Maker Pro
Maker Pro

Complex unit fails to power up

DrDick2024

Mar 16, 2024
3
Joined
Mar 16, 2024
Messages
3
My 2004 Toshiba V55HDSU DVD/VHS Home Theater sys: after elec pwr failure, no power up, internal cartridge fuse at entry checks ok. No visible damage, no smells, no schematics. User manual useless (plug it in, duh). Any help, Source for Repair manual or at least a schematic would be greatly appreciated! (Retired MSEE with a lot of circuit repair experience, but now nothing beyond a nice DMM available as a diagnostic tool) Thanks!
 
Last edited:

DrDick2024

Mar 16, 2024
3
Joined
Mar 16, 2024
Messages
3
Top O’ the moaning to ya.
Below is page 40 of the user manual

Thank you sir.

View attachment 63065View attachment 63066View attachment 63067
My 2004 Toshiba V55HDSU DVD/VHS Home Theater sys: after elec pwr failure, no power up, internal cartridge fuse at entry checks ok. No visible damage, no smells, no schematics. User manual useless (plug it in, duh). Any help, Source for Repair manual or at least a schematic would be greatly appreciated! (Retired MSEE with a lot of circuit repair experience, but now nothing beyond a nice DMM available as a diagnostic tool) Thanks!
Full model number:
SD-V55HTSU
NOT “…VSS…” and NOT “HD” (sorry)
I have the ORIGINAL paper manual, but thanks anyway. You can see that the only Symptom “No power” solution says “Plug the power cord into the wall outlet securely” … not helpful, lol

Serious help required folks, thank you
 
Last edited:

73's de Edd

Aug 21, 2015
3,634
Joined
Aug 21, 2015
Messages
3,634
Dr Edd calling the Dick Dr . . . . come in pls . . . . . .

With 2004 to 2024 having that unit plugged in, has probably left some of the units E caps in such a depleted condition, such they no longer have enough OOOMPH to start up the power supply portion of the unit after you totally lost power.
(This has happened to me twice after AC power loss . . . .but being 24/7 operated TV digital converter boxes, instead.)
Since . . . . . . if you look at the schematic . . . . . a portion of the unit runs 24 hr a day until a turn off or turn on command tells the other 2 portions of the supply what to do.

REFERENCING . . . . . . all marked up . . . . .as is being provided right 'chere. ( A dub'l left mouse click makes schema MO' biggee . . . then
a FAR left click restores full post text.)

TOSHIBA-P-S-Schema-SDV55-HTS.png



HOWTODOITTOITALLBYYOURSELF!

Initially find the main filter capacitor . . .C103, a 330ufd@450 E-cap and prepare to place DC metering probes across its + and - terminals and upon your plugging your unit into AC power, expect a mid 300'ish DC volts to be present. Keeping the neg meter lead on the E caps lead, then shift the meter + probe to pin 1 of IC101 and expect high voltage there also. Then move the + meter probe over to the pin 1 of the IC401 and if having high voltage there also . . . . . .that confirms that AC power coming in at bottom left corner, is making it up and thru a good fuse and the assorted series anti-RFI / EMI crapola and thru a good FWB rectifier at top left corner and then further on over to those 3, just metered test points.
My highest suspicion is now being with the YELLOW BOX E-caps that I marked up.
Two are related to power supply provision to those earlier tested I.C.'s and one is filtering the voltage feedback reference from a secondary windings produced supply..
My very, very last suspicion / option, would be of that 330 ufd main storage cap.
See if your parts cache will provide a 100 ufd @50VDC E cap that can alternatively be subbed in for C121 or C123. Next sub would be a 1 ufd @50VDC for C119.
For the 100 ufd units , if having full length leads / or making / with full leads, you could just shunt across a cap and test . . . .OBSERVING . . . . . proper polarity.
My suspicion would be that long time related operation at their high frequency pulse absorption speed has hammered the hell out of them and a resultant capacitive depletion along with developed high ESR. Possibly, with them now only giving 10's of uf of filtering effectiveness.
If you only have a metal film or paper for that 1 ufd, that would suffice for mere testing.
I am going to stop for you to be able to see testing results and feedback.
Then we check out the right half of the schematic to see if any developed voltages show up over there.
One uses the other cold grounds for metering over there or connector PSV01 ground pins 1-2-5-8-10 or 12. Or connector PSW1 ground pins 4-5-6 or 8.
You actually have one aspect of Built In Test Equipment associated with power transformer T102, if it is being DC powered and successfully driven by IC 104 it will provide power to pins 13-14-15 and light up the frontal display after being powered up with power switch or using remote power on.

TIME OUT . . . . .

