Toshiba TP55H60 Horizontal Output Problem

First the set was going into safe mode, with the blinking light so I started to look around and found F890 Blown. Checked current and it looks like the problem is coming from the horizontal output, not absolutley sure. But I'm not certain where the transistor is or how to dissasemble the set since I can't seem to get my hands on a service manual or a set of schematics for the set. Any suggestions or information on this subject would be well appriciated. Or if somebody could give me a good place to get the schematics or service manual from, that would also be helpful. Thank you in advance or any help.

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Here are some tips on a related model which may help you. Toshiba TP55G60 PTV instant-shut down,fish eye,fix]

This submitted from a fellow shop: shut down at turn on. Being careful not to burn a line across CRT's, He unplugged P812 (3 pin conn at front) defeating shutdown.When he saw a line appear (no vertical) he unplugged

set.This at least directed him to a specific area. At our suggestion he

ordered and replaced the two convergence IC's both STK 392-110. This helped.Now he gets picture with a "fish-eye" pattern to the display.Now

replaced the vert output IC "Q301" (LA7833S) and open resistor R327 (3.3 ohm). Fixed.

-------------------------------------------------------------------------------- QUESTION NO. P710-8: Toshiba TP55G60 projection is dead. Relay clicks on and immediately clicks off. Power LED blinks. All standby voltages look good. Can hear high voltage come on and die. Varying the input voltage using a variac was of no help. Relay cycles at about 80 - 90 volts. Heard a snap ( similar to a cap discharging) and the set started working the next time it was turned on. Power cycled twice and set continued to work. Shut off the set and turned it back on a coupe of hours later and the set was dead like before. Waited 10 minutes and turned on the set. Again heard a snap and the set started working. Shut the set off and turned it back on - set dead again as before with relay clicking and momentary presence of high voltage. Hv regulator is Q483 - IC TA755585. The flyback is arcing to the core. Replace it before you cause extensive damage.

-------------------------------------------------------------------------------- I would steer towards the convergence IC's first. Look for bad connections where the boards plug in. That blinking light only eliminates about 2 things. Unplugged and working ok.

-------------------------------------------------------------------------------- believe this set has a protect IC "IC Z801" near the front edge of the chassis that monintors a few inputs from different circuits. Start by finding out which input is triggering the protect IC. I had one that the gate input pin (pin 14 on IC Z801) was going high, should be 0v if OK. This set would get HV then shutdown imediately and HV would bleed off. Relay would click on and back off very quickly. The problem was R347 on what is called the "DPC" board had changed in value from 180K to 413K. Was a tough one to find. The DPC board stands up on the mother board. Hope this helps.

-------------------------------------------------------------------------------- You will need service manual to follow these steps I use for troubleshooting these.

  1. Pull the 130v line fuse and see if the power supply comes up and regulates at 130 volts. If it is then the power supply is 99% for sure ok. Reinstall the fuse.

  1. Ground the positive of c474 on the protect module, per the service manual. This will rule it out if the set comes up properly. Unground the capacitor.

  1. On the convergence board you will find a 3 pin plug, on of them is protect line, pull the plug and remove the protect wire. If the set comes up you have a failure in the convergence circuit. If it does come

up and stay up, some resistors may start to burn on the convergence board, unplug the tv before they go up in smoke.

  1. Physically pull all the yokes off the picture tubes and make sure they are not burnt, if one of them is, that crt probably is also damaged. VERY COMMON. If you need to replace the crt, make sure you order the high voltage lead and high voltage silicon from Toshiba. Affix the lead to the tube and wait 2 full days before putting in the set and powering up. It

must be 100% cured before appplying the high voltage.

  1. Pull the DPC board and unsolder the protect line. This can be risky so be prepared to unplug the tv ASAP. Have seen a 180k resistor increase in value and cause dead/ intermittent dead set problems.
  2. Pull all the high voltage wires to the crt's out of the hv block. If

set runs, install one at a time with the set off to find which crt is bad.

  1. As a last resort, ground the anode of each of the remaining diodes on the protect line, of course with the high voltage leads to the crt's disconnected. To find which circuit has the problem.

-------------------------------------------------------------------------------- Unplug all 3 convergence yokes and see if the set will come on with pix and sound. The pix will be there but with no geometric correction. if it does come on then troubleshoot the convergence circuit, probably the STK outputs

-------------------------------------------------------------------------------- There are 37 distinct protect circuits that can cause it to be dead in the manner you described.

-------------------------------------------------------------------------------- Does it have separate digital convergence yokes? If it does, try unplugging the digital conv connectors one at a time and try to power up the set in between. There are lots of shut downs not related to the lamps.


Phil check the audio output IC-usually shorts the 26VDC power supply

Robert McPherson Louisville, KY (502) 367-9324

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