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Author Topic: [PARTIALLY SOLVED] 8593E blank screen  (Read 4426 times)

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Offline DaxxinTopic starter

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[PARTIALLY SOLVED] 8593E blank screen
« on: December 17, 2016, 05:43:44 pm »
Just fixed psu now switching on screen is blank and getting retrace when switching off , what can be happened?

https://youtu.be/a3gV8dq1_4I
« Last Edit: January 01, 2017, 01:36:11 pm by Daxxin »
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Offline DaxxinTopic starter

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Re: 8593A blank screen
« Reply #1 on: December 18, 2016, 05:57:21 am »
here schemas

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Offline DaxxinTopic starter

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Re: 8593A blank screen
« Reply #2 on: December 18, 2016, 06:58:38 am »
simple b/w raster or bars generator schematic to test this?
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Offline DaxxinTopic starter

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Re: 8593A blank screen
« Reply #3 on: December 18, 2016, 04:15:08 pm »
powering with external ps 12+v remain blank , using  Arduino TVout for the signal , switching off no more retraces , measuring signal to B and E of Q44 2sc884 they are same

B


E
« Last Edit: December 18, 2016, 04:17:43 pm by Daxxin »
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Offline DaxxinTopic starter

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Re: 8593A blank screen
« Reply #4 on: December 18, 2016, 07:13:10 pm »
no signal coming from processor board  :-[
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Offline DaxxinTopic starter

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Re: 8593A blank screen
« Reply #5 on: December 20, 2016, 05:11:04 am »


no activity from this graphic chip even from video output theres a enabling pin?
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Offline DaxxinTopic starter

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Re: 8593A blank screen
« Reply #6 on: December 21, 2016, 07:36:10 pm »
from service guide 8595E the troubleshooting guide says  follow WRUP +5v signal on pin 54 but found it on pin 55 of J1
but its ok for other models ..very confused  |O

4. Verify the High-Power-Up signal from the A8 power supply by
checking for the +5 V TTL WRUP signal at pin 54 on the A16J1. The
A16J1 connector is on the trace side of the A16 processor/video


Note that if your analyzer is an 8590 E-Series, 8591C, or 8594Q
QAM analyzer, the WRUP signal can be measured on pin 55 of
each card-cage slot on the A15 motherboard. Refer to Figure 4-6
for the numbering order of the connector pins on A15J3 through
A15J6
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Offline DaxxinTopic starter

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Re: [SOLVED] 8593A blank screen
« Reply #7 on: December 25, 2016, 04:31:26 pm »
diode shorten burning resistor sorrounding LM339 disabling HPWRUP signal , pin 54 can measure 5v and it start on with video

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Offline DaxxinTopic starter

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Re: [PARTIALLY SOLVED] 8593A blank screen
« Reply #8 on: December 26, 2016, 06:54:08 pm »
Removed all the 4 eprom to backup forgot to put back i switched power on , front panel relays clicking many times with blank screen ,
then i put back eprom's ..suprise video is fine with message error ''FAIL 003.0000000000'' switching off and on again garbled video is back
so tried again remove all the eprom's on..off and video back fine again .. thinking volatile memory storing some video params? the only
storing mem is the dallas for constant variables.
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Offline DaxxinTopic starter

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Re: [PARTIALLY SOLVED] 8593A blank screen
« Reply #9 on: January 01, 2017, 12:20:53 pm »
this system uses cmos ram with dallas ds1259 to retain data CAL etc..
as descrind in the service manual chapter "Performing an A16 memory reset"
shorting pin 2 and 8 of U104(DS1259) analyzer boot up with correct video
shutting off and on back to garbled video , rom corrupted or ram chip failure?
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