DYNA PAT
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Hi folks,
New to this site but Ive attached a few articles you may find helpful.
Did a pretty major upgrade to my SCC 1986 ST416 over the winter and included the PC-28 resistor mods discussed within.
My 28 boards were the updated - doublesided version and I also replaced all caps - obtained from quo-co (Ed Fantasia) on eBay.
Ed used to work for Dyanco / Hafler and is a wealth of knowledge - never a problem with his parts and he responds quickly to inquiries.
My latest item I'm correcting is I had my right channel go out due to a shorted output transistor (Q5)
I ordered a new set of transistors from Mouser - ON brand - 863-MJ21194G (8) and 863-MJ21193G (8) as old ones aren't available new and a couple other transistors exhibited some flakey readings (they are over 30 years old). new transistors have better ratings and heat dissipation characteristics.
PC-28 boards do not appear damaged from checks performed. Revealed by right channel being out and one of the 4 relay board fuses being blown.
Some pics from SCC catalog forthcoming.
To date I've modified my unit (410 to 416 conversion dynakit as follows) Circa 1986:
- Replaced speaker relay with enclosed relay (on line kit) - Akitika.com RY301 (replace R142 with 1500ohm, 1W resistor to lower relay coil voltage)
- Replaced output (large) caps under relay board Akitika 22KUF80V
- Changed PC28 Caps and 6 resistors (ea) on PC-28 boards (R-28,29,30,31,32,33 to wire wound) (Mouser), new 1K trim pots (2 per board - PIHER 1K812M) (RP011 190103) "qua-co" on eBay (reliable) "Fantasia Audio"
- Installed led meters and select switch NOS
- Installed 2 speed fan thermo switch (KSD301)
- Rebuilt PC-30 board (all components) - lots of heat degradation (qua-co) eBay
- Installed short blue LEDs for power and hi-temp lights - 2152A6 NOS
- Lastly replacing all 16 output transistors as one failed (shorted) with MJ21193G, MJ21194G ON Semiconductor (8 ea)
- RCA input jacks with gold plated jacks
Hope this helps others!
Pat
Dynaco amp mods and tweeks
in Dynaco
Posted
Some pics from SCC catalog. My 416
Pat