Sony EV-S3000 Power Off/On Help??

[dankik]

I have a Sony EV-S3000 Video Hi8 VCR. When I first plug it into the AC and press the power button everything works fine. If I press the power button again, then try to power on it will not turn on or off again and some of the status lights and display remain on. I have to unplug it and let it sit for awhile, then plug it back in and it works OK again. I think it has to do with either one of the standby voltages or the parameter settings. Any ideas?

[Skiller]

Does it play tapes at all?

[dankik]

Thanks for the reply. When I initially plug it in and turn it on with the power button, all transport, play, and record functions operate properly. I can play/record both Hi8 and 8mm tapes and both PCM and Hi-Fi sound work fine. The edit/shuttle dial works fine. But, then if I power it off by pressing the Power button, most of the time it will not power back on. The display and some other indicators will remain lit, and I can press the power button and nothing will happen. When I get into this mode, I cannot insert a tape or turn power off. I have to unplug it from the AC and let it sit for a while, then plug it back in and try again. Most of the time I can get it to work again after being unplugged for a while. At other times (I just now plugged it back in and turned it on) it seems to work fine, powers on and off just like it should.

EDIT: After about 10min, now when I press the Power button again the Power light goes off, but the tape counter and channel display remains on. Also, the DNR light remains on. Pressing the Power button does nothing. If I open the door, when I press <<, >, >>, or || I get 3 fast beeps and nothing happens. If I press the EDIT button, "EDIT" appears on the display, all with the Power light off.

My thought was that there was some non-volatile memory that was not being kept alive by either a battery or capacitor or keep alive voltage when I first turned it off and so the microprocessor would try to come up in an unknown state or couldn't read some stored values in the memory. It's a very peculiar symptom. I would appreciate any ideas that anyone has. I do have the SM and have looked over the circuits and found no backup battery, only some power called "backup".

[dellsam34]

This a potential capacitor failure in the control board or power supply board.

[dankik]

Thanks @dellsam34, I can start with the electrolytics on the PS-278 PCB. I'll have to look and see how many are radial vs chip caps and see if I can test any in circuit.

[dellsam34]

You have to test your voltage points first before you start replacing parts.

[dankik]

Pulled the Power Supply board out and tested voltages on the connectors. It looks like an electrolytic cap had exploded before. There are corroded board areas on both the front and back side of the board. I cleaned the two connectors and board pins with IPA. CN2 had some oily substance on the pins and connector shell. All unswitched voltages seem good with no load. I also found a fuse F2 that had been jumpered with a wire. I need to order a replacement.

[Attachment 71429 - Click to enlarge]

[dellsam34]

If a capacitor shorts out and started blowing fuses that explain why idiots put a direct jumper wire across the fuse terminals which will transfer the load to the capacitor and pop it. I've seen it happens over the years, no surprise at all. I just hope that bridging the fuse did'nt overheat some chips and caused damage to them, Also make sure the copper traces are not corroded thru and lose their connectivity.

[dankik]

Can't find one that looks like what's in there now. I think this littlefuse should work OK. I need 1A.

[Attachment 71431 - Click to enlarge]

[dankik]

I'm back. Here's what I've done so far:
- Cleaned Power Supply board with previous electrolytic cap leakage had occurred
- Replaced 1A pico fuse that someone had previously jumpered on the PS-278 board
- Replaced a few electrolytic caps on the PS-278 Power Supply Board
- Checked output voltages
- Repaired a broken corner of the IN-42 Relay Board with epoxy (trace had already been jumpered)
- Cleaned most board and cable connectors with contact cleaner, reseated some board-board connectors

But the original problem of Power Button and non-responsiveness returns:
- After being off for a long time, I can turn on using the power button and all functions work fine
- I can turn off/on using the power button and all functions work for about 5 minutes (display and power light turn off/on)
- Then after about 5 minutest, when I press the power button, the display remains on, power light stays on, and power switch does nothing.
- If I unplug the VCR and wait 5-10 min. and turn it on again, it once again functions correctly

Any ideas? Could there be a problem reading initial values from memory? Most PS voltages are always on, only one is switched, could this be an issue?

[dellsam34]

That means you have to keep going board after board until the faulty component is identified.

[dankik]

First, I started to monitor the voltages coming out of the Power Supply connectors CN1 and CN2.
- All voltages on connector CN1 look good, but when switched off pins 7 & 8 SW5V are -0.55v when switched off?
- Power Control signal on CN2 Pin 5 in normal operation measures 0v when power button is off and 5.06v when On.
- When the Power Button stops working Pin 5 stays at 5.17v instead of 0v.
- The Power Control signal goes to the enable pin on the 5v regulator (IC5). When the signal is high, the output is on, low output is off.
- So, in the failed state, SW5V is on.
- The signal comes from IC005 Timer/Tuner/LCD Control on the FL-46 board.

I was watching a Youtube video on a similar transport that said that a dirty Mode Switch on the drive was causing a hesitation in loading a tape and that it was a common problem and it needed a squirt of contact cleaner to fix it.
- I removed a couple of boards on the bottom of the transport to get to the switch.
- Sprayed a couple of squirts of CRC contact cleaner into the slide switch then reassembled the boards.
- Then I exercised the transport load/unload, Play, FF, REW, Stop and repeat to exercise the switch.

Now, the problem seems to have been fixed. I left it on for a while, turned it off, back on, loaded and played a tape, unloaded the tape, turned it off/on again and so far it has not had a problem.

Hmmm. I'll exercise it some more again tomorrow.

[dellsam34]

Good, Hope this is it.

