Editing CDVD Drive

== Overview ==
The drive is known as MD-block in internal Sony documentation, where MD stands for "Mechanism Deck".

== Electronics ==
* [[DSP]]
* [[MechaCon]]
* [[Drivers]]
* [[RF-Amp]]

Early consoles (A, A+, AB, B, B', C, C' chassis) have separate boards with some of the disc drive electronics:
* GM-038 (early A-chassis) (SCPH-10000, early SCPH-15000, DTL-T10000)<br/> [[File:O2kHeUP.jpg|200px]]
** Contains RF-amp (Sony CXA2605R)
** requires heatsinking for RF-amp
* GM-041 (B-chassis, B'-chassis) <br/> [[File:ijlZhMf.jpg|200px]]
** Contains RF-amp (TI SP3727A) and tilt-driver (BA5912AFP)
** does not require any heatsinking
* GM-042 (late A-chassis, A+ chassis) (late SCPH-15000, GH-003 based SCPH-18000)<br/> [[File:ayV4TIz.jpg|200px]]
** Contains RF-amp (TI SP3727A)
** does not require any heatsinking, unlike GM-038 used in the same chassis; a hole in the case to place a thermal pad in is still there in these consoles, but the thermal pad has been left out from the factory
* GM-043 (C-chassis, C'-chassis) <br/> [[File:cRFTRP8.jpg|200px]]
** Contains RF-amp (TI SP3727A), spindle driver (BA6664FM) and focus/tracking/sled-motor/tray-motor driver (BA5810FP)
** requires heatsinking for BA6664FM and BA5810FP
* GM-045 (AB-chassis) (GH-008 based SCPH-18000)<br/> [[File:GM-045.jpg|200px]]
** Contains RF-amp (TI SP3727A)
** does not require any heatsinking

The [[PSX]] also has a dedicated board for drive electronics, which contains all drive components for the PSX/DVR-mode/burning part of the PSX's unique dual-pickup drive. 
Electronics for the PS2-part of the drive are however on the mainboard (spindle motor control and driving are always handled by the PSX/DVR part of the drive).

* MA-S38 (DESR-x000, DESR-x100)
** [[File:8GcBpTO.jpg|200px]][[File:tFQSjoP.jpg|200px]]
* MA-S43 (DESR-x500, DESR-x700)
** [[File:SMelZmP.jpg|200px]][[File:bq7vfM1.jpg|200px]]

== Mechanics ==

=== Fat drive assemblies ===
''Regulatory labels on the drive enclosure vary between regions''
==== A/A+ chassis drive block ====
''SCPH-10000 japanese launch consoles, SCPH-15000 consoles, some SCPH-18000 consoles, all japan only''<br/>
[[File:KnNqiXM.jpeg|200px]][[File:FHGfvMM.jpeg|200px]][[File:YXgnrZs.jpeg|200px]][[File:7CTF3pm.jpeg|200px]][[File:SLwBUGn.jpg|200px]][[File:vzMYOTs.jpg|200px]][[File:3ubGZSb.jpg|200px]]
* The only drive block to use the KHS-400A pickup, later units use KHS-400B (a picture of a drive inside a SCPH-18000 A+ chassis console using the KHS-400B pickup has been added above)
* Later units have a slightly different drive board which contains a Texas Instruments SP3727A [[RF-Amp]] instead of the Sony CXA2605R RF-Amp that was used on early units
* In these pictures, the flat flex cable between the board and the laser unit has been replaced. The only difference to the original cable is the length of the blue flap, which is longer on the original cable on the side connected to the PCB
==== B/B' chassis drive block ====
''north american early/launch SCPH-30001 consoles, north america only''<br/>
[[File:1IbnPhB.jpg|200px]][[File:Nb6CAWI.jpg|200px]][[File:Uhd08l5.jpg|200px]][[File:KCqhhZE.jpg|200px]][[File:Nixc2WV.jpg|200px]][[File:db77gPh.jpg|200px]][[File:EJf4jLE.jpg|200px]]
* Uses a radial tilt control motor only found in this drive block; all other drive blocks have their radial tilt mechanically set at the factory
* Optical pickup is always KHS-400B

