LFazio51
Active Member
Hopefully that's not a "lurk" waiting for me to fail Bert!! lol! I'm sure I'll continue to run into more unexpected problems. Not the best design to "cut your teeth" on!
CR1020 Restoration Guidance
Hopefully that's not a "lurk" waiting for me to fail Bert!! lol! I'm sure I'll continue to run into more unexpected problems. Not the best design to "cut your teeth" on!
Bert 1100
Super Member
Definitely not
Just a very informative thread with great photos, that's all...
Keep up the good work, we all learn from such threads, even the masters were happy to get a part number for the Molex header !
Hey, it's no wonder a couple of traces lifted when you see how cooked the board is....
LFazio51
Active Member
Man it fits like a glove TOO!
Can't wait to get it installed so you guys can check it out!
Oilmaster
Sonycus Peritum
Bert 1100
Super Member
Oilmaster
Sonycus Peritum
Hereby an example of the TO-220 transistors (TR712/715) mounted on the chassis behind the VU meters.
I am not happy with the wiring that I did.....they might have been a bit longer and smaller gauge.
But it was the wire that I had in stock, and I had to return the unit to the owner.
The wiring would have been redone more charming if I had the time.
You'll need a shoulder washer under the screw and TO-220 SIL pad to isolate the metal back of transistors from the chassis
Some AKer did it nice(r) using a PC board type 3-pin connector for a cooling fan; that may work out very nicely indeed
I am not happy with the wiring that I did.....they might have been a bit longer and smaller gauge.
But it was the wire that I had in stock, and I had to return the unit to the owner.
The wiring would have been redone more charming if I had the time.
You'll need a shoulder washer under the screw and TO-220 SIL pad to isolate the metal back of transistors from the chassis
Some AKer did it nice(r) using a PC board type 3-pin connector for a cooling fan; that may work out very nicely indeed
Oilmaster
Sonycus Peritum
This was the board from a CR-2020 I did not long ago....I guess I was lucky
You were !
LFazio51
Active Member
WOW! You really know how to make a guy feel lucky Avionic - and I mean that sincerely!
Component Measurement & Testing
I've still got to remove the 10k 1/2wt resistor and both 4.7k bleed resistors but after that, I'm moving forward with the installation of new components. If there are some measurements that should be taken on these diodes, please share now while the board is relatively free of most components.
Lifted Pad Photo
Also, I have to share the dam pic of the trace I lifted while cleaning!! I'm so pissed over that - it's such a rookie mistake!! That's my last forey into being a "bull in a china shop" on this one!
Pad Bypass
Ok, the attached pic below indicates the path I'm taking to mitigate one of these lifted pads. I'm pretty sure I'll be ok doing this but will need to remove the "jumper," open the pcb hole a little more, and re-install both the jumper and 33ohm resistor. The circle indicates the location on the trace side of the board where the pad is lifted. I'd like to get someone's blessing on this before proceeding.
Component Measurement & Testing
I've still got to remove the 10k 1/2wt resistor and both 4.7k bleed resistors but after that, I'm moving forward with the installation of new components. If there are some measurements that should be taken on these diodes, please share now while the board is relatively free of most components.
Lifted Pad Photo
Also, I have to share the dam pic of the trace I lifted while cleaning!! I'm so pissed over that - it's such a rookie mistake!! That's my last forey into being a "bull in a china shop" on this one!
Pad Bypass
Ok, the attached pic below indicates the path I'm taking to mitigate one of these lifted pads. I'm pretty sure I'll be ok doing this but will need to remove the "jumper," open the pcb hole a little more, and re-install both the jumper and 33ohm resistor. The circle indicates the location on the trace side of the board where the pad is lifted. I'd like to get someone's blessing on this before proceeding.
Oilmaster
Sonycus Peritum
Lifted Pad Photo
Also, I have to share the dam pic of the trace I lifted while cleaning!! I'm so pissed over that - it's such a rookie mistake!! That's my last forey into being a "bull in a china shop" on this one!
It's not you, it's the rather poor board quality (it may happen with any other board in that unit, be aware).
Regarding that track issue, I would scrape off the green solder mask from the failed isle toward the next isle (where the jumper arrives), install the new resistor at normal location, then bend the leg across the nude track and solder the whole thing up.
If you are worried about that track coming off sooner or later, the trick is to 'squeeze' the PCB between two sides.
Difficult to explain, but it takes a relatively cheap "lead forming tool" that creates a "kink" in the resistor's leg.
When you then bend the leg on the solder side, the PCB is then squeezed between two sides of the leg.
https://www.ebay.com/itm/1-pcs-Plie...231841?hash=item2848275fe1:g:T1kAAOSwcj1aIRsC
(this model can be found half price elsewhere)
Regarding the diodes: a serious assessment would take a load test, which will be out of your reach.
But using the diode test function on a regular multimeter should give 0.50~0.60 volt in one direction only.
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Oilmaster.....WOW! You really know how to make a guy feel lucky Avionic - and I mean that sincerely!
LFazio51
Active Member
You were !
As I sit and consider all comments in this thread, I can't help but wondering, AM I REALLY THAT LUCKY?
