Research Machines RM380z: Difference between revisions

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|Capacitor Types = Aluminum Electrolytic and Tantalum
|Capacitor Types = Aluminum Electrolytic and Tantalum
|Destructive Entry = No
|Destructive Entry = No
|CPU=Zilog Z80A 4 Mhz|Memory=Up to 64K with 56K accessible.|Memory Type=8116 which is a variant of the 4116.|Storage=Early systems were single density single-sided 5¼-inch disks with a capacity of up  to 72 KB later systems were up to 360K.|Graphics=40x24 or 80x24 text mode with a High-resolution graphics adapter available.|Display Interface=SO239 composite|Input Voltage=240V AC 50Hz|Power Connector=IEC 13}}
|CPU=Zilog Z80A 4 Mhz|Memory=Up to 64K with 56K accessible.|Memory Type=8116 which is the Fujitsu labelled version of the 4116.|Storage=Early systems were single density single-sided 5¼-inch disks with a capacity of up  to 72 KB later systems were up to 360K.|Graphics=40x24 or 80x24 text mode with a High-resolution graphics adapter available.|Display Interface=SO239 composite|Input Voltage=240V AC 50Hz|Power Connector=IEC 13}}


== Known Issues ==
== Known Issues ==
Power supply was blowing fuses and was outputting low voltage. The bridge rectifiers were also getting very hot after a few seconds.
The power supply was blowing fuses and was outputting low voltage. The bridge rectifiers were also getting very hot after a few seconds. This unit also exhibited no signal on the video output and no life on the bus, this was due to all the corrosion this specimen was subjected to.


===Causes===
===Causes===
*Large filter capacitors were bad.
*The large filter capacitors were bad.
*Tantalums on the cards were bad.
*The tantalums on the cards were bad.
*Sockets and ICs were corroded
*Sockets and ICs were corroded
====Solutions====
====Solutions====
*Tried reforming the large filters however this was unsuccessful.
*Tried reforming the large filters however this was unsuccessful so these were replaced.
*Replace the tantalums.
*Replace the tantalums which lowered the current draw to what was expected cooling the rectifies down to normal operating conditions..
*Replaced the sockets and replaced the ICs
*Replaced the sockets and replaced the ICs which cured the inactivity and no video output.


== Disassembly Notes ==
== Disassembly Notes ==
Simple disassembly is easy with two screws on the back of the lid. The power supply requires disordering cables and removing the whole case off the base.   
Simple disassembly is easy with two screws on the back of the lid to gain access to the cards however the power supply requires disordering cables and removing the whole case off the base. 
 
Removal of the floppy drives in the vertical configuration is also complicated as they require the removal of the front panel and all the cards. This can be quite difficult especially if the nuts and bolts are corroded like mine, the tight space doesn't help as it can be difficult to get pliers and/ or spanners into the right place.   


== Original Parts ==
== Original Parts ==


=== Disk drives ===
=== Disk drives ===
The early RM 380s use BASF 6106 floppy drives which are 2/3 height SSSD 5 1/4. the drives are Shugart interface compatible. Later on IBM PC full Hight drives were chosen and the mounts were changed from a vertical to horizontal. These are easy to replace as they are more common. The early BASF drives can badly corrode depending on storage conditions so be wary of this as 2/3 height floppy drives are not as common.
The early RM 380s use BASF 6106 floppy drives which are 2/3 height SSSD 5 1/4. The drives are Shugart interface compatible. Later on IBM PC full Hight drives were chosen and the mounts were changed from a vertical to horizontal. These are easy to replace as they are more common. The early BASF drives can badly corrode depending on storage conditions so be wary of this as 2/3 height floppy drives are not as common.


=== Keyboard ===
=== Keyboard ===
Line 34: Line 36:


hard switch to replace now as it controls the power input and also lock function.  
hard switch to replace now as it controls the power input and also lock function.  
=== Cards ===
The cards are pretty easy to service however the early RM380s use Texas Instruments chips which are know for getting corroded legs. the early ones also use cheap sockets which can corrode. For mine to get a reliable machine large scale replacements of chips and sockets was the only way as the IC legs were breaking in the sockets.


=== Power supply ===
=== Power supply ===
Line 117: Line 122:
|<nowiki>LNT1H153MSE Nichicon | Mouser United Kingdom</nowiki>
|<nowiki>LNT1H153MSE Nichicon | Mouser United Kingdom</nowiki>
|}
|}
''If parts are not available or different selection is preferred, you can use the values in the [[#Original_Parts|Original Parts]] section to perform a parametric search.''
 
