RJTech RJ-100DVRW - Distorted image when recording

[lti]

I have been using this DVD recorder a lot recently and have noticed that the image it produces is distorted when recording. There are flickering horizontal lines near the bottom of the screen, and a section of the image will sometimes shift to the right. This only happens while recording. There was also one time when the disc suddenly ejected while recording and another time when recording suddenly stopped and the disc was unplayable. The last disc I recorded filled up more quickly than it should have. I was recording in SLP mode (six hours of content can be recorded on one disc) and the disc filled up after recording an hour and a half of content.

I have also noticed that the DVD recorder runs very warm. I ran it with the cover off and found that every IC on the main board runs above 50°C, the two voltage regulators on the output board ran hot enough to burn my finger, and the output components in the power supply run between 75°C and 90°C!

I also discovered that the main outputs are produced by linear regulators. The switching power supply produces standby power, powers the display, and feeds the linear regulators that produce +12V, +5V, and +3.3V, none of which are attached to a heatsink. There is also a +2.5V output that is created by connecting two 1N5401 diodes in parallel to the +3.3V output. The voltage drop of the diodes reduces the 3.3V to 2.5V.

I checked the output voltages and most outputs seemed to produce the correct voltage. The -22V output produces -27V, and the voltage on the +5V output starts at 4.89V and drops to 4.84V while playing and 4.83V when recording.

What could cause the distorted video output and the strange problems that have occurred when recording? Also, are the 7808 and 7805 voltage regulators on the output board spaced far enough apart that I can attach heatsinks to them?

[lti]

Re: RJTech RJ-100DVRW - Distorted image when recording

I discovered that there is only one +5V supply that runs constantly. When the power button is pressed, a MOSFET is used to switch power to the DVD-RW drive and main board on.

I don't know why there is a 7805 regulator on the output board and two 2.5V regulators on the main board when the power supply has 5V and 2.5V outputs.

[lti]

Re: RJTech RJ-100DVRW - Distorted image when recording

Could the +5V caps have failed? This DVD recorder was made in 2004 and has been plugged in constantly since then. Since the +5V output is running constantly, those cheap KSD caps could have failed. The four big caps on the output are all KSD 1000uF 16V. Strangely, none of the caps on the power board are rated for less than 16V. I don't know if those are low ESR caps, but I have tons of caps that might work:
3x I.Q 1000uF 16V low ESR
1x Jackcon 1000uF 16V 105°C (unknown specs)
1x I.Q 1000uF 10V low ESR
5x I.Q 1500uF 6.3V low ESR
4x Nichicon PL 1000uF 10V

The Jackcon came from a set of computer speakers and the I.Qs and Nichicons came from dead socket 7 motherboards. Strangely, the Nichicons are larger than the other caps.

[momaka]

Re: RJTech RJ-100DVRW - Distorted image when recording

Could the +5V caps have failed?

Possibly, maybe, likely (I don't know actually ). Hard to tell without ESR meter.
If any of the 5v caps are next to those linear regulators, I'd say it's probably time to change them. KSD sounds like typical generic Chinese c(r)aps.

The four big caps on the output are all KSD 1000uF 16V. Strangely, none of the caps on the power board are rated for less than 16V. I don't know if those are low ESR caps, but I have tons of caps that might work:
3x I.Q 1000uF 16V low ESR
1x Jackcon 1000uF 16V 105°C (unknown specs)
1x I.Q 1000uF 10V low ESR
5x I.Q 1500uF 6.3V low ESR
4x Nichicon PL 1000uF 10V

I very much doubt the KSD are low ESR. These cheap Chinese generics almost never are. Since most of them are fed with power from linear regulators, they don't need to be low ESR anyways. However, the caps that filter the standby rail for the linear regulators do need to be low ESR.

From the list of caps you have:
- The Jackcon are crap. Don't use them on anything, other than maybe if you needed to fix something quickly and temporarily but didnt have any other caps on stock.
- Nichicon PL is comparable to Nichicon PM, so it should be fine to use in a power supply. Just keep in mind it's only rated for 10v.
- I.Q. is/was a subsidary or daughter company of OST, so you'd get OST-type quality (i.e. marginal) at best. Still better than the Jackcons, though (if the I.Q.s haven't been heat-abused).

