How to directly power the Leak stereo 60 without point one preamp

vaathi

baski
Subscriber
I picked up Leak stereo 60 and point one preamp a while back. I had time to set them up with Dynaco A35s today to check if they are working as well as they should. Even though I used a Variac to power the amp, I set the voltage jumper in Power Transformer to 124.

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The power cord goes through the Power amplifier and there is a specialized 8 pin DIN connected which goes to the preamp. Again another power cord draws power from the preamp. Without connecting the preamp I could not switch on the power.

Questions I have:

Can I conver the female connector which goes to the preamp into male and directly plug it into the power outlet. When I trace the cable it connects to the power transformer.

Also Right channel is very weak in the preamp. I tried connecting to the power amp directly from my Iphone and I dont see the problem. I opened the preamp and all the tubes ( Mullard EF86s) looks fine. I did not try to deoxit the connectors. I will check the EF86s today to make sure they are good. Any other area I need to focus on to diagnose the problem.

Couple more pics of amp and preamp
 

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I picked up Leak stereo 60 and point one preamp a while back. I had time to set them up with Dynaco A35s today to check if they are working as well as they should. Even though I used a Variac to power the amp, I set the voltage jumper in Power Transformer to 124.

View attachment 925712


The power cord goes through the Power amplifier and there is a specialized 8 pin DIN connected which goes to the preamp. Again another power cord draws power from the preamp. Without connecting the preamp I could not switch on the power.

Questions I have:

Can I conver the female connector which goes to the preamp into male and directly plug it into the power outlet. When I trace the cable it connects to the power transformer.

Also Right channel is very weak in the preamp. I tried connecting to the power amp directly from my Iphone and I dont see the problem. I opened the preamp and all the tubes ( Mullard EF86s) looks fine. I did not try to deoxit the connectors. I will check the EF86s today to make sure they are good. Any other area I need to focus on to diagnose the problem.

Couple more pics of amp and preamp

IMG_6913.JPG
IMG_6918.JPG
IMG_6922.JPG
IMG_6925.JPG
IMG_6929.JPG
IMG_6931.JPG

Thanks in Advance
 

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Can I conver the female connector which goes to the preamp into male and directly plug it into the power outlet. When I trace the cable it connects to the power transformer.
According to the schematic, that won't work. The purpose of the switch cable is to switch on the power amp via the preamp's on/off switch. So all the switch cable does is provide a complete circuit around the power transformer primary, thus turning on the power amp when the preamp on/off switch is thrown. If you want to power on the power amp separate from the preamp, you would wire an on/off switch to the ends of the switch cable and mount that switch on the power amp chassis. However, I would only do this if you plan to use the power amp without the preamp.
 
Very easy: remove the switch cable and rubber grommet. Replace it with a SPDT AC power switch mounted in the empty hole and connect it to the screw block where the switch cable was previously connected, and you're done. Clean and reversible.

Actually you're not done yet: ALL the old "TCC/Metalpack" leaky paper in oil capacitors must be replaced, as well as the main electrolytic filter caps cans, if you intend to put this nice amp back into service on a regular basis. I wouldn't take the risk to damage tubes or the (impossible to find) transformers. All the parts inside looks original and are 55+ years old now, and British made parts doesn't age well (also check all the resistors which have a tendency to drift widely in value). Time has come for a good restoration job.
 
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Actually you're not done yet: ALL the old "TCC/Metalpack" leaky paper in oil capacitors must be replaced, as well as the main electrolytic filter caps cans, if you intend to put this nice amp back into service on a regular basis. I wouldn't take the risk to damage tubes or the (impossible to find) transformers. All the parts inside looks original and are 55+ years old now, and British made parts doesn't age well (also check all the resistors which have a tendency to drift widely in value). Time has come for a good restoration job.

Having owned (2) Leak ST-50s, I can verify. Those all need to be broomed. I'd be more amazed if it is even marginally listenable, mine sure weren't.
 