==== C/C' chassis drive block ====
''later north american SCPH-30001 consoles, SCPH-30004 PAL launch consoles, SCPH-300xx consoles in many regions''<br/>
[[File:Gov1HNg.jpg|200px]][[File:5kfnZit.jpg|200px]][[File:gLVqrNi.jpg|200px]][[File:Kncxtr7.jpg|200px]][[File:iEjTkZ5.jpg|200px]][[File:FVtodEz.jpg|200px]][[File:BJfmUzT.jpg|200px]]
* Takes away the tilt motor introduced on the B/B' chassis drive block
* Has both driver ICs on the drive board
* Has an aluminium plate mounted as heatsink between the drive board and drive frame which thermally connects to the back of the PCB through a thermal pad, however, the ICs are also directly cooled from the other side through a thermal pad connecting them to the expansion bay frame
==== AB chassis drive block ====
''some SCPH-18000 consoles, japan-only''<br/>
[[File:AB drive top.jpg|200px]][[File:AB drive tray.jpg|200px]][[File:AB drive inside.jpg|200px]][[File:AB drive bottom.jpg|200px]][[File:AB drive mech pickup.jpg|200px]][[File:AB drive mech top.jpg|200px]][[File:AB drive mech bottom.jpg|200px]]
* Basically a C/C' chassis drive block with a different drive board that only contains the RF-amp but not the driver ICs, since these are located on the motherboard, and no heatsink

==== D/D' chassis drive block ====
''later SCPH-300xx consoles in any region, early SCPH-300xxR consoles in many regions, SCPH-350xx special editions in some regions''<br/>
[[File:D-chassis drive 1.jpg|240px|frameless]][[File:D-chassis drive block 2.jpg|240px|frameless]][[File:D-chassis drive block 3.jpg|240px|frameless]][[File:D-chassis drive block 4.jpg|240px|frameless]][[File:D-chassis drive block 5.jpg|240px|frameless]][[File:D-chassis drive block 6.jpg|240px|frameless]][[File:D-chassis drive block 7.jpg|240px|frameless]]
* all drive electronics moved to the motherboard, no dedicated drive board anymore

==== F/G chassis drive block ====
''late japanese SCPH-30000 consoles, late SCPH-300xxR consoles in many regions, japanese SCPH-37000 special editions, SCPH-390xx consoles in many regions''<br/>
[[File:P8NcLeB.jpg|200px]][[File:dqJrJCi.jpg|200px]][[File:UuwuNLx.jpg|200px]][[File:Q4KeBcc.jpg|200px]][[File:9c1lpJW.jpg|200px]][[File:kfsO92o.jpg|200px]][[File:UnMQzul.jpg|200px]]
* Optical pickup changed to KHS-400C or SF-HD7
** Pictures show the variant that uses the Sony KHS-400C pickup. Variants using the Sanyo SF-HD7 pickup are identical aside of the pickup itself; the pickups are interchangeable (different calibration data for Mechacon required, use LensChanger or PMAP)
==== H/I chassis drive block ====
''SCPH-500xx consoles in any region, SCPH-550xx special editions in some regions''<br/>
[[File:un3LrqS.jpg|200px]][[File:N13dm9Y.jpg|200px]][[File:J5g8RtO.jpg|200px]][[File:FLt0xfo.jpg|200px]][[File:y0SF82K.jpg|200px]][[File:2EeoJVp.jpg|200px]][[File:4sSITOE.jpg|200px]]
* Pictures show the variant that uses the Sanyo SF-HD7 pickup. Variants using the Sony KHS-400C pickup are identical aside of the pickup itself; the pickups are interchangeable (different calibration data for Mechacon required, use LensChanger or PMAP)
* Some markings on the mechanism have been made by the owner during alignment; they are not from the factory
* Button assembly now mounted on the drive assembly
* Mechanical changes: 
** Tilt of the two rods that the optical pickup slides on can be adjusted individually
** Slide arm of the optical pickup now made of a metal spring instead of plastic
==== J chassis drive block ====
''late SCPH-5xxxx consoles in some regions''<br/>
[[File:irvUNi2.jpg|200px]][[File:J5KaXJn.jpg|200px]][[File:uIrCwhc.jpg|200px]]
* Very different drive:
** Uses Mitsumi TDP062W drive mechanism based around the Mitsumi PVR-702W pickup

