Vintage Sun Automotive Test Equipment

This page was last updated on $Date$.

Currently have three pieces of vintage Sun automotive test equipment: a DT500 distributor tester, a VAT20 charging system tester, and a TDT-5 tach / dwell meter.

Sources of Info

  1. Sun is now part of Snap-On. Bill Larsen of Snap-On's Equi-Serv division has been able to provide copies of a couple of manuals. No, they no longer have any parts for this old stuff. Bill's email address is Bill has referred me to -
  2. Roger Kunz ( I've got to ask Roger the name of the company he works for) has been authorized by Snap-On to service the old equipment. Roger's phone number is (815) 344-6538.


  1. The funny looking screws that hold the front panel to the instrument case are called clutch screws. At least that's what some former Sun technicians I know called them. Tru-Value Hardware sells a screwdriver for these screws, the markings on mine state "Master Mechanic 367169 USA CL532".


This is currently just a list of the manuals I have. As I scan each one, I'll add the link. The files are Adobe PDF files.


I've been looking for a source for the blue hammer-tone paint. According to Roger Kunz, folks have been pleased with Sherwin-Williams Dimenso Dark Blue Enamel. The product code is 522-2302 and the Dimenso paint is described in product info sheet CC-B5. The paint seems to be available in only the gallon size and has a shelf life (unopened) of two years. So be sure to have the the sales person check the date code on the lid before you buy it.

I've bought a gallon, but haven't tried it yet.

Mercury Batteries

My distributor tester and the dwell meter use to use mercury batteries. The mercury battery had one very nice characteristic - the supplied voltage was constant until the battery was almost completely discharged. The voltage from current batteries tapers off as the battery discharges.

The AA mercury battery was Sun part number 1766-7 and was made by Mallory, part number RM12R.

For the distributor tester, I've installed a power supply to replace the 1.35 volt battery. I bought a variable DC voltage power supply kit from a local supplier. The kit (PN 68) was $13 and is also availabe from the manufacturer's web site. The kit runs off either an AC or DC input - for the distributor tester, I used line voltage through a transformer for the input voltage. I may have changed one of the resistors to drop the output voltage range.

I haven't decided what to do for the dwell meter yet.