HM8001 - Mainframe

This mainframe will hold two units from Hameg's modular instruments serie HM8000.
The HM8001 exists in two versions, the HM8001 and the HM8001-2. I will refer the HM8001 as HM8001-1 to avoid misinterpretations. The difference is that -2 has two BNC-connectors per module on the rear and a little more power. See table below for info. Note that some of the modules require HM8001-2 version since they use two rear connectors and/or consumes more power.
These unit show up on Ebay now and then. Be careful when bidding to make sure you bid on the right version. You should get the HM8001-1 (first version) for a lower price than the HM8001-2.
In some places the HM8001-2 is called HM8002.

Rear view of HM8001-1

Top view of HM8001-1 with cover removed

Bottom view of HM8001-1

Rear view of the HM8001-2 with option HO801

Top view of HM8001-2

Bottom view of HM8001-2.
Great care has been taken to separate the two compartments and to shield them electrically.
Note the coaxial cables to the rear connectors for extra in/outputs from some modules.


Each connector is clearly marked with the voltages that are supplied.
Pin 1 on lower row is connected to ground on the HM8001-1.

Pin number Signals on
Signals on
1 GND Rear BNC 1 Warning
2 Rear BNC Rear BNC 2  
4 + 5V max 0,6 A + 5V max 1 A 5 W
5 0 V 0 V  
6 + 8 V unreg + 8 V unreg  
7 + 5-20 V max 0,4 A + 5-20 V max 0,5 A 10 W
8 0 V 0 V  
9 V adjust V adjust  
10 0 V AC 0 V AC  
11 18 V AC 18 V AC  
12 25 V AC 25 V AC  
13 AC in from 11 or 12 AC in from 11 or 12  
14 + 5-20 v max 0,4 A + 5-20 v max 0,5 A 10 W
15 0 V 0 V  
16 V adjust V adjust  
17 0 V AC 0 V AC  
18 18 V AC 18 V AC  
19 25 V AC 25 V AC  
20 AC in from 18 or 19 AC in from 18 or 19  
21 0 V AC 0 V AC  
22 8 V AC max 0,5 A 8 V AC max 0,5 A 4 W

Here is the diagram for HM8001-1 in order to clarify the connections
The colours above indicates the grouping of the supply voltages.
Note that the pins on this diagram are not in numerical order

Data sheet for HM8001-2 in PDF

If you intend to use the HM8001-1 with a module that uses pin 1 as an input or worse as an output I recommend that you remove the pin from the connector since it is not possible to use it isolated.