Sony KV-13FM12 No Longer Powering Up After RGB Mod

[KPackratt2k]

My friend (who I've RGB modded several TVs for successfully at this point) brought over another TV for me to mod, this one is a 13" Sony KV-13FM12 manufactured in October 2000 with the BA-5 chassis.

I've followed the instructions from Sunthar's Super Sector website with a couple key differences. First, I'm using a DPDT switch to handle blanking rather than blanking from the SCART connector. Second, since this set has a comb filter and no S-Video input, I'm using the second pole of the switch to bypass the comb filter by removing R1323 and injecting 75-ohm terminated SCART sync into the negative lead of C1385 (Luma input of the jungle chip). The positioning of the jumpers I needed to piggyback my signals onto were different, but aside from those three caveats, the procedure was identical.

I reassembled the set after wiring it all up for the mod, I plug it in and turn it on, I hear the degaussing coil and... no picture. At that point I couldn't figure out what I did wrong until I spotted that I forgot to connect the CRT grounding strap to the neckboard terminal! So I plug that in and now the set no longer powers up. No degaussing coil, no blinking standby light, nothing. Completely dead. When I touched the grounding connector that I forgot to plug in, I felt a small spark, so right now my suspicion is I somehow killed it through ESD.

I checked the fuse (F601) with a multimeter and I get continuity which means the fuse is OK. I test the power points with a multimeter and although I have a voltage of 7.5V on the 7.5V standby rail, I'm getting nothing on the 5V set rail nor the 9V set rail, which is a possible indicator that the set cannot get out of standby mode. I checked Q607 and I'm getting excessive voltages from that transistor. I get about 10x the amount of voltage that the service manual states I should be reading in page 31. The base is 7.13V when it should be 0.7V and the collector is 1.36V when it should be 0.1V. I test every diode on the board and found five that read shorted (D601, D602, D610, D623, and D208), four of which are part of the power supply circuit. I also tested C601 (an SMD 0.1uF 0805 capacitor) with the multimeter in capacitance mode and found that it read shorted, even after taking it out of circuit. Since I didn't have any 0.1uF SMD capacitors on hand I tacked on a 104 ceramic capacitor with the leads bent to fit in place.

Is it possible that I somehow fried components on the power supply by introducing ESD when I touched the grounding strap connector of the tube and plugged it into the neckboard ground connector? I don't remember if I had the set plugged in when I did this, but knowing my forgetfulness I probably did. I talked to the owner of the set to ask him if he noticed anything suspicious when he tested it before I modded it and he said he didn't notice anything, so at least I can rule out failure from components aging. I really hope I didn't fry any of the transistors or ICs when I made this mistake, as those would probably be impossible to find nowadays. Heck, I was struggling finding replacements of the original diodes I found shorted to the point where I had to find modern equivalents to those.

For reference, here is the RGB modding guide that I'm referring to, along with the service manual:
BA-5 RGB Mod Guide: https://sector.sunthar.com/nav.01.guide ... -ba-5.html
Service Manual: https://archive.org/details/manual_BA5C ... SM_SONU_EN

If anyone has any ideas on things I could try to bring this set back to life, I'd really appreciate it. This is a really nice TV and I'd love to see RGB in action on this tube. My friend spent a good chunk of money to get this and the ones I find for sale on eBay cost at least 3x the amount he paid for this, and I cannot find the same (or similar) model for sale locally at this time.

Thanks in advance.

[KPackratt2k]

It's been 10 days, have tried many things since and still no signs of life. Here's a list of things I've done with it since then:

- Replace the diodes that I thought were suspect, when it turned out that only D208 was shorted.
- Replace IC601 (STR-F6624) with a known-working OEM replacement.
- Replace R603 with a known working replacement from a resistor kit, as my multimeter freaked out when I was trying to measure it.
- Test every electrolytic capacitor in the power and deflection circuits on the main board as well as on the neckboard, all of them measured on spec.
- Replace the MB board with one from a KV-20FS12 (found the board itself from eBay, it was a NOS replacement board with a Sony sticker on the bubble wrap).

I found that when measuring the output of the 5V standby regulator on the MB board, I was getting a very low voltage (0.47V on the original MB board), so I thought maybe it was bad. I couldn't find a replacement regulator so I thought I'd try replacing the MB board. I couldn't find the exact replacement, so I shot for one from a KV-20FS12 as its connectors had the same pinouts. Unfortunately, even on the new MB board, the output of the regulator is still too low (0.27V this time), so something in its input circuit must be throwing it off.

Another thing I should mention, I measured Q606 and am getting half the expected voltages (for example I'm getting -13.1V on every leg when it should be -36V).

I also belatedly found out that the anode cap wasn't inserted all the way when I was testing the mod, so now my suspicion is I shorted out the flyback, but I don't know if that's the only issue because even with the flyback removed it still won't get out of standby.

