Chris,
I have a friend who has a cabin in a remote area of Alaska who feels your pain. For anyone to even show up at his doorstep they have to travel over 100 miles so it usually costs $200 for a knock at his door, in addition to any services rendered.
Needless to say he brings new meaning to the term DIY whenever he can.
You must be in a similar situation or you need a new plumber.
I have a friend who has a cabin in a remote area of Alaska who feels your pain. For anyone to even show up at his doorstep they have to travel over 100 miles so it usually costs $200 for a knock at his door, in addition to any services rendered.
Needless to say he brings new meaning to the term DIY whenever he can.
You must be in a similar situation or you need a new plumber.
just think how much you saved by not having them repair it!
(BTW you got prep and paint for free).
FWIW quite a few companies use in-house part no. schemes. IDK why, perhaps to keep NTE and other poor cross reference gremlins out. most that buy in bulk >5K can even have OEMs test/ screen parts to their specs & then print their part no it.
(BTW you got prep and paint for free).
FWIW quite a few companies use in-house part no. schemes. IDK why, perhaps to keep NTE and other poor cross reference gremlins out. most that buy in bulk >5K can even have OEMs test/ screen parts to their specs & then print their part no it.
Not really a repair as my friend simply made a mistake replacing tubes. More like bull in china shop, and the Reference one has been in service since 1995 without fail which says volumes for AR quality. I guess this is the classic example of a Cadillac costing $100,000,000 if purchased part by part.
Adcom did this -- they were quite fond of Linear Tech products. See Gary Galo's excellent upgrade article on the GFP-565.
And Audio Research had their own proprietary driver operational amplifier for the early solid state amps, a precursor of the LM4702 I guess.
Some of the chips on Tektronix and HP vintage equipment were manufactured by the companies themselves.
Hi everybody ! Same story here, a friend of mine faced that problem with the specific fet in his ARC REF1 preamp.
Bad is they have no print at all (deleted by ARC ...) but only colour code (Green-White-White), and its ARC part no. is 30011011. That fet has been used in ARC REF1 and VT100 mkI.
Here it is :
But ARC send him a pair of fet with different colour code and ARC part no too. He received a Green-Green-Brown fet and its ARC part no is 30011021. This fet has been used in ARC REF 2 mkI and VT200 mkI as well.
Then my friend took some pictures and sent me them to help him if I could,so here is the new Green-Green Brown fet :
If you look at it a little closer you might see the factory numbers (ARC didn't a good job here
), it looks like the discontinued Zetex ZVN2535A or a Supertex DN2535 (Mouser have plenty of them). Hope this info helps a bit
They are depletion mode MOSFET's connected as current sources. They do come in both packages but beware of the power dissipation rating of each. They are probably sorted for threshold voltage and/or current at 0 Vgs.
http://www.redrok.com/MOSFET_DN2535_350V_120mA_25O_Vth-1.5_TO-92.pdf
EDIT - Mouser has plenty at $1.20 or so each (in the right package). Just pick a different resistor to set the current.
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You are correct. Is it not just configured as a current sink for the tube?
Then you can measure the current (or voltage across the resistor) of the working other half and just put in your own current source, even with a FET of your own selection.
Scott knows far more than I do, but the posted schematic indicates that the FET is on a heatsink which, to me at least, would suggest the -220 package. Of which Mouser has plenty as well DN2535N5-G Microchip Technology | Mouser
Right, I thought the OP might have been calling the TO220 package itself a "little heatsink". I don't see how one could repair this with a TO92 package or why they would be sending them when both are cheaply available. By right I meant left in the picture.
Hi.I agree ARC did not do a good job here.I meant my friend told to220 item is connected to a little heatsink.(additional to its own metal) Are you sure DN2535 works well in this circuit?
If not sure about it i suggested him to buy an Atlas semiconductor analyser and he can find a replacement by looking at parameter results.(he is already a repairman and it will be useful for him for future repairs)
If not sure about it i suggested him to buy an Atlas semiconductor analyser and he can find a replacement by looking at parameter results.(he is already a repairman and it will be useful for him for future repairs)
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It's a good bet there are not that many depletion mode MOSFET's in these two packages, easy to try you are only setting DC current for the valves.
Not too sound too harsh, but if you don't want to repair the unit with OEM-provided and blessed parts then don't contact the manufacturer. For a company to process your request, get the part, package it, send it to you, etc, probably cost ARC at least $50 in human capital. Then there is the cost of keeping repair parts in inventory. Could they have done it for free? Sure. But they are in the business of making money. How much do you charge or earn per hour for your labor? I don't think $30 for a part and for shipping a part is unreasonable. Nor can I blame them for wanting to keep part numbers or specs proprietary. Their IP is extremely valuable. Go buy some spark plugs for a Porche or get an oil change for a Ferrari and see what the cost is.
FWIW I buy T92 Fets by the 100, test them and then keep them in separate and properly labelled glassine envelopes.
I divide them in only 3 groups and the whole testing and packaging takes me at least 1 hour; would take much more if I labelled them individually.
The point being that if somebody asked me to sell him a selected one and he´d expect me to charge Mouser bulk prices I´d call him crazy.
I won´t charge for "the part" by itself, but my time and knowledge.
Not happy with that? No problem, Mouser sells to*anybody*, he´s free to buy there.
Of course, paying at least minimum postage charged by them.
I divide them in only 3 groups and the whole testing and packaging takes me at least 1 hour; would take much more if I labelled them individually.
The point being that if somebody asked me to sell him a selected one and he´d expect me to charge Mouser bulk prices I´d call him crazy.
I won´t charge for "the part" by itself, but my time and knowledge.
Not happy with that? No problem, Mouser sells to*anybody*, he´s free to buy there.
Of course, paying at least minimum postage charged by them.