I've got a LP12 (somewhere 1985 model) that stopped turning.
All symptoms are similar to the ones as described in this old post (copy form the audio asylum):
Yes, there are two items which experience failures that you can service yourself and fairly easily. Does the led in the switch light up? If so then the following is most likely the problem and it will just leave the motor vibrating or turning verrrry slowly. With the table plugged into the mains VERY CAREFULLY (enough voltage in there to end you listening career) measure the output to the motor between the red and blue wires, it should be between ~85 to 90+vts a/c (as I recall), depending on if you have the zener diode update. The large P/S caps will fail over time, just measure the each of the two them across the board for 160vts, if less they need to be replaced. The other field readily field serviceable failure will require a Valhalla repair kit from Linn which consists of the necessary parts. I don't remember the price. This failure is noted by blown fuses and a related triac and resistor. Hope this helps.
So I followed the instructions to repair it and replaced the capcitors with new ones. But the problem remainded the same.
The voltages were 139VTS with the old capacitors and 140 with the new, os hardly any difference. This was in line with the output voltage on the rectifier which was 280V (SHouldn't that be 311??)
Output voltage on blue connection was 35V/50HZ and on the red 28V/50HZ
I found the schematics of this board and have attached them. I also tried to figure out how it works, but I'm to electronically ignorant to understand this so I was hoping to get some help over here. The schematics say: RV1 to be set to 85V+/- 1V. But when I measure that I only find 6 volts or so so this might indicate what is wrong.
Does anybody have some suggestions how to proceed?
All symptoms are similar to the ones as described in this old post (copy form the audio asylum):
Yes, there are two items which experience failures that you can service yourself and fairly easily. Does the led in the switch light up? If so then the following is most likely the problem and it will just leave the motor vibrating or turning verrrry slowly. With the table plugged into the mains VERY CAREFULLY (enough voltage in there to end you listening career) measure the output to the motor between the red and blue wires, it should be between ~85 to 90+vts a/c (as I recall), depending on if you have the zener diode update. The large P/S caps will fail over time, just measure the each of the two them across the board for 160vts, if less they need to be replaced. The other field readily field serviceable failure will require a Valhalla repair kit from Linn which consists of the necessary parts. I don't remember the price. This failure is noted by blown fuses and a related triac and resistor. Hope this helps.
So I followed the instructions to repair it and replaced the capcitors with new ones. But the problem remainded the same.
The voltages were 139VTS with the old capacitors and 140 with the new, os hardly any difference. This was in line with the output voltage on the rectifier which was 280V (SHouldn't that be 311??)
Output voltage on blue connection was 35V/50HZ and on the red 28V/50HZ
I found the schematics of this board and have attached them. I also tried to figure out how it works, but I'm to electronically ignorant to understand this so I was hoping to get some help over here. The schematics say: RV1 to be set to 85V+/- 1V. But when I measure that I only find 6 volts or so so this might indicate what is wrong.
Does anybody have some suggestions how to proceed?
Check out this post from Audiogon. http://forum.audiogon.com/cgi-bin/fr.pl?eanlg&1102601140&read&3&4&
Local Linn Dealers do not supply the repair kit separately. They only want me to have the TT brought in for repair and asking repair prices more than I paid for the deck.
I tried to get the kit form hifi-repairs.com but got no response on my email.
any other suggestions?
I tried to get the kit form hifi-repairs.com but got no response on my email.
any other suggestions?
I've just been looking at the diagram. U3 and X1 are a crystal oscillator. U5a and b are dividers that divide the frequency of the crystal down to 50Hz (or possibly 60Hz). U2a buffers the square wave leaving the dividers. U2 b and c are 12dB/octave low pass filters that remove the higher harmonics of the square wave to leave a sine wave. U2d and associated transistors form a high voltage amplifier to drive the motor.
Unfortunately, there is no isolation transformer, so this circuit is extremely dangerous to test. I wouldn't dare poke around in it without it being connected via an isolating transformer.
What you could usefully do is to print out the diagram, disconnect the Valhalla and leave it to discharge for at least 15 minutes, then go through and determine the value of each component and mark them on the diagram. If you then take the marked-up diagram to an engineer he/she will have a decent chance of being able to fix it. The circuit isn't rocket science.
Unfortunately, there is no isolation transformer, so this circuit is extremely dangerous to test. I wouldn't dare poke around in it without it being connected via an isolating transformer.
