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rigel9999 16th September 2007 07:48 AM

Musical Fidelity P170 Blown Transistors
Would welcome any suggestions for alternatives for replacing blown Transistors, which are no longer available, in a 1988 Musical Fidelity P170 power amp.


AndrewT 16th September 2007 08:00 AM

I seem to recall these were Lateral FETs.
Can you confirm type numbers?

PMik 16th September 2007 09:15 AM

The original Hitachi 2SJ81/2SK226 (2SJ82/2SK227) is no where to find and this has been a fact for more than a decade ..., solution use Hitachi 2SJ162/2SK1058 notice these FET's have different housing (TO-3P)

AndrewT 16th September 2007 10:05 AM

Hi Rig,
is Pmik correct?
Are 2sj81/k226 the original fitment?

These are 2bolt Fpack packages.
The To247 Renases replacement are single bolt fixing and should be a straight swap. The Pin order is identical, but you'll need to move them sideways to align with one of the existing tapped fixing holes
2sj161/k1057 are the 140V equivalent.
2sj162/k1058 are the 160V equivalent, these are available from Rapid.

PMik 16th September 2007 10:30 AM

Yes they are the original ones
I have had so many of the MF P series in my hands ..., sure i know ;)

ANTHONY2181 16th September 2007 03:19 PM

I have some New 2SK343 and 2SJ99 pairs which look pretty similar in specs + they are the same package.



jaycee 16th September 2007 05:46 PM

Look at the Exicon range of mosfets from Profusion PLC

These are excellent replacements for the Hitachi originals. The ones in the TO-247 packaging should do.

rigel9999 18th September 2007 09:50 PM

Hi Andrew T,

I can confirm the originals are Hitachi 2SJ81/2SK226 (2SJ82/2SK227.

Thank you PMik and everyone else who took time to reply.


rigel9999 18th September 2007 09:50 PM

Hi PMik,

I still have one set of MOSFETS which are still intact. Should I purchase and replace the one blown pair or do you advise i replace both sets with the Hitachi 2SJ162/2SK1058?

Thank you

PMik 18th September 2007 11:39 PM

I would strongly advice you to change both pairs of MOSFET's to the 2SJ162/2SK1058 this to insure equal performance betwin the chanals ;)

An interesting detail regarding the 2SJ162/2SK1058 is the fact that the pair are equal to the 2SJ50/2SK135 pair
The 2SJ50/2SK135 where used in the MF B200, P140 and P150
Class AB standing current should be set for at least 100mA and imho for best sonic performance 200mA :)

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