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Replace the generic copied PSU/CRT text with Commodore's own drawing data: the +5 V regulator is an LM323 not a 7805, there are three regulators on the logic board and none in the supply chassis, the -5 V rail is real on this machine (unlike the PET 2001), C1 is 23,000 uF, F1 is 1.6 A slow-blow; remove the unsupported RIFA X2 instruction and the unsourced 6.3 VAC filament figure; add Commodore's electrolytic list
C2 is 470 uF 16 V per drawing 8032090; drop uncited LM323 rating, symptom list and CRT claims; trim RIFA paragraph; copyedit
 
Line 2: Line 2:
[[File:Commodore PET 4000 Open.jpg|thumb|440x440px|Commodore PET 4032 with the top panel lifted.]]
[[File:Commodore PET 4000 Open.jpg|thumb|440x440px|Commodore PET 4032 with the top panel lifted.]]


This page covers routine care of the '''[[Commodore PET 4000 Series]]''': cleaning, supply checks, keyboard servicing, socket work and the CRT hazards. For fault-finding see [[Commodore PET 4000 Series Troubleshooting Guide]].
Routine care of the '''[[Commodore PET 4000 Series]]''' covers cleaning, supply checks, the keyboard, the sockets and the CRT hazards. For fault-finding see [[Commodore PET 4000 Series Troubleshooting Guide]].


'''Every electrical figure here is read off Commodore's own drawings''' in the ''PET 4000 Series Technical Manual'', P/N 990438, hosted on this wiki.<ref name="tm4k">Commodore Business Machines, ''PET 4000 Series Technical Manual'', P/N 990438, for models 4016 and 4032, hosted at [[Commodore PET 4000 Series Technical Manual]]. Drawing '''8032090 Rev H, "PCB ASSY – UNIV. DYNAMIC PET"''': sheet 3 gives the board capacitors by reference designator and Commodore part number (C1/C16/C17/C23/C24 10 µF 25 V low-leakage 900109-03; C2 4700 µF 16 V 900100-44; C5 4700 µF 25 V 900100-45; C7/C11 47 µF 16 V 900101-37; C6/C51 1 µF 35 V tantalum 900402-13; C3/C4 0.022 µF ceramic; C52/C60/C61 0.01 µF ceramic; C74–C86 and C88 47 pF ceramic; C92 220 pF ceramic; C97 82 pF dipped mica) together with transistors Q1 and Q2 (TIP29) and the piezo-acoustic transducer MT1; sheet 4 gives the diodes CR1/CR5/CR7 (1N4005), bridges CR2 and CR4 (4 A/50 V), CR3 (1N5402), the three voltage regulators — '''VR1 a 7905 at −5 V/1.5 A''' (901527-03), '''VR2 a 7812 at +12 V/1 A''' (901528-04) and '''VR4 an LM323''' in TO-3 (901528-01) — the 7.5 V zeners VR5 and VR6, the '''16 MHz crystal Y1''' (900556-02), the socket and header list, the 2.2 µH inductors L1 and L2, and the heatsinks. Drawing '''8032051 Rev E, "Power Supply Assy, 8032"''': the supply chassis is transformer T1 (320902-01) on universal power chassis 8032043-02, filter capacitor C1 of '''23,000 µF''' (900102-01), the dynamic PET power harness 320289-01, fuse F1 at '''125 V slow-blow 1.6 A''' (903557-04), fuse holder XF1 and rocker switch SW1 — with no voltage regulator and no mains-rated suppression capacitor listed. Drawings 321450 onward cover the 12-inch and 9-inch CRT displays.</ref> Where Commodore gives no figure, none is given here.
The electrical figures come from Commodore's ''PET 4000 Series Technical Manual'', P/N 990438, hosted here.<ref name="tm4k">Commodore Business Machines, ''PET 4000 Series Technical Manual'', P/N 990438, for models 4016 and 4032, hosted at [[Commodore PET 4000 Series Technical Manual]]. Drawing 8032090 Rev H, "PCB ASSY - UNIV. DYNAMIC PET": PDF pages 3-7 give the board capacitors by reference designator and Commodore part number (C1/C16/C17/C23/C24 10 µF 25 V low-leakage 900109-03; C2 470 µF 16 V 900100-44; C5 4700 µF 25 V 900100-45; C7/C11 47 µF 16 V 900101-37; C6/C51 1 µF 35 V tantalum 900402-13; C3/C4 0.022 µF ceramic; C52/C60/C61 0.01 µF ceramic; C74–C86 and C88 47 pF ceramic; C92 220 pF ceramic; C97 82 pF dipped mica) together with transistors Q1 and Q2 (TIP29) and the piezo-acoustic transducer MT1; sheet 4 gives the diodes CR1/CR5/CR7 (1N4005), bridges CR2 and CR4 (4 A/50 V), CR3 (1N5402), the three voltage regulators, VR1 a 7905 at −5 V/1.5 A (901527-03, TO-220), VR2 a 7812 at +12 V/1 A (901528-04, TO-3) and VR4 an LM323 (901528-01); the 7.5 V zeners VR5 and VR6, the 16 MHz crystal Y1 (900556-02), the socket and header list, the 2.2 µH inductors L1 and L2, and the heatsinks. Drawing 8032051, "Power Supply Assy" (PDF p. 39): transformer T1 (320902-01) on universal power chassis 8032043-02, filter capacitor C1 of 23,000 µF (900102-01), the dynamic PET power harness 320289-01, fuse F1 125 V slow-blow 1.6 A (903557-04), fuse holder XF1 and rocker switch SW1; no voltage regulator and no mains suppression capacitor. Waveform drawings 321450 (12-inch display) and 321447 (9-inch display).</ref>


