Is it audio heresy to put some new guts in to a vintage Sony 3140f 35 watt power amp?

hbc · 12th June 2011, 08:08 AM

Following my recent road to Damascus realisation that valves (tubes) really are better than transistors, this looks like a nice victim to make into a valve and transistor-output hybrid, but would it be more ethical to fix it and put it on ebay or re gut it and transform it in to a much better sounding amp. I have no idea how covetable these amps are apart from the fact that it is cute....

any opinions welcome

SONY TA-3140F SM Service Manual free download, schematics, eeprom, repair info for electronics

(get manual)

Nrik · 12th June 2011, 08:20 AM

Tough call.
Arguments for fix-n-sell:
1) No risk of getting burned on the DIYaudio-purist-bonfire,
2) getting cash to buy new parts, when building a new one from scratch
3) you can decide all aspects of your tubeamp yourself

Arguments for gut-n-build-new-inside:
4) Outside result is already nice,
5) It is already broken ( right?) so it needs some kind of mending - why not make it 'better'
6) Even if you did fix it back to original standard - would it then be sellable at all, and for how many bucks?
7) It doesn't appear to have any unique features worth saving for historical reasons (such as V-FETs) and therefore DIYaudio purist might not get offended anyway.

defect9 · 12th June 2011, 09:25 AM

I usually base these sorts of decisions on what they sell for on ebay versus my time.

Andy5112405 · 12th June 2011, 09:49 AM

I often go the CashMart to buy DUFF amplifiers just for the cases. In this case the cases are not even worth saving.

Their only worth really is for the newbie that wants to "learn". The amps are a simple design that should not be too difficult to fix. As you have given no clue as to the fault, that statement could prove very false.

Antique transistors can be hard to find, substitutes might be disappointing. If the mains transformer(s) are faulty then you may or may not be able to fit substitute parts.

Historically manufacturers used to use custom built transformers. You might find that the voltages are unobtainable or even multiple.

I really wouldn't bother.

hbc · 6th July 2011, 11:15 PM

The Sony 3140F gets to be fixed, it has a mute switch as part of the power switch which is dirty. I have been given a Marantz PM66se, which doesn't work. it has a very agreeable internal layout, i.e. a big empty box with few bits in!

thanks for the input.

12th June 2011, 08:08 AM	#1
hbc diyAudio Member Join Date: Oct 2010 Location: Cambridge uk Blog Entries: 3	Is it audio heresy to put some new guts in to a vintage Sony 3140f 35 watt power amp? Following my recent road to Damascus realisation that valves (tubes) really are better than transistors, this looks like a nice victim to make into a valve and transistor-output hybrid, but would it be more ethical to fix it and put it on ebay or re gut it and transform it in to a much better sounding amp. I have no idea how covetable these amps are apart from the fact that it is cute.... any opinions welcome SONY TA-3140F SM Service Manual free download, schematics, eeprom, repair info for electronics (get manual)

12th June 2011, 08:20 AM	#2
Nrik diyAudio Member Join Date: Feb 2005 Location: Copenhagen	Tough call. Arguments for fix-n-sell: 1) No risk of getting burned on the DIYaudio-purist-bonfire, 2) getting cash to buy new parts, when building a new one from scratch 3) you can decide all aspects of your tubeamp yourself Arguments for gut-n-build-new-inside: 4) Outside result is already nice, 5) It is already broken ( right?) so it needs some kind of mending - why not make it 'better' 6) Even if you did fix it back to original standard - would it then be sellable at all, and for how many bucks? 7) It doesn't appear to have any unique features worth saving for historical reasons (such as V-FETs) and therefore DIYaudio purist might not get offended anyway. __________________ STOP - Hammertime!

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12th June 2011, 09:25 AM	#3
defect9 diyAudio Member Join Date: Sep 2007 Location: Carson City, NV	I usually base these sorts of decisions on what they sell for on ebay versus my time.

12th June 2011, 09:49 AM	#4
Andy5112405 Banned Join Date: Nov 2006 Location: Torpoint	I often go the CashMart to buy DUFF amplifiers just for the cases. In this case the cases are not even worth saving. Their only worth really is for the newbie that wants to "learn". The amps are a simple design that should not be too difficult to fix. As you have given no clue as to the fault, that statement could prove very false. Antique transistors can be hard to find, substitutes might be disappointing. If the mains transformer(s) are faulty then you may or may not be able to fit substitute parts. Historically manufacturers used to use custom built transformers. You might find that the voltages are unobtainable or even multiple. I really wouldn't bother.

6th July 2011, 11:15 PM	#5
hbc diyAudio Member Join Date: Oct 2010 Location: Cambridge uk Blog Entries: 3	The Sony 3140F gets to be fixed, it has a mute switch as part of the power switch which is dirty. I have been given a Marantz PM66se, which doesn't work. it has a very agreeable internal layout, i.e. a big empty box with few bits in! thanks for the input.

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