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Computer Terminal Repair - Archived Files

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QUESTION NO. P116-2: Unisys to-300 terminal and profit not to record the information. I replaced the memories U2, U3 and U9, ademas of bateria and microprocessor (8032 U6) but the problem persists.

The TO-300 terminal requires each page to be saved separately. Go into setup, the first setup page (screen) will appear. Make any necessary changes in the values shown and save the page when finished. Select F2 for the next page and perform any changes in values, insuring to perform a save before pressing F3 for the next page, etc.

QUESTION NO. P728-8: Wyse 60 terminal involved in lighting strike, comes up and setup but no communication through modem port.

Replace u25,u26,u27,u28. These are used for transmission and reception on both the modem and aux. ports. If you jumper pin 2 & 3 on the external modem and aux ports with a paper clip you will see what you type on the screen. This will validate that transmission and reception has occurred. You will need to make each port active through the setup in turn.

QUESTION NO. P619-5: Two terminals WY-60 with the same problem. First, the terminal smokes. I changed C205, C206 and R214. After I put the current switch to ON to see the results and all is OK on the screen. But, If I touch to the terminal with my hand, lots of letters and numbers appear (like 0 or 1 or z). I checked the ground on IC, it is OK. I checked components and do not find the problem.

You may have cracked solder joints on the ic's near the keyboard socket, and up and to the right of the same socket (as viewed from solder side).

QUESTION NO. P43-4: Wyse WY-60 terminal jams when I open it. Sometimes "0" fills the screen, or it can be "1" or "`". I changed some components, but did not find the problem.

See if the metal of the shield is contacting the pins of any of the IC's in the logic area of the circuit board, and shorting to them; if so, try inserting a thin insulating sheet of plastic there. Next, try looking for bad solder joints, or simply reflowing the IC's in the logic area. If these are no help, try checking the two RAM chips (2016 types).

QUESTION NO. P43-3: Wyse WY-60 terminal has no communication by the external modem port. I changed the cpu U1, the gate array U20, and others components without results.

First, try a re-set, by powering up while holding in the "G" key, or "setup" key, etc. (depending on what keyboard is attached). Then, look for hardware faults. See if there are bad solder joints on the port connectors, or the IC's; also, check for bad 1488/1489 chips (U25, U26, U27, U28), a bad UART chip (U3), or possibly a bad crystal (X3).

QUESTION NO. P921-4: I have many Wyse 50 terminals which have no video and a high pitched squeal. I have found on some that the logic board is bad.

These units are known for getting many dried-up electrolytics, so do a complete cap check. Problem caps include, but are not limited to, the big filter caps on the secondary side of the power supply, C109, C112, C115, C117, C202, C203, C206, C210, and C312. The 10 uF cap at the back of the chassis on the right is usually bad. Also check the 1 KV, 1Amp rectifier near the flyback transformer (can replace with a UF4007). If this rectifier is OK, then try disconnecting the logic board, and see if the squeal stops. If the squeal goes away, check the row of diodes on the logic board near the K/B connector. If the squeal remains, then the flyback transformer is probably bad.

QUESTION NO. P628-2: Digital VT320-C2 terminal has no picture and no H. Power LED inside lights. An electrolytic capacitor was loose inside the cabinet. The electrolytic capacitor is bulging on the top and the plastic is literally charred. It looks like the heat melted the solder joints on it,as there is no evidence that a previous tech had removed the capacitor or opened the cabinet (lots of undisturbed dust). I am assuming for now that the capacitor itslelf was the problem,but there are no markings on the capacitor to indicate its value (just an unmarked,chared black canister). The component is listed on the board as C207.

The capacior is a Non-polarised electrolytic value at 8.2mf 35volts.

QUESTION NO. P1028-8: NCD x-terminal that originally blew the hot MJF16206. I replaced it with an MJW16206 and it blew too. All I get now is a tick, tick, tick sound when I turn it on. Could the flyback be taking out the hots? Where can I get a replacement flyback? The numbers on the the flyback are Sampo FDA126 6133075020.

You may have a bad FET in the flyback voltage input circuit.

QUESTION NO. P330-10: Wyse model WY-60 terminals and they had a high pitch squeal and then the pix went out. They now will not come up. The power light comes on but no high voltage or boot screen.
Check the components around the flyback in horz. section, most common to fail are Q202 (C2898), D203 (UF4007), C209 (220uf 35v), c203 (.015J 400PP) and the flyback (4420016-01C).

The high pitched squeal in the WY-60 usually comes from the FBT, or Q202. If Q202 is bad check D201 also. I have also seen L201 cause this problem. With the high voltage If you are getting a voltage of about 12.6 volts off pins 1-4 of the FBT instead of 26 V, it could be a logic problem.

QUESTION NO. P36-4: A Wyse-50 power supply board has AC but as the transformer steps down the voltage, I totally lose all DC voltages. I haved tried new transformers but no change.

Is there ac at the secondary of the transformer?? If so then check any and all fuse devices in secondary, check rectifiers in secondary, and then look for shorted loads inclusive of filter capacitors.

QUESTION No. P1111-2: We maintain over 3000 IBM 3192 terminals for a client and when the logics go bad we just replace them. I now have many many bad logic boards and would like to know common failure cures and procedures on on how to test them.

I have repaired many Terminals, not IBM's but mostly ADDS, Wyse, Bull. The common problem I faced was in the RS232 drivers (MC1488/1489) ICs. Replacing these solved 60% of the problems.