I’ve started work on the power board, however, I’ve heard of people snapping these heat sinks protecting H: 709, 710, 711 and 712. Any suggestions please on how to remove safely. Also, may I have some suggestions on a good replacement transistors pair that will fit in the heat sinks?
thanks in advance for any suggestions
thanks in advance for any suggestions
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Have those transistors failed? I'm an old fart who worked at a store that
sold new 1060s in the early '70s and I was the service tech. I always
cringe when I read about willy nilly transistor and resistor replacement
for reasons that can't be explained. If that was mine I would unsolder
the transistor from the board and LIGHTLY wedge the heat sink to reduce
the tension and push the old transistor out. Same procedure install on the
new device. My tools and techniques have improved a lot since those days.
My 700° F Metcal tips might be too much for those old boards and would
use a 600° or even 500° tip to avoid lifting pads. Good luck
G²
sold new 1060s in the early '70s and I was the service tech. I always
cringe when I read about willy nilly transistor and resistor replacement
for reasons that can't be explained. If that was mine I would unsolder
the transistor from the board and LIGHTLY wedge the heat sink to reduce
the tension and push the old transistor out. Same procedure install on the
new device. My tools and techniques have improved a lot since those days.
My 700° F Metcal tips might be too much for those old boards and would
use a 600° or even 500° tip to avoid lifting pads. Good luck
G²
Hi mate and thanks for this reply, both have failed on the left channel as have the main 2sc897’s. I’ve had them out to test them
also, wonder if you can help with main transistors actually, (2sc897) a suitable replacement seems to be the on semi mj21194g but there out of stock at reputable suppliers, don’t suppose you have any ideas?
cheers, J
Hey Julian, you might do as stratus said, but I think my approach is easier, for removing heatsinks atleast, so, with transistors still onboard use small flat screwdriver and put it into slot on heatsink, turn it slightly to widen gap on heatsink, and pull it. With little bit of luck it would easily slide off... ofcourse you must be careful not to use excessive force...
As for replacements, here you can find some sugested replacements https://www.vintageshifi.com/marantz-1060-2.php
And for outputs 21194 are widely used but I suspect 15003, or even ancient 2n3055, would work, just doublecheck SOA and other parameters
👍
As for replacements, here you can find some sugested replacements https://www.vintageshifi.com/marantz-1060-2.php
And for outputs 21194 are widely used but I suspect 15003, or even ancient 2n3055, would work, just doublecheck SOA and other parameters
👍
nps m8 😉
oh I forgot, as stratus said earlier, be careful with soldering gun, those old boards don't like heat toomuch 😵
btw what are you up to, just repairing unit or refurbishing?
oh I forgot, as stratus said earlier, be careful with soldering gun, those old boards don't like heat toomuch 😵
btw what are you up to, just repairing unit or refurbishing?
If it were mine I'd use 2N5320 for the 2SC969, 2N5322 for the 2SA606 and
MJ15015G for the 2SC897. The MJ21194G is a good choice but the MJ1501G
is nearly as good and still significantly higher than the 2SC897s. Best of all, all
are in stock at DigiKey and can be shipped tomorrow. All are exact physical
replacements.
G²
MJ15015G for the 2SC897. The MJ21194G is a good choice but the MJ1501G
is nearly as good and still significantly higher than the 2SC897s. Best of all, all
are in stock at DigiKey and can be shipped tomorrow. All are exact physical
replacements.
G²
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I disagree on removing the heat sinks while still on the board. A pad may lift from
the mechanical stress or at least weaken the bond. Best would be to clip the leads first
since the transistors are already dead but that looks to be nearly impossible. Prime
consideration here is no board damage and no heatsink damage.
G²
the mechanical stress or at least weaken the bond. Best would be to clip the leads first
since the transistors are already dead but that looks to be nearly impossible. Prime
consideration here is no board damage and no heatsink damage.
G²
No. Anything but a 15015. It may be rugged enough but current gain is **** poor. Its a high voltage version of the 2N3055, which falls like a stone above 4A to begin with. All else being equal, hFE is inversely related to breakdown voltage. I’ve measured 7 at 7 amps, which is hell on the drivers. They are not ALL that bad but you can end up with them. I would use 15003 if buying new - go to the bigger ones if they’re out of stock.
If all else fails, use wires and put transistors in a commonly used package on a separate commonly available heat sink, and fix it to the chassis.
Then you have more choice in transistors, TO-220 package may be the choice of others here.
That uses screws, or clips, so a little bit more reliable than these heat sinks.
Maybe better heat dissipation from a bigger heat sink, so they will run cooler.
Use higher rated transistors for more reliability.
Then you have more choice in transistors, TO-220 package may be the choice of others here.
That uses screws, or clips, so a little bit more reliable than these heat sinks.
Maybe better heat dissipation from a bigger heat sink, so they will run cooler.
Use higher rated transistors for more reliability.
The oroginal 2SC897 is rated for a maximum of 7Amps. The 15015 is nominally at
20 at 25°C at 7 Amps. It's not the best choice but not as bad as you make out.
Keep in mind the 2N drivers are capable of more drive than the originals. Point is
the amp could be running reasonably well by Friday. Check page 3 of the Onsemi
datasheet. Let us know what you find for output transistors.
This unobtainium stuff is bugging me too. Try and get an OPA2134. I'll be using
OPA2132s instead. CMOS serial EEPROMs are available but not in the preferred
packages. It will work but it requires extra diddling around to get it going.
G²
20 at 25°C at 7 Amps. It's not the best choice but not as bad as you make out.
Keep in mind the 2N drivers are capable of more drive than the originals. Point is
the amp could be running reasonably well by Friday. Check page 3 of the Onsemi
datasheet. Let us know what you find for output transistors.
This unobtainium stuff is bugging me too. Try and get an OPA2134. I'll be using
OPA2132s instead. CMOS serial EEPROMs are available but not in the preferred
packages. It will work but it requires extra diddling around to get it going.
G²
Started off as repair and service, I bought it with one channel faulty. Now I’m doing a major refurb lol, you know how it goes, you sometimes get carried away 😂
They are a good replacement and original NOS Motorola /On Semi 2N3773 TO3 devices can still be found if you hunt around - and I don't mean in China!
These were used in a lot of output stages years ago.
These were used in a lot of output stages years ago.
That’s half the problem deciding what are real or fakes.
Farnell and RS have 2n3773 in stock. Does the (G) suffix have any relevance?
cheers J
These were very popular in the US and some sellers there still have NOS.
Do RS and Farnell mention that the stock they have are On Semi?
Do RS and Farnell mention that the stock they have are On Semi?
Presently, Farnell stock both Onsemi and Multicomp TO3 power transistors, the latter brand meaning sourced from any one of a number of manufacturers of generic semis. RS components stock only Onsemi power transistors, as far as I can tell. You only need specify the respective catalog numbers to ensure you get what you want, as available from stock in any case.
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Of note is the fact that the On Semi device is more than double the price of the generic types at Farnell (Element 14) but still cheaper than the RS On Semi price.
This is really good to know.
do you think there is any discernible difference between the on semi and equivalent generic option Gary?