A Retro Gaming Upscaler Buying Checklist Covering Power Delivery, HDCP, and Signal Passthrough

Before you hand over cash for any retro upscaler, start with power delivery, HDCP behaviour, and signal passthrough. Pretty pictures of scanlines come later. The single most common failure in Hong Kong is buying a unit that works on a friend's TV in another country, then watching it black-screen or hum when you plug it into your OLED in a Sham Shui Po flat. The problem is rarely the core chip. It is the supporting cast: how the device gets power, how it negotiates the HDMI handshake with your display, and whether it forwards control signals without interference. Work through this pre-acquisition technical checklist, question by question, and test the exact failure modes that will cost you an evening and a return trip to Golden Computer Centre.

First question for the seller: how does this unit get its power? The mClassic's 1.5 W over micro-USB is the classic trap. It draws power from the HDMI port of your display, and under-spec HDMI ports on budget 4K TVs or some capture-card chains drop that power during a handshake, causing signal dropouts every few minutes. The failure is intermittent and maddening. The fix is a simple powered USB hub, but you have to know to ask. USB power delivery is the most common standard on modern devices like the RetroTINK-5X, which takes a standard 5V USB-C cable. That is fine, but verify the included wall adapter's current rating. A phone charger supplying only 1A may sag under load and cause random resets.

Barrel jack power is the other option, and it is the one you want if the unit has a fan or a large framebuffer. A 5V or 12V barrel jack with a centre-positive tip is standard. The risk is polarity and voltage mismatch, so carry a multimeter to Golden Computer Centre and test the adapter before buying. A 12V adapter plugged into a 5V jack will fry the device instantly. For imported Japanese consoles, remember the Hong Kong voltage standard is 220V at 50Hz, but a Super Famicom or a PC Engine expects 100V. You need a step-down transformer permanently in line, not a travel adapter. The console's internal power supply will overheat and die on 220V. Ask the seller whether the unit's power supply is universal (100-240V) or fixed. A fixed US adapter will pop on a HK socket without a transformer.

Ground loop hum is the audio corollary. If the unit takes analogue audio from a console's RCA jacks and embeds it into HDMI, a ground loop between the console's PSU and the unit's PSU can inject a 50Hz buzz through your speakers. Use a single grounded power strip for all gear. Ask the seller if the device isolates its analogue input ground from its HDMI ground. Many budget designs from Sham Shui Po do not. If you hear hum, the unit is not necessarily broken. It is a grounding defect that a better power supply or a ground loop isolator may cure.

Testing Power Before You Pay

Bring a portable power bank with a USB-C cable that delivers 5V/2A to the shop. If the unit runs off a barrel jack, bring a universal adapter with swappable tips. The test is simple: power the device, plug in a console, and leave it running for two full minutes. If the picture drops out once, that is a power delivery fault, not a signal fault. Ask for a second unit. If it fails again, walk away. A seller at Retro.HK Gaming Expo or a Golden Computer Centre stall expects this. It is a standard check.

HDCP compliance and EDID management are where the HDMI handshake loop failure lives. The symptom: a blinking black screen every few seconds as the display and the processor continuously re-negotiate the HDMI connection. An HDCP mismatch causes this, often triggered by a capture card in the chain, or by an EDID misreport from your TV. Ask the seller: does this device support HDCP 1.4 or 2.2, and can I disable HDCP on the input? Many processors, especially the RetroTINK line, do not support HDCP at all since they assume you have a pure retro signal. That is fine. But if you want to route a modern console or a streaming stick through the HDMI input, you must have HDCP passthrough, or the screen will blink forever.

EDID management is the second half. The processor must ask the display what resolutions it supports, then pick one. If the EDID is bad, the unit may output a resolution the display cannot handle, causing a black screen or a rolling vertical bar. Ask the seller: does this device read the display's EDID correctly, or does it need a manual EDID override? The RetroTINK-4K has a web interface for this. The OSSC has a settings menu. A generic unit from Ap Liu Street will have no such options, and you will be stuck with whatever the manufacturer hardcoded.

The HDMI Handshake Loop Test

Ask the seller to demonstrate the processor with a capture card in the chain. That is where handshake loops appear. If they refuse, or if the picture blinks, walk away. Also ask about HDCP on the HDMI output. Some units strip HDCP on the output, which is fine for retro, but it will break a legal 4K stream. The professional move is to ask whether the device reports HDCP 1.4 or 2.2 to the display, and whether it can force HDCP off. If the seller does not know, test it yourself with a 4K Blu-ray player.

HDMI-CEC passthrough is the silent killer in Hong Kong flats. HDMI-CEC is the control protocol that lets your TV remote talk to a set-top box over the same HDMI cable. If a processor has broken CEC passthrough, or no CEC support at all, your Hong Kong set-top box may change inputs unexpectedly, turn off your TV, or trigger a menu you never touched. The failure mode is not subtle, but it is intermittent, so sellers miss it. Ask the seller: does this device pass through HDMI-CEC from the source to the display? Most cheap units do not. The fix is to disable CEC on your TV's HDMI input, but that means losing ARC or your soundbar control.

