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From: dds@pur-phy (Dennis D. Sallee)
Newsgroups: comp.terminals,comp.misc
Subject: Wyse 60 repair
Keywords: hardware problems & fixes
Message-ID: <2335@pur-phy>
Date: 30 Jun 89 02:46:18 GMT
Organization: Purdue Univ. Phys Dept, W.Lafayette, IN
Lines: 59


HARDWARE PROBLEMS WITH WYSE 60 TERMINAL:

We have been confronted with 2 general hardware problems with the Wyse 60
terminals in our department, and for anyone interested we will share the 
remedies we have used for correcting these specific problems.

***** Remember that opening the case of your terminal will void your
      warranty, if it is still in effect.  If you are willing to take
      that chance anyway, remember that you should never open the case
      unless the terminal is DISCONNECTED from the AC line voltage -----
      otherwise it could be a shocking experience.

Situation #1 --- The terminal does nothing when turned on (no beep, and
      no video).  This is usually indicative of a problem in the DC 
      switching supply, and can be verified in the following manner:
      1.  UNPLUG THE DEVICE.
      2.  Open the case, and make the appropriate disconnections to enable
          you to remove the circuit board from the metal framework.
      3.  Locate the fuse (F101 --- a 5mm X 13mm, 2.0 amp -- Littlefuse #
          218002) at the rear of the terminal near the AC receptacle --- 
          it should be blown.
      4.  Locate Q102 (an NPN PN2222 --- Wyse part # 270000-01) near the
          on/off switch.  Unsolder and remove it, and check the diode
          junctions of this device.  It should be blown, and if it is
          replace it with a PN2222 or a 2N4401 or an ECG 123A or an NTE123A,
          or a GE-20 or an SK3444.
      5.  If it is blown, unsolder and remove Q101 (an NPN 2SC2979 --- Wyse 
          part # 272018-01) and check the diode junctions of this device.
          It may, or may not, be blown (if it isn't, consider yourself lucky
          because this part is like hen's teeth), and if the force is with
          you and it isn't bad; gently resolder it and put the case back
          on the terminal and try it.

Situation #2 --- The terminal beeps (or whatever) when you turn it on, but
          you still have no video.
      1.  UNPLUG THE DEVICE.
      2.  Open the case, and make the appropriate disconnections to enable
          you to remove the circuit board from the metal framework.
      3.  Locate T202 (the flyback transformer) and check the label on it.
          If it is part # 420016-01, and the terminal is about a year old,
          the chances are good that it is bad and should be replaced with
          a Wyse part # 420016-01B.
      4.  If this still doesn't correct the problem, the chances are good
          that either the steering diode, D201 (a U19C --- Wyse part #
          283707-01, but you can also use an MR918 or MR856 diode); or the
          video switching transistor Q202 (a BU406 --- Wyse part # 272000-01,
          but you can also use an ECG379 or NTE379 or SK9085) are blown.  If
          this is the case, these devices should be replaced.

Every device made by humans has certain idiosyncracies, and these seem to be
the most common of the Wyse 60.  If you still have problems, and wish to 
pursue the matter further, give us a call at (317) 494-5533 and we'll try
and talk you through it over the phone.  (Since Wyse seems to have such
insurmountable problems with customer service, we users have to stick 
together.)

Dennis D. Sallee
dds@physics.purdue.edu