Do I need a donor or do I have one
Well thats the rub, I do not need large quanties to make the occasional repair. I do need compliments and I want to keep the cost down or its not cost effective to even repair the unit. So far, I have found nothing in a search of Mouser, Digi-key and Newark. Shoulld the Hafler be the donor for the Krell or vice versa..... ha ha
I could sacrafice a Threshold T2 gain board for some K170s and J74s BUT as soon as I do that I will have a busted T2 that needs them.
I read an earlier thread that implied it is not quite as simple a a single resistor.
Well thats the rub, I do not need large quanties to make the occasional repair. I do need compliments and I want to keep the cost down or its not cost effective to even repair the unit. So far, I have found nothing in a search of Mouser, Digi-key and Newark. Shoulld the Hafler be the donor for the Krell or vice versa..... ha ha
I could sacrafice a Threshold T2 gain board for some K170s and J74s BUT as soon as I do that I will have a busted T2 that needs them.
I read an earlier thread that implied it is not quite as simple a a single resistor.
What a lousy first post....
But.....one of my monoblocks fried something this morning...are there any locals who know how to repair these amps?
I have owned them since the late 80's, and sent them to Krell once for an overhaul..very expensive. Tough times and just cant afford to send them back to krell...rather put some money to those who help others.
There are so many folks here with considerable knowledge ... can anyone offer direction?
Best,
Marc
But.....one of my monoblocks fried something this morning...are there any locals who know how to repair these amps?
I have owned them since the late 80's, and sent them to Krell once for an overhaul..very expensive. Tough times and just cant afford to send them back to krell...rather put some money to those who help others.
There are so many folks here with considerable knowledge ... can anyone offer direction?
Best,
Marc
Are they KMA-160 monoblocks? Do you have any idea what happened to them? I'm in SF and could probably help you out some.
Thanks for responding!
No...went to turn them on and a flash occured. opened up the units to peek inside to see what fried, and saw a metal disc cap connected to pwoer and the switch burnt. I assume this is a protection device of some sort..a fuse.
Thoughts?
Marc
No...went to turn them on and a flash occured. opened up the units to peek inside to see what fried, and saw a metal disc cap connected to pwoer and the switch burnt. I assume this is a protection device of some sort..a fuse.
Thoughts?
Marc
Krell Mono Blocks
I have repaired a few Krell units. Your issues are most likely related to the AC mains circuit. A new disc cap, maybe a new power switch should do the trick. If you ever travel up to Lake Tahoe you could drop them by here.
I have repaired a few Krell units. Your issues are most likely related to the AC mains circuit. A new disc cap, maybe a new power switch should do the trick. If you ever travel up to Lake Tahoe you could drop them by here.
I don't know much about the power inlet or the protection circuits on the rear panel. Maybe a good photo would help?
Thanks guys!
Will try to get a photos posted this weekend.
The disc cap is labeled SG-302 and is crumbling as I handle it!
Should i try to replace it ... if so, waht do i buy..digikey, mauser, other??
Best,
Marc
Will try to get a photos posted this weekend.
The disc cap is labeled SG-302 and is crumbling as I handle it!
Should i try to replace it ... if so, waht do i buy..digikey, mauser, other??
Best,
Marc
This is SURGE-GARD™ NTC Thermistor -- SG302 inrush current limiting device
http://www.rtie.com/ntc/sgspec.htm
If NTC was blown - there was some serious fault and NTC worked as a fuse. Search for the origin of this inrush current! Ask jwb for help
I'm curious to find out what could have blown the inlets on two monoblocks at once. The simultaneous failure seems to rule out a transformer short.
Edit: Oh nevermind, I see that it's just one. Transformer short seems pretty likely then.
Edit: Oh nevermind, I see that it's just one. Transformer short seems pretty likely then.
KMA160
This unit lets the smoke out at the rear driver sections. I have replaced a 15024 and the emitter. It smoked the transistor and resistor right away at power up. Can this be powered up on a variac and bypass the relays? All the info in this post is great, but the links of dwg. and pics of many projects do not seem to be available. I am looking on wiki for the 160 info and have not succeeded yet. Any ideas?
This unit lets the smoke out at the rear driver sections. I have replaced a 15024 and the emitter. It smoked the transistor and resistor right away at power up. Can this be powered up on a variac and bypass the relays? All the info in this post is great, but the links of dwg. and pics of many projects do not seem to be available. I am looking on wiki for the 160 info and have not succeeded yet. Any ideas?
Huh, I just noticed that all my drawings disappeared from this thread. I will put them back up later today.
One thing you can do is disconnects all the outputs and the driver assemblies, and check the operation of the input board alone.
One thing you can do is disconnects all the outputs and the driver assemblies, and check the operation of the input board alone.
Here's the input, output, and the servo:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
KMA160
Thanks, jwb.
Thats certainly helpful. I have much to learn this week. I hope to keep the smoke in next time. ha ha
Thanks, jwb.
Thats certainly helpful. I have much to learn this week. I hope to keep the smoke in next time. ha ha
post133 shows just 3pair of output devices, but I've looked back and seen it's repeated 4times. Now it makes more sense.
Here are the missing photos:
Burned out original input board.
Partly disassembled KMA-160:
Close-up of power supply and protection board:
Close-up of output board:
Another detail of output:
Repaired input board, and my redesigns:
Burned out original input board.
An externally hosted image should be here but it was not working when we last tested it.
Partly disassembled KMA-160:
An externally hosted image should be here but it was not working when we last tested it.
Close-up of power supply and protection board:
An externally hosted image should be here but it was not working when we last tested it.
Close-up of output board:
An externally hosted image should be here but it was not working when we last tested it.
Another detail of output:
An externally hosted image should be here but it was not working when we last tested it.
Repaired input board, and my redesigns:
An externally hosted image should be here but it was not working when we last tested it.
analog_sa said:
Even a bit more than that : one of very few who were genuinely Full Class A.
It's biased all the way up to the nominal rail voltage level for 8 Ohm loads, 500W dissipation per channel, feeling is believing.
It's great to see folks keeping these power plants alive and well.
