Hello - I am looking for service manual of B&K ST-2140 Mosfet Power Amplifier.
In 2020 I contacted ATI who owned B&K then and I got this reply:
"Thank you for contacting us. Did a search of our legacy B&K database and could not find a service manual or any schematics for the ST2140. Sorry...
Lucky enough to pick up an old power amp for only $30. Guy said it was used for parties, events, etc. He said it turns on but he hasn't tried it with speakers so who knows. It's a Mosfet amp rated at 300 watts (per channel?) according to the label on it. Made by an Australian company called...
I just went to get some new TO3 output transistors from ProFusion / Exicon, and they are now marked as 'end-of-life'. Better get them while they last. Does anyone know of any other TO3 lateral MOSFET transistors out there that are made by reputable companies...
Hi Folks,
Got a McCormack DNA-500 that had a "firecracker effect" failure (POP! Bang, bang, bagitty-bang, bang from the output to input). Gonna use NJW3281/1302 on the outs for the C3281/A1302, but coming up dry on the MOSFET's. Don't trust the SOA (often not listed) for the in-production...
Hi,
Iam trying to build an amplifier came across Stochino amplifier (attached circuit, improvised version and related documentation).
Want to know if anyone has tried this earlier, if so how is the sound signature and overall performance.
Also DIY gurus kindly analyze the circuit and suggest...
I don't get it. I got this very unusual, very spartan high end hybrid tube amp in with the complaint: blows its fuses. The patient is a Croft Acoustics Phono Integrated amplifier. It got some rave reviews across the internet and of course it is reassuringly expensive. My amp was bought second...
I recently purchased a B&K ex4420 online, and quickly discovered that it has a problem. With everything connected (correctly) the volume is very low. To the point that the volume on the pre (tried 2 different ones) needs to be at max to get a low normal listening level.
I took it to my tech...
I am working on two of these beasts. Both have one channel blown to smithereens due to the driver MOSFETs failing. These devices, 2SJ78 and 2SK215, are low power versions of the well-known lateral audio MOSFETs like 2SJ161/K1057 and have a TO220 case with drain and source terminals swapped. I...
Many people said it couldn't be done so I saw a challenge. On the Audiofreaks forum I documented (in Dutch) my efforts in getting a dud Sony TA-4650 going again without having to resort to tying to get unobtanium 2SJ18/2SK60 SIT transistors. I decided to use IRFP(9)240 instead. Of course the...
Hey folks -
I guess I'm easily distracted... I've been working on my own copy of the @kward bench power supply, and in the back of my mind is this EL84M amp based on Heathkit AA-100 iron that I've been nudging along ever so slowly.
I've done a few design iterations of the power supply for the...
I have one and a half B&K ST-140 amps, and I'd like to convert them to a dual mono amp that would be similar in design (but not identical) to the older versions of the B&K EX-442. One of the amps I have now is the regular stereo model which I've already done some parts replacements and...
I have a Sennheiser HD598 headphone currently used with the headphone amp section of a Tianyun Zero DAC with very good results. Just for the fun of it, I decide to build a solid state separate headphone amp. I found the YuanJing assembled board at a very good price...
I picked up this "Dynaco Mystery Amp" from a fellow AK'er recently and found the boards are VanAlsine PC-489, and the outputs are Hitachi 2SK134 and 2SJ49 MOSFET's, but can't seem to find out anything more about it, like a model # or specs. Apparently it's about 55 WPC or so, based on the output...