=== Slim drive assemblies ===
* Some of the slim drives exist with different cable lengths for different chassis. K-chassis and L-chassis use same cable length between each other, as do P-chassis and R-chassis between each other. M-chassis and N-chassis both use different cable lenghts. This makes a total of 4 slim PS2 drive "types" regarding cable length.

==== Sony assemblies ====
''The Sony assemblies are identical to and fully compatible with their Mitsumi-counterparts from the same chassis. The only difference is the branding. Not found in N-chassis consoles.''
* KHM-430AAA
** K-chassis, L-chassis
** KHM-430(A) pickup ''(has only "KHM-430" embossed in it's base)

* KHM-430BAA
** M-chassis
** KHM-430B pickup
[[File:KHM-430BAA top.jpg|240px|frameless]] [[File:KHM-430BAA bottom.jpg|240px|frameless]]

* KHM-430CAA
** P-chassis, R-chassis
** KHM-430C pickup
[[File:KHM430CAA top.jpg|240px|frameless]] [[File:KHM430CAA bottom.jpg|240px|frameless]]

==== Mitsumi assemblies ====
''The Mitsumi assemblies are identical to and fully compatible with their Sony-counterparts from the same chassis. The only difference is the branding. Not found in P and R-chassis consoles.''
* TDP082W
** K-chassis, L-chassis
** PVR-802W pickup
[[File:TDP082W top.jpg|240px|frameless]] [[File:TDP082W bottom.jpg|240px|frameless]]

* TDP182W (with M-chassis compatible cable length)
** M-chassis
** PVR-802W pickup

* TDP182W (with N-chassis compatible cable length)
** N-chassis
** PVR-802W pickup

==== Sankyo/Philips assemblies ====
''The Sankyo assembly is incompatible with the Sony/Mitsumi assemblies. It requires different top shells for the case and different [[MechaCon]] calibration data. Only found in K and L-chassis consoles.''<br/>''While Sankyo is confirmed as the manufacturer of the whole assembly, the actual laser pickup might be manufacturerd by '''Philips''', as SPU3170 would be consistent with their naming scheme for pickups and Sankyo was never known to produce pickups, since their expertise lies within electromechanical systems.''
* SPU3170
** K-chassis, L-chassis
** This is likely the name of just the optical pickup, not the whole assembly
[[File:SPU3170 top.jpg|240px|frameless|top side of the spu3170 drive assembly used in some k and l-chassis slim ps2 consoles.]] [[File:SPU3170 bottom.jpg|240px|frameless|bottom side of the spu3170 drive assembly used in some k and l-chassis slim ps2 consoles.]]

=== PSX drive assemblies ===
The PS2-part of the drive is based on the H/I chassis (SCPH-50000/55000) PS2 drive, both electrically and mechanically. The whole drive assembly is connected to the motherboard using 3 flat flex cables: One is an IDE connection to the dedicated drive board of the PSX-part, one provides power (5V, 12V, GND) and also connects the PS2-part sled motor to the motherboard (since it is controlled by the motherboard directly), and one connects the KHS-400C PS2-part pickup to the motherboard, since it is also directly controlled by the motherboard. The spindle motor is always controlled by the dedicated PSX-part drive electronics over IDE, even in PS2 mode.

