Hi,
I bought a used 1970s era console stereo made by fleet wood with a garand 3000 turntable in it. It sounds pretty good (to me and for my purposes: a stereo my wife will let me have in our living room), but the left/right balance seems to be drifting, and it gets more dramatic as it warms up; but even when it’s cold the balance needs to be adjusted to be centered relative to the center position on the adjustment dial.
I’m not sure what this could be. I wonder if it’s a transistor dying or if it’s a capacitor? Anyone have any thoughts or suggestions on how I could figure it out?
I bought a used 1970s era console stereo made by fleet wood with a garand 3000 turntable in it. It sounds pretty good (to me and for my purposes: a stereo my wife will let me have in our living room), but the left/right balance seems to be drifting, and it gets more dramatic as it warms up; but even when it’s cold the balance needs to be adjusted to be centered relative to the center position on the adjustment dial.
I’m not sure what this could be. I wonder if it’s a transistor dying or if it’s a capacitor? Anyone have any thoughts or suggestions on how I could figure it out?
Audio transistors don't die of old age. they die of shorted loads like crossed speaker wires. TV horizontal transistors die of old age.
Rubber sealed water filled electrolytic capacitors die of old age, just like tires. No original tires on those antique cars at the Pebble Beach Concours. Capacitors heat up, water evaporates out of cracked rubber seals, capacitance changes and also ESR (something special $120 meters measure). Low power or too many highs or lows are usual symptoms, but wandering balance indicates your gain is changing on one channel or another. Little e-caps up in the front end on those.
One other possible cause of wandering gain, dirty potentiometers (controls) or connectors. Reseat the connectors, spray out the controls with crc contact cleaner.
I don't measure e-caps, I just change the **** things. Ever since the MacIntosh salesman told me those were the reason my 1961 35 W/ch amp was putting out 7 watts in 1970. The production date of the gear and the calender on the wall tell me they are bad. Or will go bad in a few weeks or a year. If you do just the one that is bad like the pros recommend, your antique gear is broken all the time as they fail one by one. Replacing just the one that is bad gets the lowest price repair for a shop, which is important to actually making the sale. Having antique gear broken all the time is very annoying to me, I don't follow the "just the bad ones" rule.
They have a plus near one lead, minus pointing to the other, or a red end for plus. Some rare ones say NP after the voltage for non-polar. Mark the board for plus with a sharpie as you remove them, If you put a new one in backwards it probably will pop the seal & leak.
I buy new ones rated >5000 hours service life, since the store shelf caps I put in my 1961 amp needed replacing 4 times in 40 years. farnell & digikey have the service life in the selector table. Don't buy from farnell in CA, they ship from USA and you pay a $20 UPS customs loan fee. Digikey has a cross border truck so they pay the customs.
I put 77 new caps in a 1968 Hammond organ, runs like a new one except for the 118 sustain caps I didn't replace yet. I don't use sustain anyway.
Replace them 2 at a time and test for function afterwards, newbies make a lot of bad solder joints. Wear safety glasses, solder splashes especially desoldering.
I like the vari temp soldering iron from parts-express.com , and their rubber bulb desoldering tool. Use 60/40 or 63/37 tin lead solder with rosin core. You'll have to buy a pound from a major distributor like digikey.
Solder tutorials are on jameco.com.
Have fun. Historic gear is diy, and if you put the long life caps in you'll still be enjoying it in 10-15 years. Unless a rubber belt or idler goes bad in the turntable. Those probably can be bought though, for a gerrard.
Rubber sealed water filled electrolytic capacitors die of old age, just like tires. No original tires on those antique cars at the Pebble Beach Concours. Capacitors heat up, water evaporates out of cracked rubber seals, capacitance changes and also ESR (something special $120 meters measure). Low power or too many highs or lows are usual symptoms, but wandering balance indicates your gain is changing on one channel or another. Little e-caps up in the front end on those.
One other possible cause of wandering gain, dirty potentiometers (controls) or connectors. Reseat the connectors, spray out the controls with crc contact cleaner.
I don't measure e-caps, I just change the **** things. Ever since the MacIntosh salesman told me those were the reason my 1961 35 W/ch amp was putting out 7 watts in 1970. The production date of the gear and the calender on the wall tell me they are bad. Or will go bad in a few weeks or a year. If you do just the one that is bad like the pros recommend, your antique gear is broken all the time as they fail one by one. Replacing just the one that is bad gets the lowest price repair for a shop, which is important to actually making the sale. Having antique gear broken all the time is very annoying to me, I don't follow the "just the bad ones" rule.
They have a plus near one lead, minus pointing to the other, or a red end for plus. Some rare ones say NP after the voltage for non-polar. Mark the board for plus with a sharpie as you remove them, If you put a new one in backwards it probably will pop the seal & leak.
I buy new ones rated >5000 hours service life, since the store shelf caps I put in my 1961 amp needed replacing 4 times in 40 years. farnell & digikey have the service life in the selector table. Don't buy from farnell in CA, they ship from USA and you pay a $20 UPS customs loan fee. Digikey has a cross border truck so they pay the customs.
I put 77 new caps in a 1968 Hammond organ, runs like a new one except for the 118 sustain caps I didn't replace yet. I don't use sustain anyway.
Replace them 2 at a time and test for function afterwards, newbies make a lot of bad solder joints. Wear safety glasses, solder splashes especially desoldering.
I like the vari temp soldering iron from parts-express.com , and their rubber bulb desoldering tool. Use 60/40 or 63/37 tin lead solder with rosin core. You'll have to buy a pound from a major distributor like digikey.
Solder tutorials are on jameco.com.
Have fun. Historic gear is diy, and if you put the long life caps in you'll still be enjoying it in 10-15 years. Unless a rubber belt or idler goes bad in the turntable. Those probably can be bought though, for a gerrard.
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