Lenovo ThinkCentre M90a Pro Gen4 Owner's manual

M90a Pro Gen4
Hardware Maintenance Manual

First Edition (September 2023)
© Copyright Lenovo 2023.
LIMITED AND RESTRICTED RIGHTS NOTICE If data or software is delivered pursuant to a General Services
Administration “GSA” contract, use, reproduction, or disclosure is subject to restrictions set forth in Contract No. GS-
35F-05925.

Contents
About this manua . . . . . . . . . . . . iii
Chapter 1. Important safety
information. . . . . . . . . . . . . . . . 1
General safety . . . . . . . . . . . . . . . . 1
Electrical safety . . . . . . . . . . . . . . . . 2
Safety inspection guide . . . . . . . . . . . . . 3
Handling electrostatic discharge-sensitive
devices . . . . . . . . . . . . . . . . . . . 4
Grounding requirements . . . . . . . . . . . . 4
Safety notices (multi-lingual translations) . . . . . . 4
Chapter 2. Important service
information. . . . . . . . . . . . . . . 27
Strategy for replacing FRUs . . . . . . . . . . 27
Strategy for replacing a hard disk drive or a
solid-state drive . . . . . . . . . . . . . 27
Important notice for replacing a system
board . . . . . . . . . . . . . . . . . 27
How to use error codes . . . . . . . . . . 28
Strategy for replacing FRUs for CTO, special-bid,
and standard models. . . . . . . . . . . . . 28
Product definition . . . . . . . . . . . . 28
FRU identification . . . . . . . . . . . . 28
Chapter 3. Product overview . . . . . 29
Front . . . . . . . . . . . . . . . . . . . 29
Rear . . . . . . . . . . . . . . . . . . . 31
Chapter 4. Service checkout and
symptom-to-FRU index . . . . . . . . 33
Service checkout . . . . . . . . . . . . . . 33
Problem determination tips . . . . . . . . 33
Symptom-to-FRU index . . . . . . . . . . . 34
Hard disk drive boot error . . . . . . . . . 34
Power supply problems . . . . . . . . . . 35
Beep symptoms . . . . . . . . . . . . . 35
POST error codes . . . . . . . . . . . . 36
Miscellaneous error conditions . . . . . . . 37
Undetermined problems . . . . . . . . . 39
Recover from a BIOS update failure . . . . . 39
Clear CMOS . . . . . . . . . . . . . . 40
Chapter 5. Diagnostics . . . . . . . . 41
Basic procedure for resolving computer
problems . . . . . . . . . . . . . . . . . 41
UEFI diagnostic program . . . . . . . . . . . 41
Lenovo diagnostic tools . . . . . . . . . . . 42
Use the Vantage app. . . . . . . . . . . . . 42
Self-help resources . . . . . . . . . . . . . 42
Chapter 6. Hardware remova and
insta ation . . . . . . . . . . . . . . . 45
Handling static-sensitive devices . . . . . . . . 45
Service tool kit . . . . . . . . . . . . . . . 45
Major FRUs and CRUs . . . . . . . . . . . . 46
System board . . . . . . . . . . . . . . . 50
Removing and installing hardware . . . . . . . 51
External options . . . . . . . . . . . . . 51
Computer stand . . . . . . . . . . . . . 51
Rear I/O cover . . . . . . . . . . . . . 54
System board shield . . . . . . . . . . . 55
OSD button and OSD bracket . . . . . . . 56
VESA mount bracket . . . . . . . . . . . 57
Cover presence switch (intrusion switch) . . . 58
Hard disk drive . . . . . . . . . . . . . 59
Optical drive . . . . . . . . . . . . . . 59
M.2 solid-state drive . . . . . . . . . . . 61
Thunderbolt card . . . . . . . . . . . . 62
Memory module . . . . . . . . . . . . . 63
Wi-Fi card and Wi-Fi card shield . . . . . . 64
Card reader board . . . . . . . . . . . . 64
GPU card . . . . . . . . . . . . . . . 65
System fan . . . . . . . . . . . . . . . 66
Heat sink . . . . . . . . . . . . . . . 67
Microprocessor . . . . . . . . . . . . . 68
System board. . . . . . . . . . . . . . 69
Coin-cell battery. . . . . . . . . . . . . 70
Integrated camera and microphone module . . 72
Power supply assembly . . . . . . . . . . 72
Side I/O bezel . . . . . . . . . . . . . . 74
Right bezel . . . . . . . . . . . . . . . 74
Internal speakers . . . . . . . . . . . . 75
Main frame . . . . . . . . . . . . . . . 76
Wi-Fi antennas . . . . . . . . . . . . . 77
Front decoration cover . . . . . . . . . . 78
LCD bracket and LCD panel . . . . . . . . 79
Chapter 7. Notices and
trademarks. . . . . . . . . . . . . . . 83
© Copyright Lenovo 2023 i