For a retro processor, HDMI-CEC compatibility is almost an afterthought, but broken CEC passthrough can cause a Hong Kong set-top box to change inputs. The question is worth asking before you wire everything up. The RetroTINK-5X and 4K do not implement CEC at all. That is honestly safer, because they advertise 'no CEC' and your TV will ignore them. The OSSC and OSSC Pro likewise do not care about CEC. The real risk is a unit that claims CEC support but implements it badly, causing ghost commands.

What to Ask About CEC

Ask: does the device have a CEC pin connected, or is it floating? A floating pin can send spurious commands. Bring a cheap CEC tester or ask to test with your own set-top box. If the seller cannot guarantee CEC is disabled in the firmware, assume it is broken and plan to disable CEC on your TV. A processor with absent CEC is fine. One with broken CEC is a headache.

Signal passthrough is the final technical gate. Ask the seller for the unit's input signal compatibility: composite, S-Video, component, RGB SCART, VGA, HDMI. More inputs means fewer external transcoders, and a transcoder is another point of failure. The OSSC is famously limited to SCART, component, and VGA, with HDMI via the TX0 expansion port. It has no composite or S-Video input. The RetroTINK-4K accepts everything up to HDMI 2.0, but at a price. For a Hong Kong gamer with a PAL SNES (which outputs RGB SCART) and a Japanese PlayStation (which outputs component), you want a processor that takes both, or you are buying a separate transcoder for each console.

Audio embedding is the hidden passthrough feature. Some units only pass through audio from the HDMI input. Others embed analogue audio from a 3.5mm jack into the HDMI output. If you play a NES with RCA audio and want sound through your TV's speakers, you need a unit that embeds that analogue signal. Ask the seller: does this device embed analogue audio from the console into the HDMI output, or do I need a separate audio extractor? The OSSC has a 3.5mm jack for this. The RetroTINK-5X has a built-in audio input. A processor without audio embedding forces you to buy a separate device, and that device is another handshake risk.

The table above is the quick reference for the four processors you will actually find in Hong Kong. The GBS-Control is the budget wildcard: it starts life as a cheap GBS-8200 VGA unit from Sham Shui Po, then gets a community-developed control board and firmware that gives you motion-adaptive deinterlacing. But note the claim versus reality: GBS-Control's deinterlacing works, yet it exhibits chroma artifacts on fast-moving red objects. If you play Sonic the Hedgehog, you will see it. The mClassic's 1440p output claim also needs a reality check. It outputs a 1440p frame with a 1080p active image area upscaled, not a native 1440p render. That is fine for smoothing, but it is not a retro processor. It is a post-processing dongle.

Sync Tolerance and Frame Lock Speed

When you visit a Hong Kong retro game shop, either at Golden Computer Centre in Sham Shui Po or at a Retro.HK Gaming Expo (the 2023 event was at D2 Place in Lai Chi Kok, but verify dates locally before going), ask a set of pointed questions. Do not accept a vague 'yeah it works.' Ask specifically about the unit's sync tolerance. A device with tight sync tolerance will drop sync during a SNES white flash, showing a black screen for two to three seconds. The console's sync signal dips during full-white frames. Ask the seller: have you tested this with a real SNES over SCART? If they say yes, ask them to demonstrate a white screen. If they cannot, budget for a sync combiner or a different unit.

Another seller question concerns frame lock speed: the time in seconds to re-sync after a resolution change. A PS1 game that switches from 480i to 240p mid-boot will cause a re-sync. A slow unit takes three seconds to lock; a fast one does it in under a second. Ask: how fast does this device re-sync after a resolution switch? The OSSC is nearly instant. It line-doubles without a framebuffer. The RetroTINK-5X takes about a second. A generic converter might take five, and you will miss the game's opening. Test this on the shop floor with a PS1 and a multi-region title like Castlevania: Symphony of the Night, which boots in 240p and switches to 480i in the menu.

Build Quality and Return Policies

Questions about build quality are non-negotiable. A unit with board-mounted jacks that wiggle will fail within a year of cable changes, especially in Hong Kong's humid climate where solder joints corrode. Ask the seller if the jacks are through-hole mounted or surface-mounted on the PCB. Through-hole is stronger. Pick up the device. Wiggle each connector. If there is any movement, put it down. The RetroTINK-4K uses high-quality jacks. A HKD 200 converter from Ap Liu Street may not. Ask whether the HDMI port has a metal shield or is a bare connector. A bare connector will break off in a backpack.

Finally, ask about the return policy before you hand over cash. The question that matters: if this unit fails a handshake with my TV, can I return it within 14 days? Many Hong Kong shops do not accept returns on electronics once opened, and a device that works on a 1080p shop monitor may fail on your 4K OLED because of an EDID mismatch. The honest seller will tell you to test it with your own cable. Bring your own HDMI cable to the shop. A cable that works on a laptop may not carry the unit's output if it is not certified for the bandwidth. HDMI cable certification standards change, and a cable that met the spec two years ago may not meet today's tier.

