Background
The 27FV310 is the best consumer grade television because it has good high voltage regulation to prevent bloom. Bloom is when brighter images expand the raster and dark images shrink the raster. In addition, the TV supports YPbPr inputs, is RGB moddable and has a good gamma curve.
The problem is that this TV is pretty rare because it was released during the switch between SD and HD. So most people skipped it for an HD set. Quite ironic because today HD consumer CRTs are the worst sets. The other issue is that the FV310 was a high-end SKU so if someone was willing to pay the premium over the entry (FS) and mid series (FV300) SKUs, they would likely get the 36" or 32”. For this reason the 27FV310 appears to be rarer than the 36FV310.
The biggest weakness is the geometry tends to be poor on these flatscreen Trinitrons but the quality really varies from yoke to yoke and you can generally find a decent yoke if you bin a few. Quite a few people say to avoid the flatscreen Trinitons because they do have worse geometry on avg than the curved Trinitons and that is true but it really does vary from set to set and if you want great geometry then get a 13”/14” PVM or a BVM. The trade-off for screen size is worse geometry.
With that said, let’s get to the modding.
The Problem
As I said, it’s very hard to find a 27FV310 so I decided to build my own using a 27FS210 donor chassis and 36FV310 circuit boards. You would think that it would be possible to swap the 27” components from the 27” PCBs to the 36” PCBs and you’d be correct but it’s not possible to swap T510. T510 generates the heater voltage and it’s driven by the horizontal deflection circuity so it affects horizontal deflection size and linearity. Luckily it’s pretty simple to compensate for the 36" T510 using a few 36” components.
The Guide
A Board
SWAP:
These caps control the timing so they must all be swapped to adjust from the 32" or 36" to the 27”.
- C511: 17000pF
C513: 0.047uF
C514: 0.68uF
C554: 2700pF
C553: 0.1uF (from C1501) // Decreasing capacitance from 0.24uF to 0.10uF increased raster size.
R504: 1k ohm // Transformer inrush current resistor. I recommend upgrading to a 1K 2W resistor
R526: 4.7 ohm // This resistor separates the pin correction circuit from H drive circuit but it also effects raster size.
R576: 22 ohm // Horizontal centering resistor.
These components control pincushion, vertical deflection and over current protection. I swapped these components on my set but I would recommend leaving the 32/’36” values unless you have issues, e.g. pincushion not calibrating properly.
- R501: 330 ohm // I believe this resistor forms a voltage divider with R502. If so decreasing the value of the resistor from 470 to 330 increases the voltage range. I used 330 ohm on my set but I would recommend leaving the value at 470 ohm.
R516 & R523: 8.2k & 22k // I believe these resistors form a voltage divider. 4.7k & 12k = 6.47v, 8.2k & 22k = 6.56v. .1v difference. Very minor.
R531: 180k // Possibly a voltage divider with R529 and R530. Regardless it’s parallel with R530 so it’s 12K & 56K = 9.9k, 12K&180k=11.3kohm. I swapped these on my set but I would recommend leaving 56k unless you have problems with pincushion not working,
R534, R558, R666, R568: 10K & 15k in parallel = 6k // Don’t swap these. The value is close to the 27” 6.8k. Furthermore the 32” uses 5.6k so the pattern isn’t consistent.
R593: 1k // Didn’t swap. Protection resistor.
The components are part of the size adjustment and dummy yoke circuit. I initially swapped these values to the 27” but my raster was too small. I changed these values back to 36” and I was able to get adequate raster size in the service menu and horizontal linearity. Hsiz 59-63 with 2.5% overscan.
- T505: 098 // IIRC using 098 (36FV310) over 850 (27FS210) increased the raster size. 27FV300 has a different part (693).
T510: 848 // Can’t swap.
L505 150mH inductor // IIRC increasing inductance from 100mH to 150mH increased the raster size.
C516 1.2uF // IIRC increasing capacitance from .82uF to 1.2uF improved horizontal linearity..
This board controls dynamic focus and protection circuits. You probably don’t need to swap any components but it’s a good idea to swap the dynamic focus resistors and capacitors.
SWAP:
- C8512: 3900pF
C8542: 220pF
C8850: 680pF
R8542: 8.2k
R8554: 8.2k
R8554: 15k
These components are all part of the protection circuit and don’t require swapping.
- R8009:
R8017:
R8021:
R8040:
R8046:
R8052:
This board controls the heater voltage. The voltage must be 6.3v+/-.2v. The problem here is that the voltage is AC and runs at 15.7khz. Most multimeters aren’t designed to sample this high frequency. I use a Fluke 189. I think a Fluke 87V would work as well.
SWAP:
- R717:
R718: 2.2Ohm?
This is a fairly simple conversion once you know what you're doing: you're changing some parts to 27" spec, you're leaving a few parts 36" spec as to compensate for the 36" heater transformer, you're not swapping some parts because they're not required or very similar to 27" spec, and you're measuring heater voltage. So if you're in the unique situation of having both a 27FS210 or 27FV300 and a 32/36FV310, you too can make your own 27FV310. Enjoy.
Pictures
Spoiler
https://www.slideshare.net/JamesWebb15? ... sslideview
1 _CRT Display Design_
2 _CRT Display Design_A_
3 _CRT Display Design_A_
https://elektrotanya.com/sites/default/ ... BET%5D.pdf
https://twitter.com/turom_/status/1011142753751793666