SD9500E PSU board blown transformer

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Mr.Ian

Member
Joined 2005
#1
My old but loved Toshiba SD9500E wont switch on, power light comes on but wont switch on. Lots of the PSU caps were out of spec but nothing major. the problem seems to be a burned out transformer on the SMPS PSU Board.

But where in the world might I find a replacement transformer or a replacement board. Any one know of any possible sources for old boards.

I am in the UK but happy to source from abroad if needs be

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many thanks for looking

Ian
 
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#3
Remove the transformers from the board to check.
Those are ferrite transformers, difficult to rewind, and hard to source.
Also, unless you had a bad spike, not likely to fail.
Best to check the components and voltages, after getting the service manual.
 
#4
as far as I can tell the diodes are ok. I went back to my friend who made the orginal diagnosis, he repairs electronics for a living, and he says the diodes are fine, he stuck to his position that the transformer had failed. The mains power supply feeding the DVD player has surge protectors built in.

I have a copy of the service manual but its coverage of the PSU is very limited. All it really does is give a list of components

EU02 79085107 PC Board Assy Power

- TRANSISTORS -
! Q801 79050098 Transistor FS5KM-18A
! Q802 79040327 IC TA1319AP
! Q803 79060106 Photo Coupler TLP421F
Q821 79040146 IC TA76431S
Q823 79050099 Transistor 2SA1020-Y
Q824 79050077 Transistor 2SC1740STP-Q
Q827 79040288 IC PQ05RD11
Q828 79040289 IC PQ3RD13
! Q861 79040405 IC MIP2E4DMYOLE
Q862 79050101 Transistor XN04A8800L
! Q871 79060106 Photo Coupler TLP421F
Q872 79040146 IC TA76431S
Q873 79040269 IC BA05T
- DIODES -
! D802 79060104 Diode LN4SB60
D805 79060069 Diode HER108G
D806 79060070 Diode HT15G
D807 79060080 Diode AK06
D808 79060029 Diode,Zener 6.8V
D810 79060103 Diode 1ZB220Y
D821 79060105 Diode 31DF2
D822 79060105 Diode 31DF2
D825 79060093 Diode HER153G
D826 79060089 Diode HT16G
D827 79060070 Diode HT15G
D829 79060012 Diode ERA15-02
D830 79060080 Diode AK06
D831 79060080 Diode AK06
D832 79060034 Diode,Zener MTZJT-77-10B
D833 79060034 Diode,Zener MTZJT-77-10B
D834 79060005 Diode,Zener UZ11BSB
D835 79060007 Diode,Zener UZ3.0BSB
D861 79060103 Diode 1ZB220Y
D862 79060069 Diode HER108G
D863 79060070 Diode HT15G
D864 79060027 Diode,Zener UZ12BSB
D871 79060105 Diode 31DF2
D872 79060105 Diode 31DF2
D873 79060105 Diode 31DF2
D874 79060105 Diode 31DF2
D875 79060105 Diode 31DF2
D876 79060105 Diode 31DF2
- CAPACITORS -
! C801 79020196 Cap,Film 0.22MF M 275V
! C802 79020028 Cap,Ceramic 470pF Z 250V
! C803 79020028 Cap,Ceramic 470pF Z 250V
! C804 79020196 Cap,Film 0.22MF M 275V
! C811 79020197 Cap,Ceramic 1000pF K 250V
- RESISTORS -
! R802 79030055 Res,Oxide Metal 1Mohm J 1/2W
- MISCELLANEOUS -
! F801 79087014 Fuse B252TLS
! F821 79087013 Fuse 3.00A,125V
! F822 79087009 Fuse 3.50A,125V
! F823 79087009 Fuse 3.50A,125V
! F824 79087013 Fuse 3.00A,125V
! P802 79089118 AC Inlet
! RF821 79030015 Res,Fusible 2.2ohm J 1/4W
! RF822 79030125 Res,Fusible 3.9ohm J 1/4W
! T801 79080006 Line Filter 253YOR7
! T802 79080006 Line Filter 253YOR7
! T803 79010039 Power Transformer SRW2820ED5-212
! T871 79010040 Power Transformer SRW2820ED5-213

anything else on there that could be a missed culprit

anyother suggestions
 
#5
Did you lift one side of that resistor (white arrow) in an attempt to fault-find?

You say a friend told you transformers are bad... bad how? Open winding(s)? Or shorted windings? Do they (transformers) smell like the lacquer has been melting? It doesn't seem from the photos, but...

Remove the transformers and then with the help of a circuit diagram, buzz the windings out to confirm they are bad (or good)

There are some 3.5A fuses there... I assume they are okay?
 

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#6
He said one of the transformers had shorted and smelt like it too. I am wondering if i need to get the board to another engineer. General thoughts seem to be that the other components would burn out quicker than the transformer and in effect protect them.
 
#9
ianfromnotts said:
He said one of the transformers had shorted and smelt like it too. I am wondering if i need to get the board to another engineer. General thoughts seem to be that the other components would burn out quicker than the transformer and in effect protect them.
Click to expand...

Not necessarily. The switching voltage and frequency may have changed due to a fault, causing the transformer to overheat. Or... it was just a bad transformer. Difficult to say. Have you tried contacting Toshiba for a spare SMPS unit?
It is rare to see those transformers fail.
 
#11
So, triple check the value to confirm it is indeed close to 1Mohm. If it is -> then it failed open because ... there's something wrong after the transformers' secondaries.... so... it's very unlikely the transformers are the root cause. Most likely the BJT and/or 3 legged regs used to control/regulate the DC rails. I think you should take the SMPS to a sensible electronics technician to check it (unless you can do it...??)
 
#13
quick update for completeness. Second engineer, but not a SMPS specialist, looked at it, replaced the lifted resistor and said there was power on the secondary rails so not the transformers but when back in the DVD player the standby light doesnt even come on now so it looks like iit is terminally deceased.
 
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