Putting heatsinks on the linear regulators is definitely a good idea.

[lti]

Re: RJTech RJ-100DVRW - Distorted image when recording

Those four KSDs actually filter the switching portion of the power supply. Two are used on the +5V output. The other two filter the +3.3V regulator (one on the input, one on the output). The +12V regulator has two CHC 470uF 25V caps on its input. I don't have any low ESR caps other than the I.Qs and Nichicons listed above.

I am recording a program using this DVD recorder and it is 9:30. I will have to mess with it tomorrow. I don't have an ESR tester, so I don't know if any of the possible replacements are good. Two of the 16V I.Q caps should still be good since they were coupling caps for the motherboard's built-in audio amp (the amp was never used).

The filter cap on the output of the 3.3V regulator is sitting against the metal tab of the MOSFET that is used as a regulator. That MOSFET was the warmest component on that board and measured about 92°C when I made a recording with the cover off. That cap could be bad as well.

[momaka]

Re: RJTech RJ-100DVRW - Distorted image when recording

Those four KSDs actually filter the switching portion of the power supply. Two are used on the +5V output. The other two filter the +3.3V regulator (one on the input, one on the output). The +12V regulator has two CHC 470uF 25V caps on its input. I don't have any low ESR caps other than the I.Qs and Nichicons listed above.

In that case, replace all of the input filtering caps you can. Slightly bigger capacitance rating won't hurt either. The input caps are more important because if there is too much ripple and noise, the power supply may not regulate properly and the linear regulators may drop out. I've seen this happen before in an old Daewoo L700C LCD monitor (I have a thread here somewhere too) - power supply was mostly linear galore. The thing ran so hot some of the caps's sleeves were darkened. Doesn't help when most of the caps were 85C rated either.

The filter cap on the output of the 3.3V regulator is sitting against the metal tab of the MOSFET that is used as a regulator. That MOSFET was the warmest component on that board and measured about 92°C when I made a recording with the cover off. That cap could be bad as well.

Yeah, it probably is. Linear regulators don't really care much about their output caps, though. As long as you have something in there that meets the minimum capacitance on the spec sheet, they work fine. They don't need to be low ESR either.
Still, I do agree it would be a good idea to replace it, as well as add a heatsink. Maybe even move the capacitor to a different location, if possible.

[lti]

Re: RJTech RJ-100DVRW - Distorted image when recording

Replacing the caps didn't fix anything. The video is still distorted and it screwed up another disc. The disc recorded successfully, but the recording has unreadable portions. One DVD player started the playback in the middle of the recording.

The 3.3V regulator is actually an FDP6030 MOSFET and a transistor-based control circuit. There is an identical MOSFET on the +5V output that is used as a switch to send the power from the standby output to almost all devices that require 5V. Strangely, the I/O board has its own 7805 regulator that is powered by the power supply's +12V output. The locations for the 16V caps that were originally installed are labeled for 10V caps. I replaced the +5V caps with the Nichicon PLs and the 3.3V filter cap with the 1000uF 10V I.Q, and those caps became extremely warm. I don't know if they were heated by the components around them or if they had too much ripple going through them. The Nichicons were the warmest of the four and the remaining KSD was the coolest.

There have been three times where a recording screwed up. The first one occurred after the DVD recorder had not been used for a long time. The next two screwups occurred after I had unplugged it. This causes the date and time time to reset to midnight on January 1, 2000. The different date and time could have caused the firmware to screw up and produce a bad recording. I could have bad discs as well. These were cheap and old Sony DVD+RW discs.

There is another problem. After the recording stops, the display is supposed to display "PrOCE" during the postprocess. Instead, you get what is shown in the picture below.

[momaka]

Re: RJTech RJ-100DVRW - Distorted image when recording

Replacing the caps didn't fix anything. The video is still distorted and it screwed up another disc. The disc recorded successfully, but the recording has unreadable portions. One DVD player started the playback in the middle of the recording.

