trashedcabs
Professional
I seem to be the one in my area who has to fix all my friends monitors, so here's my logs for the past year and will continue to update whenever I have a new repair. I will skip over any basic ones like cap kits etc because they're beginner stuff and not really interesting. Will only note it if it's an unusual monitor or something. Also I'm not an electrical engineer, so expect some technical details to be wrong.
And no, I won't fix your monitor, sorry. Too busy.
Neotec NT-2702
From a local who attempted their first cap kits.
Chassis 1:
Symptom: Very green and smeary
Q906 shorted. This was caused by the cap kit installer lifting a pad and bridging the component to an incorrectly neighboring pad.
Chassis 2:
Symptom: Vertical jittering, blooming issues
C901 in backwards
C904 had a lead bent touching a neighboring resistor
C954, C955 were not replaced. Caps read extreme ESR
C957 was reading open
Replaced broken color cutoff pots
Chassis 3:
Symptom: Raster lines, shutdown when B+ turned up. Low heater voltage that takes a long time to get up (4.5v)
C906 was in backwards and vented
C430 had installed 100uf, supposed to be 10uf (xray protect circuit)
C502 has installed 4.7uf, supposed to be 2.2uf
There were several weak traces around the drive transistors on the neck board. This was courtesy of PNL who previously serviced it.
There was a bodge between the emitter of the red drive transistor, and a cap near the video amp. The wire had rubbed against the heatsink and shorted. Replaced bodge with silicone insulated wire.
Shorted Q901. Part is 2SC4367
C952, a newly installed 10uf 50v cap, was failed. Looks like when the pad was lifted, the trace was incorrectly bridged above it to L903 (directly attached to blue drive output... 125v) instead of to the pad of C953 to the left where it should go. Replaced cap and redid patch.
New filter cap installed
Red missing. Reflowed input connector to finish repair.
Chassis 4:
Symptom: Dim picture
B+ pot was turned all the way down. Turned it up until heater voltage hit 5v. I know the tube datasheet says 6.3v but the other chassis I checked run at 5v. After it warmed up for about an hour, the brightness was now WAY high! Heater voltage was now 6.3v and the picture was super wide. Chassis had been recapped except the filter cap. Replaced filter cap and re-adjusted B+ to fix.
Chassis also had some absolutely abysmal rework on done by some amusement vendor I won't name. Many torn up pads and traces which needed to be fixed.
MS-2930:
Symptom: Ticking, no start
Did a full cap kit and noted many high ESR caps all over the board. The monitor now starts with HV but no deflection, and shuts down after 3 seconds. Manual for the similar 2931 states that shutdown after 3 seconds is part of the U451 protection circuit that looks for deflection faults. Had a giant bag of LA7838 from aliexpress, so I took a guess on replacing it and the monitor fired right up with no issues since.
Toshiba PF PB9929:
Bought 3 these "untested" for very cheap. Of course, we all know what untested really means.
Symptom: Unknown condition, working with no video.
First board is a PB9929. Arrived with the H drive transformer and the flyback partially desoldered for some reason. A coil at L402 was torn apart so I pulled the coil from a parts chassis, soldered everything back on and powered it up. Chassis worked and says no signal! Good sign. I gave it a video signal and it syncs, but no video is displayed.
I checked the video amp and also checked all the passives around it. All seemed good. Considering it said No Signal, I shouldn't have suspected the amp as it's also responsible for OSD mixing.
This ended up being a bad MCU. No amount of screwing with the external EEPROM would bring it back. I swapped the MCU from a parts chassis and it worked perfectly.
Toshiba PF PE0493:
Symptom: Arcing under the secondary power transformer. Noises from flyback and static on screen.
Untested chassis. Noticed arcing under the secondary power transformer. Quickly shut it off--but I did hear HV and the fuse wasn't popped. Removed the transformer and noticed an oily substance under it. I decided to clean the whole board off with simple green and an IPA rinse, followed by air compressor to dry.
Noticed D702 on the bottom was cracked in half. Tiny little SMD diode near the edge of the board--marking only says 1B with 3 dots around it. I did some digging and it appears this is a Panasonic MA2J111. Ordered some similar diodes, installed one and the chassis worked perfectly.
One of the relay covers had also popped off and the contacts were bent. Replaced the relay with one from a parts chassis.
Addendum: Pulled chassis off the shelf to use in a monitor and noticed a weird snowy artifacting in the dark areas, and the flyback was also making noises. Turns out this chassis was originally used with a Matsushita tube, and was missing the extra focus divider pot on the neck board. Pulled pot from parts chassis and it now works great on the Toshiba tube.