My next steps are to replace the flyback (also found from the same seller who sold me the replacement MB board) and Q502 as I found it was shorted from base to collector (not sure if it was supposed to be like that, but it doesn't hurt to replace). If that doesn't help, then I guess the next thing I can try to do is replacing everything in the power supply circuit, but that would be a huge undertaking as there are some SMD components involved and quite frankly there are likely parts that I'm not going to have any luck finding replacements for.

I called every TV repair service in my area and unfortunately they all no longer work on CRT TVs. This sucks, I wish there was someone who was skilled in CRT TV repair like 12voltvids or shango066 in my area. My friend only works on recapping and tube calibration, so having him take a look at it is out of the picture. I'd be willing to ship this to someone who'd be willing to take a crack at it, but I'm saving up for a new computer and quite frankly attempting to ship this both directions would likely break it (and not to mention it'd be worth more than buying another one on eBay, which would also break during shipping).

[BazookaBen]

Wow, sorry man. I wonder if having the anode cap only partially plugged in may have led to overvoltage somewhere else?

But you actually have way more experience than I do so I'm sure you may have already thought of that.

You've probably already seen my post, but I did an s-video mod on one of these and it went super smoothly. Digikey even had the video-switching chip in stock. The only problem with it is a minor scratch on the glass in the top middle, only noticeable on flat shaded backgrounds.

My intention was actually to sell it after I attempt to polish off the scratch, so I'll send you a PM

[jetblue]

hi,i recently rgb modded a kv-13fm13 and the same issue as yours occurred within minutes of plugging in a console with scart. the tv worked perfectly fine for hours with me playing before the mod. the standby light starts flashing and everything goes black. the rgb looks great for the few minutes its on but the time it stays on gets less and less until it shows nothing. i leave it off for a while and i can turn it on. the green text when i hit menu looks fine but in a short time it starts to glitch looking like language from another planet then shuts off. the standby light flashing tells me its caps but it was fine before. thats when i started to google and saw your post. this is a no svid unit just rf and av. i suspect this model is slightly different from the svid unit where the successful mods and tutorials are for.
i recently got my hands on a KV-13FM12 and was just gonna trash this one i have and replace with this. now i fear the same thing will happen. did you make any progress on fixing yours? i can experiment with swapping parts with the KV-13FM12 but dont know how to go about this.

[BazookaBen]

i suspect this model is slightly different from the svid unit where the successful mods and tutorials are for.

There is no s-video "unit". None of them come with s-video. They're just easily moddable for s-video thanks to the jungle chip and service menu.

And the service manual I used lists the fm12,13,14 as all the same set. I think just color is different

My guess is there's some sensitivity with RGB mods that hasn't been documented.

There is one user on reddit who successfully did not only a RGB mod, but component YPbPr and s-video as well. Maybe you could look him up and see what he thinks.

[KPackratt2k]

My friend managed to get another KV-13FM12, which I have successfully RGB modded following the instructions from these guides:

https://sector.sunthar.com/guides/crt-r ... -ba-5.html
https://sector.sunthar.com/guides/crt-r ... 4fv12.html

What I did differently was I used a manual blanking switch (like the KV-24FV12 guide in the second link), disconnect a jumper running from the Comb Filter Luma/Y output to the Y input of the jungle chip (basically the jumper that comes after R1323), and run the SCART sync pin into the jungle chip Y input (with a 75 ohm termination resistor on my SCART connector) via a switch. The reason I ran sync directly to the jungle chip instead of the Composite video input is the Composite video input goes through the comb filter, which causes the image to be shifted excessively to the point where it can't be corrected.

You can use a DPDT switch to toggle between the stock Composite/RF inputs and RGB in this configuration:

Pin layout for switch:
1 2 3
4 5 6

Switch wiring:
Pin 1: Comb Filter Luma Output
Pin 2: Jungle Chip Luma Input (Pin 9)
Pin 3: SCART Sync
Pin 4: NC
Pin 5: RGB Blanking pin on Jungle Chip (Pin 29)
Pin 6: 5V supply with a 1n4148 diode and a 2.2K resistor

It's possible that your 13FM13 was malfunctioning because you were feeding 5V directly without any components to pull down the voltage, resulting in the voltage getting fed back to the microcontroller.

[jetblue]

thanks for all the helpful replies. but as i was sitting here i decided to remove the rgb mod and see if i could return the tv to the way it was installing the old resistors. it did the same thing no change then i noticed the standby light flashing was in code! i work on so many lcd tvs it didnt occur to me they installed error codes on crts. so i looked at service manual page 4 that you linked in your first post and sure enough 4 lights flashing says the ic 502 has died. ic 502 is TDA8172 and i ordered one and it should be here soon. will let you all know

[Osirus]

Good news I hope replacing the IC works.

[jetblue]

the chip finally arrived and placed it in. no change. the service manual also says ic 702 may be dead wich is a TDA6108jf. il order it shortly and the wait continues for the slow boat from china. after this i will give up