* DESR-x000 and DESR-x100 drive
** Uses Sony KWS-200A optical pickup (in addition to a KHS-400C)
[[File:8UIuNSN.jpg|200px]]

* DESR-x500 and DESR-x700 drive
** Uses Sanyo SF-DB11 optical pickup (in addition to a KHS-400C)
[[File:XkMxA6G.jpg|200px]]

== Optical pickup ==
=== Notes ===
* KHS-400R is an alternative name given to the Sanyo SF-HD7 by the community; it is not an official term
* KHS-400B and KHS-400C are electrically compatible, but differ in thickness of their bases, making them mechanically incompatible (putting a KHS-400C in place of a KHS-400B in B/B'/C/C' (maybe AB?) chassis will seem to work at first, but the flex cable will bend heavily once the pickup reaches the outer area while moving)
* KHS-400C and SF-HD7 are mechanically fully compatible, but require different calibration data for [[MechaCon]] (use LensChanger or PMAP)
* There are 2 different lens assemblies for KHS-400B and KHS-400C, which require different calibration data for MechaCon: T487 (white ring around lens) and T609K (yellow ring around lens). T609K seemingly was introduced with the D/D'-chassis. Some T609K have a white ring around the lens. These pickups may have a violet marking at the adjustment screw (Markings in other colors don't indicate any lens assembly variant, only violet does). Alternatively, they might also have "609" hand-written on their base.
** Until early C-chassis (included), only the T487 lens is supported. D-chassis (and some later C-chassis consoles with a D-chassis MechaCon) as well as F-chassis support both lens types (MechaCon needs to be configured for the installed lens type, e.g. using PMAP). Starting from G-chassis, only the T609K lens is supported.
* KHS-400B (with T487 lens assembly) can fully drop-in replace KHS-400A, but not vice versa (mechanical reasons: KHS-400A in a drive meant for KHS-400B can't press the home-position switch near the spindle).
* PSX consoles always have 2 pickups: One KHS-400C (for PS2 games only) and KWS-200A (XPD-001 motherboard) or SF-DB11 (XPD-005 motherboard). Every disc will first be detected by the KWS-200A / SF-DB11, so if this pickup is broken, the console also won't read PS2 games, since the KHS-400C only becomes active once a Disc to be read by it has been detected by the other pickup
* The drive mechanisms of earlier and later PSX consoles are completely different from each other (except the KHS-400C), so you can't replace a KWS-200A with a SF-DB11 or vice versa
* PVR-802W and KHM-430(A/B/C) seem to be mostly identical; KHM-430(A/B/C) is probably a rebadged PVR-802W
* Several variants of the Sanyo SF-DB11 pickup exist, with only some of them being compatible with the PSX. Trying to install an incompatible one will (sometimes? always?) burn the flat flex cable and/or blow the 5V drive-power fuse on the motherboard depending on your luck (known compatible variants: bottom sticker number starts with DB11B; known incompatible revisions: bottom sticker number starts with DB11N, 11NX or 11NXL). It didn't seem to damage anything else though; most notably all electronics (after replacing the blown fuse) AND the laser pickup (after being installed into a compatible PC drive that uses this variant) survived. 
** These different types are seemingly actually called "SF-DB11B" (the one compatible with the PSX), "SF-DB11NS", "SF-DB11NX" and "SF-DB11NXL" (all three incompatible with PSX). These are best differentiated by the bottom sticker, not by the embossed revision number on the top.
** [[File:jPNVCqr.jpg|200px]][[File:Vo2DfEx.jpg|200px]]
** Comparison of an compatible type (left) with an incompatible type (right) of SF-DB11 with the bottom shielding removed:<br />[[File:UJjmXaf.jpg|200px]]
* There is an official documentation of the KWS-200A used in the DESR-x000 and DESR-x100 PSX, released by Sony itself:<br/> [[File:TxkqxiO.jpg|200px]] [[File:tyimnzA.jpg|200px]]

