Hello All
I am planning to build the Citation 12 from the HK manual.
Could you suggest suitable replacements for the obsolete 40408, 40594 and 40595 transistors?
It seems to me that the specs for the 2n3055 closely matches those of the 40636.....what are your thoughts?
Appreciate any help you can give.
I am planning to build the Citation 12 from the HK manual.
Could you suggest suitable replacements for the obsolete 40408, 40594 and 40595 transistors?
It seems to me that the specs for the 2n3055 closely matches those of the 40636.....what are your thoughts?
Appreciate any help you can give.
motorola transistor substitutes
Hello can the Zetex ZTX653 / ZTX753 be substituted for the Motorola MPS-L51 and MPS-L01 that are specified in the Citation 12 PASS mod ??? I have a few of each of these types, their ratings are similar but are heavier duty is what im seeing.
I would like to substitute these Zetex types.... comments ?
Hello can the Zetex ZTX653 / ZTX753 be substituted for the Motorola MPS-L51 and MPS-L01 that are specified in the Citation 12 PASS mod ??? I have a few of each of these types, their ratings are similar but are heavier duty is what im seeing.
I would like to substitute these Zetex types.... comments ?
Mosfet Citation 12 Bias
I have finished my Citation 12 now running the Pass circuit.
So far it did full power no load, I did make the mistake of turning up the bias too high, this fried R13 and im guessing Q3,4,5.
What I was wondering is the bias have a range of very low current to a high that will destroy components ?
I plan on replacing the transistors and setting the amp by actual current flow.
But it sounded pretty darn nice, until the mistake, has anyone had the same problem ?
I have finished my Citation 12 now running the Pass circuit.
So far it did full power no load, I did make the mistake of turning up the bias too high, this fried R13 and im guessing Q3,4,5.
What I was wondering is the bias have a range of very low current to a high that will destroy components ?
I plan on replacing the transistors and setting the amp by actual current flow.
But it sounded pretty darn nice, until the mistake, has anyone had the same problem ?
Done it a few times
Hi
Hi
Turned it into smoke generator o few times, i think You did the mod on original boards as i cant see i´ve got Your post adress so havent sent You any boards. Check for correct wiring, seems ok as it worked from start, if using original heatsink You have to be carefull with bias, stop at 300mA/device. If drivers have died also check mosfets for shorts before powering up again
citation 12 bias
Ingvar;
Thanks, the outputs were fine what was damaged are Q3, mpsl01, this heated the 820 ohm resistor, and weakend Q4 also mpsl01 and Q5 mpsl051
The amp played fine until i raised the bias, the outputs still look fine, they were never over heated. as soon as i saw the 820 ohm heating up I killed the power.
turning up the bias killed q3-q5 before damagiing the output mosfets.
I have triple checked the board and couldn't find any mistakes.
I am going to replace the Q's and the small tantalium, replacing it with a same value electrolytic.
Ingvar;
Thanks, the outputs were fine what was damaged are Q3, mpsl01, this heated the 820 ohm resistor, and weakend Q4 also mpsl01 and Q5 mpsl051
The amp played fine until i raised the bias, the outputs still look fine, they were never over heated. as soon as i saw the 820 ohm heating up I killed the power.
turning up the bias killed q3-q5 before damagiing the output mosfets.
I have triple checked the board and couldn't find any mistakes.
I am going to replace the Q's and the small tantalium, replacing it with a same value electrolytic.
Minor problems then, if You replace the driver Mototrola transistors with the Zetex types be carefull with pinconfiguration, as i remember, long since the mpsl01/51 vanished from market here, the pins are swapped so just check wich is C,B and E.
If You´re waiting for my boards i put them in the mail today, first class letter seems to take 4-6 days to USA, drawing with pindesignations on board is attached.
If You´re waiting for my boards i put them in the mail today, first class letter seems to take 4-6 days to USA, drawing with pindesignations on board is attached.
Thanks
Ingvar:
Thank you....
I did get quite a few motorola transistors at the local electronic surplus, and later found the zetex types so got 20 of each.
I got started on the Citation as a project and will replace the transistors with the zetex types.
Im getting a low resistnce on my mosfets, gate to drain reversing the meters leads the mosfets read the same so im thinking they were destroyed by my mistake.
I am also gathering parts for the boards you are sending, to build the home brew mosfet citation.
thanks again
Ingvar:
Thank you....
I did get quite a few motorola transistors at the local electronic surplus, and later found the zetex types so got 20 of each.
I got started on the Citation as a project and will replace the transistors with the zetex types.
Im getting a low resistnce on my mosfets, gate to drain reversing the meters leads the mosfets read the same so im thinking they were destroyed by my mistake.
I am also gathering parts for the boards you are sending, to build the home brew mosfet citation.
thanks again
citation 12 transistors
Hello; I rebuilt a Citation 12 and kept in original condition.
The transistors I used are NTE 159 for the input diff pair.
I used the 2SC1222 or NTE 199 for the bias transistor.
predirver I used NTE 16005, driver and pre driver I used the npn/pnp pair 16004 and 16005 with heat sinks, for the outputs I used Toshiba 2SD424. The amp bias is set to the stock setting and the outputs run as cool as originals.
The amp sounds very nice, clean clear and has a really nice and solid low end. Actually betters my modded Quad 405 in the low end.
I did try the cross transistors based on the Citation 12 tech manual, numbers Nte 128 for the pre driver, NTE 184,185 for the drivers but found the stock circuit didn't bias at the normal level checking at the test points.
I think the 159,2SC1222,16004,16005 and 2SD424
Hello; I rebuilt a Citation 12 and kept in original condition.
The transistors I used are NTE 159 for the input diff pair.
I used the 2SC1222 or NTE 199 for the bias transistor.
predirver I used NTE 16005, driver and pre driver I used the npn/pnp pair 16004 and 16005 with heat sinks, for the outputs I used Toshiba 2SD424. The amp bias is set to the stock setting and the outputs run as cool as originals.
The amp sounds very nice, clean clear and has a really nice and solid low end. Actually betters my modded Quad 405 in the low end.
I did try the cross transistors based on the Citation 12 tech manual, numbers Nte 128 for the pre driver, NTE 184,185 for the drivers but found the stock circuit didn't bias at the normal level checking at the test points.
I think the 159,2SC1222,16004,16005 and 2SD424
Its nice that you were able to restore it to its original "stock" form. Back when they were being sold new I repaired many of them. I would however highly reccomend that you go the full route with the Pass mod as it blows the stock Citation off the map. I also did many of htose mods and every customer raved about the improvements.
Best,
Mark
Best,
Mark
)Hope?
Ingvar,
I recently purchased a rather trashed citation 12 hoping to do the Nelson Pass mod. Of course I have been having some trouble finding the mosfets he recommended back in the 80's. And I hoped to be able do the mods like on his forum with the original board.
I give up. I can't figure out how to do it. So I was hoping you might still have some of your boards and could tell me how to acquire them. I see other ones on ebay, but Pass himself approved of yours.
Any help would be appreciated.
nate
Ingvar,
I recently purchased a rather trashed citation 12 hoping to do the Nelson Pass mod. Of course I have been having some trouble finding the mosfets he recommended back in the 80's. And I hoped to be able do the mods like on his forum with the original board.
I give up. I can't figure out how to do it. So I was hoping you might still have some of your boards and could tell me how to acquire them. I see other ones on ebay, but Pass himself approved of yours.
Any help would be appreciated.
nate
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