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Couple 'O 700M Nudies

Zeners are cheap, and are high-failure items. The 700M has no offset adjust, so that accounts for replacing four of the transistors. The other two are relay drivers.
 
rockin1150 said:
Damn, I shouldn't have read this post with all my OCD tendencies... now I want to rip apart the denon.... Why replace zeners and transistors? those values fade with time too? what actually holds up to the test of time in an amp? It seems not much. I bet some repair guys go even further, like replacing wiring and other goods..

Good job Glenn, as always...
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I am right there with you! With my OCD if I were to create a BASIC program for the last 3 years of this hobby it would read:

10 Read AK
20 Put unit on bench for performing upgrade
30 go to 10

With people here like Glenn it's so easy to get caught in the neverending loop! First it was replacing capacitors, then fuse resistors, then relays, then dc/bias pots, then ripple filter caps, then mylar caps, then... then... then.....!
 
I will add I just finished restoring my 700M in a similar manner (didn't notice the bias bypass cap until today) and it sounds wonderful! Thanks to EW for all the pointers.
 
EchoWars said:
700minternalparts5rj.jpg

The 2.2µf 250V metal polyester caps on the large power supply filter caps are added, and you can see the 1.5µf 250V rust-colored metal polypropylene caps on the driver boards which replace the stock 1µf Mylar cap.
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It looks like there's female connectors for the bypass caps. Is that for "dial-a-cap" purposes, sort of like installing sockets for opamps and ceramic filters?

John
 
I'm not at all sure what you're referring to, but all caps are either soldered in place, of connected with a ring terminal and bolt.
 
EchoWars said:
I'm not at all sure what you're referring to, but all caps are either soldered in place, of connected with a ring terminal and bolt.
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That's sort of what I was talking about. Couldn't tell from the pic that they were ring terminals that the cap leads go into, but it does have me thinking, since they are for bypassing, could you get away with not soldering them in place, at least temporarily, to experiment with different brands, values, types, etc. until settling on what sounds best, and then solder for stability/continuity?

John
 
You're making an assumption that they have some major effect on sonics. They don't. Their addition is theoretically and mathematically grounded, but their effect on sonics is a bit more 'pie-in-the-sky'. I put 'em in because it's the right thing to do, but as far as auditioning bunches of caps I really have a lot better things to do. ;)
 
EchoWars said:
You're making an assumption that they have some major effect on sonics. They don't. Their addition is theoretically and mathematically grounded, but their effect on sonics is a bit more 'pie-in-the-sky'. I put 'em in because it's the right thing to do, but as far as auditioning bunches of caps I really have a lot better things to do. ;)
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As I've only started to add filter bypass caps I was just curious since some folks like certain brands over others, polypropelene vs polyester vs...

I've typically used whichever is cheapest in the value I want from the major brands figuring that they'll be equally good.

John
 
jheu02 said:
I've typically used whichever is cheapest in the value I want from the major brands figuring that they'll be equally good.
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There's no sense in spending a lot of money here. The Panasonic metallized polyester caps I use do a fine job, and are cheap. I suspect that the less someone knows/understands about electronics, the more money they will spend. ;)
 
EchoWars said:
Typical pile 'O parts replaced in a 700M restoration...

700mpartsreplacementex9.jpg


31 electrolytic caps
10 resistors
6 transistors
4 zener diodes
3 relays
2 Mylar film caps
2 trimpots
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Glenn, which resistors do you usually replace? Can you tell their location and part #? Thanks.
 
Offhand, no. I just look for heat-discolored resistors, or resistors that have been glopped in assembly glue and replace them.
 
Karl vd Berg said:
Unfortunately all the pics are gone by this date...

Here via the 700C nudies thread which are awesome...
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Any chance the pics of the 700M can be re-posted or refreshed in this old thread?? (Or are they somewhere else?)

Would love to have that to accompany the 600C pics that are still visible......

I am finding the information very helpful in my recap / refurbish process. Thanks!
 
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