Polytron Standby


Often we get questions about Polytron who die do not want to stand by "on". Therefore here we review how little work 0n-off control circuit that uses Polyton power supply as shown below (usually using FET FS7UM)




When the stand-by position.

     * Pin-36 controls the power of issuing mikrokontrol voltage "high"
     * Base voltage is approximately 0.6V T506>> transistor "on" and CE as shorten>> collector voltage is zero>> and transistor T505 condition "on"
     * Flow photocoupler would like short directly to ground via D511>> T506. As a result all secondary voltage drops. The voltage on C505 D504/elko still low at only about 12v
     * Suply mikrokontrol 5v to 12v voltage will be given of this>> T505>> T504 5v regulator (existing zener 5.6v)
     * In the st-by voltage B + is only about 30V, the voltage is 40v only about 12v, 14V voltage only about 4v.

When Power-on position

     * Pin-36 Power of mikrokontrol control will change to "zero"
     * T506 Basin zero voltage>> transistors "off">> collector voltage is>> the transistor T505 changed to "off".
     * Flow photocoupler originally short directly to ground will be passed now replace IC504 KA431 from pin to pin-3-2 (ground). KA431 is an "error correction" to stabilize the voltage B +.


* All of the secondary voltage will turn up to be normal.
  * Because the T505 is now changed to "off", then the voltage of 5v to supply mikrokontrol will replace the 14V supplied from a source>> R512>> D510.
  * At the same time supply Vcc for Horizontal-start would get a supply voltage of 8V 14V source>> R508>> Regulator 8V T502.

Do not want to stand by "on"

     * Check whether the supply voltage Vcc 5v to normal mikrokontrol
     * Most frequently encountered because of Elko filter for voltage 40v C505 dry. Elco become dry resulting in the output voltage drops.
     * The aircraft continued to die on a minute. Sometimes the damage caused by D510. Because of this led 5v voltage during power-on to mikrokontrol drops

When the "power-on" voltage B + do not want to go up to normal (115V)

     * Check if the base voltage are T506 can be changed to zero. If not zero
     * Try disconnecting T505 - B + voltage should be increased to normal. If it can not rise to normal then the problem could be in the switching regulator. Check Elco B + FET may be dry or damaged.

When "power-on" horizontal does not work

     * Check if already got Hor Vcc voltage 8V
     * Check the supply voltage of 14V
     * Problems can be caused Elko flter dry 14V or 8V regulator circuit some problems

problem mikrokontrol

     * Base T506 unwilling to change to zero when the-power-on
     * Check the supply voltage Vcc 5v mikrokontrol
     * Check the pin oscillator is there a voltage of about 1 ~ 2v.
     * Check pin-reset if already there  4v
     * Check the path SDA / SCL might have short

1 comment:

  1. My CRT Polytron MX Mimimax CRT Tv Screen plays video OK, Volume is UP, Audio ports and speaker is OK but no sound. How could I fix this problem

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