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JVC JAS22 no output.
JVC JAS22 no output.
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Old 19th September 2019, 03:01 PM   #1
Snailster is offline Snailster  Wales
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Default JVC JAS22 no output.

Hi I have been using a JVC JAS22 amp for some years now and to be honest I know it's vintage but the sound is great and looks great too.The problem I have is it now no longer has any output.It all lights up as it should but there is no click on start up.I'm suspecting it could be the protection circuit relay but not 100% sure.I'm wondering what peoples thoughts are on this and if parts are available for this amp.I'm using a Duel 505-1 turntable with Mordaunt Short MS815 speakers with it.Any help will be greatly appreciated as I would hate to throw it out but realise it's not the newest amp on the block.
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Old 19th September 2019, 09:27 PM   #2
Ylli is offline Ylli  United States
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There is a service manual available at JVC JA-S22 SERVICE MANUAL Pdf Download.. It's a pretty basic amp utilizing hybrid modules for the power amp. Both channels out and no click - protection is a good place to start looking.

How are your testing/measuring/soldering skills? What do you have available for test equipment? We can work through it if you wish.
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Old 20th September 2019, 09:24 AM   #3
Snailster is offline Snailster  Wales
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Hi Ylli many thanks for your reply.Completely new to audio repairs to be honest.Test equipment is a standard multimeter and no measuring equipment I'm afraid.I am very good at soldering though.I was an alarm and cctv installer for 26 years but have had to give up recently due to ill health and sold/gave away almost everything.I have a repaired many things over the years and have a good knowledge of electrics but this is a new ball game to me.I think my lack of proper test and diagnostic equipment will be a major problem here.
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Old 20th September 2019, 09:33 AM   #4
Mooly is offline Mooly  United Kingdom
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JVC JAS22 no output.
This amp appears to use thick film hybrid type output chips and its quite likely the fault lies there.

Two things to check for starters.

1/ That the supply voltages are correct to those chips.

2/ That there is zero volts DC at the junction of the 0.22 ohm resistors on the chip output.
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Old 20th September 2019, 05:51 PM   #5
Ylli is offline Ylli  United States
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After following Mooly's instructions, if the voltage at the junction of the 0.22 ohm resistors - both channels) (R335/R337 & R336/R338) is 100 mV or less, then measure the voltages on IC401 pins 1, 2, 3, and 6.
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