Sanwa PFX:
Symptom: Squashed width and burning smell, rolling OSD
Chassis was clearly mishandled and was missing the filter cap entirely, and some resistors nearby were loose. Whole mounting tray was bent. After fixing that I did caps because these things use junk no name caps that always fail. Great chassis, shame about that. Powered it on and it did display an image, but there was a burning smell and the width was squashed. Noticed that a big ceramic resistor R488 was replaced next to the drive transformer T401. Looking at the schematic, it says it is supposed to be two 33ohm 2W in parallel, but someone replaced it with a single 68 ohm ceramic. That's not how that works. Replaced with a 15ohm 5W and width was good and no more burning smell. Next I noticed funny enough the OSD was rolling! OSD generator IC102 gets a horizontal feedback pulse from T401, and inspecting this it had some bad solder joints, and reflowing them fixed it.
Nanao MS9:
Symptom: No video, no H size, no sync, bad geometry
Bought this mystery chassis off YAJ. Noticed immediately someone replaced C457 and was installed backwards, so we're off to a good start. Fixed this and powered it up and had no video--also had foldover and horrible pincushion. Horizontal size controls didn't work either. I replaced the vertical IC and pincushion amp Q508. Crazy pincushion went away and foldover got much better. Still no video and I could tell sync was out from the noises it was making.
C223, C201, C202, and C203 were all reading open. C221, C561, and C405 all had crazy high ESR values. I noticed a few of the previously replaced caps on the board had leakage residue under them. Replacing all the caps fixed the foldover.
I checked all the passives around the video amp IC and found R243 open. Replacing this restored video.
Still had issues with the vertical sync and horizontal controls not working. I previously bought some LA7853 and noticed the markings on a few were suspect. Hoping it was just re-etched markings done by a recycler, I installed one and the sync was now way worse. Looks like I got a fake. Installed another one with original markings and I had an intermittent stable image...for two power cycles. The image also had strange artifacting and color issues. I could finally adjust the horizontal width and position again though.
Vsync went out again so I started digging into the sync circuit looking for anomalies. I used my scope to check the pin 21 vsync input on the LA7853 and I could see the sync pulse but there was also garbage in the signal. Wasn't sure if this was normal and didn't have a convenient way to check, so I followed the flowchart in the manual and it said to check U550, C452, and U101. I knew U550 was good and C452 tested fine, so the only chip left to test was U101 which is a quad gate array on the bottom. My friend had a parts chassis so decided it would be easier just to swap it. Swapping it fixed my sync.
I could now adjust the horizontal width and position, but the entire raster was shifted far to the left. Hitting the H size limit pot with some contact cleaner and turning it back and forth fixed this.
Nanao MS9:
Symptom: Unknown scrap chassis. Cut wires missing components
Another junk MS9 from YAJ, this time for REALLY cheap. How can I pass up a $30 MS9?
Ridiculously dirty, can't see the PCB in some spots. Time to give it a bath.
Now that it's clean and I can touch it: the neck board is missing. Pulled a neckboard from a parts chassis that was missing a few components.
The remote board was also missing. I picked one up for $20 on YAJ. Cable was missing, so I modified a spare E31S harness to fit by crimping a new connector on one end. Neck board harness was also cut so I crimped new connectors on those. Once everything was all ready to go it was time to power it on.
All good. Amazing considering how nasty it was. Installed the negative G1 mod and paired it with a crappy Orion tube that had trash focus on every chassis I tried. Looks awesome now, absolutely usable in a cabinet.
Neotec NT-500DX:
Symptom: No start, rapid clicking.
Not shutting down, but B+ wouldn't go higher than 60v. Found many failed caps around the power supply. Also replaced the filter cap for good measure. All fixed after recap, easy.
Toei TC-L292:
Symptom: No V size or linearity control
Mystery cheapo YAJ purchase. Liquid damage completely ate a few resistors and jumpers in the top corner of the chassis near the deflection IC. Replaced resistors and jumpers to fix. Easy.
Toei TC-L292:
Symptom: No brightness control. Horizontal shaking and flyback LOUD.
Started with caps because we had one with similar issues and caps fixed it, but on this one it made no change. Noticed the HOT was replaced with one that was similar but slightly under spec. Original is a 2SC5150 in case anyone wants to know. Pathing back from the HOT I did notice R29 a resistor marked 1W 27ohm looked damaged and was reading 100ohm. Replaced resistor to fix the shaking issues and flyback noise.
