Repairing A Mercedes EQC 300 BEV Battery

April 22, 2026 by Maya Posch 15 Comments

When [OGS Mechanics] got a Mercedes EQC 300 battery-electric car in for repair, it was found to have a bit of a weird issue: after sitting in a garage for a while, its range on battery had suddenly reduced significantly without clear cause. Although the typical response here is to just mark the battery pack as ‘faulty’ and replace the whole unit, [OGS] decided to dig into the pack to see what was going on.

The short version is that this particular battery pack consists of two individual batteries, each with its own BMS, one of which had reported a condition to the master BMS that triggered the ‘replace battery module’ error observed with the scan tool. From this it could also be seen that the first battery was at a 10% state-of-charge (SoC), and the second at 95%, making them incredibly unbalanced. Unfortunately the dealer procedure to rebalance did not work here, with only the second battery wanting to charge even after draining both to the same initial level.

To diagnose the underlying issue in earnest required gently prying open the battery pack like a massive glued-shut smartphone. Going by the theory that it is a software glitch, since the first battery was still at a healthy voltage level, it was decided to manually charge it. With both batteries now fully charged, the BMS for the first battery was then removed to have its memory overwritten with that of a known good BMS module, clearing the ‘replace battery module’ error.

Although in the preview for the next video it’s hinted that there’s also an internal balancing issue in the first battery pack, this could be another symptom of its BMS glitching out. Either way, it would seem that BEVs battery modules are both heavily dependent on software, as well as afflicted by the same throw-away culture that has people just buying a new smartphone when the battery fails.

Continue reading “Repairing A Mercedes EQC 300 BEV Battery” →

Fixing A GameCube’s Dodgy Optical Drive With Fresh Capacitors

April 17, 2026 by Maya Posch 3 Comments

Generally when a game console with an optical drive stops reading discs the first thing that people do is crank on the potentiometer that controls the power to the laser diode to ramp up its output. While this can be a necessary solution to eke out a bit more life out of a clearly dying laser diode, this can actually massively shorten the lifespan of a good diode that’s just held back by bad capacitors. This is demonstrated by [Skawo] with a fix on a GameCube that stopped reading discs.

While it’s absolutely true that laser diodes have a limited lifespan, so do the capacitors and other components in the system. Thus, after tearing down this Japanese GameCube, [Skawo] accesses the optical PCB for some delicate plier-based capacitor surgery. One can absolutely question such violence, as well as the replacement mix of MLCC ceramics and a stray THT electrolytic capacitor, but the results after reassembly are obvious.

Without having to adjust the laser diode’s potentiometer, the game console now happily reads the game disc while the laser diode breathes a sigh of relief. Although all GameCube consoles will face the inevitable demise of their optical drives – barring a replacement optical pickup solution appearing – with this capacitor replacement solution it’s at least possible to stave off that undesirable time for a bit longer.

Continue reading “Fixing A GameCube’s Dodgy Optical Drive With Fresh Capacitors” →

Heathkit Tuner Saved From Junk Pile

April 4, 2026 by Al Williams 4 Comments

We miss the old Heathkit. You could build equipment that rivaled or even surpassed commercial devices. The cost was usually reasonable and, even if you could get by with less, the satisfaction of using gear you built yourself was worth a lot. Not to mention the knowledge you’d gain and your confidence in troubleshooting should the need arise. So we were jealous of [RCD66] when he found a Heathkit AJ-43C stereo tuner in the recycle bin.

As you can see in the video below, it needed a lot of love to get back to its former self. The device dates from around 1965, when the kit cost $130. In 1965, that was a lot of money. Back then, that would have bought you about four ounces of gold and would have been a great down payment on a $1,500 VW bug.

Things were a bit of a mess, so he removed all the parts and replaced most of them. Unsurprisingly, the electrolytic capacitors all tested bad. The transistors were all germanium, but if they tested good, his plan was to reuse them. There were several PCBs inside, and he made some changes, such as replacing the zener diode power supply with something more modern.

How did it sound? Watch the video and see for yourself. We usually like troubleshooting specific problems on gear like this, but in this case, it was probably smart to just do a total rework.

Heathkit had quite an origin story. This isn’t the first time we’ve seen someone strip and rebuild a Heathkit.

Continue reading “Heathkit Tuner Saved From Junk Pile” →

Fixing An E-Waste ASUS P5A-B Socket 7 Mainboard

April 3, 2026 by Maya Posch 9 Comments

A fun part of retro computing is saving ‘e-waste’ that was headed for certain destruction. These boards can have any number of defects, modifications and more that have to be remedied prior to using them. In the case of the Asus P5A-B Socket 7 mainboard that [Bits und Bolts] rescued from the scrapheap at least one issue was obvious: someone had ripped off the plastic part of the ZIF socket, leaving only the metal pins poking out like an awkward kind of LGA socket.

In addition to the busted PGA ZIF socket there was additional damage, including a broken SMT capacitor and missing resistor. Interestingly, someone had apparently modded the ATX power connector to permanently power on the system by removing a pin and bridging to the power-on signal. Obviously this mod had to be undone by removing the bridge and installing a new pin. After this cracked solder joints had to be addressed, before the tedious task of removing the stray PGA socket pins one by one started.

Exactly what was done to this mainboard and why will likely forever remain a mystery, but at least there didn’t seem to be any serious damage. After installing a CPU it was possible to boot and access the BIOS as well as run a couple of tools, confirming that one more Socket 7 board has been saved from the scrapper.

