to get them through the BK Precision / ITECH route instead.

It appears that only the keypad and outer chassis (that’s “shazzy” – if you’re from Australia) differ from the 8601. VFD appears to be identical, and I suspect it’s even running the same firmware too – it does report the same startup message “BIOS Ver1.10” seen on the 8601.

Conclusion

Despite being less than impressed with the physical build – the specification is of course significantly better than my existing £200 unit (which barely has any written specifications at all).

Given the identical spec to the BK Precision 8601 (understandable given it has the same internals) – I’m not quite sure where the value is for that extra £450 asking price.

If I’ve misunderstood anything here – please correct me.

Retrofitting a Bosco IXO cordless screwdriver with a USB-C charger connector

In this age of USB-C – I’m beginning to tire of things which require Micro USB to charge.

Today’s annoyance: My Bosch IXO. At the time of writing neither my model or the current one charge with USB-C. No doubt people at Bosch are beginning to ask “Do we need to take this new USB seriously?” – but that doesn’t help us much right now.

So let’s open it up.

Damnit. It’s all on one PCB, and there’s a nasty piece of rock hard epoxy behind the micro USB connector. This rules out making a ‘Retrofit’ PCB – which would have been a cool project.

After a good blasting with my Leister Hot Jet S – the old connector and the epoxy is gone. Small bummer that I tore those unused pads from where the connector was, but we don’t need those anymore. I’ve also got a couple of wires there to lead to the new connector

Now – what are we gonna put in its place?

I bought a few Micro-USB to USB-C adapters off eBay and tore the plastic case off one of them. They are compact and have everything we need.

We now have the new connector soldered down. This was quite tricky. I found that the easiest way was to position it by tying it down with some copper wire before soldering. The shell of the USB-C connector is soldered down to the ground pad on the PCB previously used by the Micro USB connector.

Wiring is simple. With those red/black wires I previously soldered on connected to the Micro USB GND/VBus connections. The required 5.1K resistor is already on the adapter PCB.

For added strength that copper wire also goes through the PCB.

You can also see a tiny piece of Kapton tape under the connector. This was to stop the shield of the USB-C connector from shorting the pads used by the old micro-USB connector. By not outright removing all of those pads I made life rather difficult for myself – too late now.

And finally some new epoxy to ensure we’ve got a nice strong bond to the PCB.

Last job is to grab some needle files to increase the aperture in the case to the new larger size needed by the USB-C connector.

In the end it turns out we have something a lot tougher than the original arrangement, because of the longer length of the USB-C connector it now protrudes from the case meaning we can make a nice snug fit for it, significantly lowering the chances of damage by yanking of the charging cable.

That extra length of the connector also means we don’t have the annoying problem of plugs which aren’t the same shape as the supplied charger not fitting in either.

Conclusion

Unfortunately this doesn’t get our IXO all the way into the world of USB-C. PD aware “true” USB-C chargers like for example the Apple 18W iPhone charger, or USB-C Macbook chargers refuse to charge it.

To get full USB-C compatibility we would need an extra chip to negotiate the charge voltage. There are quite a few of these on the market now but we would have to make a custom PCB due to space limitations in the IXO. This is good enough for me – anything which has a USB-A connector on it will work just fine.

This all took me about 2 hours. Not an easy mod unfortunately. But if you have the skill and patience – well worth attempting.

Fixing a Sony KDL-40W5810 with a “14 blink” error code

My dinosaur TV back in action after repair – reassuring to see that little has changed in the world since it last powered on

A little while back I bought this TV cheaply off Gumtree – probably one of the dumber things I’ve done, as it had an array of small but annoying problems, but recently it upped the game and failed to turn on, giving the above described blink code (which shows as 13 blinks, then followed by 14 blinks continuously).

Frustratingly there doesn’t appear to be any official triage documentation for this model online. A bit of googling around offers a few possible causes ranging from mainboard failure, LCD panel failure (?) and TCON (timing controller) failure.

But which is it? I first checked all the voltages on the power supply, all good, looked briefly at the TCON, couldn’t see any obvious issues there. I also took a look at the backlight – the mainboard wasn’t even attempting to power it on, so not likely the issue, but just to be double sure I powered it up manually by applying +3.3V to the BACKLIGHT_ON signal on the power supply. Sure enough it came on and none of the error signals were asserted.

Now I know the problem is either the mainboard or the TCON. I took a stab replacing the mainboard – hitting up eBay for a cheap second hand part. Upon installing it, I now get an 8 blink error code? More googling reveals an issue with the audio amplifier.

Ah. I see, so someone has torn the connector from the PCB when removing it from the donor TV. We can see those small traces have been torn the pads the connector was soldered to.

This was causing the 8 blink error code, as those small traces lead to an ADC which tests for DC offsets from the audio amplifier. This check ensures that we don’t end up with smoke pouring out of the speakers in the case of a blown transistor in the audio amplifier. In this case there was no DC offset, the error was just the ADC inputs drifting all over the place because they weren’t connected to anything.

JST PH header bodged in place of the missing original header

Above you can see I’ve dickied a JST PH connector in place of the missing original – not quite the same as what was there but close enough, also taking care to reconnect those small traces. The original harness mates with it OK – just doesn’t latch.

So I switched it back on with the new mainboard… 8 blink error is gone, and now we’re back to 14 blinks. FFS. The good news is that the eBay seller fully refunded me when I complained of the damage, and I’ve still got the replacement mainboard, but, my TV still ain’t workin’.

So, let’s look at that TCON then.

The TCON is under the aluminum shield circled in red. It converts the serialised picture data from the mainboard to the parallel signals required to drive the LCD panel.

I had purposely not gone down the path of replacing this because it’s not an easy part to find and I had read on other sites that if you disconnect the LVDS cable (the large black one which interlinks it to the mainboard), then power on the TV and it remains powered on (without a picture), then you definitely know that the TCON is at fault.

This was not I observed. In my case I get the 14 blink code regardless of whether or not the LVDS cable was connected. Additionally I had also spent a bit of time checking all of the supply voltages on the board, everything looked OK, hence attempting the mainboard first.

It turns out that bit of advice was rubbish in the case of my TV, because the 14 blink error code is seen both in the case of a TCON which fails self test, and when the TCON is disconnected.

I know this, because I found another (brand new) TCON very cheaply at a local TV service company, mis-labeled as “for Samsung” – knowing this is a rare and pricey part, I wasn’t going to be asking any questions. Upon installing it, my TV is now working again.

The old TCON PCB

I’m picking that few faulty TCONs can easily be repaired, because this board subject to more thermal stress than anything else in the whole unit. After years of thermal cycling it’s likely that this one has died as a result of cracked BGA solder joints.

If you are keen to repair a TCON with this kind of fault – a good starting point would be to re-flow or re-ball, perhaps even replace the gamma processor and its memory (the three BGA chips on the left). The TCON itself (silver topped chip in the centre) is less likely to be an issue due to cooler running temperature.

Conclusion

Success in the end, with a lot of time spent on a worthless item. Perhaps a small bonus that the largely needlessly replaced mainboard fixed a couple of other minor faults. I’d have been a lot more successful if I’d never bought the damn thing in the first place.