I'm still on the E.Cap board and one (and every AKer familiar) can only speculate what other obstacles will be encountered. I believe these units sound good but I'm not sure that they perform well enough to endure every difficulty they present when considering there are lots of good sounding receivers in this era. But as you indicated earlier, once I get to my Marantz 2265, LIFE WILL BE GOOD! ...if this unit doesn't become the reason I ditch the hobby first!! 
I just use scrap component lead clippings.
Mrv8q
Audiofool
You guys are scaring me with the pix of those boards! I will open my 1020 now with trepidation, but really,
my hat is off to all who have posted, commented, advised, and taken great photos!
Looks like it will be next year before I get back into my 1020 to heal a diminished left channel.(Already done the
Deoxit shuffle).
my hat is off to all who have posted, commented, advised, and taken great photos!
Looks like it will be next year before I get back into my 1020 to heal a diminished left channel.(Already done the
Deoxit shuffle).
LFazio51
Active Member
Power Supply C. Board -1: Proposed changes to TR712/715 for improved cooling
Oilmaster and others have proposed and alternate location for TR712/715 to gain efficiency in cooling. This seems to be a very interesting modification considering the heat generated by both these particular components and overall design. And while the option to mount these just beneath the panel meters on the horizontal flat plate would appear to be a good one, it seems a location requiring less modification may be appropriate as well. This led me to consider the primary heat sink. It seems that if you could fabricate a bracket that would attach to the existing bolts, extend horizontally, then elbow down, so that the transistor could use the external surface for both a mount and cooling, you would improve overall cooling in a manner less invasive to the original design. Upon further consideration, I decided to make a quick prototype (see pics below) to get the old creative juices flowing. I took some scrap 1/8" aluminum, some quick measurements, and began to cut and bend. I was worried that the heatsink bolts would not be long enough to add another 1/8" created by the aluminum, but I was able to get a few turns and secure both the bracket and heatsink back to the frame. Unfortunately, 1/8" is the maximum height you can add, which leaves no room for anything isolating this bracket if desired.
CONSIDERATIONS:
This location appears to be extremely appropriate at first glance but I believe its necessary to consider the effects of heat developing from the main heatsink and its transmission to the bracket, ultimately heating the transistor. It seems obvious that the transistor rate of cooling would need to outpace the heat transmission from the main heatsink. I feel the design of the bracket, along with it's coupling to the main heatsink, can reduce or eliminate this issue entirely. An insulator of some kind inserted between the bracket and main heatsink would significantly reduce the transfer of heat. Adding additional surface area should also help the heat generated by the transistor AND heatsink for which it's mounted, cool much quicker, therefore, cutting some "fins" into the sides would seem appropriate (see hand sketches below).
Overall, I believe this is a reasonable idea but am certain it can be better, especially with the input from those monitoring this thread. I also believe it makes this thread more interesting, which is always a good thang! Please understand, I'm well aware that these modifications are not nearly as necessary as those associated with the CR2020, I'm simply enjoying the hobby and viewing this modification as a way to build skills. Hopefully this idea will peak some interest and get everyone's creative juices flowing and the net result is something for all to use. So, please comment freely and provide as much direction and constructive advice as possible.
Prototype Pics
Hand Sketch of Proposed Changes
Oilmaster and others have proposed and alternate location for TR712/715 to gain efficiency in cooling. This seems to be a very interesting modification considering the heat generated by both these particular components and overall design. And while the option to mount these just beneath the panel meters on the horizontal flat plate would appear to be a good one, it seems a location requiring less modification may be appropriate as well. This led me to consider the primary heat sink. It seems that if you could fabricate a bracket that would attach to the existing bolts, extend horizontally, then elbow down, so that the transistor could use the external surface for both a mount and cooling, you would improve overall cooling in a manner less invasive to the original design. Upon further consideration, I decided to make a quick prototype (see pics below) to get the old creative juices flowing. I took some scrap 1/8" aluminum, some quick measurements, and began to cut and bend. I was worried that the heatsink bolts would not be long enough to add another 1/8" created by the aluminum, but I was able to get a few turns and secure both the bracket and heatsink back to the frame. Unfortunately, 1/8" is the maximum height you can add, which leaves no room for anything isolating this bracket if desired.
CONSIDERATIONS:
This location appears to be extremely appropriate at first glance but I believe its necessary to consider the effects of heat developing from the main heatsink and its transmission to the bracket, ultimately heating the transistor. It seems obvious that the transistor rate of cooling would need to outpace the heat transmission from the main heatsink. I feel the design of the bracket, along with it's coupling to the main heatsink, can reduce or eliminate this issue entirely. An insulator of some kind inserted between the bracket and main heatsink would significantly reduce the transfer of heat. Adding additional surface area should also help the heat generated by the transistor AND heatsink for which it's mounted, cool much quicker, therefore, cutting some "fins" into the sides would seem appropriate (see hand sketches below).
Overall, I believe this is a reasonable idea but am certain it can be better, especially with the input from those monitoring this thread. I also believe it makes this thread more interesting, which is always a good thang! Please understand, I'm well aware that these modifications are not nearly as necessary as those associated with the CR2020, I'm simply enjoying the hobby and viewing this modification as a way to build skills. Hopefully this idea will peak some interest and get everyone's creative juices flowing and the net result is something for all to use. So, please comment freely and provide as much direction and constructive advice as possible.
Prototype Pics
Hand Sketch of Proposed Changes