Continue reading “Fixing An E-Waste ASUS P5A-B Socket 7 Mainboard” →

Resin Injection CRT Cataract Surgery On Macintosh Monitor

March 21, 2026 by Tyler August 10 Comments

Nothing lasts forever, but you’d think the leaded-glass face of a CRT would not be a place you’re likely to see Father Time causing failures. Alas, the particle accelerators we all lovingly stared at were very often not unitary pieces of glass: in case of implosion, safety glass was glued onto the front of the CRT. That glue will inevitably fail, as happened to the 20″ Mac-branded Triniton [Epictronics] had with a PowerPC 6100 that needed a few other repairs.

His version of cataract surgery was the most interesting. Usually cataracts are an issue for much older CRTs than the 90s-era Macintosh display featured here, but this particular display was literally pulled out of the trash and not stored well before that, so that’s probably what accounts for its accelerated aging. Usually what people do with CRT Cataracts is use heat to remove the safety glass and failing adhesive. [Epictronics] has a safer technique, however: inject fresh adhesive into the gap that’s forming around the edge of the display.

With a syringe and UV cure resin, he slowly and laboriously goes around the edge of the display to fill in the bubbles that can be reached. Luckily, the delamination on this CRT doesn’t extend very far beyond the edges, so a standard syringe tip could reach all the problem areas.

It looks good now, but if it doesn’t hold, [Epictronics] points out he can still remove the glass with the traditional hot-air technique. We hope it holds up; this is a nice technique to try if you have a CRT with the early stages of cataract delamination. For future reference, it took about one milliliter of resin to fill each square centimeter of affected area, which implies the cataract gap is quite small indeed.

Having repaired the monitor by about fifteen minutes into the video, [Epictronics] spends the remaining seventeen minutes getting the Mac running with its original CD-ROM drive (that needed recapped) and a DOS compatibility card.

We’ve featured [Epictronics] repairs here before, like when he tore down and rebuilt an IBM Model F keyboard.

Continue reading “Resin Injection CRT Cataract Surgery On Macintosh Monitor” →

User Repair Of A Not User-Repairable Victron CCGX Issue

March 20, 2026 by Maya Posch 4 Comments

Power banks come in many sizes, and those that target construction sites are probably among the largest. The massive four ton unit based around lead-acid batteries which the [Buy it Fix it] YouTube channel got handed is a good example. Inside it are Victron CCGX inverters among a lot of other Victron electronics, with the control panel for the system throwing up an error that was deemed to be not user-serviceable. Naturally, this makes for a good challenge.

The exact error as thrown up on the central control panel is error #42, indicating a storage corruption issue on the device. According to the manual this means an issue with the internal flash memory that stores settings, serial numbers and WiFi credentials, requiring it to be shipped back to the manufacturer.

To further diagnose the issue, this Color Control unit was taken out of the power bank and coaxed onto a repair bench. This device has a whole host of Ethernet, CAN and other buses on the back, along with a USB host feature, but using the latter to reflash the firmware made no difference. Fortunately it’s just an embedded Linux system running on the System-on-Module and gaining remote SSH access was a snap due to easy root access.

Interestingly, running a diagnostic on the flash IC showed it to be still in good condition. Instead an ECC issue was logged that caused it to be marked as bad. This seems to have been due to the flash IC requiring 4 bits of ECC per 528 bytes, but the software using only a single bit. After reformatting and clearing the error it seems to have fixed the issue. Apparently it was just a weird configuration error that soft-bricked the device, raising the question of how that happened.

Continue reading “User Repair Of A Not User-Repairable Victron CCGX Issue” →

Diagnosing A Mysterious Fault With A Commodore 1541 Disk Drive

March 9, 2026 by Maya Posch 3 Comments

Some PCB corrosion on the bottom of the 1541 drive. (Credit: TheRetroChannel, YouTube)

Recently [TheRetroChannel] came across an interesting failure mode on a Commodore 1541 5.25″ floppy disk drive, in the form of the activity LED blinking just once after power-up with the drive motor continuously spinning. Since the Flash Codes that Commodore implemented and bothered to document start at 2 flashes (for RAM-related Zero Page), this raised the question of what fault this drive had, and whether a single flash is some kind of undocumented error code.

A cursory check showed that the heads were okay and not shorted, ruling out a common fault with the used floppy mechanism. Cleaning up the corrosion on IC sockets and similar basic operations were performed next, without making a change, nor did removing the ICs to induce it to produce the documented error codes, but this helped narrow down the potential causes. Especially after swapping in known-good ICs failed to make a difference. One possibility was that the drive was boot looping, as the activity LED is lit up once on boot.

Some probing around with an oscilloscope between the faulty and a working drive seemed to point to a faulty RAM IC, but while probing the faulty drive suddenly initialized successfully. After some more poking around it appeared that the drive was fine after it had a chance to warm up, which just deepened the mystery.

The drive did talk to a C64 with diagnostic cartridge at this point, but would often glitch out. Ultimately it appears that a dodgy IC socket and a few bad traces were to blame for the behavior, making it an ‘obvious in hindsight’ repair. The bottom of the PCB had some clear corrosion on it, but the affected traces were apparently still hanging on for dear life with the drive still initializing once warmed up.

Continue reading “Diagnosing A Mysterious Fault With A Commodore 1541 Disk Drive” →