=== Pickup types ===

==== Sony ====
* '''KHS-400A''' (A-chassis, some A+-chassis)
* The first pickup to be used in consumer consoles
* Almost identical to the more common KHS-400B (with T487 lens assembly); the only differences are a small mechanical change to the base (see below) and a slightly different design of the plastic cap; all parts of the optical system are identical
** always has the '''T487''' lens assembly
<gallery>
File:Difference between KHS-400A and KHS-400B.jpg|Differences between KHS-400A (left) and KHS-400B (earlier type) (right)
</gallery>
* '''KHS-400B''' (some A+-chassis, AB-chassis, B/B'-chassis, C/C'-chassis, D/D'-chassis)
** increases height of a small piece of the metal base so it can activate the home position switch on the motor board in the B/B'/C/C'/D/D' chassis drive blocks
*** the height of this piece actually was increased once more for D/D'-chassis; see below
** base assembly exists in 2 main variants:
*** Earlier type, shorter piece at the metal base (but taller than on KHS-400A) that activates the home position switch near the motor spindle (made for A+/AB/B/B'/C/C' chassis, also compatible with A-chassis, but mind the correct lens type!, '''incompatible with D/D' chassis''')
*** Later type, taller piece at the metal base that activates the home position switch near the motor spindle (made for D/D' chassis, also mechanically compatible with A/A+/AB/B/B'/C/C' chassis, but mind the correct lens type!)
** lens assembly exists in 2 main variants:
*** with '''T487''' lens assembly (white lens, no violet marking at skew adjustment screw), supported by any chassis compatible with the KHS-400B
*** with '''T609K''' lens assembly (yellow lens, or white lens with violet marking at skew adjustment screw), '''only supported in D/D' chassis and late C/C' chassis consoles''' (which already have a D/D' chassis MechaCon; C/C' chassis consoles never directly came with the T609K lens out of the factory, though)
** the T487-variant can drop-in replace KHS-400A in A/A+ chassis (this was also done by Sony itself in some A+ chassis consoles), but not vice-versa
** Different revisions of the FPC (the "circuit-board") on the bottom exist, with some having an amber solder mask and others having a green solder mask. Also, component layout and placement differs between revisions. These differences don't cause any compatibility issues.
<gallery>
File:400B differences.jpg|Differences between the earlier (left) and the later (right) KHS-400B metal base type
File:Old 400B in D chassis.jpg|Demonstration of an earlier type KHS-400B failing to activate the home switch in a D-chassis console
</gallery>
* '''KHS-400C''' (F-chassis, G-chassis, H-chassis, I-chassis, PS2-mode laser in all PSX consoles)[[File:Difference between KHS-400B and KHS-400C.jpg|240px|thumb|A picture showing the height difference between KHS-400B (earlier type) (left) and KHS-400C (right)]] [[File:T609K.jpg|thumb|KHS-400C with newer T609K object lens. Note the yellow (instead of white) protective ring.]]
**Decreases total height of the pickup, to fit into F/G/H/I chassis and PSX/DESR
**Does technically also fit into D/D' chassis, although this was never done by Sony. Does NOT fit into B/B'/C/C' (maybe AB?) chassis despite seemingly working at first (will bend and damage the flat flex cable when reaching the outer area of the disc)
**Different plastic cap styles exist, with earlier ones only having a SONY logo embossed on the top side and later ones also having the model number "KHS-400C" embossed. These differences don't cause any compatibility issues.
**Different revisions of the FPC (the "circuit-board") on the bottom exist, with some having an amber solder mask and others having a green solder mask. Also, component layout and placement differs between revisions. These differences don't cause any compatibility issues.
**Exists in 2 main variants:
***with '''T487''' lens assembly (white lens, no violet marking at skew adjustment screw, no "609" or similar written on the pickup's base), '''only supported in F-chassis consoles'''
***with '''T609K''' lens assembly (yellow lens, or white lens with violet marking at skew adjustment screw, or white lens with "609" or similar hand-written on the pickup's base), supported by any chassis compatible with the KHS-400C
*'''KHS-400R''' (F-chassis, G-chassis, H-chassis, I-chassis) 
** Is actually just a name given by the community to the Sanyo SF-HD7, before it's proper name was known; for further details, see the paragraph about the SF-HD7
** Some places differentiate between the metal-body variant as "KHS-400R" and the plastic-body variant (and sometimes also the metal-body variant with a full plastic top cover) as "SF-HD7", however, this is also false
*'''KWS-200A''' (DVR/DVD-burning laser in earlier PSX consoles) 
** The only pickup in this list which has a skew sensor (little black part on a separate segment of the FPC) which works in conjunction with a skew motor
*'''KHM-430(A)''' (K- and L-chassis slim consoles) 
**Is actually just a rebadged '''Mitsumi PVR-802W''' and also identical to KHM-430B and KHM-430C
** Actually not handled as a separate part by Sony, but as a fully integrated component of the KHM-430AAA drive mechanism it is part of (hence the "M" in the name which stands for fully integrated drive mechanisms in Sony's nomenclature)
*'''KHM-430B''' (M-chassis slim consoles)
**Is actually just a rebadged '''Mitsumi PVR-802W''' and also identical to KHM-430(A) and KHM-430C
**Actually not handled as a separate part by Sony, but as a fully integrated component of the KHM-430BAA drive mechanism it is part of (hence the "M" in the name which stands for fully integrated drive mechanisms in Sony's nomenclature)
*'''KHM-430C''' (P- and R-chassis slim consoles)
**Is actually just a rebadged '''Mitsumi PVR-802W''' and also identical to KHM-430(A) and KHM-430B
**Actually not handled as a separate part by Sony, but as a fully integrated component of the KHM-430CAA drive mechanism it is part of (hence the "M" in the name which stands for fully integrated drive mechanisms in Sony's nomenclature)