Not sure what it could be then. Perhaps bad caps somewhere else, perhaps not. Intermittent issues like this can hard to find sometimes. I'd replace the caps near every regulator on the other boards as well, just to rule out bad caps as a possibility.
Other than that, check for loose cables and bad solder joints.

The locations for the 16V caps that were originally installed are labeled for 10V caps. I replaced the +5V caps with the Nichicon PLs and the 3.3V filter cap with the 1000uF 10V I.Q, and those caps became extremely warm. I don't know if they were heated by the components around them or if they had too much ripple going through them. The Nichicons were the warmest of the four and the remaining KSD was the coolest.

Did you check the voltage across them with the PSU on. If it's over 16v, that could explain why the original 16v caps didn't get warm.

[lti]

Re: RJTech RJ-100DVRW - Distorted image when recording

The voltage was 4.90V on the +5V filter caps (the Nichicons), slightly over 5V on the input filter cap for the 3.3V regulator (the cap I did not replace), and 3.26V on the 3.3V filter cap. At the same time, the switched +5V output was 4.88V, and the only thing between it and the +5VSB output is the MOSFET used as a switch.

The filter caps for the regulators on the I/O board are probably still good, but I only have a capacitance tester.

The main board is the only place where a fault could still remain, and it uses surface mounted components. I am not going to mess with that board. I did notice that the two DF1117 2.5V regulators produce 2.46V (U11 produces 2.47V when nothing is recording), the 018EZ02 1.8V regulator produces 1.76V, and the 7808 on the I/O board produces 7.78V. Those seem low, but the 7808 is the only part I am able to replace with my current soldering tools if any are bad. The 7805 produces 5.08V.

There is still be the possibility that the discs were bad. They are old and were the cheapest DVD+RWs I could find when they were new. I recorded a lot of material on another disc in between the last two bad recordings.

[lti]

Re: RJTech RJ-100DVRW - Distorted image when recording

I still have this piece of crap, but it is close to getting thrown away.

I discovered that the display distortion only occurs when a DirecTV DVR is used as a video source for recording.

It looks like the discs are bad or the burning laser is getting weak. The bad recordings play like the disc is badly scratched. If the drive is the problem, I might be able to replace it with a PC DVD burner. The drive is a Lite-On DDW-411S, which appears to be a standard IDE DVD burner with the metal case removed that is only capable of writing to DVD+R/RW media.

Also, the display is so dim that it is almost unreadable. It gets slightly brighter when the recorder is turned on and dims again when power is turned off and the display shows the time.

[b700029]

Re: RJTech RJ-100DVRW - Distorted image when recording

Also, the display is so dim that it is almost unreadable. It gets slightly brighter when the recorder is turned on and dims again when power is turned off and the display shows the time.

VFDs tend to do that with age. The brightening and dimming is normal too. You may be able to increase the filament voltage to brighten it a little.

[lti]

Re: RJTech RJ-100DVRW - Distorted image when recording

Is the filament voltage the -22V from the power supply?

Also, the display is the brightest in the center and fades to solid black on the left and right edges. Is that normal?

[kc8adu]

Re: RJTech RJ-100DVRW - Distorted image when recording

i bet all the sm lytics are cooked.the acting worse when cold nails it.
dim vfd is low supply voltages esp heater.
more roasted caps.
you need an esr meter.

[lti]

Re: RJTech RJ-100DVRW - Distorted image when recording

Those caps could be the problem, but I haven't had good luck removing surface mounted electrolytics.

The voltages seem normal. Today, the -22V output fluctuated between -21.9V and -23.0V. The FL+ and FL- pins have the same voltage on them. The FL+ label in the picture is partially covered by the resistor. The -22V appears to be created from the four transistors next to the transformer.

I also tried to connect an old junk DVD-ROM drive in place of the DVD burner, but the player froze when the tray on the drive got stuck closed and when trying to read the disc after I got the tray unstuck. In both cases, I had to unplug the recorder to get it to turn off.