Symptom Diagnosis

1. Insufficient width or height:

A. Horizontal line (due to "Y" amplifier defect).

• Bad "Y" amplifier output transistors.

• Open fusible resistor in the "Y" amplifier.

• Yoke pins not making good contact (very common).

B. Vertical line (due to "X" amplifier defect).

• Bad "X" amplifier output transistors.

• Open fusible resistor in the "X" amplifier.

• Yoke pins not making good contact (very common).

2. Picture spread out too far and/or crushed in certain areas:

A. Controls for linearity (located on the deflection board and set at the factory) are misadjusted.

3. Poor focus:

A. Low focus voltage from the high voltage board.

B. Defective diode off the flyback.

C. Defective focus control.

D. Defective picture tube (CRT).

4. Picture not bright enough:

A. If the CRT voltages are present, the picture tube is probably bad. The surest way to cure this on an X-Y monitor is to replace the picture tube (CRT).

B. Weak 90 volt supply from the EHT power supply.

C. Loose wire to socket of CRT for G2 voltage.

5. Silvery effect to the white lines, or picture looks dim, washed out:

A. If the CRT voltages are present, the picture tube is probably bad. The surest way to cure this on an X-Y monitor is to replace the picture tube (CRT).

6. Increasing brightness causes an increase in picture size and weakens focus:

A. For the most part, this is normal in X-Y monitors. But if this should occur at normal viewing levels, either:

• The high voltage rectifier is weak.

• Or the high voltage circuitry has poor regulation.

7. Picture rapidly blinks on and off:

A. Internal short in the picture tube (arcing).

8. A dot on the middle of the screen — Red LED is turned on (located on the deflection board):

A. The "X" and "Y" signals are not making it into the monitor.

B. Check cabling, jacks, and logic boards.

C. "X" and "Y" amplifier failure. See Number 1 above and check the fuses first.

9. Monitor won't turn on:

B. A defect in the power supply; check:

• Open fusible resistor.

C. Check jack to make certain all pins are obtaining their voltage from the other game circuitry.

D. Check for loose foil, especially by D100.

10. Blown 5 amp fuses:

A. Caused by bad luck. Change fuses.

B. If they keep blowing, check all power transistors that are heat-sinked on the side (as in the 19" version) or the bottom (as in the 13" version) of the monitor.

11. Extremely bright picture; spider-web like retrace lines floating around on the picture:

A. Defective "Z" amplifier circuitry; check:

• The brightness and contrast controls.

• For peeled foil on the deflection board.

• Semiconductors, etc.

B. See symptom 4, diagnosis "B" and "C" ONLY. A bad EHT power supply or loose G2 wire can cause the same thing.

12. Hazy blob of light that shimmers on the screen.

A. Open secondary on flyback winding.

B. Failure of some component in the high voltage section.

13. Corners of the picture are missing:

A. Yoke is too far back on the picture tube neck.

14. Picture is too far up, down, or not centered properly:

A. Metallic yoke tabs'need to be adjusted.

15. A shadowy image of the game remains on the screen, even after monitor is off:

A. Picture tube has burnt phosphor.

16. 2 amp fuses keep blowing:

A. Check the large heat-sinked power transistors.

B. Check D608 and D708

C. Check semiconductors, especially the transistors in the "X" and "Y" amplifiers.

17. Video information is distorted: letters and fig-, ures are "crinkly" — like crumpled paper, and it shakes slightly:

A. Bad 90 volt power being supplied by the EHT unit. If everything looks good, check the electrolytics.

B. The regulator control (R905) may need adjusting.

• On the Wells Gardner monitor, the anode voltage is supposed to read 14.5KV High Voltage. That's 14,500volts with the beam current at zero. R905 adjusts this output voltage. To read this voltage, your meter needs a separate high voltage probe. Follow the directions EXACTLY as stated with the literature that comes with the probe. IF you don't, or you touch something you shouldn't, you're dead. If this scares you, have someone qualified (a technician) perform this adjustment for you. Better SAFE than sorry.

• In the case of the Electrohome monitor, the adjustment is complex and, of course, potentially DANGEROUS. Basically, the Electrohome anode voltage from the "flyback" and rectifier is supposed to be set at 12,000 volts with the beam current at zero. That's right — THOUSANDS of volts! To read this voltage, your meter needs a separate high voltage probe. Follow the directions EXACTLY as stated with the literature that comes with the probe. IF you don't or you touch something you shouldn't, you're dead. If this scares you, have someone qualified (a technician) perform this adjustment for you. Better SAFE than sorry.

If you are still unsure, it may be best if you call Electrohome at (519) 744-7111 and obtain exact information from one of their staff engineers.

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