Found 33nF film cap at C33 shorted causing the brightness pot to effectively be grounded. Replacing cap fixed brightness control.
And no, I won't fix your monitor, sorry. Too busy.
Neotec NT-2702
From a local who attempted their first cap kits.
Chassis 1:
Symptom: Very green and smeary
Q906 shorted. This was caused by the cap kit installer lifting a pad and bridging the component to an incorrectly neighboring pad.
Chassis 2:
Symptom: Vertical jittering, blooming issues
C901 in backwards
C904 had a lead bent touching a neighboring resistor
C954, C955 were not replaced. Caps read extreme ESR
C957 was reading open
Replaced broken color cutoff pots
Chassis 3:
Symptom: Raster lines, shutdown when B+ turned up. Low heater voltage that takes a long time to get up (4.5v)
C906 was in backwards and vented
C430 had installed 100uf, supposed to be 10uf (xray protect circuit)
C502 has installed 4.7uf, supposed to be 2.2uf
There were several weak traces around the drive transistors on the neck board. This was courtesy of PNL who previously serviced it.
There was a bodge between the emitter of the red drive transistor, and a cap near the video amp. The wire had rubbed against the heatsink and shorted. Replaced bodge with silicone insulated wire.
Shorted Q901. Part is 2SC4367
C952, a newly installed 10uf 50v cap, was failed. Looks like when the pad was lifted, the trace was incorrectly bridged above it to L903 (directly attached to blue drive output... 125v) instead of to the pad of C953 to the left where it should go. Replaced cap and redid patch.
New filter cap installed
Red missing. Reflowed input connector to finish repair.
Chassis 4:
Symptom: Dim picture
B+ pot was turned all the way down. Turned it up until heater voltage hit 5v. I know the tube datasheet says 6.3v but the other chassis I checked run at 5v. After it warmed up for about an hour, the brightness was now WAY high! Heater voltage was now 6.3v and the picture was super wide. Chassis had been recapped except the filter cap. Replaced filter cap and re-adjusted B+ to fix.
Chassis also had some absolutely abysmal rework on done by some amusement vendor I won't name. Many torn up pads and traces which needed to be fixed.
MS-2930:
Symptom: Ticking, no start
Did a full cap kit and noted many high ESR caps all over the board. The monitor now starts with HV but no deflection, and shuts down after 3 seconds. Manual for the similar 2931 states that shutdown after 3 seconds is part of the U451 protection circuit that looks for deflection faults. Had a giant bag of LA7838 from aliexpress, so I took a guess on replacing it and the monitor fired right up with no issues since.
Toshiba PF PB9929:
Bought 3 these "untested" for very cheap. Of course, we all know what untested really means.
Symptom: Unknown condition, working with no video.
First board is a PB9929. Arrived with the H drive transformer and the flyback partially desoldered for some reason. A coil at L402 was torn apart so I pulled the coil from a parts chassis, soldered everything back on and powered it up. Chassis worked and says no signal! Good sign. I gave it a video signal and it syncs, but no video is displayed.
I checked the video amp and also checked all the passives around it. All seemed good. Considering it said No Signal, I shouldn't have suspected the amp as it's also responsible for OSD mixing.
This ended up being a bad MCU. No amount of screwing with the external EEPROM would bring it back. I swapped the MCU from a parts chassis and it worked perfectly.
Toshiba PF PE0493:
Symptom: Arcing under the secondary power transformer. Noises from flyback and static on screen.
Untested chassis. Noticed arcing under the secondary power transformer. Quickly shut it off--but I did hear HV and the fuse wasn't popped. Removed the transformer and noticed an oily substance under it. I decided to clean the whole board off with simple green and an IPA rinse, followed by air compressor to dry.
Noticed D702 on the bottom was cracked in half. Tiny little SMD diode near the edge of the board--marking only says 1B with 3 dots around it. I did some digging and it appears this is a Panasonic MA2J111. Ordered some similar diodes, installed one and the chassis worked perfectly.
One of the relay covers had also popped off and the contacts were bent. Replaced the relay with one from a parts chassis.
Addendum: Pulled chassis off the shelf to use in a monitor and noticed a weird snowy artifacting in the dark areas, and the flyback was also making noises. Turns out this chassis was originally used with a Matsushita tube, and was missing the extra focus divider pot on the neck board. Pulled pot from parts chassis and it now works great on the Toshiba tube.
