Re: My poor Yamaha....
Give it here... I'll fix it...
hehe
Andy Graddon said:.. I'm beginning to think I will never hear her again
It seems the power-up circuit or something is totally shot, and they can't get the original parts, and are having trouble getting replacement parts to behave properly.
Give it here... I'll fix it...
hehe
and merge it with "The last word". It has the same qualities
Re: My poor Yamaha....
There are a couple of Yamaha amps that incorporate the power switch illumunating lamp in the power up circuit.
If this lamp goes open the amp will not power up.
Eric.
Andy,Andy Graddon said:.. I'm beginning to think I will never hear her again
It seems the power-up circuit or something is totally shot, and they can't get the original parts, and are having trouble getting replacement parts to behave properly.
There are a couple of Yamaha amps that incorporate the power switch illumunating lamp in the power up circuit.
If this lamp goes open the amp will not power up.
Eric.
Why Did They Do This ?.!!!!
Yeah, I know that sounds funny and I forget the details of the circuit.
From memory there is a 4mm lamp behind the square power switch button, and this lamp is part of the power supply control circuit, and when the lamp goes O/C the amplifier won't bloody work at all.
I know this from bitter experience in the past when I had one in for repair and I spent too much time checking that everything else checked ok (no need to bother to check a panel lamp, right ?).
When I got a copy of the schematic all was revealed, and I wrote a big loud note about this on the cover of the service manual.
This fault mode is a perfect trap for the unwary.
Eric.
Yeah, I know that sounds funny and I forget the details of the circuit.
From memory there is a 4mm lamp behind the square power switch button, and this lamp is part of the power supply control circuit, and when the lamp goes O/C the amplifier won't bloody work at all.
I know this from bitter experience in the past when I had one in for repair and I spent too much time checking that everything else checked ok (no need to bother to check a panel lamp, right ?).
When I got a copy of the schematic all was revealed, and I wrote a big loud note about this on the cover of the service manual.
This fault mode is a perfect trap for the unwary.
Eric.
wow.... I am just loving this amplifier repair business...
I found one of the output transistors was short circuit... so, I removed it... powered up the amp, but it still blew fuses..
upon abit more investigation I found that one of the diodes in teh bridge was short also.....
so, I replaced the 4 diodes with a single bridge.... fuse still blew... I then discovered I had the polarity around the wrong way...
I corrected this and inserted a new fuse... it was 1.5amps instead of the "suggested" 2amps.... it powered up.... I scrounged around and found some transistors that looked suitable for the sub.. pulled out the one still remaining, and replaced them with a matching pair......
I powered up the amp for a few seconds, the lights came on, and all was good.. I turned it off and replaced the bottom cover...
Turned the amp back up the right way.. powered up the amp and enjoyed the lights.. then the transformer started buzzing... it got louder... and then POP, the fuse blew... lol
I checked the circuit and there was a short across teh output from the bridge again!!!! but this time it wasn't the bridge... I checked a few things and found that one of my newly replaced transistors had gone short circuit... hmmm
All pins are shorted to all pins.... same as the first faulty transistor... only difference is that this is in teh opposite position to the first blown transistor!!!!!!!!!!!!!!
I QUIT!!! HE CAN HAVE HIS STUPID AMP BACK!!! i offered to buy it off him for $15 - $20 but he wouldn't sell... ohh well... it seems to have more problems now than when I started...
SEEYA!!
I found one of the output transistors was short circuit... so, I removed it... powered up the amp, but it still blew fuses..
upon abit more investigation I found that one of the diodes in teh bridge was short also.....
so, I replaced the 4 diodes with a single bridge.... fuse still blew... I then discovered I had the polarity around the wrong way...
I corrected this and inserted a new fuse... it was 1.5amps instead of the "suggested" 2amps.... it powered up.... I scrounged around and found some transistors that looked suitable for the sub.. pulled out the one still remaining, and replaced them with a matching pair......
I powered up the amp for a few seconds, the lights came on, and all was good..
I turned it off and replaced the bottom cover...Turned the amp back up the right way.. powered up the amp and enjoyed the lights..
then the transformer started buzzing... it got louder... and then POP, the fuse blew... lolI checked the circuit and there was a short across teh output from the bridge again!!!! but this time it wasn't the bridge... I checked a few things and found that one of my newly replaced transistors had gone short circuit...
hmmmAll pins are shorted to all pins.... same as the first faulty transistor... only difference is that this is in teh opposite position to the first blown transistor!!!!!!!!!!!!!!
I QUIT!!! HE CAN HAVE HIS STUPID AMP BACK!!! i offered to buy it off him for $15 - $20 but he wouldn't sell... ohh well... it seems to have more problems now than when I started...