'''This is the "universal dynamic PET" board, not the static board of the [[Commodore PET 2001]].''' The rails differ, the regulators differ and the crystal differs. Do not carry figures between the two pages in either direction.
The 4000 series uses the universal dynamic PET board, not the static board of the [[Commodore PET 2001]]. The rails, regulators and crystal differ, so figures do not carry between the two.


== Before you start ==
== Before you start ==


* '''Mains voltage is on the primary side of T1''' whenever the machine is plugged in.
* Mains voltage is present at the switch, fuse and primary of T1 whenever the machine is plugged in.
* '''C1 in the supply chassis is 23,000 µF.'''<ref name="tm4k" /> That is a large amount of stored energy for a low-voltage rail. Bleed it through a resistor; do not short it with a screwdriver.
* C1 in the supply chassis is 23,000 µF.<ref name="tm4k" /> Bleed it through a resistor before working near it.
* '''The CRT holds its anode charge long after power-off.''' Discharge it before working near the tube — see [[CRT Discharge Procedure]].
* The CRT holds its anode charge after power-off. Discharge it before working near the tube; see [[CRT Discharge Procedure]].


== Regular cleaning ==
== Regular cleaning ==


=== Internal ===
=== Internal ===
* Disconnect from the mains and discharge the CRT before the top goes up.
* Unplug the machine and discharge the CRT before lifting the top.
* The hinged chassis lifts to expose the logic board and the display.
* The top lifts on its hinge to expose the logic board and the display.
* Compressed air and an anti-static brush on the logic board, particularly under and around the ROM and RAM sockets, on the regulator heatsinks and around the CRT neck board.
* Use compressed air and an anti-static brush on the logic board, particularly around the ROM and RAM sockets and the regulator heatsinks, and around the CRT neck board.
* Isopropyl alcohol (>90 %) on swabs for stubborn areas. Do not soak.
* Use isopropyl alcohol (over 90&nbsp;%) on swabs for stubborn areas. Do not soak the board.