==== Sanyo====
*'''SF-HD7'''  (F-chassis, G-chassis, H-chassis, I-chassis)
**Same form factor as KHS-400C and used in the same PS2 chassis as it (minus PSX/DESR), but requires different MechaCon configuration/calibration data
**Variants with a full and with a partial plastic cover exist. Only the full plastic cover spells "HD7" on it. They are fully compatible with each other, so this does not really matter.
**Variants with a metal (like KHS-400 A/B/C) and with black plastic base exist. They are fully compatible with each other, so this does not really matter.
*'''SF-DB11''' (DVR/DVD-burning laser in later PSX consoles)
** Several variants exist, of which only some are compatible with the PSX; see above
''Oddly enough, the I-chassis service manual also mentions Sanyo SF-HD8, SF-HD9 and SF-HD10, which seem to be very different from SF-HD7 in construction. Never seen in any consumer PS2 console.''

====Mitsumi====
*'''PVR-702W''' (J-chassis)
*'''PVR-802W''' [https://archive.org/details/pvr-802-w-datasheet (download datasheet)] (K/L/M/N-chassis slim consoles)
**Identical to Sony '''KHM-430(A)''', '''KHM-430B''' and '''KHM-430C''', which are all just rebadged PVR-802W pickups

====Sankyo/Philips====
''While Sankyo is confirmed as the manufacturer of the whole drive assembly in consoles using this pickup, the actual pickup might be manufacturerd by '''Philips''', as SPU3170 would be consistent with their naming scheme for pickups and Sankyo was never known to produce pickups, since their expertise lies within electromechanical systems.''
*'''SPU3170''' (some K/L-chassis slim consoles)

====Third party replacements/clones====
*'''KHS-400H''' / '''PS-400H''' (replaces SF-HD7)
*'''KHS-400Q''' / '''PS-400Q''' (replaces KHS-400C)
*'''KHS-400W''' (replaces KHS-400C)

