TRS-80 Model 6000 Capacitor Replacement Guide

The 6000's major assemblies (service manual Figure 1-1). The power supply sits in the electronics module at the centre.

Tandy's 1985 service manual for the Tandy 6000 has parts lists for every board in the machine, the Astec AA11082 power supply, the keyboard and the TCE video monitor, so the electrolytic and tantalum capacitors below are all taken from Tandy's own lists. Small ceramic, film and monolithic capacitors are left out. The hard disk's own power supply (model AA 11330) and the Tandon drives have no capacitor list in the manual.

Power supply (Astec AA11082, Tandy 8790047)

AA11082 electrolytics (parts list, pp. 202-206)

Refs	Capacitance	Rating	Note as printed	Astec part no.
C5, C6, C7, C8	220 µF	250 V	+100/−10%	057-22120200
C12	330 µF	25 V		057-33120160
C14	220 µF	10 V	SxA	059-22120300
C19	470 µF	35 V	SxA	057-47120230
C20, C21	470 µF	25 V	SxA	057-47120220
C22, C23, C24, C25	2200 µF	25 V	SxA	057-22220130
C26	100 µF	25 V	SxA	057-10120270
C34	1000 µF	35 V	SM	057-10220190
C35	100 µF	25 V	SxA	057-10120270
C36	1000 µF	16 V	SxA	057-10220180
C37	470 µF	25 V	SxA	057-47120220
C38	100 µF	25 V	SxA	057-10120270

C5 to C8 are the input capacitors that hold the rectified mains; Tandy's no-output check names them along with the bridge DB1, fuse F1, R5, D12 and D13. The list also has mains-rated suppression capacitors: C1 0.1 µF and C2 0.22 µF (250 V AC), C3 and C4 2200 pF (400 V AC), and C9 0.01 µF (250 V AC). Replace those only with parts of the same safety rating. After any work, run the supply on a load and check it against the performance test on the TRS-80 Model 6000 Troubleshooting Guide; it must never be run without a load.

Boards in the card cage and electronics module

Board electrolytics and tantalums (Tandy parts lists)

Board (Tandy part no.)	Refs	Capacitance	Rating	Type as listed	Tandy part no.
Mother board (8897701)	C4, C6, C8	470 µF	16 V	Electrolytic, axial	8317471
MC68000 CPU board (8898855)	C54, C55	100 µF	16 V	Electrolytic, radial	8327101
Memory board (8898854)	C1, C2	100 µF	16 V	"Mono-Axial" (see note)	8327101
Memory board (8898854)	C29, C49	100 µF	10 V	Electrolytic, axial	8317100
Memory board (8898854)	No reference given	1 µF	16 V	Not stated	8325101
I/O processor board (8898423)	C3, C24	1 µF	16 V	Electrolytic, radial	8325101
I/O processor board (8898423)	C4, C50, C99	10 µF	16 V	Electrolytic, radial	8326101
I/O processor board (8898423)	C96, C97, C100	33 µF	16 V	Electrolytic, radial	None printed
I/O processor board (8898423)	C60	0.68 µF	35 V	Tantalum	8334683
Video/keyboard interface (8898022)	C26, C27	33 µF	16 V	Not stated	8326331
Sound board (8898429)	C3	1 µF	16 V	Electrolytic, axial	8395111
Sound board (8898429)	C5	10 µF	16 V	Electrolytic, radial	8326101
Hard disk controller (8898798, 6000 HD)	C25	10 µF	16 V	Electrolytic, radial	8326101
Hard disk controller (8898798, 6000 HD)	C26	0.47 µF	16 V	Electrolytic, radial	8324471
Hard disk controller (8898798, 6000 HD)	C28, C32, C33	100 µF	16 V	Electrolytic, axial	8317101

Sources: board parts lists, pp. 59, 93-95, 114-115, 144-151, 186-188, 211 and 232-235.

• The sound board list prints its capacitor values in "mF" (for example "1 mF, 16V Elec Axial" for C3); they are given here in microfarads.
• The memory board list describes C1 and C2 as "Mono-Axial" while giving them part number 8327101, which is the 100 µF 16 V radial electrolytic on the CPU board. Check the parts on the board before ordering.
• On the I/O processor board, C24 and C3 set the power-on reset: C24 slows the +5 V rise into comparator U4 and C3 is charged to time the reset pulse.
• C61 on the I/O processor board is a trimmer for the floppy data separator; do not swap it for a fixed part. Its adjustment is on the TRS-80 Model 6000 General Maintenance page.

Keyboard (8790522)

Keyboard capacitors with type letter T (parts list, pp. 214-215)

Ref	Capacitance	Rating	Maker's part no.
C2	10 µF	10 V	32-00106-010
C4	22 µF	15 V	32-00226-015

The list marks these two with the letter "T" and the small ceramics with "C"; it does not explain the letters.

Video monitor (TCE 8790614)

The CRT assembly came from several makers; the appendix covers the TCE version, and Tandy replaces the CRT and its monitor board together as an assembly. The appendix gives each capacitor's value, rating and the maker's code but not its type. The capacitors of 0.33 µF and above are:

TCE monitor capacitors of 0.33 µF and above

Ref	Capacitance	Rating	Maker's code
C101	4.7 µF	50 V	CE04(RB)475M
C104	22 µF	100 V	CE04C226M
C204	0.33 µF	50 V	CE04(RB)334K
C205, C206	4.7 µF	35 V	CS15E475M
C207, C208	33 µF	16 V	CE04C336M
C209	1000 µF	16 V	CE04C108M
C211	220 µF	16 V	CE04C227M
C212	100 µF	16 V	CE04C107M
C302	0.47 µF	50 V	CE04(RB)474K
C307	4.7 µF	50 V	CE04C475M
C309	220 µF	16 V	CE04C227M
C313	1000 µF	25 V	CE04C108M
C316	1 µF	250 V	CE04C105M
C322	15 µF	25 V	CE04(RP)A01M
C401	220 µF	16 V	CE04C227M

The capacitor pages are headed 8790614; a later page of the same list is headed 8790608. Confirm which monitor board is fitted before ordering, and check polarity markings on the board, since the list does not say which parts are polarised.

Procedure

• Work on one board at a time and note each capacitor's polarity before removing it.
• Use an earthed wrist strap and mat: the trs-80.com notes stress that static damage is cumulative.
• After work on the boards, run Tandy's SYSTEM, MEMII and DISKDG8 tests, and the 68000 memory, interrupt and offset/limit tests, listed on the TRS-80 Model 6000 Troubleshooting Guide.

See also Capacitor Failure Symptoms.

Related pages

• TRS-80 Model 6000
• TRS-80 Model 6000 General Maintenance
• TRS-80 Model 6000 Troubleshooting Guide
• TRS-80 Model 16 Capacitor Replacement Guide
• TRS-80 Model II Capacitor Replacement Guide
• Tandy 6000 Service Manual