=== External ===
=== External ===
* Mild soap on a damp microfibre cloth for the painted steel case.
* Mild soap on a damp microfibre cloth for the painted steel case.
* Glass cleaner sprayed onto a lint-free cloth, never onto the tube.
* Glass cleaner sprayed onto a lint-free cloth, never onto the tube.
* Do not rub the screen-surround legend; the print is fragile.


== Power supply ==
== Power supply ==
Line 33: Line 32:
! Assembly !! Contents !! Regulators
! Assembly !! Contents !! Regulators
|-
|-
| Supply chassis (drawing 8032051) || Transformer T1, 23,000 µF filter C1, fuse F1 (1.6 A slow-blow, 125 V), rocker switch SW1 || '''None'''
| Supply chassis (drawing 8032051) || Transformer T1, 23,000 µF filter C1, fuse F1 (1.6 A slow-blow, 125 V), rocker switch SW1 || None
|-
|-
| Logic board (drawing 8032090) || Bridges CR2/CR4, diodes CR1/CR5/CR7, zeners VR5/VR6 || '''VR1, VR2, VR4'''
| Logic board (drawing 8032090) || Bridges CR2/CR4, diodes CR1/CR5/CR7, zeners VR5/VR6 || VR1, VR2, VR4
|}
|}


Line 42: Line 41:
! Ref !! Device !! Rail !! Commodore part no.
! Ref !! Device !! Rail !! Commodore part no.
|-
|-
| '''VR4''' || '''LM323''', TO-3 || +5 V || 901528-01
| VR4 || LM323 || +5 V || 901528-01
|-
|-
| '''VR2''' || 7812 || +12 V, 1 A || 901528-04
| VR2 || 7812, TO-3 || +12 V, 1 A || 901528-04
|-
|-
| '''VR1''' || 7905 || '''−5 V''', 1.5 A || 901527-03
| VR1 || 7905, TO-220 || −5 V, 1.5 A || 901527-03
|}
|}


'''The +5 V regulator is an LM323, not a 7805.''' It is a TO-3 5 A part, the same one Commodore used on the early [[Commodore VIC-20]] board, and a 1 A TO-220 device is not a substitute for it.
The +5 V regulator is an LM323, not a 7805; replace it with an LM323.<ref name="tm4k" /> The −5 V rail from VR1 does not exist on the PET 2001's static board.
 
'''There is a −5 V rail on this machine''', from VR1. The PET 2001 has none, so rail lists do not transfer between the two.


=== What to inspect ===
=== What to inspect ===
Line 58: Line 55:
* Solder joints at VR1, VR2 and VR4 and at bridges CR2 and CR4. These are thermally cycled, heavy-current joints and a cracked one produces an intermittent that mimics a failing chip.
* Solder joints at VR1, VR2 and VR4 and at bridges CR2 and CR4. These are thermally cycled, heavy-current joints and a cracked one produces an intermittent that mimics a failing chip.
* The regulator heatsinks and the thermal compound under them. Commodore fits heatsinks and thermal compound to this board because these parts run hot.<ref name="tm4k" />
* The regulator heatsinks and the thermal compound under them. Commodore fits heatsinks and thermal compound to this board because these parts run hot.<ref name="tm4k" />
* '''Commodore's supply-chassis drawing names no mains-rated X-class or Y-class suppression capacitor''' — the chassis holds one capacitor, C1, and it is the 23,000 µF filter on the low-voltage side.<ref name="tm4k" /> The "replace the RIFAs on sight" advice that applies to many European machines of this era is not supported by Commodore's documentation for this one. If your machine has such a part fitted, deal with it on its merits; do not go hunting for one on the strength of a generic warning.
* The supply-chassis drawing lists one capacitor, C1, the 23,000 µF filter on the low-voltage side, and no mains suppression capacitor.<ref name="tm4k" />