ii M90a Pro Gen4 Hardware Maintenance Manual

About this manua
This manual provides service and reference information for ThinkCentre® computers listed on the front cover.
Illustrations in this manual might look different from your product.
Use this manual along with the advanced diagnostic tests to troubleshoot problems.
Important: This manual is intended only for trained service technicians who are familiar with ThinkCentre
computers. Use this manual along with the advanced diagnostic tests to troubleshoot problems effectively.
Before servicing a ThinkCentre computer, be sure to read and understand Chapter 1 “Important safety
information” on page 1.
© Copyright Lenovo 2023 iii

iv M90a Pro Gen4 Hardware Maintenance Manual

Chapter 1. Important safety information
Genera safety
Follow these rules to ensure general safety
• Observe good housekeeping in the area of the machines during and after maintenance.
• When lifting any heavy object
1. Ensure you can stand safely without slipping.
2. Distribute the weight of the object equally between your feet.
3. Use a slow lifting force. Never move suddenly or twist when you attempt to lift.
4. Lift by standing or by pushing up with your leg muscles; this action removes the strain from the
muscles in your back.
Attention: Do not attempt to lift any objects that weigh more than 16 kg (35 lb) or objects that you
think are too heavy for you.
• Do not perform any action that causes hazards to the customer, or that makes the equipment unsafe.
• Before you start the machine, ensure that other service representatives and the customer's personnel are
not in a hazardous position.
• Place removed covers and other parts in a safe place, away from all personnel, while you are servicing the
machine.
• Keep your tool case away from walk areas so that other people will not trip over it.
• Do not wear loose clothing that can be trapped in the moving parts of a machine. Ensure that your sleeves
are fastened or rolled up above your elbows. If your hair is long, fasten it.
• Insert the ends of your necktie or scarf inside clothing or fasten it with a nonconductive clip, approximately
8 centimeters (3 inches) from the end.
• Do not wear jewelry, chains, metal-frame eyeglasses, or metal fasteners for your clothing.
Remember: Metal objects are good electrical conductors.
• Wear safety glasses when you are hammering, drilling, soldering, cutting wire, attaching springs, using
solvents, or working in any other conditions that might be hazardous to your eyes.
• After service, reinstall all safety shields, guards, labels, and ground wires. Replace any safety device that
is worn or defective.
• Reinstall all covers correctly before returning the machine to the customer.
CAUTION:
Keep fingers and other parts of your body away from hazardous, moving parts. If you suffer an injury,
seek medica care immediate y.
CAUTION:
Avoid contact with hot components inside the computer. During operation, some components
become hot enough to burn the skin. Before you open the computer cover, turn off the computer,
disconnect power, and wait approximate y 10 minutes for the components to coo .
© Copyright Lenovo 2023 1