What you could usefully do is to print out the diagram, disconnect the Valhalla and leave it to discharge for at least 15 minutes, then go through and determine the value of each component and mark them on the diagram. If you then take the marked-up diagram to an engineer he/she will have a decent chance of being able to fix it. The circuit isn't rocket science.
I think that's 85vac at the output.
What happens at the output when you adjust RV1?
Take huge care, an isolation transformer is really necessary for safe working. It's possible to work with an oscilloscope in differential mode, but really not recommended.
Paul
Valhalla repair
Eric, I just repaired the Valhalla board for my LP12. I changed the electrolytic capacitors and it still wouldn't work. The motor just sat there and vibrated. The switch LED lit. I was about to give up on it but decided to give it one more try. I reheated the solder joints for the new electrolytics just to make sure they were good. While I was at it I decided to add a little solder to the resistor joints that get so hot. I checked and resoldered a couple of joints where electrolytics attach to the board elsewhere . One in particular looked like it had broken away from the trace. I put things back together and away it went. It has been working perfectly for a couple fo months now. It was running slightly fast. I compensated for this by wrapping the platter with 2 turns of black electrical tape. I read about this trick at the Audio Asylum. There is no way to adjust speed with the Valhalla board. Give this a try. If that switch LED is working this will probably work. Good Luck!
Eric, I just repaired the Valhalla board for my LP12. I changed the electrolytic capacitors and it still wouldn't work. The motor just sat there and vibrated. The switch LED lit. I was about to give up on it but decided to give it one more try. I reheated the solder joints for the new electrolytics just to make sure they were good. While I was at it I decided to add a little solder to the resistor joints that get so hot. I checked and resoldered a couple of joints where electrolytics attach to the board elsewhere . One in particular looked like it had broken away from the trace. I put things back together and away it went. It has been working perfectly for a couple fo months now. It was running slightly fast. I compensated for this by wrapping the platter with 2 turns of black electrical tape. I read about this trick at the Audio Asylum. There is no way to adjust speed with the Valhalla board. Give this a try. If that switch LED is working this will probably work. Good Luck!
Thanks for all the comments,
I only measure 37 volts at the output, so that's way too low.
I've got a reply from Hifi-repairs who sells at kit containing all parts that wear on the walhalla board. At a very reasonable price.
For the time being I've made a Naim Armageddon clone. This might be one of the easiest DIY projects around.
It took a 3*55VAC / 550VA transformer 2 resitors to lower te voltage to about 90V and 2 capacitors for the phase shift.
And sonically I can't find anything wrong with it.
But I still prefer the convenience (and resell value) of the valhalla.
I only measure 37 volts at the output, so that's way too low.
I've got a reply from Hifi-repairs who sells at kit containing all parts that wear on the walhalla board. At a very reasonable price.
For the time being I've made a Naim Armageddon clone. This might be one of the easiest DIY projects around.
It took a 3*55VAC / 550VA transformer 2 resitors to lower te voltage to about 90V and 2 capacitors for the phase shift.
And sonically I can't find anything wrong with it.
But I still prefer the convenience (and resell value) of the valhalla.
Speed adjustment on the LP12 is achieved by tilting the motor. You should find the setup manual on the web with a search.
Wrapping the inner platter in tape seems a good way to damage the performance.
Paul
Thanks for the tip Paul. I did play with the motor height and tilt after I reassembled. The belt was climbing too high and rubbing against the plastic part that prevents the belt from derailing. I will drop the belt further. Thanks again
Got it fixed
It turned out that Paul and LFM were both right.
I double checked all joints on the board, and all joints around 2 resistors that get very hot (judging from the color of the board around it) were basically barely, connected. It was not easy to get it soldered again, i needed to make scrathes on the pcb layer to get a firm connection.
After taht I was able to get the motor running if I gave it a sweep, it wouldn't start by itself. But adjusting RV1 fiexed that.
Thanks for the advise.
It turned out that Paul and LFM were both right.
I double checked all joints on the board, and all joints around 2 resistors that get very hot (judging from the color of the board around it) were basically barely, connected. It was not easy to get it soldered again, i needed to make scrathes on the pcb layer to get a firm connection.
After taht I was able to get the motor running if I gave it a sweep, it wouldn't start by itself. But adjusting RV1 fiexed that.
Thanks for the advise.
LP12 VALHALA
Hello all,
does anybody know a value of the resistor R26 of the VALHALA PSU board?
