Awesome wealth of knowledge.
I just picked up one of these, with several problems, maybe even burnt. Not powering it up yet without checking it and cleaning it a little.
How does the thing come apart. Do you have to take the face off, or if it easier to take the back off and removing the top.
Thanks.
Srinath.
I just picked up one of these, with several problems, maybe even burnt. Not powering it up yet without checking it and cleaning it a little.
How does the thing come apart. Do you have to take the face off, or if it easier to take the back off and removing the top.
Thanks.
Srinath.
Hi Srinath,
Take the two end covers off. The case will then split apart. You'll have to disconnect various things from the outside covers to get at everything. The biggest issue is normally cleaning out 20+ years of dust bunnies and possibly greasy deposits. At this age, I often take the amplifier apart and clean the heat sinks once I determine what the current state of it is. Don't try this with a Carver cube!
-Chris
Take the two end covers off. The case will then split apart. You'll have to disconnect various things from the outside covers to get at everything. The biggest issue is normally cleaning out 20+ years of dust bunnies and possibly greasy deposits. At this age, I often take the amplifier apart and clean the heat sinks once I determine what the current state of it is. Don't try this with a Carver cube!
-Chris
Yea and the fan really compacts the dust into some sort of fossilized layer. The thing is hard and crusty. Not easy to get off. Thanks, I'll try it and see.
Cool.
Srinath.
Cool.
Srinath.
Hi Srinath,
While working on this, take digital pictures and draw diagrams of anything you might need to know while putting it back together. Continue doing this as you work through the unit.
This has complimentary differential pairs that are typically out of match. They are flat bodied, 5 legged transistors. They can be replaced with a matched pair with a common emitter lead (that's why there are 5 leads instead of 6, b-c-e-c-b is the arrangement). If you can, try to get the beta (Hfe) matched for each pair, and also for the pair to pair sets.
The heat sink comes apart, so you can clean it like it was brand new. Wash in dish washing soap or with a Simple Green solution for the final rinse. You will need a solvent to dissolve the thermal compound. Replace with fresh thermal compound when you are putting it back together. If you do that, and replace the capacitors with new, then it will work as new once you have reassembled it. You should probably replace the speaker relay while you're in there. Check the bias, and the voltage across the speaker terminals. Note that this amplifier is actually four amplifier sections, each channel operated in bridged mode. That means that each speaker terminal is "hot", or driven. Shorting the black terminals together will generally cause damage and you cannot operate this amplifier in any bridged mode since it is internally already bridged.
I would highly recommend that these amplifiers are always connected directly to the speakers they will be driving. No in-wall volume controls, or any form of speaker switching! In other words, don't get creative when using these amplifiers. Just use them as directed, and never, ever play with speaker leads while the amplifier is powered up - ever. They are nice amplifiers.
-Chris
While working on this, take digital pictures and draw diagrams of anything you might need to know while putting it back together. Continue doing this as you work through the unit.
This has complimentary differential pairs that are typically out of match. They are flat bodied, 5 legged transistors. They can be replaced with a matched pair with a common emitter lead (that's why there are 5 leads instead of 6, b-c-e-c-b is the arrangement). If you can, try to get the beta (Hfe) matched for each pair, and also for the pair to pair sets.
The heat sink comes apart, so you can clean it like it was brand new. Wash in dish washing soap or with a Simple Green solution for the final rinse. You will need a solvent to dissolve the thermal compound. Replace with fresh thermal compound when you are putting it back together. If you do that, and replace the capacitors with new, then it will work as new once you have reassembled it. You should probably replace the speaker relay while you're in there. Check the bias, and the voltage across the speaker terminals. Note that this amplifier is actually four amplifier sections, each channel operated in bridged mode. That means that each speaker terminal is "hot", or driven. Shorting the black terminals together will generally cause damage and you cannot operate this amplifier in any bridged mode since it is internally already bridged.
I would highly recommend that these amplifiers are always connected directly to the speakers they will be driving. No in-wall volume controls, or any form of speaker switching! In other words, don't get creative when using these amplifiers. Just use them as directed, and never, ever play with speaker leads while the amplifier is powered up - ever. They are nice amplifiers.
-Chris
I managed to pull the top off, need to still blow it out. The top actually can be removed by taking the face off. I will blow clean it and see what it looks like, some spots look a bit like they have a broken solder joint. Else it seems to be OK. Hope it was as simple as that.
The 5 legged ones etc etc I'll look for next time I am getting in there.
The thing is, I dont need to clean the heat sink to where it looks new. Just to where it loses heat when that fan runs. The heat sink isn't visible, so I'd settle for just clean. Not clean and shiny.
I'll not be doing anything creative, those in wall speaker connections are all just crap to my eyes/ears. Stereo systems need to be where any component can be swapped out in a moments notice. So no in wall anything or in ceiling anything.
Thanks.
Srinath.
The 5 legged ones etc etc I'll look for next time I am getting in there.
