Relay clicking and no image Toshiba D29CQ51 / PB9929

[fox_tango]

I recapped the working Toshiba D29CQ51 from my F-Zero AX. After powering back up and having an image for a few minutes, the monitor is now blank and one of the relays is continuously cycling. About once per second it will double click (assuming trying to turn on, then immediately turning off). I put my fingers on the three relays in the vicinity and think I can feel the clicking coming from this one:


Prior to recapping, the monitor had a red cast to everything. I didn't (still don't yet) have the secret menu board to try to turn down the red gain. I was thinking a recap would be my starting point before trying to adjust the color gains.

After powering up, the Triforce splash screen looked like this:


Turning up the screen adjustment on the flyback resulted in getting more of a white background on the image. I still didn't have a clean white though. I was about to go into the on-screen display menu and adjust the contrast and brightness when the picture went out and the relay noted above started clicking. All subsequent power-ups will only result in the relay clicking on-off quickly about once per second.

I could barely sleep last night trying to figure out what the heck I did wrong. I have double checked (quickly) the polarity and soldering of each cap. I'll perform a more rigorous inspection this morning. The ONE thing I did that has me extremely worried is that I washed the board with simple green cleaner and rinsed it all off about a week ago. I had the board sitting inside in front of an air purifier (just because it's running 24/7) getting a light breeze blown over it for about a week to make sure all was dry. I'm really pissed at myself for not putting it in the oven or using compressed air on it too. I saw no signs of water, no sparks or puffs of smoke, nor any sizzle / crackle noises when I powered up the monitor but I have to wonder if this is related.

Anyway, any advice anyone can provide would be GREATLY appreciated. Note, I have two more functioning identical monitors if any swapping or process of elimination would be helpful, but at this point I'm so paranoid of even touching the others.... NOTE: I'm not a complete newbie at this. I've recapped about a dozen monitors (no issues) and have good soldering equipment and decent skills. With that said, I absolutely will still be checking for bad solder joints, bridges, etc but like I mentioned, my initial inspection didn't turn up anything.

Thanks for reading.

 

[nem]

Look for shorts in the large transistors.

Considering it worked for a while, my best advice would be to then start checking the replacement caps against the originals. I once put a cap with a lower voltage rating in. The monitor worked for a while, then the cap blew and basically turned into a resistor, which shut down the monitor. The cap still looked fine after blowing, no change in appearance. Luckily I had an identical chassis I could compare to which helped me to find my mistake.

 

[dewmansnk]

Those top 3 relays are used to add in S-Caps and bypass a linearity coil - these are needed as you switch frequencies (15, 24, 31) to keep the picture from having squished sides or top. I am pretty sure that even with these 3 relays missing you would not cause a total loss of picture, just squished at the right side or the top/bottom.

The fact that relay is cycling seems more like a sign either your monitor can't decide what frequency to use, or it is constantly going through a cycle of start up, engage relays, HV shutdown, dis-engage relays, repeat.

At 31 Khz, I believe you want the linearity coil bypassed (Relay S401 engaged) and no additional S-capacitance so (Relays S402, S403 disengaged)

S401 is used to bypass the lin coil, so engaged is bypassed
S402,S403 are used to add-in the S-caps, so engaged is More S-Caps


You mentioned adjusting the screen brightness pot on the flyback, have you tried turning that back down to see if picture is restored ?

The IC in the bottom right of your photo (Q201 I think) - Has a row of caps on each side of the IC. Can you verify those caps?

I see on my PB9929 that I have :

C221, 218, 215 - 2.2uF (50V)
C238,237,236 - 100uF (25V)

C210 - 10uF (50V)
C201,202,203 - 100uF (25V)
C213 - 220uF (25V)

 

[fox_tango]

Thanks for the advice guys!

@nem: So, I've been over the caps to ensure that the polarity is correct. I used a kit from arcadepartsandrepair and confirmed as each cap was pulled off the board that the cap going in was equal or higher voltage, and capacity matched exactly. I will still put eyes on each and every cap to make sure, but I'm pretty confident that they're equal or better on voltage rating. I did check each cap as best I could with my fluke meter, measuring capacitance. Of course, in circuit the values won't necessarily match the printed value on the can, but I was hoping that this would potentially locate a shorted cap. Didn't find any of those.

I poked at every large transistor (and also the large diode on the heatsink) and they all give similar diode drops (fluke meter on diode check mode) as a known good chassis. I haven't progressed yet to checking the small transistors (yet). Some of the larger IC packages I'm not sure what they are, but I poked around using diode mode and then if I got a reading, I'd check the other chassis for comparison... nothing stood out as different.

@dewmansnk: On the caps around the IC: mine are exactly as you call out EXCEPT for C213, which on mine is a 100uf @25V. I have two more of these same chassis and compared to one of my others (it's currently pulled so I can compare readings from the failed chassis to the known good chassis).

These caps were the last ones I replaced and while I said above that I checked each as I pulled it off of the board, once I got to these, I'll admit that I pulled them all off at one time so I didn't actually check what was coming off. I'm thinking I'll go through my garbage bin and catalog the old caps and see if I can account for a 220 uf that may have come from that spot. With that said, do you think that would cause the functional difference?

Thanks for the info on the relay purpose/functions. I was curious what they heck there were doing.

Other things I've done:
1. confirmed that the triforce is still booting and putting out a video signal by connecting a PC monitor.
2. Plugged the non-working chassis into a second monitor frame and tube (on another machine) and tried it there. Same result: relay clicking.
3. Reflowed and added solder to many of the joints for the larger components. Some looked a bit questionable, but nothing bad.

AS I was inspecting the solder joints on the bottom of the board, I did find a problem. There is a tiny surface mount ceramic cap (C467) between a couple of the electrolytics. I must have bumped it when replacing the caps near it. I tried straightening it out, but at some point, it fell off the board and was lost. I have no idea what value it was. I assumed it was a noise filter cap so I installed a 100 nf 100 v ceramic surface mount cap in it's place. I have no idea what value it was supposed to be. I also have a few 0.1 uf 50v caps that I could use also if that may be closer to the correct value. This cap was located between electrolytic caps C468 (4.7uf @ 50V) and C466 (100uf @ 25V). After replacing this, it made no change in the behavior of the board.


Here I've cleaned up the area prior to soldering on the 100nf 100V cap.


In general, I've gone over the entire bottom of the board to try to eliminate as much of the flux residue as I could. I used alcohol, but this always seems to leave a white film. I then tried some simple green to wash the white residue away, but it really isn't as clean as I'd like. Now that I've relowed a bunch of the joints, I may try something a bit stronger (and outside) like some Acetone on the bottom to wash away the flux residue and hopefully not leave the white residue.

With all the small surface mount components on the bottom, could the residue from washing the board with alcohol after the initial rework have led to some of the residue creating electrical issues? I always try to get them super clean so that that green solder mask is shiny again. I'm going to try this after dinner tonight and see what I can do.

Finally, attached is a video of the attempted power up on the 2nd monitor frame/tube/machine. Results were identical.
https://drive.google.com/file/d/1JKbg5DZVPN_iq-AzidymL8HNq5hdJKKp/view?usp=sharing

Thanks for the help guys!

 

[fox_tango]

So before going much further, is there any way to identify the proper value for the small surface mount cap that I buggered and replaced? As noted, the original was hit with my desoldering gun originally, and during the attempted correction I lost it. So I placed an on-hand surface mount 100pf 100V ceramic surface mount cap in it's place. With these small surface mount ceramics, I'm just not sure how critical the exact value is.