E ectrica safety
CAUTION:
E ectrica current from power, te ephone, and communication cab es can be hazardous. To avoid
persona injury or equipment damage, disconnect the attached power cords, te ecommunication
systems, networks, and modems before you open the computer covers, un ess instructed otherwise
in the insta ation and configuration procedures.
Observe the following rules when working on electrical equipment.
Important: Use only approved tools and test equipment. Some hand tools have handles covered with a soft
material that does not insulate you when working with live electrical currents. Many customers have, near
their equipment, rubber floor mats that contain small conductive fibers to decrease electrostatic discharges.
Do not use this type of mat to protect yourself from electrical shock.
• Find the room emergency power-off (EPO) switch, disconnecting switch, or electrical outlet. If an electrical
accident occurs, you can then operate the switch or unplug the power cord quickly.
• Do not work alone under hazardous conditions or near equipment that has hazardous voltages.
• Disconnect all power before
– Performing a mechanical inspection
– Working near power supplies
– Removing or installing Field Replaceable Units (FRUs)
• Before you start to work on the machine, unplug the power cord. If you cannot unplug it, ask the customer
to power-off the wall box that supplies power to the machine and to lock the wall box in the off position.
• If you need to work on a machine that has exposed electrical circuits, observe the following precautions
– Ensure that another person, familiar with the power-off controls, is near you.
Remember: Another person must be there to switch off the power, if necessary.
– Use only one hand when working with powered-on electrical equipment; keep the other hand in your
pocket or behind your back.
Remember: There must be a complete circuit to cause electrical shock. By observing the above rule,
you may prevent a current from passing through your body.
– When using a tester, set the controls correctly and use the approved probe leads and accessories for
that tester.
– Stand on suitable rubber mats (obtained locally, if necessary) to insulate you from grounds such as
metal floor strips and machine frames.
Observe the special safety precautions when you work with very high voltages; these instructions are in
the safety sections of maintenance information. Use extreme care when measuring high voltages.
• Regularly inspect and maintain your electrical hand tools for safe operational condition.
• Do not use worn or broken tools and testers.
• Never assume that power has been disconnected from a circuit. First, check that it has been powered-off.
• Always look carefully for possible hazards in your work area. Examples of these hazards are moist floors,
nongrounded power extension cables, power surges, and missing safety grounds.
• Do not touch live electrical circuits with the reflective surface of a plastic dental mirror. The surface is
conductive; such touching can cause personal injury and machine damage.
• Do not service the following parts with the power on when they are removed from their normal operating
places in a machine
2M90a Pro Gen4 Hardware Maintenance Manual

– Power supply units
– Pumps
– Blowers and fans
– Motor generators
and similar units. (This practice ensures correct grounding of the units.)
• If an electrical accident occurs
– Use caution; do not become a victim yourself.
– Switch off power.
– Send another person to get medical aid.
Safety inspection guide
The intent of this inspection guide is to assist you in identifying potentially unsafe conditions on these
products. Each machine, as it was designed and built, had required safety items installed to protect users
and service personnel from injury. This guide addresses only those items. However, good judgment should
be used to identify potential safety hazards due to attachment of features or options not covered by this
inspection guide.
If any unsafe conditions are present, you must determine how serious the apparent hazard could be and
whether you can continue without first correcting the problem.
Consider these conditions and the safety hazards they present
• Electrical hazards, especially primary power (primary voltage on the frame can cause serious or fatal
electrical shock).
• Explosive hazards, such as a damaged CRT face or bulging capacitor
• Mechanical hazards, such as loose or missing hardware
The guide consists of a series of steps presented in a checklist. Begin the checks with the power off, and the
power cord disconnected.
Checklist
1. Check exterior covers for damage (loose, broken, or sharp edges).
2. Power-off the computer. Disconnect the power cord.
3. Check the power cord for
a. A third-wire ground connector in good condition. Use a meter to measure third-wire ground
continuity for 0.1 ohm or less between the external ground pin and frame ground.
b. The power cord should be the appropriate type as specified in the parts listings.
c. Insulation must not be frayed or worn.
4. Remove the cover.
5. Check for any obvious alterations. Use good judgment as to the safety of any alterations.
6. Check inside the unit for any obvious unsafe conditions, such as metal filings, contamination, water or
other liquids, or signs of fire or smoke damage.
7. Check for worn, frayed, or pinched cables.
8. Check that the power-supply cover fasteners (screws or rivets) have not been removed or tampered
with.
Chapter 1.Important safety information 3

Hand ing e ectrostatic discharge-sensitive devices
Any computer part containing transistors or integrated circuits (ICs) should be considered sensitive to
electrostatic discharge (ESD). ESD damage can occur when there is a difference in charge between objects.
Protect against ESD damage by equalizing the charge so that the machine, the part, the work mat, and the
person handling the part are all at the same charge.
Notes:
1. Use product-specific ESD procedures when they exceed the requirements noted here.
2. Make sure that the ESD protective devices you use have been certified (ISO 9000) as fully effective.
When handling ESD-sensitive parts
• Keep the parts in protective packages until they are inserted into the product.
• Avoid contact with other people while handling the part.
• Wear a grounded wrist strap against your skin to eliminate static on your body.
• Prevent the part from touching your clothing. Most clothing is insulative and retains a charge even when
you are wearing a wrist strap.
• Use the black side of a grounded work mat to provide a static-free work surface. The mat is especially
useful when handling ESD-sensitive devices.
• Select a grounding system, such as those listed below, to provide protection that meets the specific
service requirement.
Note: The use of a grounding system is desirable but not required to protect against ESD damage.
– Attach the ESD ground clip to any frame ground, ground braid, or green-wire ground.
– Use an ESD common ground or reference point when working on a double-insulated or battery-
operated system. You can use coax or connector-outside shells on these systems.
– Use the round ground-prong of the ac plug on ac-operated computers.
Grounding requirements
Electrical grounding of the computer is required for operator safety and correct system function. Proper
grounding of the electrical outlet can be verified by a certified electrician.
Safety notices (mu ti- ingua trans ations)
The caution and danger safety notices in this section are provided in the following languages
• English
• Arabic
• Brazilian/Portuguese
• Chinese (simplified)
• Chinese (traditional)
• French
• German
• Hebrew
• Italian
• Korean
4M90a Pro Gen4 Hardware Maintenance Manual

