Icarium Posted January 16, 2015 Report Posted January 16, 2015 Nod, thanks spritzer. I may reach out in PM when I'm in a position to start really getting my shit together. Thanks in advance and hope Iceland is good My friends keep visiting and I keep trying to steer them to visiting your bakery
GeorgeP Posted January 16, 2015 Report Posted January 16, 2015 No capacitors or resistor issues that I'm aware of. These are generic parts so there are always subs. Some of the xicon resistors in the batteries are no longer available. I recall there were some other brands that people had success with, but that for the most part if xicon's weren't used in the batteries you would end up with a noisy t2. For someone like icarium he needs to make sure the large caps are short enough to safely fit in the case without being accidentally hit by a case screw. The one in the original bom is no longer available, though alternatives are probably out there.
GeorgeP Posted January 16, 2015 Report Posted January 16, 2015 Thanks Spritzer. Any advice on 2SA1486 or is bdent the spot? I'm probably going to hit the 200 quantity price break. You just need 34 1486 and 34 3675 per amp, if you are going with "all original" parts, so 200 is a lot more than you would need.
spritzer Posted January 16, 2015 Author Report Posted January 16, 2015 Some of the xicon resistors in the batteries are no longer available. I recall there were some other brands that people had success with, but that for the most part if xicon's weren't used in the batteries you would end up with a noisy t2. For someone like icarium he needs to make sure the large caps are short enough to safely fit in the case without being accidentally hit by a case screw. The one in the original bom is no longer available, though alternatives are probably out there. Use Vishay's and lift them off the board which does the same thing.
nopants Posted January 16, 2015 Report Posted January 16, 2015 I hope there's a package deal for a spritzer t2 with bread, I would purchase that
spritzer Posted January 16, 2015 Author Report Posted January 16, 2015 I could throw in a loaf of sourdough...
Icarium Posted January 16, 2015 Report Posted January 16, 2015 (edited) You just need 34 1486 and 34 3675 per amp, if you are going with "all original" parts, so 200 is a lot more than you would need. Oh yah I know. I'm an inveterate parts/gear hoarder so I want to keep some around just for the who knows what. And also in case they are used in other designs. I don't ever want to pay 6 dollars+ a piece if I had a chance to pay 3 dollars It seems like they will appreciate for sure so if I can afford it now. Also who knows what I might need to trade for in the future Edited January 16, 2015 by Icarium
mypasswordis Posted January 16, 2015 Report Posted January 16, 2015 Almost all of the sand in the T2 can be replaced by modern parts. Look into JoaMat's updated T2 a few pages back. I plan to build something similar but fully solid state at some point, since there are now 1000V+ FETs with low enough capacitance available.
luvdunhill Posted January 16, 2015 Report Posted January 16, 2015 Use Vishay's and lift them off the board which does the same thing. Depending on the part you are referring to and the exact resistor you are replacing, I can tell you this won't work.
Craig Sawyers Posted January 21, 2015 Report Posted January 21, 2015 I populated my build with fake 3675's. Generated frightening cracking sounds and sparks. Took out a bunch of FETS as collateral damage. With good parts it hasn't missed a beat. I also got some fake FET's too that did not make the build. All from Dalbani in the UK - be warned.
GeorgeP Posted January 21, 2015 Report Posted January 21, 2015 Good to see you posting here again! I found all your bad experiences very helpful in building my t2 - I am sure it helped many others as well. Any way to repost son of your photos of the fakes again as they are not working any longer.
Craig Sawyers Posted January 22, 2015 Report Posted January 22, 2015 (edited) Dunno why the pics are dead. Attached below. I *think* the one on the right was the fake. Breakdown voltage was far too low - heaven knows what POS silicon is actually in the package. Edited January 22, 2015 by Craig Sawyers
CraigBuckingham Posted January 22, 2015 Report Posted January 22, 2015 I believe under the JIS system that Sanyo had exclusive use of the 2SC3675 numbering. The right side transistor is obviously not Sanyo. The one on the left looks like a perfect copy or genuine. If the numbering is not etched below the surface and printed instead or the tab and leads are not all copper, completely non-magnetic it's a fake.
spritzer Posted January 22, 2015 Author Report Posted January 22, 2015 The one on the left is real but the one on the right... yeah... Even though I have more than 1000 2SC3675's in stock I don't think there is any sense to use them with the 2SC4686A available. Having the main CCS short to the chassis isn't fun...
CraigBuckingham Posted January 22, 2015 Report Posted January 22, 2015 (edited) I do prefer isolated tabs. Does make mounting easier. It goes without saying that isolated heatsinks are a solution. But if it's a clone amplifier or a repair then that may not be how the original was designed. The data sheet device parameter curves are interesting to me to their differences given that both are stated as being Triple Diffused Planar types. Edited January 22, 2015 by CraigBuckingham
Craig Sawyers Posted January 22, 2015 Report Posted January 22, 2015 The original SRM-T2 had many of the active devices mounted on isolated heatsinks
spritzer Posted January 23, 2015 Author Report Posted January 23, 2015 No good way to do that with our boards. Going this way and using KSA1156 for the front end CCS means only the fets are non isolated. That plus the new batteries will make the amp far easier to deal with.
s_r Posted February 7, 2015 Report Posted February 7, 2015 (edited) Is it more important for the 3675's in the batteries to have matching hfe's, or for that hfe to be of higher value? Aside from three 3675's (which are 41x2 and 46) the rest of mine have a hfe between 50-70. Edited February 8, 2015 by s_r
Kerry Posted February 8, 2015 Report Posted February 8, 2015 I'd go for the higher hfe and get them as close as you can.
s_r Posted February 8, 2015 Report Posted February 8, 2015 Alright, I happen to have four which measure right on 65, so I'll use those in the batteries. I take it the hfe outside of the battery is less critical then?
Kerry Posted February 8, 2015 Report Posted February 8, 2015 The Darlington pair should be high hfe. No need to match within the pair. That's all I can think of at the moment. 1
s_r Posted February 15, 2015 Report Posted February 15, 2015 Thanks Kerry. Figured I may as well show my progress with the build: Still missing a number of xicons (as per the ad I posted) though. Unless someone has a chunk of them they're willing to spare I might pick up carbon takmans instead. Maybe just for the batteries in case vishays are fine outside of there.
Kerry Posted February 16, 2015 Report Posted February 16, 2015 (edited) The resistors in the batteries were the ones that were leaking. Make sure whatever you use are well insulated and are lifted off of the board. I originally used the red PRP and had them lifted, but they still caused problems. EDIT: Looks nice so far Edited February 16, 2015 by Kerry
G600 Posted February 24, 2015 Report Posted February 24, 2015 Can anybody help me source KG's original T2 transistor ? I don't want to fall into the fake drama.
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