Toshiba RD-XS24SB - HDD & DVD Recorder - Dead

[tmcw]

I got this recorder, and trying to see if I can get it to work...

When powered on, there are no indications of life on the display or power light.

I found the service manual online. I've attached the schematic for the power board, as I'm thinking the problem may lie there. The troubleshooter in the manual begins with saying PCON 2 - Pin 10 should be high, and if it's not, to check the fuse. Fuse is ok. I checked the pin 10 with a logic probe, and the pin was fluctuating high and low. Similar with a voltmeter.

Voltages elsewhere are nowhere near the required. For instance, the 33VDC on PCON1, pin 1 is actually only about 24V.

Anyone with any ideas on where to start with this one?

[retiredcaps]

Re: Toshiba RD-XS24SB - HDD & DVD Recorder - Dead

Everyone has different methods, but I would start

1) at the large filter cap and carefully make sure it is a steady 165 to 170VDC

2) if that is good, I would move onto the smps chip and see if pin 6 has the correct voltage according to its datasheet



3) if that is good, then I would check the output diodes like DS130 and see if I get 33V DC there

PS. Finding a schematic helps a lot. However, I would like to see the actual board. A schematic doesn't show dodgy solder joints, bad caps, burned out components, glue that may have turned conductive, etc. I'm not saying you have missed any of the above, but it costs you nothing to post a picture and have some extra eyes look at it.

[tmcw]

Re: Toshiba RD-XS24SB - HDD & DVD Recorder - Dead

Thanks for the pointers. Have uploaded a couple of pictures.

I tested at the large cap, and it's nowhere near the 165-170VDC, the voltage is just fluctuating about zero volts, like between -0.010 and +0.200 volts.

Does this mean the cap is bad? Whilst none of the caps appear bloated or damaged, they all appear to be SamYoung branded.

[multimeter]

Re: Toshiba RD-XS24SB - HDD & DVD Recorder - Dead

check both line filter input transformers for open circuit,there shpuld be 4 pins on each one

[retiredcaps]

Re: Toshiba RD-XS24SB - HDD & DVD Recorder - Dead

I tested at the large cap, and it's nowhere near the 165-170VDC, the voltage is just fluctuating about zero volts, like between -0.010 and +0.200 volts.

Check your bridge rectifier for shorts. I normally do it this way and test it in circuit. Number the pins 1,2,3, and 4. Measure the resistance between pins 1-2, 1-3, 1-4, 2-3, 2-4, and 3-4. Any reading under 30 ohms suggests a short and warrants desoldering the component to verify out of circuit.

[tmcw]

Re: Toshiba RD-XS24SB - HDD & DVD Recorder - Dead

I think the line transformers are ok. There is continuity through each winding, and 1.3 ohms on each.

Testing the bridge rectifier between the pins gave all high numbers, between 1M ohms and 2.5M ohms.

Found another 450V/220uF cap to put in, and the PCON1, pin 1 voltage has gone up to 27V, but it still won't come to life.

[retiredcaps]

Re: Toshiba RD-XS24SB - HDD & DVD Recorder - Dead

Found another 450V/220uF cap to put in,

So just to make sure we are on the same page, I measure the large cap for DC voltage by putting my black probe on the negative cap leg and red probe on the positive cap leg.

You should get AC mains x 1.414. For example,

120V AC x 1.414 = 170V DC

[b700029]

Re: Toshiba RD-XS24SB - HDD & DVD Recorder - Dead

ITesting the bridge rectifier between the pins gave all high numbers, between 1M ohms and 2.5M ohms.

In both directions? If so, it's open and should be replaced.

[tmcw]

Re: Toshiba RD-XS24SB - HDD & DVD Recorder - Dead

So just to make sure we are on the same page, I measure the large cap for DC voltage by putting my black probe on the negative cap leg and red probe on the positive cap leg.

You should get AC mains x 1.414. For example,

120V AC x 1.414 = 170V DC

Alright, I wasn't measuring that correctly then. I'm getting a fairly steady 322VDC there (+/- 0.3V). Measured mains voltage is about 227V, so by the calculation, looks to be ok.

In both directions? If so, it's open and should be replaced.

I didn't think it was, but from before, I've seen that testing diodes and rectifiers in-circuit can be problematic, so I pulled the BR and tested it following the short tutorial I found on youtube (http://www.youtube.com/watch?v=dqkT6hF0O3E), and it tested exactly the same as in the video, so it seems to be good too.

I'll put it back on, and start looking at the SMPS chip.

EDIT: Pin 6 on the SMPS chip, voltage fluctuates between about 10-13V (manual says between operating voltage is between 8.5V and 21V), when I use pin 7 (GND) as the common. Is this the correct way to do it? When I use the chassis, or one of the ground pins on PCON01 or PCON02, the voltage just goes wild (fluctuates wildly about zero volts).

The voltage on PCON01, pin 1 (33VDC) is about 29.5 volts when I put the leads on it, but begins to decay at a rate of 1V per 5 seconds.