Sanwa PFX:
Symptom: Squashed width and burning smell, rolling OSD
Chassis was clearly mishandled and was missing the filter cap entirely, and some resistors nearby were loose. Whole mounting tray was bent. After fixing that I did caps because these things use junk no name caps that always fail. Great chassis, shame about that. Powered it on and it did display an image, but there was a burning smell and the width was squashed. Noticed that a big ceramic resistor R488 was replaced next to the drive transformer T401. Looking at the schematic, it says it is supposed to be two 33ohm 2W in parallel, but someone replaced it with a single 68 ohm ceramic. That's not how that works. Replaced with a 15ohm 5W and width was good and no more burning smell. Next I noticed funny enough the OSD was rolling! OSD generator IC102 gets a horizontal feedback pulse from T401, and inspecting this it had some bad solder joints, and reflowing them fixed it.
Nanao MS9:
Symptom: No video, no H size, no sync, bad geometry
Bought this mystery chassis off YAJ. Noticed immediately someone replaced C457 and was installed backwards, so we're off to a good start. Fixed this and powered it up and had no video--also had foldover and horrible pincushion. Horizontal size controls didn't work either. I replaced the vertical IC and pincushion amp Q508. Crazy pincushion went away and foldover got much better. Still no video and I could tell sync was out from the noises it was making.
C223, C201, C202, and C203 were all reading open. C221, C561, and C405 all had crazy high ESR values. I noticed a few of the previously replaced caps on the board had leakage residue under them. Replacing all the caps fixed the foldover.
I checked all the passives around the video amp IC and found R243 open. Replacing this restored video.
Still had issues with the vertical sync and horizontal controls not working. I previously bought some LA7853 and noticed the markings on a few were suspect. Hoping it was just re-etched markings done by a recycler, I installed one and the sync was now way worse. Looks like I got a fake. Installed another one with original markings and I had an intermittent stable image...for two power cycles. The image also had strange artifacting and color issues. I could finally adjust the horizontal width and position again though.
Vsync went out again so I started digging into the sync circuit looking for anomalies. I used my scope to check the pin 21 vsync input on the LA7853 and I could see the sync pulse but there was also garbage in the signal. Wasn't sure if this was normal and didn't have a convenient way to check, so I followed the flowchart in the manual and it said to check U550, C452, and U101. I knew U550 was good and C452 tested fine, so the only chip left to test was U101 which is a quad gate array on the bottom. My friend had a parts chassis so decided it would be easier just to swap it. Swapping it fixed my sync.
I could now adjust the horizontal width and position, but the entire raster was shifted far to the left. Hitting the H size limit pot with some contact cleaner and turning it back and forth fixed this.
Nanao MS9:
Symptom: Unknown scrap chassis. Cut wires missing components
Another junk MS9 from YAJ, this time for REALLY cheap. How can I pass up a $30 MS9?
Ridiculously dirty, can't see the PCB in some spots. Time to give it a bath.
Now that it's clean and I can touch it: the neck board is missing. Pulled a neckboard from a parts chassis that was missing a few components.
The remote board was also missing. I picked one up for $20 on YAJ. Cable was missing, so I modified a spare E31S harness to fit by crimping a new connector on one end. Neck board harness was also cut so I crimped new connectors on those. Once everything was all ready to go it was time to power it on.
All good. Amazing considering how nasty it was. Installed the negative G1 mod and paired it with a crappy Orion tube that had trash focus on every chassis I tried. Looks awesome now, absolutely usable in a cabinet.
Neotec NT-500DX:
Symptom: No start, rapid clicking.
Not shutting down, but B+ wouldn't go higher than 60v. Found many failed caps around the power supply. Also replaced the filter cap for good measure. All fixed after recap, easy.
Toei TC-L292:
Symptom: No V size or linearity control
Mystery cheapo YAJ purchase. Liquid damage completely ate a few resistors and jumpers in the top corner of the chassis near the deflection IC. Replaced resistors and jumpers to fix. Easy.
Toei TC-L292:
Symptom: No brightness control. Horizontal shaking and flyback LOUD.
Started with caps because we had one with similar issues and caps fixed it, but on this one it made no change. Noticed the HOT was replaced with one that was similar but slightly under spec. Original is a 2SC5150 in case anyone wants to know. Pathing back from the HOT I did notice R29 a resistor marked 1W 27ohm looked damaged and was reading 100ohm. Replaced resistor to fix the shaking issues and flyback noise.
Found 33nF film cap at C33 shorted causing the brightness pot to effectively be grounded. Replacing cap fixed brightness control.
