What am i doing wrong, why wont my JLH operate in class A / get warm?

[Ian Finch]

Hi Shamron
Back in post 54 you said the 3N3773s supplied were "round as a rockling chair" on the baseplate (I assume) and there was a circular impression in its centre.
This circle marks the attachment point of the heat spreader inside the case. It's not always evident on low current types but many On-Semi T03s have it. I'm looking at genuine Motorola MJ15003/4s assembled in Mexico and they have this mark. It doesn't prove much but the warped base is....well..a disgrace.

Jim's Audio does not often get a bad rap but most of these Ebay guys buy from another group of suppliers who make the kits up, since you see the same marked and documented wares in several stores. The price competition must be incredible to have products sell with such high fake content. You know it cannot work as you expect if the parts, as we have seen and post often, are usually low gain, tiny size or no chip inside at all. Most people will be too ashamed to admit they bought something suspected to be fake, and selling under suppliers bulk part cost but still expect it to work in acceptable fashion.

'Amazing that we are driven by bargains above common sense and I am guilty too, so I am learning to buy just the PCBs. In most cases as DIYs, that is a good way and helps us build part stocks that make DIY so much easier and assured in the long run.

[Nico Ras]

I am luckier than most I guess. We have most of the manufacturers reps calling on us wanting you to design product containing their parts and when I want a particular manufacturers component to "try/test" I always get the real thing.

Unfortunately hobbyists buy from buying houses who also try to make the best profit they can and the customer get rubbish counterfeit components for the price of the real thing.

[Shamron]

Originally Posted by Ian Finch

Hi Shamron
Back in post 54 you said the 3N3773s supplied were "round as a rockling chair" on the baseplate (I assume) and there was a circular impression in its centre.
This circle marks the attachment point of the heat spreader inside the case. It's not always evident on low current types but many On-Semi T03s have it. I'm looking at genuine Motorola MJ15003/4s assembled in Mexico and they have this mark. It doesn't prove much but the warped base is....well..a disgrace.

Jim's Audio does not often get a bad rap but most of these Ebay guys buy from another group of suppliers who make the kits up, since you see the same marked and documented wares in several stores. The price competition must be incredible to have products sell with such high fake content. You know it cannot work as you expect if the parts, as we have seen and post often, are usually low gain, tiny size or no chip inside at all. Most people will be too ashamed to admit they bought something suspected to be fake, and selling under suppliers bulk part cost but still expect it to work in acceptable fashion.

'Amazing that we are driven by bargains above common sense and I am guilty too, so I am learning to buy just the PCBs. In most cases as DIYs, that is a good way and helps us build part stocks that make DIY so much easier and assured in the long run.

I as well try to buy only the pcb when available except for in this case where i was looking for alternative drivers. I usually buy 15003's from the US or from a local dealer. I also replace the caps with elna silmic II's.

I am thankful for all the help you guys have given and i hope i too can be of help to the forum some time inthe future. :-)

[Nico Ras]

You know that you can purchase diectly from most manufacturers, smaller quantities may be supplied by their local agent from stock - so you know what you get. On Semi would supply samples if requested - you may pay for postage.