The thing is, I dont need to clean the heat sink to where it looks new. Just to where it loses heat when that fan runs. The heat sink isn't visible, so I'd settle for just clean. Not clean and shiny.
I'll not be doing anything creative, those in wall speaker connections are all just crap to my eyes/ears. Stereo systems need to be where any component can be swapped out in a moments notice. So no in wall anything or in ceiling anything.
Thanks.
Srinath.
Hi Srinath,
I think you have to remove the heat sink to do any work on it. Could be wrong on that, it would be nice if I was. You can remove the heat sink without taking it apart. Get it as clean as you reasonably can.
-Chris
I think you have to remove the heat sink to do any work on it. Could be wrong on that, it would be nice if I was. You can remove the heat sink without taking it apart. Get it as clean as you reasonably can.
-Chris
Hi Chris,
The main circuit board is on top, solder side up. The pre drivers are all mounted sorta hanging down and mounted on the side wall of the heat sink. Easy swap, desoder on top, unscrew on the side and drops out.
The main transistors are mounted hanging down in the center on the heat sink in a row. That top curcuit board has to come off and the heatsink has to be taken out and split I think.
Thanks.
Srinath.
The main circuit board is on top, solder side up. The pre drivers are all mounted sorta hanging down and mounted on the side wall of the heat sink. Easy swap, desoder on top, unscrew on the side and drops out.
The main transistors are mounted hanging down in the center on the heat sink in a row. That top curcuit board has to come off and the heatsink has to be taken out and split I think.
Thanks.
Srinath.
Hi Srinath,
Ahhh, that's right. when working on these, you might find yourself flipping it back and forth. After a few years, all you can really remember is that the components are between the cover and the heat sink.
The components may fall out easily, but getting them back in can be more difficult as you get nearer the output section. Take pictures of component locations before you remove them. Especially capacitor and transistor orientation!
You will also have to unscrew the bias transistors, and maybe the drivers from the main heat sink before you can separate the PCB. The heat sink is made up of "U" sections, three I think, could be two. Just take your time and work carefully. You don't have to take the heat sink apart. Use new insulators and grease if you remove anything from the heat sink.
-Chris
Ahhh, that's right. when working on these, you might find yourself flipping it back and forth. After a few years, all you can really remember is that the components are between the cover and the heat sink.
The components may fall out easily, but getting them back in can be more difficult as you get nearer the output section. Take pictures of component locations before you remove them. Especially capacitor and transistor orientation!
You will also have to unscrew the bias transistors, and maybe the drivers from the main heat sink before you can separate the PCB. The heat sink is made up of "U" sections, three I think, could be two. Just take your time and work carefully. You don't have to take the heat sink apart. Use new insulators and grease if you remove anything from the heat sink.
-Chris
How do you take that front panel off. The switches have to be desoldered ? or do they plug in under all that heat shrink tape ?
Thanks.
Srinath.
Thanks.
Srinath.
Hi Srinath,
As I recall, you just move it away and to the side. The power switch is the main problem, and there is an LED for power (I think) that pokes through the face plate.
I've rebuilt tons of these over time, but they get a bit confused with all the other bits of equipment I've also worked on. Once I see one in front of me, all the details come back to me. Just like all the other bits of gear I've serviced over time.
-Chris
As I recall, you just move it away and to the side. The power switch is the main problem, and there is an LED for power (I think) that pokes through the face plate.
I've rebuilt tons of these over time, but they get a bit confused with all the other bits of equipment I've also worked on. Once I see one in front of me, all the details come back to me. Just like all the other bits of gear I've serviced over time.
-Chris
The LED poking through is not an issue, its soldered to the circuit board.
The power switch - I will see if I can unplug it, if not, I guess I'll desolder it and modify it to take spade connectors.
Thanks.
Srinath.
The power switch - I will see if I can unplug it, if not, I guess I'll desolder it and modify it to take spade connectors.
Thanks.
Srinath.
Hi Srinath,
Yes, the LED is soldered on the main PCB. These get bent or traces can get ripped up when the face plate is either put back, or when it is allowed to contact the PCB. Just something to watch for.
You can do that with the power switch. It would make it easier to replace in the future if needed.
-Chris
Yes, the LED is soldered on the main PCB. These get bent or traces can get ripped up when the face plate is either put back, or when it is allowed to contact the PCB. Just something to watch for.
You can do that with the power switch. It would make it easier to replace in the future if needed.
-Chris
OK I'll make the switches un-pluggable. LED - I'll be careful when re assembling the face plate. For right now I need to clean the living daylights out of it with compressed air. The fan is rather loud from what I have heard in other complaints, and spinning it by a pencil it seems mine will likely be loud too.
Is there a way to lube it ? what lube ? 0wt motor oil applied via syringe ?
Thanks.
Srinath.
Is there a way to lube it ? what lube ? 0wt motor oil applied via syringe ?
Thanks.
Srinath.
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