Regards
munja (Robert)
Hello all,
does anybody know a value of the resistor R26 of the VALHALA PSU board?
Regards
munja (Robert)
Valhalla repair
Resurrecting an old thread here.....
I'm planning on replacing the three capacitors in my Vallhalla board. I have a schematic for it, but a more detailed "parts list" would be helpful. I know the values of the capacitors, but would like to get something as close to the original spec as possible.
Any info about them - or where to purchase them - would be greatly appreciated!
Resurrecting an old thread here.....
I'm planning on replacing the three capacitors in my Vallhalla board. I have a schematic for it, but a more detailed "parts list" would be helpful. I know the values of the capacitors, but would like to get something as close to the original spec as possible.
Any info about them - or where to purchase them - would be greatly appreciated!
valhalla
oh dear. does anyone have a -simple- schematic for a 50hz ps to replace the valhalla i am trying to, once again, repair?
thanks
oh dear. does anyone have a -simple- schematic for a 50hz ps to replace the valhalla i am trying to, once again, repair?
thanks
Valhalla Repair
Munja
R26 is a 22R 0.5W 1% Metal Film.
Butch1970
RS Components do a nice BC 47uF 450V axial capacitor that I have used to great effect.
Frolic
Do you have a circuit diagram? The Valhalla PCAS 022 diagram (available off the net) is representative of the latest Valhalla's and all the component values are shown. The Valhalla is quite reliable once sorted and will give you many years service. I would recommend that when changing the bridge rectifier, you replace with a 6A 1000V device. This is far more robust and reliable. The three large 47uF caps should be 450V devices as apposed to the 250V devices often used, this improves the reliability too! Don't give up, it's worth doing.
Hope this helps
Regards
Peter
Munja
R26 is a 22R 0.5W 1% Metal Film.
Butch1970
RS Components do a nice BC 47uF 450V axial capacitor that I have used to great effect.
Frolic
Do you have a circuit diagram? The Valhalla PCAS 022 diagram (available off the net) is representative of the latest Valhalla's and all the component values are shown. The Valhalla is quite reliable once sorted and will give you many years service. I would recommend that when changing the bridge rectifier, you replace with a 6A 1000V device. This is far more robust and reliable. The three large 47uF caps should be 450V devices as apposed to the 250V devices often used, this improves the reliability too! Don't give up, it's worth doing.
Hope this helps
Regards
Peter
ciao peter. thanks so much for the info re higher v caps and rectifier. i have replaced the 3 caps and the 2 ww 15k resistors and all is well! adjusted for 85v and works like new, ie. takes a few seconds to get up to speed... but nice.
peace,
ed
peace,
ed
uh oh... after several hrs of operation the 47ohm R1 resistor burned up .. does this mean the bridge rectifier is fried???
lp12 60hz motor and spindle needed
well now i have great need for a 60hz motor with pulley. the valhalla board is kaput (regardless of my last post..) and i can't get the 21mm spindle off the 50hz motor so i could replace it with a 17mm piece i made...
figured for now to just go with a 60hz motor off the mains through a 47m cap and
a .1 across the r - b windings. maybe a resistor to drop the v a bit. but a motor seems not to be easy to find. and i don't want to destroy the good 50hz set up for
somebody with a valhalla.
peace
ed
well now i have great need for a 60hz motor with pulley. the valhalla board is kaput (regardless of my last post..) and i can't get the 21mm spindle off the 50hz motor so i could replace it with a 17mm piece i made...
figured for now to just go with a 60hz motor off the mains through a 47m cap and
a .1 across the r - b windings. maybe a resistor to drop the v a bit. but a motor seems not to be easy to find. and i don't want to destroy the good 50hz set up for
somebody with a valhalla.
peace
ed
no a new rect. 400piv. perhaps not enough?? my head hurts. and i can't believe i can't fix a simple @##^%power supply prob. age i guess.... i thought it might be one of the xsitors at the output. it's really a 50hz amp after all... so am now disconnecting everything and then reconn incrementally... however we'll see. in the mean time i figure i can get it up and
playing those heifitz vinyls while i get a real solution.
thanks.
peace,
ed
playing those heifitz vinyls while i get a real solution.
thanks.
peace,
ed
I recently found a thread on another forum (pink fish maybe), that discussed the need to replace the stock rectifier with a more robust one. I'll look around and see if I can find the thread.
Jeff
Jeff