• Spanish
DANGER
Electrical current from power, telephone and communication cables is hazardous.
To avoid a shock hazard:
• Do not connect or disconnect any cab es or perform insta ation, maintenance, or reconfiguration
of this product during an e ectrica storm.
• Connect a power cords to a proper y wired and grounded e ectrica out et.
• Connect to proper y wired out ets any equipment that wi be attached to this product.
• When possib e, use one hand on y to connect or disconnect signa cab es.
• Never turn on any equipment when there is evidence of fire, water, or structura damage.
• Disconnect the attached power cords, te ecommunications systems, networks, and modems
before you open the device covers, un ess instructed otherwise in the insta ation and configuration
procedures.
• Connect and disconnect cab es as described in the fo owing tab es when insta ing, moving, or
opening covers on this product or attached devices.
To Connect To Disconnect
1. Turn everything OFF.
2. First, attach all cables to devices.
3. Attach signal cables to connectors.
4. Attach power cords to outlet.
5. Turn device ON.
1. Turn everything OFF.
2. First, remove power cords from outlet.
3. Remove signal cables from connectors.
4. Remove all cables from devices.
CAUTION:
When rep acing the ithium battery, use on y Part Number 45C1566 or an equiva ent type battery
recommended by the manufacturer. If your system has a modu e containing a ithium battery, rep ace
it on y with the same modu e type made by the same manufacturer. The battery contains ithium and
can exp ode if not proper y used, hand ed, or disposed of. Do not:
• Throw or immerse into water
• Heat to more than 100°C (212°F)
• Repair or disassemb e
Dispose of the battery as required by oca ordinances or regu ations.
CAUTION:
Chapter 1.Important safety information 5

When aser products (such as CD-ROMs, DVD-ROM drives, fiber optic devices, or transmitters) are
insta ed, note the fo owing:
• Do not remove the covers. Removing the covers of the aser product cou d resu t in exposure to
hazardous aser radiation. There are no serviceab e parts inside the device.
• Use of contro s or adjustments or performance of procedures other than those specified herein
might resu t in hazardous radiation exposure.
DANGER
Some aser products contain an embedded C ass 3A or C ass 3B aser diode. Note the fo owing:
Laser radiation when open. Do not stare into the beam, do not view direct y with optica
instruments, and avoid direct exposure to the beam.
≥18 kg (37 lb) ≥32 kg (70.5 lb) ≥55 kg (121.2 lb)
CAUTION:
Use safe practices when ifting.
CAUTION:
The power contro button on the device and the power switch on the power supp y do not turn off the
e ectrica current supp ied to the device. The device a so might have more than one power cord. To
remove a e ectrica current from the device, ensure that a power cords are disconnected from the
power source.
1
2
6M90a Pro Gen4 Hardware Maintenance Manual

Chapter 1.Important safety information 7

≥18 kg (37 lb) ≥32 kg (70.5 lb) ≥55 kg (121.2 lb)
1
2
8M90a Pro Gen4 Hardware Maintenance Manual

