Any one know a good replacement power transformer for a eico hf 60, looking at some Hammonds but not sure which one to get. Open for suggestions
The schematic pretty much tells you what you need, electrically. Checking with a measuring tape informs you about mechanical fit suitability.
Hammond's 375X seems "correct". However, a key discrepancy lies in the bias tap voltage. Roughly 70 VDC, less losses, will be available at the 1st filter cap. of the bias supply. The EICO schematic shows 115 V., at that point. Therefore, you need to rework the resistance values around the bias adjust control. FWIW, I'd "attack" 33 Kohm R25.
BTW, selenium rectifiers are ticking toxic time bombs. If the bias rectifier in situ is selenium, replacement with a modern low noise silicon device is mandatory.
Hammond's 375X seems "correct". However, a key discrepancy lies in the bias tap voltage. Roughly 70 VDC, less losses, will be available at the 1st filter cap. of the bias supply. The EICO schematic shows 115 V., at that point. Therefore, you need to rework the resistance values around the bias adjust control. FWIW, I'd "attack" 33 Kohm R25.
BTW, selenium rectifiers are ticking toxic time bombs. If the bias rectifier in situ is selenium, replacement with a modern low noise silicon device is mandatory.
When replacing the selenium rectifier with a silicon one, rectified voltage will be higher. Check the voltage after replacing the rectifier to be sure it's still in spec for your application.
Thanks for the info Eli that was the one of the trans I was looking at and the other being the 378x, the 378x foot print would of worked better but I can make either one work. Also thanks for answering another question that I was thinking to myself about meaning bias. Would you have any suggestion for a replacement size at the R25 possition, I am still learning the electrical side of these amps and am always open for suggestion. Also thanks egellings for that suggestion, I will make sure to check when I finish the rebuild.
The 378X is electrically heftier than the 375X. If installing a 378X means less labor, by all means go for it. Better extra "grunt" than not enough.
The HF-60 manual contains info. about what the voltages at the O/P tube sockets should be. Maybe tweaking R23 (22 Kohms), instead of R25, is best. Try 15 Kohms for R23 and see what happens.
The HF-60 manual contains info. about what the voltages at the O/P tube sockets should be. Maybe tweaking R23 (22 Kohms), instead of R25, is best. Try 15 Kohms for R23 and see what happens.