SEEYA!!
What do we think of these speakers?
* Each Box comprises of 2x 12 inch Woofers & 2x Titanium Tweeters.
* They have undergone many hours of maticulous Computer designing, using Bass Box Pro (latest Version)
* The Cabinets have been crafted and built by hand, using only the very best materials available, ie:- 18mm MDF through out the entire box construction, (most top end speakers manufacturers only put MDF in the front baffle panel, the rest is chipboard)
* The Boxes have been Tuned to the 'Exact Resonant Frequency' of the Dual 12 inch Woofers (35 Hz) in a Parrallel configuration, resulting an extremely powerfull but beautifully natural sounding Bass response.
* The Boxes are VERY heavily double and triple braced (internaly) for extreme rigidity.
* Internal screw and glue method of build has been employed, using the strongest glues available. (these boxes could roll down a mountain and be unharmed) (humour)
* They are finished in Cabots Woodcraft Black Stain, for a super deep black lustre and an almost unique look and feel.
* Heavy accoustic internal wodding has been used in the boxes.
* The Drivers used are TOP Quality (and very under rated) Asian equivilents and modeled of famous brands like "Responce and Peerless"
* They have all been wired up using Quality 12db per octave 2 way X-Overs, and Super high quality American Pure Oxygen Free Monster Cable, used through out and are terminated to Gold Banana connectors. (for Pro hook-up to your Amp)
* Metal (Silver) Grills are used to protect the Woofers and enhance a unique "Look"
http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=3037898944
hmm... I emailed the guy with a few argument starting points... oops.. lol
* Each Box comprises of 2x 12 inch Woofers & 2x Titanium Tweeters.
* They have undergone many hours of maticulous Computer designing, using Bass Box Pro (latest Version)
* The Cabinets have been crafted and built by hand, using only the very best materials available, ie:- 18mm MDF through out the entire box construction, (most top end speakers manufacturers only put MDF in the front baffle panel, the rest is chipboard)
* The Boxes have been Tuned to the 'Exact Resonant Frequency' of the Dual 12 inch Woofers (35 Hz) in a Parrallel configuration, resulting an extremely powerfull but beautifully natural sounding Bass response.
* The Boxes are VERY heavily double and triple braced (internaly) for extreme rigidity.
* Internal screw and glue method of build has been employed, using the strongest glues available. (these boxes could roll down a mountain and be unharmed) (humour)
* They are finished in Cabots Woodcraft Black Stain, for a super deep black lustre and an almost unique look and feel.
* Heavy accoustic internal wodding has been used in the boxes.
* The Drivers used are TOP Quality (and very under rated) Asian equivilents and modeled of famous brands like "Responce and Peerless"
* They have all been wired up using Quality 12db per octave 2 way X-Overs, and Super high quality American Pure Oxygen Free Monster Cable, used through out and are terminated to Gold Banana connectors. (for Pro hook-up to your Amp)
* Metal (Silver) Grills are used to protect the Woofers and enhance a unique "Look"
http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=3037898944
hmm... I emailed the guy with a few argument starting points...
oops.. lolAttachments
I Have Said This Before, And I'll Say It Again.....
Wire a 240V 40W or 60W lamp in series with the 240V power feed.
This will save blowing semis or resistors or speakers while you measure and confirm DC operating conditions and bias currents.
Check for dry joints and resistors having gone high.
How old is this amp, and make and model ?.
Eric.
What is your first name ? - Darren ?.
Wire a 240V 40W or 60W lamp in series with the 240V power feed.
This will save blowing semis or resistors or speakers while you measure and confirm DC operating conditions and bias currents.
Check for dry joints and resistors having gone high.
How old is this amp, and make and model ?.
Eric.
What is your first name ? - Darren ?.
Re: I Have Said This Before, And I'll Say It Again.....
umm... yeah... a globe..hmm.. too lazy.. lol
teh bias currents must be fine... lol I think... umm.. yeah... I gotta check for resistors and stuff still I guess... but the funny thing seems to be that the amp will run with 3 of the 4 outpiut transistors inplace... no matter which of the replaced ones are in... Its a Kenwood KA-51 and it uses 46volt rails!!! (no load) hmmm ..
mrfeedback said:
umm... yeah... a globe..hmm.. too lazy.. lol
teh bias currents must be fine... lol I think...
umm.. yeah... I gotta check for resistors and stuff still I guess... but the funny thing seems to be that the amp will run with 3 of the 4 outpiut transistors inplace... no matter which of the replaced ones are in... Its a Kenwood KA-51 and it uses 46volt rails!!! (no load) hmmm ..
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