Help with the identifying unknown transistor - Page 1
Forum section: electronics / repair

author: PPS
author_rank: Newbie
timestamp: November 19, 2022, 10:58:22 pm
content: Hello guys.I need your help with the identifying of this transistor.It is on the small PCB which adjusts the rotation speed of the Dewalt 707 miter saw.Cant find this marking anywhere.markingon the top - 18 508on the bottom - BSGZ348as I can readlook at the pic

author: fzabkar
author_rank: Super Contributor
timestamp: November 19, 2022, 11:05:39 pm
content: Are you sure it's a transistor and not a TRIAC?

author: PPS
author_rank: Newbie
timestamp: November 20, 2022, 12:56:19 am
content: No, I am not sure what is it.

author: fzabkar
author_rank: Super Contributor
timestamp: November 20, 2022, 01:20:00 am
content: It looks like item #61 in the exploded view (p/n 947064-04):https://www.wmv-dresden.de/documents/DeWalt/dw_707_e_kappsaege_dewalt.pdfI'd say it is definitely a TRIAC. Try to trace out the circuit, and tell us the power rating of the saw.Edit:https://forum.toolsinaction.com/topic/2959-my-dewalt-dw304-type-2-recipication-saw-quit-working-bad-switch/Try replacing it with a "BTB12-12A 600V Triac ST Microelectonics".

author: PPS
author_rank: Newbie
timestamp: November 20, 2022, 01:44:16 am
content: This is definitely this PCB from Elu PS274 (Dewalt DW707 ). so, according to manual Motor power (input) - 1200w

author: fzabkar
author_rank: Super Contributor
timestamp: November 20, 2022, 01:51:24 am
content: The DW304 is a 10 amp, 120V, 1150W saw:https://www.dewalt.com/product/dwe304/100-amp-reciprocating-sawTherefore, I think the TRIAC is a good fit.https://www.farnell.com/datasheets/81403.pdf

author: PPS
author_rank: Newbie
timestamp: November 20, 2022, 02:05:23 am
content: Thanks a lot, but I've mentioned not DW304.This is ELU 274https://www.manualslib.com/manual/1143044/Elu-Ps274.html?page=22#manual-- page 22 on website . It was old name. It was rebranding and now it Dewalt 707.Working voltage- 220V. input power - 1200W. Fuse is - 10AWhy I can't find marking of the original triac?

author: fzabkar
author_rank: Super Contributor
timestamp: November 20, 2022, 02:21:30 am
content: Quote from: PPS on November 20, 2022, 02:05:23 amI understand. All I'm saying is that these saws use similar designs for the switch and speed control. Since the DW304 has the same power rating, then its TRIAC should be more than adequate for your saw. In fact, your 220V saw will only consume 5A. The 600V rating would still be OK, but you could choose the 800V TRIAC for extra headroom.As for the part number, I suspect that the TRIAC has been specially marked with Dewalt's own internal numbers rather than the manufacturer's.

author: PPS
author_rank: Newbie
timestamp: November 20, 2022, 11:33:19 am
content: Thank you indded. You helped me much. So I can use BTA10 and install it as previuos on the pcb without any position changes?

author: PPS
author_rank: Newbie
timestamp: November 20, 2022, 01:29:49 pm
content: And how can I determine which Igt in mA and Voltage Gate Trigger (Vgt) for correct work i? if my Triac is burnt

author: fzabkar
author_rank: Super Contributor
timestamp: November 20, 2022, 06:26:22 pm
content: I would choose a "standard" TRIAC. Don't use logic level triggering. I don't think there would be a need for sensitive gate triggering, either.If possible, I would choose a "snubberless" TRIAC, ie one with a high dV/dt rating.This thread may be helpful:https://forum.toolsinaction.com/topic/3092-dw304-just-stopped-working/BTW, "ST2 GE" is a DIAC.