Which transistors are they out of?
Basic recap and restore BOM parts list on Kenwood KA-4002 integrated amp
- Thread starter dlucy
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Which transistors are they out of?
ok what? KSC945CG and KSC1815* are not avail? tis dark times if true! I have a couple I can send if they have none
lol we think alike
Ok, let's take a look at the problem and we'll figure out what an alternative would look like.
I've just run the BOM from one of my early posts in this thread thorough the BOM tool at Mouser and, at least of this morning, the only parts in there which aren't in stock are:
- FK22C0G1H224J TDK Multilayer Ceramic Capacitors MLCC - Leaded 0.22uF 50V C0G 5%
These ceramic caps can be replaced by any one of these that are in stock:
- FA22C0G1H22400 TDK Multilayer Ceramic Capacitors MLCC - Leaded 50V 0.22uF C0G 5% RAD LS:5mm AEC-Q200
- FG22C0G1H224JNT6 TDK Multilayer Ceramic Capacitors MLCC - Leaded RAD 50V 0.22uF C0G 5% LS:5mm
- FK22C0G1H224J TDK Multilayer Ceramic Capacitors MLCC - Leaded 0.22uF 50V C0G 5%
The transistors in the BOM are in stock at Mouser as of this morning:
- KSC1845FTA 24,124 available
If it was a different transistor, just reply here and we'll help out.
It can be frustrating when using old BOM and navigating the Mouser, Digi-key and Arrow Electronics web pages. Good thing those vendors have all of AK to provide customer support and guidance through the lists!
Trance88
Vintage Furry
When you guys say "Q" is that the same as "Qe"?? I've only ever replaced 1 transistor in my life.
ok yes, on some schematics (like marantz) they are 'H', but on this its Q, or in fact Qe if that is what the schematic says
In some vintage Kenwood gear the second letter of a component number indicates the specific board on which the component appears.
So you might find a Qa1 as a transistor (Q) on the power supply board (e) and a Qe1 on the main amp board.
Trance88
Vintage Furry
I'm just saying, because I don't see a "Q17, 18 or 19, but I do see a Qe 17-19 in the list. Also, the transistors have a bunch of code variants like KSC945CGBU, KSC945YTA, KSC945CYTA. Which one do I choose?!?
This is all confusing the heck out of me!!!
The trailing few letters on a distributor's part number are just the kind of packaging the parts are in. TA = tape reel, BU = bulk or loose, etc.
The first set of letters and numbers is the component or device model
KSC945
If a single letter C follows that, then that part is a variant and has the collector pin in the middle, as opposed to the end. So, ECB instead of its normal EBC.
KSC945
as opposed to the same part
KSC945C
which just has the collector pin moved to the middle position
The very next letter will sometimes be the hfe gain code from the datasheet. E.g. Y = gain of between 240-600, O = gain code of 120-300, etc.
The above are just examples, not an always-true definition. There is no requirement or regulation for naming part numbers, so they will vary.
Trance88
Vintage Furry
Ok! Very interesting. Does the Kenwood KA-4002 require the ECB or the EBC configuration?
Each application (I.e. Each place a transistor is used on the board) could be different. The transistors in my BOM are all the right pinout. If you see a KSC945C or KSC773C in any such list, then THAT one is different.
So, you have to take care to note the pinout (EBC vs ECB) when you pull the transistor. I always test the outgoing transistor with a $20 cheap component tester and try to match those results with the silkscreened label for that transistor on the board. There are many incorrect labels on vintage PCB's (printed circuit board), so noting the pinout when you first pull the device is important.
The BCxxx series of small transistors have pinout order from most of the others. FYI
Which component models were the ones you pulled out? E.g. 2SC458
Trance88
Vintage Furry
Son of a B****. I decided to just replace Qe13 and 14 to start. After plugging it in to test it, the damn fuse in the back blew. What the f.
In the several times this exact same thing has happened to me, it has always turned out to be installing the new transistors in the wrong pinouts. For instance when I replace 2SC458 transistors with KSC1845, I sometimes forget to install the latter rotated 180 degrees since the new transistor's pinout is ECB and the old one was BCE and needed that rotation to keep the right transistor leads in the right PCB holes.
hopjohn
Silver Face
AFAIK 2SC458 has always been ECB, it's the package orientation that fools people as the ID is on the back side with the slant roof outhouse style.
Great point.
I was using this example as it was one (reversing the pinouts) that I knew off the top of my head. It was just meant as an example.
hopjohn
Silver Face
The 2SC458 has been a headache for a lot of people here, both in the noise problems they create and the subsequent replacement being installed incorrectly because of the confusing package of the original. Again for all who are going to replace the older, slant-roofed, outhouse styled, Hitachi 2SC458. They are ECB pinout. The slant is the FRONT of the package, the flat is the back. The transistor ID is on the BACK.
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