Marko, this may not be of much help, but do you recall the last Tarantula monoblock I was posting about on the PG board? The one that the PS would intermittently come up and go down, sometimes oscillating on and off, and a very few times just working for a few minutes and then not.
I think the continuum is roughly the same era, so this may be applicable, but it may not. I'd have to see the prints. Anyhow, the Tarantula uses several p-channel j-fets to drive both one side of the SG3524's error amp and the thermal/OL protection which pulled down the comp pin if I recall correctly. Anyhow, someone had brilliant plan of swapping out all of the JFETs with PNP small signal transistors. I didn't catch it for a long time, because the JFETs were to-92 case as well and the bjts. For some reason, the BJT's allowed for erratic operation, the few times the supply worked, the amp would hunt for it's impedance range which was caused by more JFETs subbed with BJT's.
Like I say, it may be way off base, I have never looked at the continuum before, but it is something to check closely, especially if you already found some subbed parts.
Later,
Jason
I think the continuum is roughly the same era, so this may be applicable, but it may not. I'd have to see the prints. Anyhow, the Tarantula uses several p-channel j-fets to drive both one side of the SG3524's error amp and the thermal/OL protection which pulled down the comp pin if I recall correctly. Anyhow, someone had brilliant plan of swapping out all of the JFETs with PNP small signal transistors. I didn't catch it for a long time, because the JFETs were to-92 case as well and the bjts. For some reason, the BJT's allowed for erratic operation, the few times the supply worked, the amp would hunt for it's impedance range which was caused by more JFETs subbed with BJT's.
Like I say, it may be way off base, I have never looked at the continuum before, but it is something to check closely, especially if you already found some subbed parts.
Later,
Jason
made a little progress today, got one of the front channels working then tried to get the other one working but there was distortion and the ps went crazy, realised the little yellow cap was missing 
never spotted that before! in hind sight i should of used a 10amp fuse but i plan to replace all ps fets anyway 
there's a lesson there about not clamping to heatsink and being complacent..
i'm still stumped as to why i can't get the amp to turn on without jumping pin 1 replaced TS2 and went over all solder connections but still no luck..
if i can get the amp to turn on OK and 2 channels working i'll be very happy
Mark.
never spotted that before! in hind sight i should of used a 10amp fuse but i plan to replace all ps fets anyway there's a lesson there about not clamping to heatsink and being complacent..i'm still stumped as to why i can't get the amp to turn on without jumping pin 1
replaced TS2 and went over all solder connections but still no luck..if i can get the amp to turn on OK and 2 channels working i'll be very happy
Mark.
Morning Marko,
I have seen the ceramic disk caps go shorted and they appear to be connected across the rails to ground. I have seen this failure before on SS products all though rarely I do recall having to replace these before and they did pull huge current while in circuit and shorted to ground. try Mylar caps they should work fine if you got any laying about. I believe these are simple noise bypass/decoupling caps and they do take a beating from high frequency noise from the switching supply. I also recall replacing these on McIntosh amps also, and tantalum caps on Orion's used to bypass the supply rails to ground... just pulling on old memories lol..hope this helps some..C
made another bit of progress today, after damaging the PS i figured out why one side of the FETs kept blowing, A1562 was bad on one side, this took quite a bit of figuring out as it was ohming out OK in and out of circuit but presenting an open circuit at the actual fets. only way i worked it out was to swap it out for the other A1562 and the problem followed! so with a new A1562 and a fresh set of PS fets the PS should be OK. any ideas what i can sub the A1562's out with?
still no joy with TS2 though
still no joy with TS2 though
There aren't many subs for the 1562. Use the original if it's available. Something like the MJE172 may work but would have to be installed facing the opposite direction due to the reversed pin configuration.
The problem with TS2 is likely insignificant. Get all channels working properly, then we can troubleshoot the protection circuit.
The problem with TS2 is likely insignificant. Get all channels working properly, then we can troubleshoot the protection circuit.
typically the spare board i have that is shot has the 1562's missing! at least i'm on the right track now
next on the to do list is get 6 working FEB boards, some are missing and i do have some used and new ones but not sure how to fully test them, i noticed the 50ohm resisitors blow out but not sure on what else that's a common failure..
next on the to do list is get 6 working FEB boards, some are missing and i do have some used and new ones but not sure how to fully test them, i noticed the 50ohm resisitors blow out but not sure on what else that's a common failure..
4 weeks on and I finally get my parts from Jaime! and it's good news, I have a working Continuum!! she idles at 1.2amp with brand new PSU fets and a bunch of other new parts
only one more problem to figure out then I can put her back together and add it to my SS collection, TS2 still needs an earth "jump" to pin 1 to fire up, tried a different thermal switch from my spares amp but still the same..
Mark.
only one more problem to figure out then I can put her back together and add it to my SS collection, TS2 still needs an earth "jump" to pin 1 to fire up, tried a different thermal switch from my spares amp but still the same..
Mark.
so if I permanently bypass this switch it will be of no harm? the switch is closed so I'm guessing working OK, just when the amp powers up it goes into some kinda protection after a second or too..
I have followed the trace from earth through TS2 then R171/R169 and all is fine up to pin1, I even changed C78 too..
EDIT- as C78 not 82, was close to other..
I have followed the trace from earth through TS2 then R171/R169 and all is fine up to pin1, I even changed C78 too..
EDIT- as C78 not 82, was close to other..
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After a bit of reading, it appears that this amp has a thermal rollback. This thermostat (TS2) is the one responsible for that rollback.
With the amp in otherwise good working order, unless there is a design flaw in the amp, the amp should operate without the thermal in place (with TS2 missing or open when the amp reaches the rollback point the circuit is the same). It may have another fault or there could have been some changes in the amps that won't allow the thermal rollback to function (I've seen a LOT of factory mods on SS amps).
The thermal switch will have to be a normally closed switch. If the one you have is open until you heat it, it's the wrong thermostat.
As the amp is now, instead of going into rollback, the proper thermostat would cause it to shut down completely.
I don't think that it will cause any problems if you leave it jumped out. Unless you abuse the amp, it's unlikely that it would ever reach the rollback point.
With the amp in otherwise good working order, unless there is a design flaw in the amp, the amp should operate without the thermal in place (with TS2 missing or open when the amp reaches the rollback point the circuit is the same). It may have another fault or there could have been some changes in the amps that won't allow the thermal rollback to function (I've seen a LOT of factory mods on SS amps).
The thermal switch will have to be a normally closed switch. If the one you have is open until you heat it, it's the wrong thermostat.
As the amp is now, instead of going into rollback, the proper thermostat would cause it to shut down completely.
I don't think that it will cause any problems if you leave it jumped out. Unless you abuse the amp, it's unlikely that it would ever reach the rollback point.
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