Chip Resistor Type Code for Turkey: 114 of 14,630 Walsin W Parts Sit in the X Band and 840 Use an Undocumented F

The chip resistor type code is the one field of Walsin’s six-field ordering key nobody had tested. We checked the fifth character of all 62,757 WR and MR part numbers for buyers in Turkey: X and W follow the datasheet bands on 61,803 of 61,917 rows, 114 W parts break them, and 840 rows use an undefined F.

Two Walsin sheets print the same six-field key, and five of the six fields have been checked against the export. The fifth character, the type code, had not. Venatech Limited, an authorised Walsin distributor in Hong Kong, holds all 137 chip resistor export files published by Walsin Technology (Walsin) and the two chip resistor datasheets, ASC_WR_V24 of September 2016 and ASC_MR_V13 of March 2024. This post is written from the key on page 3 of each sheet and from the Part Number, Resistance and Tolerance columns of the 62,757 WR and MR rows. Every part number below is real.

What does the type code in a Walsin WR or MR part number select?

A tolerance and a resistance band, according to the key. In WR06X1002FTL the type code is the X after the size code WR06. The key prints two letters. X covers jumpers, 5% parts from 1 ohm to 10 megohm, and 1% parts from 10 ohm to 1 megohm. W covers 1% parts below 10 ohm and above 1 megohm. The two bands are meant to be disjoint, so the letter should settle which side of 10 ohm and 1 megohm a part sits on. We tested that on every row of Thick_Film_General_Purpose_*.xlsx, the files that hold the WR and MR parts.

We have not seen this counted anywhere. 61,917 rows carry a documented letter and 61,803 of them sit inside their documented band. The other 114 are all W parts inside the X band, and 840 further rows carry a letter that neither sheet explains.

How do the X and W bands split by prefix?

Cleanly, with one gap. We split every WR and MR row by resistance band and tolerance. X carries every 5% part and every jumper in the set, and W carries no 5% part at all. The WR and MR halves behave the same way except in one cell.

The key reads as a hard rule on X and on both MR rows. It reads as a rule with one exception on WR, W.

Which 114 W parts sit in the X band?

One size, one series, one file. We filtered the W rows between 10 ohm and 1 megohm and found 114, all at 1210 in Thick Film General Purpose Chip Resistor, all rated 1/2 W, all ±1%, all ≦±100 ppm/°C, and all in Thick_Film_General_Purpose_1_1_2W.xlsx. They run from 102 kilohm to 1 megohm, 114 distinct values, and WR10W1023FTL is the first. The WR sheet we hold covers WR12, WR08, WR06 and WR04 only, so 1210 is outside it; the MR sheet does cover 1210 and its MR10 W rows keep to the key.

The same 102 kilohm, 1210, ±1%, ≦±100 ppm/°C position is therefore written three ways in the WR10 group and a fourth in MR10:

A parser that infers the band from the letter decodes WR10W1023FTL as a part below 10 ohm or above 1 megohm. It is neither. The commercial 1210 series is the only one of the four that writes this stretch of the resistance range with a W; the LF 100ppm and anti-sulfuration series at the same size write the same stretch with an X on 571 rows each, and the commercial series itself uses X on 457 rows below 102 kilohm. We did not find a Walsin document that explains why.

Which 840 rows carry an F that the key never defines?

Three prefixes, 280 rows each. We counted every fifth character in the 62,757 rows: 47,287 X, 14,630 W and 840 F, all in WR12, WR20 and WR25, across 140 distinct values from 1.00 to 10.00 ohm, with 690 parts at ±1% and 150 at ±5%. The first is WR12F1R00FTL. Neither sheet lists F as a type code, and none of the 840 shares size, value, tolerance, TCR and rated power with any WR X or W part.

Half of the 840 are the tailed parts we decoded in our note on the power and TCR letters after a Walsin part number, and the other half are the tail-less stems that sit beside them at lower power. F, on the evidence of the export, marks a low-ohm 1.00 to 10.00 ohm family at the largest three WR sizes, with two power ratings per size. That is our reading, not Walsin’s.

Do the band edges in the export match the key?

No, not at the edges: 127 W rows sit where the MR key’s strict inequalities say W stops. The sheet ASC_MR_V13 writes W as 1 < R < 10 and 1M < R < 10M, and X as 10 ~ 1M for 1% parts. We counted the endpoints: 64 W rows sit at exactly 1 ohm and 63 at exactly 10 megohm, which the strict inequalities exclude, and 64 X rows at 1% sit at exactly 10 ohm and 63 at exactly 1 megohm. That is 127 W rows on edges the key says W does not cover.

This looks like a sheet convention, not a data defect: the printed range for the series is 1 ohm to 10 megohm, so the endpoints must belong to some letter, and W is where the export puts them. It matters only if you build a band rule from the key’s symbols. The edges are the first place such a rule fails.

What should a buyer in Turkey do with the type letter?

Read the series and the resistance column, not just the letter: the letter agrees with its band on 61,803 of 61,917 rows and disagrees on 114. For a buyer in Turkey checking a WR or MR list, three steps cost under a minute each.

1. Do not infer a resistance band from X or W at 1210. 114 commercial WR10 parts break the key, and the same position carries four different part numbers across four series.
2. Do not decode an F. 840 rows use it and no document we hold defines it. Read the tolerance, power and TCR columns of the export row instead.
3. Paste your list into the free cross-reference tool. It decodes 18 manufacturers’ part numbers, takes up to 500 at a time or an Excel or CSV file, and states every difference from your original rather than hiding it.

For the power-rating picture across case sizes, see chip resistor power rating by case size. What is in Hong Kong is on ready stock: 1,125 part numbers as at 23 September 2026, a dated snapshot and not a live feed. The range sits on the Walsin chip resistor page. We hold 28 Walsin datasheets, 451 pages, and will send the two chip resistor sheets on request; our address is Unit 207, 2/F, Sun Ling Plaza, 30 On Kui Street, Fanling, N.T., Hong Kong, telephone (852) 2628 4777. Confirm against both datasheets and qualify in your own circuit.

The short version

The type letter is the fifth character of a WR or MR part number, and the key prints X for 5% parts and 1% parts from 10 ohm to 1 megohm and W for 1% parts below 10 ohm and above 1 megohm. We tested all 62,757 rows: X holds on 47,287 of 47,287, W holds on 14,516 of 14,630, and the 114 exceptions are all commercial WR10 parts between 102 kilohm and 1 megohm. 840 rows use an F the key never defines. 127 W rows sit on edges the key’s strict inequalities exclude. We will not tell you a part sits in a band because of its letter. We will show you the resistance column the export holds. Qualification stays with you.

Send us the WR and MR lines off your bill of materials and we will return the type letter, the resistance band it implies and the band the export states, flagged wherever they differ. And a question back: if your decoder reads the type letter as a resistance band, which of your 1210 lines did it place on the wrong side of 1 megohm?

Frequently asked questions