PERIGO
A corrente elétrica proveniente de cabos de alimentação, de telefone e de comunicações é perigosa.
Para evitar risco de choque elétrico
• Não conecte nem desconecte nenhum cabo ou execute instalação, manutenção ou reconfiguração deste
produto durante uma tempestade com raios.
• Conecte todos os cabos de alimentação a tomadas elétricas corretamente instaladas e aterradas.
• Todo equipamento que for conectado a este produto deve ser conectado a tomadas corretamente
instaladas.
• Quando possível, utilize apenas uma das mãos para conectar ou desconectar cabos de sinal.
• Nunca ligue nenhum equipamento quando houver evidência de fogo, água ou danos estruturais.
• Antes de abrir tampas de dispositivos, desconecte cabos de alimentação, sistemas de telecomunicação,
redes e modems conectados, a menos que especificado de maneira diferente nos procedimentos de
instalação e configuração.
• Conecte e desconecte os cabos conforme descrito na tabela apresentada a seguir ao instalar, mover ou
abrir tampas deste produto ou de dispositivos conectados.
Para Conectar: Para Desconectar:
1. DESLIGUE Tudo.
2. Primeiramente, conecte todos os cabos aos
dispositivos.
3. Conecte os cabos de sinal aos conectores.
4. Conecte os cabos de alimentação às tomadas.
5. LIGUE os dispositivos.
1. DESLIGUE Tudo.
2. Primeiramente, remova os cabos de alimentação das
tomadas.
3. Remova os cabos de sinal dos conectores.
4. Remova todos os cabos dos dispositivos.
CUIDADO:
Ao substituir a bateria de ítio, uti ize apenas uma bateria com Número de Peça 45C1566 ou um tipo de
bateria equiva ente recomendado pe o Se o seu sistema possui um módu o com uma bateria de ítio,
substitua-o apenas por um módu o do mesmo tipo e do mesmo fabricante. A bateria contém ítio e
pode exp odir se não for uti izada, manuseada ou descartada de maneira correta.
Não
• Jogue ou coloque na água
• Aqueça a mais de 100°C (212°F)
• Conserte nem desmonte
Descarte a bateria conforme requerido pelas leis ou regulamentos locais.
Chapter 1.Important safety information 9

PRECAUCIÓN:
Quando produtos a laser (como unidades de CD-ROMs, unidades de DVD-ROM, dispositivos de fibra ótica
ou transmissores) estiverem instalados, observe o seguinte
• Não remova as tampas. A remoção das tampas de um produto a laser pode resultar em exposição
prejudicial à radiação de laser. Não existem peças que podem ser consertadas no interior do dispositivo.
• A utilização de controles ou ajustes ou a execução de procedimentos diferentes dos especificados aqui
pode resultar em exposição prejudicial à radiação.
PERIGO
Alguns produtos a laser contêm diodo de laser integrado da Classe 3A ou da Classe 3B. Observe o seguinte
Radiação a laser quando aberto. Não olhe diretamente para o feixe a olho nu ou com instrumentos ópticos e
evite exposição direta ao feixe.
≥18 kg (37 lb) ≥32 kg (70.5 lb) ≥55 kg (121.2 lb)
CUIDADO:
Utilize procedimentos de segurança para levantar equipamentos.
CUIDADO:
O botão de controle de alimentação do dispositivo e o botão para ligar/desligar da fonte de alimentação não
desligam a corrente elétrica fornecida ao dispositivo. O dispositivo também pode ter mais de um cabo de
alimentação. Para remover toda a corrente elétrica do dispositivo, assegure que todos os cabos de
alimentação estejam desconectados da fonte de alimentação.
1
2
10 M90a Pro Gen4 Hardware Maintenance Manual

Chapter 1.Important safety information 11

1
2
12 M90a Pro Gen4 Hardware Maintenance Manual

Chapter 1.Important safety information 13

1
2
DANGER
Le courant électrique provenant de l'alimentation, du téléphone et des câbles de transmission peut présenter
un danger.
Pour éviter tout risque de choc électrique
• Ne manipulez aucun câble et n'effectuez aucune opération d'installation, d'entretien ou de reconfiguration
de ce produit au cours d'un orage.
• Branchez tous les cordons d'alimentation sur un socle de prise de courant correctement câblé et mis à la
terre.
• Branchez sur des socles de prise de courant correctement câblés tout équipement connecté à ce produit.
• Lorsque cela est possible, n'utilisez qu'une seule main pour connecter ou déconnecter les câbles
d'interface.
• Ne mettez jamais un équipement sous tension en cas d'incendie ou d'inondation, ou en présence de
dommages matériels.
• Avant de retirer les carters de l'unité, mettez celle-ci hors tension et déconnectez ses cordons
d'alimentation, ainsi que les câbles qui la relient aux réseaux, aux systèmes de télécommunication et aux
modems (sauf instruction contraire mentionnée dans les procédures d'installation et de configuration).
• Lorsque vous installez, que vous déplacez, ou que vous manipulez le présent produit ou des
périphériques qui lui sont raccordés, reportez-vous aux instructions ci-dessous pour connecter et
déconnecter les différents cordons.
14 M90a Pro Gen4 Hardware Maintenance Manual