A DB78 cable is the market name for a 78-position high-density D-Sub assembly. Current D-Sub manufacturer literature identifies the 78-position high-density D-shell configuration with four rows of contacts. It suits dense I/O and fan-out assemblies, but the 78 positions do not define a universal signal map.
The Four-Row Identification Check
The 78-position high-density connector is notable for its four-row arrangement. This separates it from 44- and 62-position high-density variants, which use three rows.
Count contacts/rows and verify the mating connector drawing rather than relying on the product name alone.
DB78, HD78 and Engineering Naming
DB78 and HD78 are common market labels. Engineering documentation may use a shell-letter naming convention. To avoid disputes, specify 78-position high-density D-Sub, contact gender, and exact mating-part reference.
That description is more robust than a shorthand label copied from an online listing.
Why DB78 Is Used for Breakouts and Dense I/O
Seventy-eight contacts allow one panel connector to aggregate many channels. The cable may break out to several smaller D-Sub connectors, terminal blocks, test points, or bare wires.
The branch architecture must come from the host equipment map. Connector density does not imply a particular number of serial ports or I/O channels.
Mechanical Design Challenges
High conductor count increases cable diameter and branch complexity. Check backshell capacity, strain relief, bend space, panel retention, and branch support. In test fixtures, label each branch so technicians can trace it back to the host drawing.
If the cable must flex, treat that as a separate cable-construction requirement rather than assuming a generic 78-conductor cable is suitable.
DB78 RFQ Checklist
Provide mating connector reference, gender, full pinout, fan-out architecture, trunk/branch dimensions, shielding/grounding requirement, backshell, labels, quantity, and inspection method.
For OEM repeatability, use revision-controlled drawings and a first-article approval.
Buyer / Engineer Checklist
- Confirm the exact equipment model and port function.
- Identify connector type, contact count, row layout, and cable-side gender.
- Use an approved pinout, equipment manual, or verified original sample.
- Define trunk/branch dimensions, cable support, backshell capacity, and label scheme for the 78-position fan-out.
- State sample quantity, production quantity, and required electrical inspection.
Ordering Mistakes to Avoid
Assuming 78 contacts equal a specific number of serial channels; under-specifying fan-out mechanics; or using an undocumented host mapping.
Frequently Asked Questions
How many rows does a 78-position high-density D-Sub use?
The common 78-position high-density D-shell configuration uses four rows.
Is DB78 wiring standardized?
No. The connected equipment defines the pinout.
Can a DB78 cable break out to multiple DB9 cables?
It can when the host signal map is designed that way, but the mapping must be explicitly defined.
Need a Custom Cable or Compatibility Review?
For a DB78/HD78 fan-out, send the host pinout, 78-position mating details, branch destinations and dimensions, shield/ground instructions, labels, and quantity. BespokeCable can build the assembly around the actual I/O architecture.