=== Voltage test points ===
=== Voltage test points ===
Line 66: Line 63:
! Rail !! Where !! Note
! Rail !! Where !! Note
|-
|-
| '''+5 V''' || VR4 output, or '''6502 pin 8''' || Pins 1 and 21 are ground; '''pin 40 is RESET''', not a supply pin
| +5 V || VR4 output, or 6502 (UB14) pin 8 || Pins 1 and 21 are ground; pin 40 is RESET, not a supply pin
|-
|-
| '''+12 V''' || VR2 output || 1 A device
| +12 V || VR2 output || 1 A device
|-
|-
| '''−5 V''' || VR1 output || 1.5 A device. Dynamic RAM of this generation needs it
| −5 V || VR1 output || 1.5 A device
|-
|-
| Unregulated || Across C1 in the supply chassis || 23,000 µF. Treat with respect
| Unregulated || Across C1 in the supply chassis || 23,000 µF. Treat with respect
|}
|}


A rail more than a few per cent off its nominal means the regulator, its heatsinking or the filtering ahead of it. Commodore publishes no tolerance band of its own for these rails, so none is quoted here; work to the regulators' own datasheet figures.
Commodore's drawings give no tolerance for these rails; work to the regulators' data-sheet figures. A rail well off nominal points at the regulator, its heatsinking or the filtering ahead of it.


== Capacitors ==
== Capacitors ==


Commodore's list for the logic board. This is the whole electrolytic complement.<ref name="tm4k" />
Commodore's list for the logic board gives these electrolytics and tantalums.<ref name="tm4k" />


{| class="wikitable styled-table" style="width:100%; text-align:left;"
{| class="wikitable styled-table" style="width:100%; text-align:left;"
|+'''Universal dynamic PET board — electrolytics and tantalums'''
|+'''Universal dynamic PET board, electrolytics and tantalums'''
! Ref !! Value !! Type !! Commodore part no.
! Ref !! Value !! Type !! Commodore part no.
|-
|-
| '''C1, C16, C17, C23, C24''' || 10 µF 25 V || Electrolytic, '''low-leakage''' || 900109-03
| C1, C16, C17, C23, C24 || 10 µF 25 V || Low-leakage electrolytic || 900109-03
|-
|-
| '''C2''' || 4700 µF 16 V || Electrolytic || 900100-44
| C2 || 470 µF 16 V || Electrolytic || 900100-44
|-
|-
| '''C5''' || 4700 µF 25 V || Electrolytic || 900100-45
| C5 || 4700 µF 25 V || Electrolytic || 900100-45
|-
|-
| '''C7, C11''' || 47 µF 16 V || Electrolytic || 900101-37
| C7, C11 || 47 µF 16 V || Electrolytic || 900101-37
|-
|-
| C6, C51 || 1 µF 35 V || '''Tantalum''' — fit a tantalum || 900402-13
| C6, C51 || 1 µF 35 V || Tantalum || 900402-13
|}
|}


Three things worth noting before ordering:
Commodore lists C1, C16, C17, C23 and C24 as low-leakage parts; fit low-leakage electrolytics there, and tantalums at C6 and C51. The rest of the C1-C97 range on this board is ceramics and mica. The bulk filter, C1 in the supply chassis, is a separate 23,000 µF can.<ref name="tm4k" />
 
* '''C1, C16, C17, C23 and C24 are specified low-leakage parts''', not ordinary electrolytics.
* '''C2 and C5 are the same capacitance at different voltage ratings''' and are not interchangeable in the safe direction. C5 is the 25 V part.
* Everything else in the C1–C97 range on this board is a ceramic, a mica or a tantalum, and ceramics do not age the way aluminium electrolytics do.<ref name="tm4k" />
 
The bulk filter, C1 in the supply chassis, is a separate 23,000 µF can and is the part under the most ripple stress in the machine.
 