Would like to know testing results now and if you have a working AM pocket size transistor radio. And also . . . not an old generation Incandescent . . . . . . . nor a new generation LED . . . . . . . . .BUT . . . a mid generation Compact Fluorescent Lamp.
It'sa looka' like'sa 'dis . . . . .

1710705597013.png
Then we tackle the right side of the schematic.
PLUS
If you have / can round up those items I will show you and the worldwide AUDIENCE / READERS sitting up in the peanut gallery, how to rig up a fast digital switching aural "oscilloscope" to add to your . . . . . pre-professed . . . . . meager test equipment stable.
Thaaasssssit . . . . . . . .

73's de Edd . . . . .

If a tree falls in the forest and no one is there to see it.
A chihuahua 500 miles away will be barking at it.


.
 
Last edited:

DrDick2024

Mar 16, 2024
3
Joined
Mar 16, 2024
Messages
3
Dr Edd calling the Dick Dr . . . . come in pls . . . . . .

With 2004 to 2024 having that unit plugged in, has probably left some of the units E caps in such a depleted condition, such they no longer have enough OOOMPH to start up the power supply portion of the unit after you totally lost power.
(This has happened to me twice after AC power loss . . . .but being 24/7 operated TV digital converter boxes, instead.)
Since . . . . . . if you look at the schematic . . . . . a portion of the unit runs 24 hr a day until a turn off or turn on command tells the other 2 portions of the supply what to do.

REFERENCING . . . . . . all marked up . . . . .as is being provided right 'chere. ( A dub'l left mouse click makes schema MO' biggee . . . then
a FAR left click restores full post text.)

TOSHIBA-P-S-Schema-SDV55-HTS.png



HOWTODOITTOITALLBYYOURSELF!

Initially find the main filter capacitor . . .C103, a 330ufd@450 E-cap and prepare to place DC metering probes across its + and - terminals and upon your plugging your unit into AC power, expect a mid 300'ish DC volts to be present. Keeping the neg meter lead on the E caps lead, then shift the meter + probe to pin 1 of IC101 and expect high voltage there also. Then move the + meter probe over to the pin 1 of the IC401 and if having high voltage there also . . . . . .that confirms that AC power coming in at bottom left corner, is making it up and thru a good fuse and the assorted series anti-RFI / EMI crapola and thru a good FWB rectifier at top left corner and then further on over to those 3, just metered test points.
My highest suspicion is now being with the YELLOW BOX E-caps that I marked up.
Two are related to power supply provision to those earlier tested I.C.'s and one is filtering the voltage feedback reference from a secondary windings produced supply..
My very, very last suspicion / option, would be of that 330 ufd main storage cap.
See if your parts cache will provide a 100 ufd @50VDC E cap that can alternatively be subbed in for C121 or C123. Next sub would be a 1 ufd @50VDC for C119.
For the 100 ufd units , if having full length leads / or making / with full leads, you could just shunt across a cap and test . . . .OBSERVING . . . . . proper polarity.
My suspicion would be that long time related operation at their high frequency pulse absorption speed has hammered the hell out of them and a resultant capacitive depletion along with developed high ESR. Possibly, with them now only giving 10's of uf of filtering effectiveness.
If you only have a metal film or paper for that 1 ufd, that would suffice for mere testing.
I am going to stop for you to be able to see testing results and feedback.
Then we check out the right half of the schematic to see if any developed voltages show up over there.
One uses the other cold grounds for metering over there or connector PSV01 ground pins 1-2-5-8-10 or 12. Or connector PSW1 ground pins 4-5-6 or 8.
You actually have one aspect of Built In Test Equipment associated with power transformer T102, if it is being DC powered and successfully driven by IC 104 it will provide power to pins 13-14-15 and light up the frontal display after being powered up with power switch or using remote power on.

TIME OUT . . . . .

Would like to know testing results now and if you have a working AM pocket size transistor radio. And also . . . not an old generation Incandescent . . . . . . . nor a new generation LED . . . . . . . . .BUT . . . a mid generation Compact Fluorescent Lamp.
It'sa looka' like'sa 'dis . . . . .

View attachment 63072
Then we tackle the right side of the schematic.
PLUS
If you have / can round up those items I will show you and the worldwide AUDIENCE / READERS sitting up in the peanut gallery, how to rig up a fast digital switching aural "oscilloscope" to add to your . . . . . pre-professed . . . . . meager test equipment stable.
Thaaasssssit . . . . . . . .

73's de Edd . . . . .

If a tree falls in the forest and no one is there to see it.
A chihuahua 500 miles away will be barking at it.


.
I will get into the guts sometime this week, thanks for the schematic & notes!
Also bought another unit that has been photographed working (we’ll see!)

BTW - nothing lights up, so it would seem failure is early on in the power supply section. Fuse is good
 
Top