Hello all, I was given a Marantz 500 that was in pretty bad condition. Taking the top off you could immediately see components that had exploded, several burnt to a crisp. I decided to go ahead and completely tear it down and rebuild it. It was fully recapped, all tantalums were replaced, all carbon comp resistors were replaced, pretty much all diodes in the power supply replaced, new relays, and even though the outputs were measuring okay they were replaced with new On-Semi transistors that are more robust.
Anyways, I’m the driver board there are two transistors, Q117 and Q118, that have diodes (Fairchild FH1100) strapped across them and are thermally connected with compound. One board have the devices that are labeled in the manual, 2N5415 and 2N3440 with the FH1100 across them. I noticed on the other board in place of the FH1100 there were 1N4001s. I was told by a forum member well acquainted with this Marantz that the FH1100 is a hot carrier and the 1N4001 will not work in that position. The transistors under those 1N4001 were different as well, got to looking and nearly all of the transistors on the board are different than the other board, but the solder joints look stock.
Anyways, on the other board for Q117 and Q118 they are using 2N5322 and 2N5320. It took me awhile, but I for the correct FH1100 hot carrier diodes. Not I just need to know if these transistors will work in this circuit as the specs between the transistors are different. If the 25322/2N5320 will work I can finally move on. I’m hoping to get some input as I don’t want to put the amp all together only to tear it all apart when it won’t work.
Thank you for any help!
Dan
Anyways, I’m the driver board there are two transistors, Q117 and Q118, that have diodes (Fairchild FH1100) strapped across them and are thermally connected with compound. One board have the devices that are labeled in the manual, 2N5415 and 2N3440 with the FH1100 across them. I noticed on the other board in place of the FH1100 there were 1N4001s. I was told by a forum member well acquainted with this Marantz that the FH1100 is a hot carrier and the 1N4001 will not work in that position. The transistors under those 1N4001 were different as well, got to looking and nearly all of the transistors on the board are different than the other board, but the solder joints look stock.
Anyways, on the other board for Q117 and Q118 they are using 2N5322 and 2N5320. It took me awhile, but I for the correct FH1100 hot carrier diodes. Not I just need to know if these transistors will work in this circuit as the specs between the transistors are different. If the 25322/2N5320 will work I can finally move on. I’m hoping to get some input as I don’t want to put the amp all together only to tear it all apart when it won’t work.
Thank you for any help!
Dan
Attachments
I don't know whats going on here --are you sure BOTH boards are the same and the Q numbers are related to the same components in each board ?
The reason I say this is the older BJT,s you quote are not even near equivalents--different hfe bias for a start etc etc .
If the schematic you have provided is the genuine article then that is the only honest amount of information you have .
In cases like this you revert to ORIGINAL specs.
It looks like somebody has modded a board I always go by original design to locate a fault not somebody fitting different components thinking - "this will make it better ".
The reason I say this is the older BJT,s you quote are not even near equivalents--different hfe bias for a start etc etc .
If the schematic you have provided is the genuine article then that is the only honest amount of information you have .
In cases like this you revert to ORIGINAL specs.
It looks like somebody has modded a board I always go by original design to locate a fault not somebody fitting different components thinking - "this will make it better ".
Thank you for the reply, yes both boards are identical as far as traces go, same circuit. As far as I can tell all of the resistor values are the same, same capacitor values, etc. The only difference I’ve found between them are the transistors.
Here is a photo of a list of the transistors on each board. The left column is labeled manual board as it matches the manual, then the right column is the the board I’m asking about. I highlighted in pink the ones that are different (don’t match). The ones highlighted in blue are Q117 and Q118, the transistors under the FH1100s.
Q103 and Q122 are clamped together so I can’t see their device numbers, but they definitely look like the match, they both have the same colored paint on them. Also attaching a photo of the schematic of this area. It would be a real pain to completely rebuild this one board as I’m sure there are devices I can’t get (don’t trust ebay, Chinese sites)
Dan
Here is a photo of a list of the transistors on each board. The left column is labeled manual board as it matches the manual, then the right column is the the board I’m asking about. I highlighted in pink the ones that are different (don’t match). The ones highlighted in blue are Q117 and Q118, the transistors under the FH1100s.
Q103 and Q122 are clamped together so I can’t see their device numbers, but they definitely look like the match, they both have the same colored paint on them. Also attaching a photo of the schematic of this area. It would be a real pain to completely rebuild this one board as I’m sure there are devices I can’t get (don’t trust ebay, Chinese sites)
Dan
Attachments
on high voltage VAS , MJE340 and 350 will do the job
I’m sorry, I don’t understand. Are you saying I should use the MJE340 and 350 in place of the 2n5415, 2N5322, 2an3440, 2N5320? If so, would I just make sure the FH1100 is touching the back of them? I happen to have them on hand.
Dan
Attachments
Just out of curiosity, I have way more of the KSA1381 and KSC3503 and wondering how they would do in this circuit.
It seems there were supposed to be a couple more 2N5415/2N3440 on these boards, but were replaced with MPSA92/MPSA43, Q110, Q111, Q112, Q113.
Would the KSA1381/KSC3503 work in those positions as well? Or maybe the MPSA92/43 were good.
Maybe use MJE15032/33/34/35 as super overkill?
Dan
It seems there were supposed to be a couple more 2N5415/2N3440 on these boards, but were replaced with MPSA92/MPSA43, Q110, Q111, Q112, Q113.
Would the KSA1381/KSC3503 work in those positions as well? Or maybe the MPSA92/43 were good.
Maybe use MJE15032/33/34/35 as super overkill?
Dan
Genuine MJE15032/33 are perfect in 1st stage of output darlington trio (predriver) , just before MJ15024/25 (driver) , and n MJ15024/25 (// output)