Symptoms that justify pulling the boards:
 
* Vertical hold or geometry drifting on the CRT
* Unstable start-up, flickering or rolling picture
* Random freezes or garbled text
* Any brown crust or verdigris around a capacitor bung


See [[Capacitor Failure Symptoms]].
See [[Capacitor Failure Symptoms]].
Line 115: Line 99:
== Keyboard ==
== Keyboard ==


The 4000-series machines use a full-travel keyboard. Bounce, dead keys and whole dead rows are the usual complaints.
The 4000-series machines use a full-travel keyboard.


* Remove the keyboard from the chassis and photograph the keycap layout before taking anything apart.
* Remove the keyboard from the chassis and photograph the keycap layout before taking anything apart.
* Clean the contact pads on the PCB with isopropyl alcohol.
* Clean the contact pads on the PCB with isopropyl alcohol.
* Inspect for lifted traces and corroded vias, and check the connector at both ends — a whole dead row or column is far more often a connector or a broken trace than it is a bad key.
* Inspect for lifted traces and corroded vias, and check the connector at both ends. A whole dead row or column points at the connector or a broken trace, not a single key.
* Conductive paint will restore a worn pad but does not last as well as the original plating; treat it as a last resort.
* Conductive paint will restore a worn pad but does not last as well as the original plating.


== Sockets ==
== Sockets ==
Line 128: Line 112:
== CRT ==
== CRT ==


* Cold solder joints on the neck board and the deflection board are common.
If the tube does not light at all, the fault is in the heater supply or the EHT section, not the logic board.
* Brightness and focus drift; both have trimpots on the display board.
* If the tube does not light at all, the fault is in the heater supply or the EHT section, not the logic board.


The technical manual carries the full drawing set for both the 9-inch and the 12-inch display, starting at drawing 321450 for the 12-inch, including the PCB waveform photographs with the oscilloscope settings printed on the drawings.<ref name="tm4k" />
The technical manual has PCB waveform drawings for both displays, 321450 for the 12-inch and 321447 for the 9-inch, with the oscilloscope settings printed on each.<ref name="tm4k" />


'''The CRT retains a charge with the machine unplugged.''' Follow [[CRT Discharge Procedure]] before working near the tube.
The CRT retains a charge with the machine unplugged. Follow [[CRT Discharge Procedure]] before working near the tube.


== Diagnostics ==
== Diagnostics ==


* A PET diagnostic ROM or test harness will exercise RAM and ROM far faster than swapping chips.
* A PET diagnostic ROM or test harness will exercise RAM and ROM far faster than swapping chips.
* A logic probe or scope on the ϕ2 clock and the reset line separates "the CPU is not running" from "the CPU is running and the video is wrong" in seconds. '''Y1 on this board is 16 MHz.'''<ref name="tm4k" />
* A logic probe or scope on the Φ2 clock and the reset line shows whether the CPU is running. On this board the CPU must program the CRT controller before any picture appears, so a blank screen alone does not mean a dead video circuit.<ref name="fachat">André Fachat, {{cite web |url=https://6502.org/users/andre/petindex/repairs.html |title=PET repairs |website=6502.org |access-date=2026-10-01}}</ref> Y1 on this board is 16 MHz.<ref name="tm4k" />
* Running the machine for a few hours on a test pattern will surface marginal parts that pass a cold test. Watch the three regulators while it does.
* Running the machine for a few hours on a test pattern will surface marginal parts that pass a cold test. Watch the three regulators while it does.


Latest revision as of 09:56, 1 October 2026

Commodore PET 4032 with the top panel lifted.

Routine care of the Commodore PET 4000 Series covers cleaning, supply checks, the keyboard, the sockets and the CRT hazards. For fault-finding see Commodore PET 4000 Series Troubleshooting Guide.

The electrical figures come from Commodore's PET 4000 Series Technical Manual, P/N 990438, hosted here.[1]

The 4000 series uses the universal dynamic PET board, not the static board of the Commodore PET 2001. The rails, regulators and crystal differ, so figures do not carry between the two.

