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Hammond ECL86/6GW8 conversion
Hammond ECL86/6GW8 conversion
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Old 26th February 2010, 01:43 AM   #21
Eli Duttman is online now Eli Duttman  United States
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Location: Monroe Township, NJ
UPW series Nichicons are a good choice. Don't go larger than 47 μF. for C11.

There is a way to improve the PSU, but it's not straight forward. Taking O/P tube anode B+ from the 1st filter cap. is poor. To do better, you have to switch to SS rectification and CLC filtration for O/P tube anode B+. The value of the 1st cap. has to be held down to keep the rail voltage where it is now, as forward drop in SS diodes is much smaller than that in vacuum rectifiers. At least a 5 H. choke is needed to lower ripple and isolate the remaining filter parts. Now, a 100 μF. reservoir cap. is both safe and good.
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Old 26th February 2010, 02:00 PM   #22
nightanole is offline nightanole  United States
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Should i do a full bridge or just 2 diodes ( i never understood the 2 diodes setup used just for center taped stuff)

ISL9R8120P2_Q Fairchild Semiconductor Rectifiers

150ohm 5h choke good for 150ma

158Q Hammond Common Mode Inductors

So let me walk through this once.

remove the rec tube and multicap
install a full bridge rec
install a 47uf cap in c11
install the choke after c11
install a 100uf cap after the choke as like a 2nd c11
connect B+1 to 100uf cap
Should i replace c12,13,14 with the standard sized caps or leave them out?

Last edited by nightanole; 26th February 2010 at 02:11 PM.
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Old 27th February 2010, 12:29 AM   #23
Eli Duttman is online now Eli Duttman  United States
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Location: Monroe Township, NJ
Quote:
Should i do a full bridge or just 2 diodes ( i never understood the 2 diodes setup used just for center taped stuff)

FWCT is what's there now using the 6CA4 and FWCT using "sand" is what you go to. Bridge rectifying the entire winding would double the B+ rail voltage and halve the available current.

A pair of UF4007s, costing approx. 15 cents each, is quite suitable. "Wrestle" with TO220 case parts, only when absolutely necessary. Parallel each UF4007 with a high WVDC 10 nF. cap., as a snubber. Start with 4.7 μF. in the 1st position and adjust that value (probably upwards), at the bench, to get 310 V. at the 100 μF. reservoir (2nd) cap., with the PSU loaded down. A 6 H. Triad C-14X choke from Allied Electronics (stock # 967-1006) goes between the 1st and 2nd filter capacitors. R19, R20, and R21 along with C12, C13, and C14 are retained. C11 has been replaced by a CLC network, whose performance is much better.

BTW the DCR of the C-17X combines with the 100 μF. reservoir cap. to form a time constant, which slows B+ rise down a bit. That's a good thing.
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Old 27th February 2010, 02:14 AM   #24
nightanole is offline nightanole  United States
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Hehe the triad had 1 in stock. 10min later it was gone, guess a simple SE builder got it...
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Old 27th February 2010, 02:24 AM   #25
Eli Duttman is online now Eli Duttman  United States
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AES has the 5 H./150 mA Hammond 158Q at $21.10, which is not as favorable at the Triad part, but still not insane. AES' stock # is P-T158Q
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Old 21st March 2010, 01:05 PM   #26
nightanole is offline nightanole  United States
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Well its up and running. I used a the hammond choke and a 50ohm resistor. It wanted 2uf before the choke to get the B1+ to 305vdc. B2+ is correct, however B3+ and B4+ are 10v high. Should i try to up the 5.7k to b3+ or should i leave it as is.

I star grounded it and it sounds alot better then out of the box. No more hum, and it seems to start distorting at ipod max volume. I havent hooked it up to my preamp yet.
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