Ages ago I bought on eBay a Kenwood LM-07 Mk11
It died an inglorious death but I have been hanging on to it.
I just started to disassemble it and found NEC capacitors A1007A & C2337A and not the high speed originals so it had been rebuilt at some point before I bought it.
I am assuming that all the T0-3 on sale from China are clones [ to put it politely] but I am wondering if there is anything I can do to reuse the chassis as it really is a work or art in some respects
It died an inglorious death but I have been hanging on to it.
I just started to disassemble it and found NEC capacitors A1007A & C2337A and not the high speed originals so it had been rebuilt at some point before I bought it.
I am assuming that all the T0-3 on sale from China are clones [ to put it politely] but I am wondering if there is anything I can do to reuse the chassis as it really is a work or art in some respects
the kenwood L07M is a mono amplifier ,if you have juste one,you will not do much with .
take one or two pictures to judge if it's possible
take one or two pictures to judge if it's possible
I have a pair of LM-07s driving my stereo, this was used [ until it blew up] to drive a small subwoofer. I just thought it was a shame to waste such a nice chassis and heat sink not to mention the massive storage capacitors and the trannie which are still good
Probably oscillation. Blew a huge hole in the PCB and vapourised a few wires. I haven't checked the TO-3s and I simply assume they are kaput
if you don't have a original drivers/output device and if in it took a fire on a pcb, you can recycle it without remorse.
this kenwood series is based on a range of very specific components that are still available, but in view of what you describe, it would be necessary to start on a total reconstruction, which is feasible to the extent that the circuit is not very complicated.
this kenwood series is based on a range of very specific components that are still available, but in view of what you describe, it would be necessary to start on a total reconstruction, which is feasible to the extent that the circuit is not very complicated.
Hi,
the LM07s are prone for oscillation (Mk 0 and Mk2 )
Check all the little comp-C´s in the circuit. esp. the 4piko for which was a
sparepart like a styroflex.
The outputtransis are ringemiters like 2sc2565 and2sa1095
Happy working!!
Ingo
the LM07s are prone for oscillation (Mk 0 and Mk2 )
Check all the little comp-C´s in the circuit. esp. the 4piko for which was a
sparepart like a styroflex.
The outputtransis are ringemiters like 2sc2565 and2sa1095
Happy working!!
Ingo
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The LM are far beyond my talents as an amp builder and this one is far beyond redemption. I was simply wondering if the chassis was re-usable for a simple project while some T0-3 output transistors were still available. The only amplifier I have ever built was a small chip amp from a kit.
Something that would drive a subwoofer perhaps was in my head?
Being a tyro your comment went over my head ingo50
Something that would drive a subwoofer perhaps was in my head?
Being a tyro your comment went over my head ingo50
Subwoofer amplifiers don't necessarily benefit from using advanced (i.e. ring emitter, perforated emitter or LAPT type) power transistors so you can build a medium power subwoofer amp. using good 'ol TO3 transistors like MJ15003/4 or higher power versions if you really want and you can locate a suitable proven design. High power anything usually means trouble, no matter who designed or built the stuff so starting a project doesn't always mean there will be a happy ending and you need to prepare yourself with some test gear and use it properly to satisfy yourself and perhaps others assisting, that all is proceding correctly before you connect to the real world. See the cautionary comments by Rod in the linked article
The L-07M has 3 pairs of TO3 transistors with a main +/- 66V power supply for 150W/8R so, assuming you re-use the power supply and heatsink, you'll be restricted to that rating for your sub. too. However, subs tend to be nasty speaker loads that demand high peak currents so the choice of design and components needs to be well suited to subs. As you say you don't have much experience with design and construction, I'd choose a design that was well supported by the DIY community and I think Rod Elliott's P68 in its basic form with 3 pairs of transistors would work out OK. Using old Motorola type semis in modern designs doesn't always work out though and you'll find that the few available TO3 versions of modern semis, such as MJ21193/4, are rather expensive.
Decisions, decisions 😕
Kenwood L-07M - Manual - DC Monophonic Power Amplifier - HiFi Engine
300/500W Subwoofer Power Amplifier
The L-07M has 3 pairs of TO3 transistors with a main +/- 66V power supply for 150W/8R so, assuming you re-use the power supply and heatsink, you'll be restricted to that rating for your sub. too. However, subs tend to be nasty speaker loads that demand high peak currents so the choice of design and components needs to be well suited to subs. As you say you don't have much experience with design and construction, I'd choose a design that was well supported by the DIY community and I think Rod Elliott's P68 in its basic form with 3 pairs of transistors would work out OK. Using old Motorola type semis in modern designs doesn't always work out though and you'll find that the few available TO3 versions of modern semis, such as MJ21193/4, are rather expensive.
Decisions, decisions 😕
Kenwood L-07M - Manual - DC Monophonic Power Amplifier - HiFi Engine
300/500W Subwoofer Power Amplifier
It is probably just a small boat anchor now.
There are some moderately high power T0-3 MOSFET around and my mind did toy with the idea of 6 in parallel but I won't be doing that.
There are some moderately high power T0-3 MOSFET around and my mind did toy with the idea of 6 in parallel but I won't be doing that.
I still have the working Mk 1's but the Mk2 bits were given to a local feller who works with the new high power TO3