Hi Guys!!!😱
I'd like to upgrade this amp circuit board! (This is one of the two amp modules!)
The pink Facon capacitor you can see and the other smaller black capacitor, are both 220 uF...the pink Facon has 50 V, whilst the black one has 16 V.
I want to replace them with two bigger capacitors (for example with two 470uF) but I've a dubt (I'm a newbie, so please forgive me if Im wrong!😕)
The Power supply unit has a stabilized current circuit (you see it in the picture)...so could this capacitors up-grade is a problem for the amplifier?😕
Thank you!
Regards😉
I'd like to upgrade this amp circuit board! (This is one of the two amp modules!)
The pink Facon capacitor you can see and the other smaller black capacitor, are both 220 uF...the pink Facon has 50 V, whilst the black one has 16 V.
I want to replace them with two bigger capacitors (for example with two 470uF) but I've a dubt (I'm a newbie, so please forgive me if Im wrong!😕)
The Power supply unit has a stabilized current circuit (you see it in the picture)...so could this capacitors up-grade is a problem for the amplifier?😕
Thank you!
Regards😉
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Make and model of amplifier?
Schematics?
Without knowing exactly where they are in the circuit, it is not wise to change values.
What are you trying to do anyway?
Schematics?
Without knowing exactly where they are in the circuit, it is not wise to change values.
What are you trying to do anyway?
Measure the output AC voltage just below clipping on 8 ohms load, speaker will do. P=(V^2)/Z where Z is speaker impedance. P is 50 W the sticker says. If the V is 20 vac, then there is nothing wrong with the electrolytic capacitors. Use an analog voltmeter or a scope, cheap DVM make random numbers on music. Cheap analog VOM with 20 vac scale are about $25.
Those capacitor values are available. It is best to use the same ones. Maybe upgrade the 25 v rated ones on power board to 35 V or so. If you like it, use capacitors rated >3000 hours service life. One can burn up 2000 hours of life in one year.
This can't be that old, toroid transformers didn't hit the market until maybe the nineties?
I'd be about as worried about those cheap resistors. Measure them, they could have gotten water in them and changed value. Resistor color code is on wikipedia.
Using TO92 transistors as drivers is pretty iffy unless the output transistors are darlingtons or fets. If the OT part number is an industry number, you can look up datasheet on datasheetcatalog.com If a house number, b to e > 1v means they are darlingtons. If they are darlingtons, I wouldn't fool with it. If OT are fets, Score! Nice heat sink.
Those capacitor values are available. It is best to use the same ones. Maybe upgrade the 25 v rated ones on power board to 35 V or so. If you like it, use capacitors rated >3000 hours service life. One can burn up 2000 hours of life in one year.
This can't be that old, toroid transformers didn't hit the market until maybe the nineties?
I'd be about as worried about those cheap resistors. Measure them, they could have gotten water in them and changed value. Resistor color code is on wikipedia.
Using TO92 transistors as drivers is pretty iffy unless the output transistors are darlingtons or fets. If the OT part number is an industry number, you can look up datasheet on datasheetcatalog.com If a house number, b to e > 1v means they are darlingtons. If they are darlingtons, I wouldn't fool with it. If OT are fets, Score! Nice heat sink.
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You posted the same picture in another section, maybe Power Supplies?
This appears to be a low-price amplifier. The cheapest caps you can buy from a GOOD vendor will be better than what the factory bought.
This appears to be a low-price amplifier. The cheapest caps you can buy from a GOOD vendor will be better than what the factory bought.
Thank you, this was not at all a cheap amplifier in the 1977 in Italy (made in Italy!)
It was a very expansive tuner-amplifier at the time made by Imperial/Telefunken (in Italy it has been a long Joint Venture)
I Would just to recapping the old capacitors with new ones.
In the picture below you can see also the power supply unit (with a stabilizer power current circuit): In this power supply unit, could I use new bigger capacitance capacitors? or do I replace them with new ones with the same capacitance?
Same question for the amp circuit board: do I left the original capacitors value or can I use modern capacitor with higher capacitance values? and what about the white resistors, Is it better replace them too? that's all!🙂 Sorry for my ignorance, guys! I'am ashamed.
Thank you!🙂
Regards
It was a very expansive tuner-amplifier at the time made by Imperial/Telefunken (in Italy it has been a long Joint Venture)
I Would just to recapping the old capacitors with new ones.
In the picture below you can see also the power supply unit (with a stabilizer power current circuit): In this power supply unit, could I use new bigger capacitance capacitors? or do I replace them with new ones with the same capacitance?
Same question for the amp circuit board: do I left the original capacitors value or can I use modern capacitor with higher capacitance values? and what about the white resistors, Is it better replace them too? that's all!🙂 Sorry for my ignorance, guys! I'am ashamed.
Thank you!🙂
Regards
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Super-cute! As a teenager and aspiring DJ in the 70ies I would have killed for this modular but expensive design. I started building my own modules but got diverted into a different career path leaving them unfinished...
Do the measurements, don't go blindly replacing stuff. questions answered in post 3.
Most common electrolytic caps at distributors are 1000 hours rated. Means they start wearing out at 6 months of use 6 hours a day. Check the service life rating. Digikey & farnell will show you service life in the selector table. Mouser makes you download each datasheet & read it. Don't know about RS & Reichelt. I got nothing but garbage grade at local stores, had to replace e-caps in a 1961 amp 4 times for low power. Now with debit cards I can buy long life rated caps from farnell or digikey.
I just put some 5000 hour 105C e-caps in my 1984 75 w/ch amp that won't put out more than 1 vac. "Broken" is a matter of degree, it sounds good but not very loud. Should put out 23 vac on 8 ohm speaker. Power board done, more to replace on the input board.
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2 nichicon, 2 rubicon, 2 kemet
I've installed hundreds of nichicon & rubicon in organs & amps without failure. Kemet is new to me.
1984 M-2600 amp was putting out a volt with all old caps. Now with new PS caps puts out a volt & a half. 6 more old e-caps on input board. Don't measure capacitance, dried up ones are usually 10-20% high. ESR is useful but the meter costs $120, not worth the time to measure I've decided. If you replace "only the bad ones" your device is broken all the time as the rest dry up one by one. OTOH some 30 year old amps lived life on a shelf, don't have a cap limited wattage problem. My 12 hours a day MMA-875t amp has old caps; was not used because of a flaky solder joint from the factory. Is monaural, trying to get M-2600 working for stereo.
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