[dankik]

Thanks for your help.
UPDATE:
Did some more testing this AM.
- Turning it on/off many times, it seems to work OK
- Played a tape for short time and it seems OK
- Played a tape for about an hour and it plays fine, it turns off fine, but when I press the Power button again to turn it on... only the tape counter comes on (no vu meters)
- Power button is non-responsive and transport controls do nothing, but TV/VTR button seems to work
- Unplug power, wait a minute, plug back in sometimes fixes it... other times not (but if I wait 5 min, then it starts up OK)
- Left it powered on for now about 10 min without playing the tape and it seems to turn on/off OK???
I guess my next step is to put a scope on some of the pins of the control board and see if the microprocessor is working OK.

Kept it on for another hour without playing a tape and the on/off button seems to work OK, no issues. So, it looks like the problem is likely something with the tape transport electronics with a tape loaded an played. It has improved from its initial issue.

Maybe I need to clean that mode switch a little more and see if it helps, since the power off/on problem seems to occur after I use the transport to play a tape.
More testing!

[dellsam34]

Yeah, You should have disassebbled and cleaned the mode switch when you had access to it, Just note the timing mark.

[dankik]

I'm confused!
1. Removed the PCB from the bottom of the drive, cleaned with IPA, checked electrolytic caps (in circuit) with Peak ESR70, reassembled.
2. Without a tape inserted, I can turn it off/on as many times as I want and it works fine
3. With a tape inserted (but not playing, just wrapped around the head drum)... no problems. I can turn it on/off without issue
4. With a tape inserted and playing (while checking Stop, Turn-off, Turn-on) checked every 1 min or so. It works fine for about 10 minutes, then the turn-off/turn-on issue returns.
5. Previously, when the lockup occurred, I sprayed some can air on some of the big chips to see if it was heat sensitive, but nothing
6. The other thing that I observed is that when I press the Power button just before it locks-up, the drum spins-up then it locks-up.
7. Is there some safety interlock that is happening when the drum spins up or the tape threads that could be causing a shut-down??

Any ideas?

[dankik]

I came up with an experiment to see how long it would play before being non-responsive and to isolate the problem to a board or component.
- Start play, stop, turn-off, turn-on then play... repeat every min. It went for about 8 min. before locking up.
- Put a fan blowing room air directly on the top board VI-104. Worked fine, did not lock up.
- Lifted up the board and put a fan blowing on the backside of the board. Locked up in about 6 min.
- Put fan back on the top side while covering 1/2 of the board with cardboard to determine which half of the board the problem was on.
- Covering rear side of board locks up in 10 min.
- Covered front 1/2 of VI-104 and it ran good for 10 min.
- Managed to isolate it to the "big" chip on the board, Sony CXA1207AQ (Luminance Signal Processing) by covering all but this chip
- With fan blowing on it, it seems to work fine... turn the fan off and it locks up after a time
- (It could also be a component in the vicinity of the chip. I'll check ESR of any caps nearby)
- Next, I'll look for any damaged traces or via holes nearby, then I'll reflow the IC pin to board solder connections in case of a cold solder joint.
This has been a tough one to troubleshoot.

[dankik]

Here's what I've done so far.
* Recapped electrolytics on the power supply board PS-278 and cleaned up traces on damaged portion of the board. Also, reflowed any suspect solder joints.
* Lock-up still occurs.
* Reflowed some solder joints on the DS-55 board in the vicinity of the big chip.
* Lock-up still occurs.
Since the problem seems to occur when you turn-on/turn-off the unit, I looked at which voltages get turned-off with the Power Switch. (see diagram)
* The power supply has a switch for controlling the SW 5V signal output.
* That switched 5V also controls Pin 4 of two switched voltage regulators (9V & 12v) on the DS-55 Mode Control board.
* The schematic shows the 5v goes thru a dropping resistor to 2.4v connected to Pin 4 for the two regulators. I measured 12.2v regardless of whether the switched 5v is 5 or 0.
* Looks like IC104 (PQ12RF11) is bad. I'll remove the part and see if I get my 2.4v control voltage back.

[Attachment 72305 - Click to enlarge]

[dankik]

Pulled the 12V regulator, IC104, then tested control On/Off voltage on pin 4 of both IC105 and IC104 and both read 5v. Tested transistor leads and all show open. Ordered a new part.

[dankik]

OK, I installed the new 12V regulator and now the voltage is normal. But, now I have a different problem... no video out.
I'm getting video sync, but no video. If I connect a monitor to the Monitor Out Video port, it sync's-up and I can see the characters on the screen... but video is black.
Looking at the video waveform on the scope, it looks OK, again except no video.
Also, I do get audio out of the L & R RCA connectors.
I checked to make sure that I re-installed all wires and it looks OK. Guess I'll need to trace it down.

[dankik]

FINAL CHAPTER - Success:
1. Found and corrected the problem with "no video". I had a couple of solder bridges when I reflowed the solder on IC101 (VI-104 board).
2. Cleaned that up and now have video, but with noise? Same with 2 tapes (Sony & Maxell). Cleaned heads. Finally 3rd tape & it was OK. Solved.
3. Last thing, now remote doesn't work. IR is working. Turns out, on the remote setting got changed to VTR1 instead of VTR2? Solved.
4. To summarize:
a) re-capped electrolytics in the P/S,
b) replaced fuse that someone had jumpered,
c) replaced 12V regulator (IC104, PQ12RF11),
d) fixed my own soldering errors.

[Attachment 72588 - Click to enlarge]

Now, tapes play OK and Power On/Off does not hang-up after playing a tape for a while.
Hope this might help someone in the future.

[dellsam34]

I admire your persistence; this sure will be an eye opener for someone in the same situation. Good job.