=== Notes ===
C12 replacement is smaller in diameter to the original however is the same specifications.''If parts are not available or different selection is preferred, you can use the values in the [[#Original_Parts|Original Parts]] section to perform a parametric search.''


== Related Links ==
== Related Links ==

Revision as of 13:06, 20 August 2023

Research Machines RM 380Z
Preliminary Information
Release Year Introduced 1977 Discontinued 1985
Mounting Technology Sockets, DIP, through hole and screw mount
Capacitor Types Aluminum Electrolytic and Tantalum
Destructive Entry No
Hardware Specifications
CPU Zilog Z80A 4 Mhz
Memory Capacity Up to 64K with 56K accessible.
Memory Type 8116 which is the Fujitsu labelled version of the 4116.
Storage Early systems were single density single-sided 5¼-inch disks with a capacity of up to 72 KB later systems were up to 360K.
Graphics 40x24 or 80x24 text mode with a High-resolution graphics adapter available.
Display Interface SO239 composite
Power Requirements
Input Voltage 240V AC 50Hz
Power Connector IEC 13

Known Issues

The power supply was blowing fuses and was outputting low voltage. The bridge rectifiers were also getting very hot after a few seconds. This unit also exhibited no signal on the video output and no life on the bus, this was due to all the corrosion this specimen was subjected to.

Causes

  • The large filter capacitors were bad.
  • The tantalums on the cards were bad.
  • Sockets and ICs were corroded

Solutions

  • Tried reforming the large filters however this was unsuccessful so these were replaced.
  • Replace the tantalums which lowered the current draw to what was expected cooling the rectifies down to normal operating conditions..
  • Replaced the sockets and replaced the ICs which cured the inactivity and no video output.

Disassembly Notes

Simple disassembly is easy with two screws on the back of the lid to gain access to the cards however the power supply requires disordering cables and removing the whole case off the base.

Removal of the floppy drives in the vertical configuration is also complicated as they require the removal of the front panel and all the cards. This can be quite difficult especially if the nuts and bolts are corroded like mine, the tight space doesn't help as it can be difficult to get pliers and/ or spanners into the right place.

Original Parts

Disk drives

The early RM 380s use BASF 6106 floppy drives which are 2/3 height SSSD 5 1/4. The drives are Shugart interface compatible. Later on IBM PC full Hight drives were chosen and the mounts were changed from a vertical to horizontal. These are easy to replace as they are more common. The early BASF drives can badly corrode depending on storage conditions so be wary of this as 2/3 height floppy drives are not as common.

Keyboard

The keyboard is just standard parallel ASCII foam and foil unit external to the unit via a 15 pin cable. The foam pads in mine are still in good shape but are the same size as most replacement pads making replacement easy. My unit was made by alphametric in the UK.

Keylock

The keylock is a old off the shelf part from RS however the keys are unique to each machine so check to see if you have the keys as it is a

hard switch to replace now as it controls the power input and also lock function.

Cards

The cards are pretty easy to service however the early RM380s use Texas Instruments chips which are know for getting corroded legs. the early ones also use cheap sockets which can corrode. For mine to get a reliable machine large scale replacements of chips and sockets was the only way as the IC legs were breaking in the sockets.

Power supply

Early supplies use the types below. Later revisions use different types.

Capacitor Specifications and Footprint Information
RefDes Qty Capacitance Voltage Mount Diameter/Size Height Lead Spacing Temp Type Brand Series
C1 3 470uf 63v Through hole 105 c Aluminium electrolytic
C8 1 22000uf 25v Screw mount +85c Aluminium electrolytic Mallory CGS223U025V3C
C12 1 15000uf 40v Screw mount +85c Aluminium electrolytic Mallory CGS153U040V4C

Replacement Parts

Power supply

Capacitors
RefDes Qty Compatible Part Number Order Links
C1 3 598-477TTA063M 477TTA063M CDE / Illinois Capacitor | Mouser United Kingdom
C8 1 661-36DA223F025BA2A 36DA223F025BA2A Chemi-Con | Mouser United Kingdom
C12 1 647-LNT1H153MSE LNT1H153MSE Nichicon | Mouser United Kingdom

Notes

C12 replacement is smaller in diameter to the original however is the same specifications.If parts are not available or different selection is preferred, you can use the values in the Original Parts section to perform a parametric search.

Related Links

References

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