[Th3_uN1Qu3]

Re: Toshiba RD-XS24SB - HDD & DVD Recorder - Dead

Since you get voltage on the main capacitor then the bridge rectifier is okay. And yes it is normal to have oddball readings when measuring between primary and GND, because if the controller IC is in the primary then it isn't referenced to case ground. When probing in the primary use the negative lead of the large filter capacitor as ground reference.

[retiredcaps]

Re: Toshiba RD-XS24SB - HDD & DVD Recorder - Dead

EDIT: Pin 6 on the SMPS chip, voltage fluctuates between about 10-13V (manual says between operating voltage is between 8.5V and 21V), when I use pin 7 (GND) as the common. Is this the correct way to do it?

Yes.

1) Check DC voltage across C1S13 (33uF 35V). If it is fluctuating, change it out with something like Panasonic FC. For test purposes, you can try a 47uF 50V.

2) 13V is the minimum for the smps IC to start.

3) It is possible that one of the output diodes is shorted causing the fluctuations. Check all the output diodes (D1S30, D1S31, D1S32, D1S33) to see if the are shorted with your diode test function on the multimeter. You can measure them "in circuit" first.

[tmcw]

Re: Toshiba RD-XS24SB - HDD & DVD Recorder - Dead

1) Voltage was fluctuating as before, (10-13V), had a FM 47uF/50V that I swapped in, but it still fluctuates around the same range.

3) I had pulled them already before seeing your post, and got the following:

D1S30 28v (should be 33V)
D1S31 Essentially zero (should be 12V)
D1S32 3V (should be 12V)
D1S33 Essentially zero (should be 3.3V)

Diode test: (Fwd bias/Rev bias)

D1S30 (0.461/OL)
D1S31 (0.001/0.001)
D1S32 (0.423/OL)
D1S33 (0.251/OL)

So, it looks like D1S31 is shot, D1S33 on it's way, but what about the other 2?

[shovenose]

Re: Toshiba RD-XS24SB - HDD & DVD Recorder - Dead

Try replacing the startup capacitor.

[retiredcaps]

Re: Toshiba RD-XS24SB - HDD & DVD Recorder - Dead

1) Voltage was fluctuating as before, (10-13V), had a FM 47uF/50V that I swapped in, but it still fluctuates around the same range.

The FM is a good cap so that is not the problem.

Diode test: (Fwd bias/Rev bias)

D1S30 (0.461/OL)
D1S31 (0.001/0.001)
D1S32 (0.423/OL)
D1S33 (0.251/OL)

So, it looks like D1S31 is shot, D1S33 on it's way, but what about the other 2?

D1S31 is definitely bad if you test it out of circuit.

D1S33 is good. It will read lower because it is a Schottky diode. See

http://en.wikipedia.org/wiki/Schottky_diode

The other two are fine.

[tmcw]

Re: Toshiba RD-XS24SB - HDD & DVD Recorder - Dead

Try replacing the startup capacitor.

Is that C1S14? If it is, I have some Nichicon PW(M)'s, are they a good sub?

[Scenic]

Re: Toshiba RD-XS24SB - HDD & DVD Recorder - Dead

more like C1S13 (33uF 35V)

Replacing it with a 47uF (if you don't have a 33uF at hand) shouldn't cause any problems. If anything, it'll delay the powersupply startup by a second or less. (If everything else is OK that is..)

[retiredcaps]

Re: Toshiba RD-XS24SB - HDD & DVD Recorder - Dead

Replacing it with a 47uF (if you don't have a 33uF at hand) shouldn't cause any problems.

33uF 35V isn't too common of a cap value which is exactly why I suggested a 47uF 50V as a test only. I see a lot more 47uF 50V in lcd and ATX SMPS.

If it was the startup cap that was the problem, I would have obviously recommended a proper 33uF 35V cap like EEU-FC1V330 as per post #11.

http://search.digikey.com/us/en/prod...0290-ND/266299

[shovenose]

Re: Toshiba RD-XS24SB - HDD & DVD Recorder - Dead

Just a note, when I replaced the cap in my Linksys switch with a higher capacity one, now it takes about 5 seconds after plugin for the lights to come on... but at least it fires up the first try

[tmcw]

Re: Toshiba RD-XS24SB - HDD & DVD Recorder - Dead

Thanks for the help so far. So it looks like I need to replace that bad diode before proceeding?

I don't have much of a stock of diodes, but I do have a few scrap boards that I can have a look at to see if I can replace the bad diode D1S31.

From the parts list in the manual, I get the following details for that diode:

D1S31 0402-001194 BY430010 DIODE-RECTIFIER; SHG2D,200V,2A,-,TP

On one of the scrap boards, I found a BYV27-200; it seems to have similar properties as regards the 200V and 2A, so can I try it, or am I totally off the mark? I can't seem to find a datasheet for the SHG2D.

[retiredcaps]

Re: Toshiba RD-XS24SB - HDD & DVD Recorder - Dead

On one of the scrap boards, I found a BYV27-200; it seems to have similar properties as regards the 200V and 2A, so can I try it, or am I totally off the mark?

Unfortunately, I don't know enough about diodes to know which parameters are really critical and which are not. Maybe someone else can answer and explain what parameters are important when searching for a replacement other than the basic voltage and amps rating.