The return policy question is your last line of defence. A shop that offers a 7-day exchange, not a refund, is the norm. A shop that offers 30 days with full refund is a rarity worth paying extra for. Ask what happens if the unit works on the shop's TV but not yours. If they blame your TV and refuse, you have your answer. The failure mode is real: a device that has not been updated may have a stale EDID that your TV rejects. Ask if the firmware is updatable, and if the seller will handle an update for you. The RetroTINK-5X and 4K have USB ports for updates. The OSSC requires a programmer or a USB-serial adapter. A processor with no update path is a brick the day a new TV model ships.

If the normal route of buying in a shop is closed, or it is 1am and you are online, the failure case is tempting a cheap converter from an overseas site. Do not. A generic HDMI converter that claims 1080p output for HKD 50 treats a 240p game signal as 480i video, applies a destructive deinterlace, discards half the vertical resolution, and adds 2-4 frames of lag. You will play a SNES game that looks like a smeared mess, and you will have wasted your money. The same goes for a Raspberry Pi running emulation. The MiSTer FPGA is the superior alternative if you are emulation-pragmatic, but it costs as much as a RetroTINK-4K. If you cannot physically test it in Hong Kong, do not buy it. There is a reason the Retro.HK Gaming Expo sells out. People want to touch the hardware first.

When the Shop Is Shut: The 1am Plan

If you are reading this at 1am, you are likely staring at an online listing. Here is your 1am rule: only buy a unit from a Hong Kong-based seller who lists a physical shop address and a phone number. A listing with no address is a scam. A listing with an address you can visit tomorrow is an honest business. If you must order, buy from a seller who clearly states 'tested with a Super Famicom before shipping.' That tells you they know what sync tolerance means. Do not order from abroad. The shipping cost, the voltage difference, and the return hassle are not worth it.

For the Hong Kong AC mains reality, remember you need a step-down transformer for any Japanese 100V console. Do not plug a Super Famicom into a 220V socket without one. You will see smoke, and the console will be a brick. The transformer should be rated at least 50W for a console, and it must be a step-down type, not a voltage regulator. Ask at a hardware store in Sham Shui Po for a '220V to 100V transformer, 100W,' and test it with a multimeter before trusting it. The Hong Kong plug type is BS 1363, three rectangular pins with a fuse. Bring an adapter for any device with a different plug.

Input lag is the metric that matters most. The physics: a frame at 60Hz is 16.67ms, and any processing step that buffers a full frame adds at least that much. The OSSC has no framebuffer, so its lag is measured in microseconds, not milliseconds. That claim holds in practice. The RetroTINK-5X adds under one frame in its default mode, but its motion-adaptive deinterlacing can add up to two frames depending on the game. A TV's game mode still adds 10-15ms at 1080p and 30-40ms at 4K, even on a 2023 OLED. That is the panel's inherent processing, and no processor can fix it. For a fighting game player, the unit is not the bottleneck. The TV is. You cannot buy your way out of physics.

Deinterlacing and Chroma Quality

Deinterlacing quality is the visual metric. A 480i signal must be deinterlaced, and the method matters. Bob deinterlacing weaves every other line and causes jitter on motion. Weave deinterlacing combines two fields but causes combing on fast movement. Motion-adaptive deinterlacing is the best, but it is not perfect. The RetroTINK-5X and 4K have motion-adaptive deinterlacing. The OSSC has bob only, or passes through 480i to the TV, which then deinterlaces. For a PAL game running at 50Hz, note that a 60Hz unit will stutter unless it handles frame rate conversion. Ask the seller: what deinterlacing method does this device use on a 480i source? If they say 'auto,' press for specifics. Chroma subsampling is the last visual check: 4:4:4 preserves full colour resolution, 4:2:2 halves it, 4:2:0 quarters it. A retro game with a lot of red, think Sonic, will show bleeding if the unit forces 4:2:0. Ask for 4:4:4 output, and test with a red-heavy screen.

The honest caveat: no retro upscaler will ever make a 240p game look like a 4K render. The RetroTINK-4K is the ceiling, and it still produces a picture that a broadcaster from 1995 would laugh at if you compared it to a Sony PVM-20L5 (the multiformat CRT reference, 800 TVL) or a Sony BVM-D24E1WU (1000 TVL, the absolute peak). Your choice is between a unit that preserves the original signal's artefacts honestly, like the OSSC, or one that processes it into something smooth and fake, like the RetroTINK-4K's CRT filter. Neither is wrong. Both are a lie in different ways. The caveat is that if you have the space, a PVM is better than any processor. But Hong Kong apartments do not have that space, so you buy a unit, and you live with the compromise. The one sentence on this page that no competitor will write: if you are buying a scaler in Hong Kong and you are not willing to spend at least HKD 1,500, you are wasting your money, because every converter under that price in Sham Shui Po is a 240p-as-480i misdetection machine that will ruin your library.