Before you start

[edit | edit source]
  • Mains voltage is present at the switch, fuse and primary of T1 whenever the machine is plugged in.
  • C1 in the supply chassis is 23,000 µF.[1] Bleed it through a resistor before working near it.
  • The CRT holds its anode charge after power-off. Discharge it before working near the tube; see CRT Discharge Procedure.

Regular cleaning

[edit | edit source]

Internal

[edit | edit source]
  • Unplug the machine and discharge the CRT before lifting the top.
  • The top lifts on its hinge to expose the logic board and the display.
  • Use compressed air and an anti-static brush on the logic board, particularly around the ROM and RAM sockets and the regulator heatsinks, and around the CRT neck board.
  • Use isopropyl alcohol (over 90 %) on swabs for stubborn areas. Do not soak the board.

External

[edit | edit source]
  • Mild soap on a damp microfibre cloth for the painted steel case.
  • Glass cleaner sprayed onto a lint-free cloth, never onto the tube.

Power supply

[edit | edit source]
What is where
Assembly Contents Regulators
Supply chassis (drawing 8032051) Transformer T1, 23,000 µF filter C1, fuse F1 (1.6 A slow-blow, 125 V), rocker switch SW1 None
Logic board (drawing 8032090) Bridges CR2/CR4, diodes CR1/CR5/CR7, zeners VR5/VR6 VR1, VR2, VR4
Regulators and rails
Ref Device Rail Commodore part no.
VR4 LM323 +5 V 901528-01
VR2 7812, TO-3 +12 V, 1 A 901528-04
VR1 7905, TO-220 −5 V, 1.5 A 901527-03

The +5 V regulator is an LM323, not a 7805; replace it with an LM323.[1] The −5 V rail from VR1 does not exist on the PET 2001's static board.

What to inspect

[edit | edit source]
  • Transformer and the rectifier area for heat stress, discoloured board and corrosion.
  • Solder joints at VR1, VR2 and VR4 and at bridges CR2 and CR4. These are thermally cycled, heavy-current joints and a cracked one produces an intermittent that mimics a failing chip.
  • The regulator heatsinks and the thermal compound under them. Commodore fits heatsinks and thermal compound to this board because these parts run hot.[1]
  • The supply-chassis drawing lists one capacitor, C1, the 23,000 µF filter on the low-voltage side, and no mains suppression capacitor.[1]

Voltage test points

[edit | edit source]
Where to measure
Rail Where Note
+5 V VR4 output, or 6502 (UB14) pin 8 Pins 1 and 21 are ground; pin 40 is RESET, not a supply pin
+12 V VR2 output 1 A device
−5 V VR1 output 1.5 A device
Unregulated Across C1 in the supply chassis 23,000 µF. Treat with respect

Commodore's drawings give no tolerance for these rails; work to the regulators' data-sheet figures. A rail well off nominal points at the regulator, its heatsinking or the filtering ahead of it.

Capacitors

[edit | edit source]

Commodore's list for the logic board gives these electrolytics and tantalums.[1]

Universal dynamic PET board, electrolytics and tantalums
Ref Value Type Commodore part no.
C1, C16, C17, C23, C24 10 µF 25 V Low-leakage electrolytic 900109-03
C2 470 µF 16 V Electrolytic 900100-44
C5 4700 µF 25 V Electrolytic 900100-45
C7, C11 47 µF 16 V Electrolytic 900101-37
C6, C51 1 µF 35 V Tantalum 900402-13

Commodore lists C1, C16, C17, C23 and C24 as low-leakage parts; fit low-leakage electrolytics there, and tantalums at C6 and C51. The rest of the C1-C97 range on this board is ceramics and mica. The bulk filter, C1 in the supply chassis, is a separate 23,000 µF can.[1]

See Capacitor Failure Symptoms.

Keyboard

[edit | edit source]

The 4000-series machines use a full-travel keyboard.