===Laser units===
*Pickups in fat consoles (except J-chassis), including the ones made by Sanyo, all use a Sony "Laser Coupler" (combined dual wavelength laser diode + dual wavelength PDIC)
**There are (at least) two variants of this Laser Coupler: One to be used in T487-pickups (see above) and one to be used in T609K-pickups. It is not known whether the variant used in the Sanyo Pickups is either of these two variants.
***The difference between these variants lies within the polarization filter
**The first variant of the Laser Coupler is known to have the part number SLK3201PE, thanks to official Sony publications
**According to a single source, the PDIC inside SLK3201PE has the part number "CXA250BH2" <ref>https://books.google.de/books?id=38Aj3CjHgc8C</ref>
**The PDIC of some or all KHS-400C pickups with T487-lens (and maybe also those with a T609K-lens?) has a "A2508A" marking, which would suggest a part number of "CXA2508A"
<gallery>
File:PS2 lasercoupler angle view.jpg|
File:O4ZGd9F.jpg|
File:FlbDFEw.jpg|
File:jyypmjM.png|
</gallery> 

*All slim pickups (both, those made by Mitsumi/Sony and those made by Sankyo) as well as the J-chassis pickup use a more traditional approach, consisting of a laser diode (dual-wavelength, with power monitoring photo diode) and a separate dual-wavelength PDIC
<gallery>
File:KHM-430C bottom.jpg|Bottom side of the KHM-430/PVR-802W pickup
File:KHM-430 laser diode.jpg|Laser diode of the KHM-430/PVR-802W pickup
File:KHM-430 PDIC.jpg|PDIC of the KHM-430/PVR-802W pickup
File:KHM-430 laser diode closeup.jpg|Close-up of the laser diode
File:KHM-430 PDIC closeup.jpg|Close-up of the PDIC
</gallery>

==Adjustments==
The two 2-kOhms potentiometers on the pickups (one for each, CD and DVD) do not directly adjust laser output power. Laser output power is actually regulated in real time by the drive electronics (APC, automatic power control). Instead, these potentiometers adjust the output level of the monitoring photodiode which the drive electronics uses for monitoring the laser output power. Hence, any weakening of the laser output power over time is already being compensated by the drive electronics. '''This means that adjusting these potentiometers should never be necessary.''' The only way of properly adjusting these potentiometers would be by using a laser power meter, which would however only be necessary in case someone already tinkered with the potentiometers.

What turning these potentiometers actually does is overdriving the laser to higher than specified output power. The reason why this might allow discs to be read again is that it gives the drive higher tolerance to dirt on or inside the pickup's lens/prism system and/or misadjusted drive mechanics (tilt/skew).

Instead of overdriving the laser diodes (and causing long-term damage to them), the actual issues should be adressed (dirt and dust on or inside the laser, miscalibrated mechanics etc). Mechanical and electrical calibration can be done by connecting to Mechacon from a PC via UART (see [[Test points]]) and then using a tool called PMAP.

KHS-400A, KHS-400B and KHS-400C have the current needed for driving the laser diode to achieve the specified light emission printed on their labels. E.g. "D565 C668" means 56.5 mA for the DVD laser diode and 66.8 mA for the CD laser diode. These values vary for each individual unit and are also based off the condition the laser was in directly after manufacturing, not after decades of use.

SF-HD7 with a metal body also has the specified current written on it's labels. The top/green label has the CD current encoded in the first 2 digits, which can directly be interpreted as the current in mA (no decimal value is given; the third digit is already part of a datecode). The bottom/red label has the DVD current encoded in the 4th and 5th digit, which can also directly be interpreted as the current in mA (again, Sanyo does not give a decimal value, unlike Sony).

SF-HD7 with a plastic body has a single label on it's side, which can be decoded in a similar manner: 4th and 5th digit give the DVD current in mA, 7th and 8th digit give the CD current in mA.
<references />