Thanks @Tubologic . So to rephrase what you said, I need to remove the switch cable from the preamp and install a Power switch? I try to find a round spt switch if I can.
@soundmotor As of now it sounds not bad at all. If I go by changing those caps, What are your suggestion with respect to brfand. I may have to recap the preamp unit too i guess.
 
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Thanks @Tubologic . So to rephrase what you said, I need to remove the switch cable from the preamp and install a Power switch? I try to find a round spt switch if I can.
@soundmotor As of now it sounds not bad at all. If I go by changing those caps, What are your suggestion with respect to band. I may have to recap the preamp unit too i guess.

When I did mine up I used Panasonic dipped films from Digikey. There were not a huge number of choices then.
 
Hi,
I have picked up Power Leak 60 & Pre Verislope Stereo. Owner had removed all the 3 transformers of the power amp for repair and it never happened, those faulty transformer are not traceable. subsequently, Verislope is in excellent condition and both came at cost of Pre. Now, Power has all the Valves and overall condition of the power Amp is good, am tempted to restore this machine. Of coerce, if some one can help me with ratings of these 3 transformers and I know a winder who can wind it for me. He has asked me the gauge of the wire, turns in primary & secondary, for different tapping and impedance for both, I don't know if all these are required. He has shown the size of the plates which were fitting on the place of transformer of power AMP. I have found details over the net about Mullard Amp CKT and some tutorial on Transformer but nothing has helped to find required details. I need help with those parameter or anyone can suggest a manual where details can be available.

Thanks for reading,
SachD
 
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Very easy: remove the switch cable and rubber grommet. Replace it with a SPDT AC power switch mounted in the empty hole and connect it to the screw block where the switch cable was previously connected, and you're done. Clean and reversible.

Actually you're not done yet: ALL the old "TCC/Metalpack" leaky paper in oil capacitors must be replaced, as well as the main electrolytic filter caps cans, if you intend to put this nice amp back into service on a regular basis. I wouldn't take the risk to damage tubes or the (impossible to find) transformers. All the parts inside looks original and are 55+ years old now, and British made parts doesn't age well (also check all the resistors which have a tendency to drift widely in value). Time has come for a good restoration job.

Exactly what ^^^^^^ this fellow has said,but with one caveat: Do not delay or put off this work and just continue using or troubleshooting the unit in it's present condition. You are taking an unnecessary and potentially expensive risk if you do this.
 
Exactly what ^^^^^^ this fellow has said,but with one caveat: Do not delay or put off this work and just continue using or troubleshooting the unit in it's present condition. You are taking an unnecessary and potentially expensive risk if you do this.
This page surely has the information you need to get new transformers wound: http://www.44bx.com/leak/8615tx.html
Thanks for the information, have checked the link and found details on output transformer but not for Power, I don't know if me understanding is correct.

Thanks
 
HI Sachin, sorry I didn't notice that you need a power transformer too. That should be easier to obtain, and you might find something suitable secondhand. A new one will need to meet the requirements mentioned in the schematic (available via the same link). Something like: Primary winding whatever line voltage you have locally. Secondaries: 380V, 250mA with center tap; 6.3V, with center tap, 3A and 5V, 5A. The Stereo 60 will also need a small 0.3H choke.
 
HI Sachin, sorry I didn't notice that you need a power transformer too. That should be easier to obtain, and you might find something suitable secondhand. A new one will need to meet the requirements mentioned in the schematic (available via the same link). Something like: Primary winding whatever line voltage you have locally. Secondaries: 380V, 250mA with center tap; 6.3V, with center tap, 3A and 5V, 5A. The Stereo 60 will also need a small 0.3H choke.

Thank You Dandy for the Information, My Winder wants the output transformer unwinding drawing with turns. I don't know if the information provided on the link does make it clear, if it needs clarification or my winder does't understood it!!

SachD
 
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Sorry, I can't help further. He might be able to get help from a UK transformer company like Sowter. They may hold information on classic transformers like those made for/by Leak.
 
Sorry, I can't help further. He might be able to get help from a UK transformer company like Sowter. They may hold information on classic transformers like those made for/by Leak.

I will check with Sowter, thank you for the help.
 
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