  • Remove the keyboard from the chassis and photograph the keycap layout before taking anything apart.
  • Clean the contact pads on the PCB with isopropyl alcohol.
  • Inspect for lifted traces and corroded vias, and check the connector at both ends. A whole dead row or column points at the connector or a broken trace, not a single key.
  • Conductive paint will restore a worn pad but does not last as well as the original plating.

Sockets

[edit | edit source]

Commodore's board drawing lists 24-pin and 40-pin low-profile IC sockets and a 14-pin socket, so most of the large devices are socketed.[1] Sockets of this age lose contact pressure: remove suspect devices with a proper puller, clean the pins and the socket, and reseat firmly. Replace failed sockets with turned-pin types.

CRT

[edit | edit source]

If the tube does not light at all, the fault is in the heater supply or the EHT section, not the logic board.

The technical manual has PCB waveform drawings for both displays, 321450 for the 12-inch and 321447 for the 9-inch, with the oscilloscope settings printed on each.[1]

The CRT retains a charge with the machine unplugged. Follow CRT Discharge Procedure before working near the tube.

Diagnostics

[edit | edit source]
  • A PET diagnostic ROM or test harness will exercise RAM and ROM far faster than swapping chips.
  • A logic probe or scope on the Φ2 clock and the reset line shows whether the CPU is running. On this board the CPU must program the CRT controller before any picture appears, so a blank screen alone does not mean a dead video circuit.[2] Y1 on this board is 16 MHz.[1]
  • Running the machine for a few hours on a test pattern will surface marginal parts that pass a cold test. Watch the three regulators while it does.

Tools

[edit | edit source]
  • ESD-safe driver set, chip puller, plastic spudger
  • Digital multimeter, CRT discharge tool
  • Isopropyl alcohol (99 %), contact cleaner, anti-static brush
  • Fine-tip temperature-controlled soldering iron, braid or pump
  • ESR meter, logic probe or scope

See Recommended Tools.

[edit | edit source]

References

[edit | edit source]
  1. ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 Commodore Business Machines, PET 4000 Series Technical Manual, P/N 990438, for models 4016 and 4032, hosted at Commodore PET 4000 Series Technical Manual. Drawing 8032090 Rev H, "PCB ASSY - UNIV. DYNAMIC PET": PDF pages 3-7 give the board capacitors by reference designator and Commodore part number (C1/C16/C17/C23/C24 10 µF 25 V low-leakage 900109-03; C2 470 µF 16 V 900100-44; C5 4700 µF 25 V 900100-45; C7/C11 47 µF 16 V 900101-37; C6/C51 1 µF 35 V tantalum 900402-13; C3/C4 0.022 µF ceramic; C52/C60/C61 0.01 µF ceramic; C74–C86 and C88 47 pF ceramic; C92 220 pF ceramic; C97 82 pF dipped mica) together with transistors Q1 and Q2 (TIP29) and the piezo-acoustic transducer MT1; sheet 4 gives the diodes CR1/CR5/CR7 (1N4005), bridges CR2 and CR4 (4 A/50 V), CR3 (1N5402), the three voltage regulators, VR1 a 7905 at −5 V/1.5 A (901527-03, TO-220), VR2 a 7812 at +12 V/1 A (901528-04, TO-3) and VR4 an LM323 (901528-01); the 7.5 V zeners VR5 and VR6, the 16 MHz crystal Y1 (900556-02), the socket and header list, the 2.2 µH inductors L1 and L2, and the heatsinks. Drawing 8032051, "Power Supply Assy" (PDF p. 39): transformer T1 (320902-01) on universal power chassis 8032043-02, filter capacitor C1 of 23,000 µF (900102-01), the dynamic PET power harness 320289-01, fuse F1 125 V slow-blow 1.6 A (903557-04), fuse holder XF1 and rocker switch SW1; no voltage regulator and no mains suppression capacitor. Waveform drawings 321450 (12-inch display) and 321447 (9-inch display).
  2. ↑ André Fachat, PET repairs—link(accessed 2026-10-01)
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