dds@pur-phy (Dennis D. Sallee) (06/30/89)
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.edumlewis@unocss.UUCP (Marcus S. Lewis) (07/02/89)
From article <2335@pur-phy>, by dds@pur-phy (Dennis D. Sallee): > > HARDWARE PROBLEMS WITH WYSE 60 TERMINAL: > > 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 We have over 100 Wyse-85 terminals. We are diligently avoiding purchasing a maintenance contract with Avnet, but they are getting more attractive by the day. These tubes are all "about" 2 years old, and in the last three weeks we have sent 13 tubes in for service - replacement of the logic board AND LOGIC POWER SUPPLY. The failure modes are simple: Either the flyback transformer shrieks (I can't hear it but many can) or the video just goes away. Some slowly, some suddenly. 'Tanyrate, Avnet's flat rate is $125, and is "cheaper" than their contract. We can get 1 day turnaround from our local office (in Omaha). My own observation is that the Wyse people don't spec their power supplies very well. For ANY of their equipment. We are OEMing WYSE386 PC's, and more than one has fried one part or another, including the PS itself, and the oldest machine we have is ~6 months old. We do have dirty power, but I have dirty power at home too, and have never had any power supply problems from the Heathkit machine I am working on at this moment. Just had to add my $0.06 worth. Marc -- Na khuya mne podpis'? | Internet: cs057@zeus.unl.edu | UUCP: uunet!btni!unocss!mlewis Go for it! | Bitnet: CS057@UNOMA1 ---------------------------------------------------------------------------