United States Patent  [li] Patent Number: 4,952,871
Driller et al.  Date of Patent: Aug. 28, 1990
U.S. Patent Aug. 28,1990 Sheet 2 of 5 4,952,871
 METHOD AND APPARATUS OF TESTING PRINTED CIRCUIT BOARDS AND ASSEMBLY EMPLOYABLE THEREWITH
 Inventors: Hubert Driller; Paul Mang, both of Schmitten, Fed. Rep. of Germany
 Assignee: Mania Elektronik Automatisation Entwicklung und Geratebau GmbH, Weilrod, Fed. Rep. of Germany
 Appl. No.: 469,717
 Filed: Jan. 24,1990
Related U.S. Application Data
 Continuation of Ser. No. 401,509, Aug. 30, 1989, abandoned, which is a continuation of Ser. No. 63,658, Jun. 18, 1987, abandoned.
 Foreign Application Priority Data
Jun. 25, 1986 [EP] European Pat. Off. 86108680.9
 Int. CI.' G01R 1/02; G01R 1/067
 U.S. CI 324/158 F; 324/691;
 Field of Search 324/62, 72.5, 149, 158 P,
 References Cited
U.S. PATENT DOCUMENTS
4,321,533 3/1982 Matrone .
4,471,298 9/1984 Frohlich .
4,496,903 1/1985 Paulinski 324/73 PC
4,626,776 12/1986 Wilkinson : 324/158 P
4,626,779 12/1986 Boyle 324/73 PC
Primary Examiner—Reinhard J. Eisenzopf
Assistant Examiner—W. Burns
Attorney, Agent, or Firm—Wenderoth, Lind & Ponack
A printed circuit board having thereon a plurality of conductors including connection points is tested for insulation resistance between the conductors by measuring current flowing between one conductor and the other conductors in an arrangement whereby each connection point is connectable to a first potential through a first transistor and to a second potential through a second transistor and a current measuring device. During testing, only a single connection point of each conductor is connected to the second potential, and all other transistors of that conductor are mechanically isolated from electrical connection with respective connection points. This prevents leakage current through the transistors associated with the other connection points of a given conductor.
23 Claims, 5 Drawing Sheets