Hello,
I have a Lectron JH 50 amp which I love but recently has stopped working. Opening up I noticed that the power supply board under the power transformer has burnt out (see the attached picture). There is an ic chip with the number erased. I believe that this power supply board eventually fails. I have tried to contact the Swiss manufacturers of the Lectron JH 60 amps and Nick Doshi who I believe modifies these amps but have had no reply to my queries.
I believe that other members have had similar problems. Does anyone have a schematic for this amp? Or if anyone has a working replacement for the damaged board in question I would be glad to follow your design with kind permission. Any suggestions are welcome.
Many thanks.
I have a Lectron JH 50 amp which I love but recently has stopped working. Opening up I noticed that the power supply board under the power transformer has burnt out (see the attached picture). There is an ic chip with the number erased. I believe that this power supply board eventually fails. I have tried to contact the Swiss manufacturers of the Lectron JH 60 amps and Nick Doshi who I believe modifies these amps but have had no reply to my queries.
I believe that other members have had similar problems. Does anyone have a schematic for this amp? Or if anyone has a working replacement for the damaged board in question I would be glad to follow your design with kind permission. Any suggestions are welcome.
Many thanks.
Attachments
I really hate it when manufactures put power resistors on circuit boards like that without proper ventilation. But I'll bet that IC is a 555 timer for the relay.
There is one for sale on FleaBay. You may want to ask the seller if he/she has a schematic...
http://cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&item=160177144324
-- josé k.
http://cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&item=160177144324
-- josé k.
HollowState, yes you are probably right about it being a 555. It is a timer for the relay.
Jose, thank you for the info. Unfortunately the eBay seller does not have a schematic. I wonder if anyone has a copy of the old French magazine L'Audiophile. Apparently there was a schematic in issue #41 or 42 (I forget which). If someone has a copy I will be glad to purchase this.
An alternative is to redesign the whole power supply.
Jose, thank you for the info. Unfortunately the eBay seller does not have a schematic. I wonder if anyone has a copy of the old French magazine L'Audiophile. Apparently there was a schematic in issue #41 or 42 (I forget which). If someone has a copy I will be glad to purchase this.
An alternative is to redesign the whole power supply.
I'm guessing
I think the resistors and relay are combined to form a slow turn-on circuit. The 55 delays the relay, which bypasses the resistors after a preset time. Maybe delays the B+ while the tubes are warming up.
Doesn't look that complex,. from what I can see.
I think the resistors and relay are combined to form a slow turn-on circuit. The 55 delays the relay, which bypasses the resistors after a preset time. Maybe delays the B+ while the tubes are warming up.
Doesn't look that complex,. from what I can see.
Esteemed colleagues from DIYaudio,
I recently bought a 2nd hand Lectron JH50 from Germany.
If someone could help with the circuit diagram it would be helpful.
Thank you
I recently bought a 2nd hand Lectron JH50 from Germany.
If someone could help with the circuit diagram it would be helpful.
Thank you