Discussion in 'Marantz Audio' started by AsRock, Apr 27, 2018.
KSC1845. Ideally all 2SC458s should be replaced but wait until this is working.
Thanks all, and @catrafter (PMs)
Have only the working module in. I am now getting sound though the right channels ( Main Front \ Remote Front ), the other module was coursing a short at the relays stopping all from working before.
Getting stereo though the front headphone socket still and nothing though the rear headphone socket,
Compered both P700 boards and finding nothing else majorly different, there are 6 transistors that show as a short on each while in circuit so to be sure i removed them all and tested each one and found no shorts.
KSC1845 has a 13 week lead time so nothings going be added until at least that time lol.
Was thinking of checking the slot the cards plug into as well see if the voltages and such are the same too.
Did i miss some thing ?.
There is some thing i need and that's the 4 screws that hold the card slots in place, the ones i have barely do it and do not hold up at all. I thought i had found some good replacement's ( same thread ) but were to long.
Looked in the SM and they are 1822 and says they are B.H.M screws no size of any kind. I think i will just go the hardware store and take one of the screws that did fit, and they fit really well.
If mouser is out of KSC1845s, check eBay.
Put a back order in for 100,. i can wait.
OOh look what i got early, figures though as i put it away then these pop up . Just after some fire resistant 1/2w 100Ohm resistors now.
As just buying a few resistors it's going cost like $5 so was thinking of replacing the caps on the power board (P800), and wanted to know which i should pick for the unit.
Well went though 80\100 of them listed the hfe \ Vbe \ IB and the gains much lower so i am asking is this going be a issue for any other part of the boards.
The one original that is working has hfe of 97 now the replacements have at least a hfe of 371
hfe 97 \ VBE 0.766 \ Is 4.194
Best match i can find
370 \ 0.741 \ 4.217
371 \ 0.741 \ 4.217
Question, should the 4 pots on the board be changed as 2 of the main transistors have been replaced ( anticlockwise minimum ? )
well like to thank all those who have helped so far with this. The resistors have been replaced along with the transistors.
The channels work, how ever the left channel has distortion which i have found out that is due to 2sb527 transistor being faulty. I don't really know how to go about this as that part is tricky to get hold of today, any thoughts would be nice.
Suggested parts, although the person who told me was not 100% positive.
2N4920G for the 2SB527
2N4923G for the 2SD357
what board id for those ?
i see one of the drivers is
check out bd140 and pair with bd139 .
Thanks for getting back to me, sadly i have decided to call it a day with the unit, and maybe i can find some one who has the one transistor it needs to solve it's issue and keep it more original.
So Big thank You to @petehall347 , @EastPoint , @mbz , @jstang , @wlhd1610 @catrafter and Mark @ Blueglow Electronics ( if i missed some one sorry ).
How ever there are 2 more things i am planning for the unit and that's a replacement string for the tuner, so i can have a try of fixing that. And i just picked up some Vellum Diffuser Paper which i may give a try.
do what you can .. put it away for a while and work on something else for a while .. i have scrapped things in past that i could easily fix now with the internet as a reference . i wouldn't get too hung up about original transistors unless it had to be that one for a rare reason . even then it can be worked around .
have also passed things on to folk that can fix it .
What transistor do you need?
Ooh not going scrap it, just like to keep it as original as possible, chances are i will sell it as i am more of a Yamaha person, how ever i did really want to hear what it had to give. More hung on keeping it as original as possible is due too the chance i will end up selling it and a buyer would get hung up .
IMHO as long as the unit is working most buyers will never know nor care that a modern replacement part was used. There is no premium paid for original transistors.
2SB527 —> MJE15033 or KSA1220
Or you can get one on eBay, but they’re Chinese and who knows.
Well just finished cleaning the front, replaced the vellum diffuser paper and replaced the cord string. Now selling it would be a issue again as it looks real nice. So going rap it up and put it away in the bedroom in a safe space ( no pun intended ) as we all know what happens to stuff in the basement \ loft.
Hopefully i will come across that single part some day. Appreciate all the info\help from those who helped.
Looks nice. Inspires me to work on mine, purchased from a repair shop in 1981, passed on to my brother in 1987 with issues and reacquired in 2017.
I have an amp board here. let me know if you would like one of the 2SB527s out of it.
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