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SAE MK 31B Amplifier Resistor Question

cemerson

cemerson

Active Member
This may be a stupid question, but I have a few burnt resistors on a XXXIB I picked up a while back and most are listed in the Parts List as being 1/3W. Since it appears that these are no longer available (or I don't know where to look for them), is the best option going to a 1/4W or 1/2W? I'd rather not stray too far from the designers intent. I've been able to find everything else I need to get it going and I'm down to these resistors that need replaced.

Thanks, Chris
 
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I rebuild a lot of these, strip and start over is what I usually do. I use 1/2W metal film in all places except for the larger Wattage resistors. Depending on which resistors are bad you can probably bet that there are some bad transistors also. The driver and protection transistors are no longer available so I use 2SA1837 and 2SC4793. Do you need the Service Manual?

Craig
 
llwhtt said:
I rebuild a lot of these, strip and start over is what I usually do. I use 1/2W metal film in all places except for the larger Wattage resistors. Depending on which resistors are bad you can probably bet that there are some bad transistors also. The driver and protection transistors are no longer available so I use 2SA1837 and 2SC4793. Do you need the Service Manual?

Craig
Click to expand...

craig: i have one that needs work so i could use the service manual. thanks in advance.
 
Craig,

Thanks, this helps me a lot. I was planning on replacing all the transistors and have located them over time. I have a copy of the service manual I've been working off of. It's not a really complicated little amp, and fortunately doesn't have an over abundance of parts, so the strip & start over method was going to be my approach.

Thanks again, Chris
 
They are 40+ years old and possibly many paws have been in them over the years. Let me know if you need any parts info.

MUSCMP, where do you want me to send the Service Manual? Where in SoCal are you?

Craig
 
llwhtt said:
They are 40+ years old and possibly many paws have been in them over the years. Let me know if you need any parts info.

MUSCMP, where do you want me to send the Service Manual? Where in SoCal are you?

Craig
Click to expand...
craig: i assumed you meant via pdf file but i am in ventura county. i'll send whole address in a PM. thanks, mikeB
 
cemerson said:
This may be a stupid question, but I have a few burnt resistors on a XXXIB I picked up a while back and most are listed in the Parts List as being 1/3W. Since it appears that these are no longer available (or I don't know where to look for them), is the best option going to a 1/4W or 1/2W? I'd rather not stray too far from the designers intent. I've been able to find everything else I need to get it going and I'm down to these resistors that need replaced.

Thanks, Chris
Click to expand...
No question should be considered stupid! If you think about fractions 1/3 is more than 1/4 so 1/2 which is more than 1/3 is the winner.
 
hamrules said:
No question should be considered stupid! If you think about fractions 1/3 is more than 1/4 so 1/2 which is more than 1/3 is the winner.
Click to expand...
In some applications.. ie fusible resistors -- going larger may be flirting with disaster.;)
 
llwhtt said:
I rebuild a lot of these, strip and start over is what I usually do. I use 1/2W metal film in all places except for the larger Wattage resistors. Depending on which resistors are bad you can probably bet that there are some bad transistors also. The driver and protection transistors are no longer available so I use 2SA1837 and 2SC4793. Do you need the Service Manual?

Craig
Click to expand...
Was given a SAE 31B AMP with a loud hum coming from the unit w/o speakers attached. I opened up the unit and found a grey color lead from the transformer just sitting unattached. At the end of the lead is a spade type connector. Any idea if this is supposed to be attached and where? This is the second lead I found un attached the other being a black lead from the transformer that had come unattached from the fuse holder (its now reattached).
 

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Do you want the Service Manual to help figure out the wiring? It's hard to tell what's going on from the picture. PM me with your email.

Craig
 
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