My friend Mike Rivers recently acquired over Ebay an old monaural audio amplifier using vacuum tubes. But the person selling it did not know it's origin or have any information on it.
It looks like this (set of 8 photos):
Query: Does anyone here recognize this amp, or have any idea how to obtain info (such as schematics) on it?
-- Cheers, Robbie Hatley Midway City, CA, USA lonewolf [at] well [dot] com http://www.well.com/user/lonewolf/ https://www.facebook.com/robbie.hatley
Robbie Hatley schrieb:
Sorry, but obviously only Facebook members can see your photos.
Regards
Reinhard
El martes, 11 de octubre de 2016, 21:23:23 (UTC-3), Robbie Hatley escribi
Hi. The booklet shown there
As an experienced tech let me share my impressions:
This amplifier had good maintenance. APPARENTLY Capacitors (look like orang e drop style) are not modern, same as small electrolytic capacitors in the pictures.
Technicians attempting to repair this should be aware of dangerous high d.c . voltages inside the equipment.
Is your friend a technician? Has he tried to power up the equipment, connec t speakers and an audio source to see what happens?
Pass him the following info:
Use the XTAL PU input.
Place the slide switch in PU, not mike.
Unless you have a MAGNETIC TYPE pickup turntable you should not use the mag input. BTW this is monoaural one channel only not stereo.
The MIC input should be high impedance intended for an old style Crystal Mi ke, these are hard to see.
A modern dynamic microphone should have high impedance and level (10,000 oh ms or more) to work properly here. Unbalanced connection. Electret battery powered microphones should work as well.
To me it looks like a push-pull amplifier. Output tubes are 6V6.Output shou ld be around 10 watts. Quality of sound should be well above a common solid state amplifier (provided all components are in working condition)...
Do not attempt to replace the rectifier(5y3) with solid state. DC voltage w ill be much more higher, may result in electrolytic capacitors exploding or leaking, and decreased tube life or faliure.
El martes, 11 de octubre de 2016, 21:23:23 (UTC-3), Robbie Hatley escribi
Let me correct myself, most capacitors look modern in the picture. The exce ption would be the high voltage aluminium capacitor that filters the B+, it looks like original, then it should be replaced. No need to remove, just d isconnect it from the circuit and install modern axial capacitors... Hope t hat helps... best regards...
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