Pioneer Tuner/Amp repair [FIXED]

[on4top]

i got bd249 .. but that's tooo beefy

bd139 i should find in someones junk box

[KhronX]

To be on the safe side (and i'm a bit "OCD" about symmetry ), i'd replace both of them (ie. on both channels).

Since mzacharias said they often fail, might as well save yourself some headaches down the line

[on4top]

yep that is the plan ..

wil order some now ..  just want a proof of concept now en see both channels working

will have to wait until next week ..

[mzacharias]

Late '90s Pioneer stereo and surround receivers were rife with the things. Noisy channels, protection issues, etc. Due to difficulty for access to replace them, it was standard to replace all of them in a given unit. A five-channel model might get 20 transistors replaced in total, mainly to prevent re-do's and similar future problems. Seems the transistors were somewhat "stressed" over time by circuit voltage etc. I asked our Pioneer service rep if there was any recommended upgrades - there were none. Guess they just "didn't care" to re-engineer or research proper substitutes.

[KhronX]

Even though those long TO92 package are rated for 1W usually, it's still a bit of a stretch, in VAS duties. TO126-packaged ones are more usually seen (in more "proper" designs)

[on4top]

seems i was lucky yesterday ..

local electronics store had  2 pairs of them on stock ..  2,40euro a piece ..

swapped them yesterday night ..

https://www.youtube.com/watch?v=8iUOQ0PnjG8&feature=youtu.be

Now stress testing ...

Thanks everyone here on eevbog forum for your input !    I learned a lot with this repair  ..

Happy new year !

[mzacharias]

Even though those long TO92 package are rated for 1W usually, it's still a bit of a stretch, in VAS duties. TO126-packaged ones are more usually seen (in more "proper" designs)

Glad that worked out for you!