Hi everyone
My friend have an Pioneer A-717 amp , he matched with Wardafle Diamond 12.4 speakers, so when he put the second speaker there was no sound we saw fumes coming out of the amp , It looks like the bare ends of wire shorted Spk+ with-
So I opened it up , I saw 2 pairs of one channel Transistors measuring short (2SA1265+2SC3182) , and cermaic resistors measure open (RGC55) , and two resisotrs in the block 47ohm and 260ohm were open , so I didn't had the same Transistor pair ,, I used 2SA2151+C6011 pair which has more power handling capacity, however lesser transition frequency of 20Mhz ,compared to orginal which is 30Mhz is that a concern , ? Is it suitable ?
Actually , I did replaced and power on , but I didn't get audio although I replaced Resisotrs, then I find one of the diode surrounding PA0016 IC measuring low resistance of 135ohms in both directions, which is not the measurement in the other working channel , when I Desolder IC PA0016 the short is gone and the IC measures low resistance like 32ohm and 57ohm in the adjacent pins , I feel the IC is shorted , Im thinking of swapping IC from working channel however before that I wanted to confirm that the newly repalced equivalent Transistors will cause any harm to IC PA0016 ?
(sorry for the long post , )
My friend have an Pioneer A-717 amp , he matched with Wardafle Diamond 12.4 speakers, so when he put the second speaker there was no sound we saw fumes coming out of the amp , It looks like the bare ends of wire shorted Spk+ with-
So I opened it up , I saw 2 pairs of one channel Transistors measuring short (2SA1265+2SC3182) , and cermaic resistors measure open (RGC55) , and two resisotrs in the block 47ohm and 260ohm were open , so I didn't had the same Transistor pair ,, I used 2SA2151+C6011 pair which has more power handling capacity, however lesser transition frequency of 20Mhz ,compared to orginal which is 30Mhz is that a concern , ? Is it suitable ?
Actually , I did replaced and power on , but I didn't get audio although I replaced Resisotrs, then I find one of the diode surrounding PA0016 IC measuring low resistance of 135ohms in both directions, which is not the measurement in the other working channel , when I Desolder IC PA0016 the short is gone and the IC measures low resistance like 32ohm and 57ohm in the adjacent pins , I feel the IC is shorted , Im thinking of swapping IC from working channel however before that I wanted to confirm that the newly repalced equivalent Transistors will cause any harm to IC PA0016 ?
(sorry for the long post , )
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Khm, this is quite a strange strategy of fault finding...
You have the schematics?
The service manual has voltages indicated - also for IC 101. Do your measurements match these?
Also - do you use a DBT (dim bulb tester)?
The fried outputs can cause damage upstream beyond the IC101 frontier and bulk replacement of some found defective components will not guarantee you success.
I don't get the voltages on IC PA0016 as mentioned in the service manual, and yeah I checked the voltages in the working channel IC is same as per manual.
I used 60W bulb tester , can I use 200W bulb ?
At this point , before installing the new IC , just want to know what are the consequences of using a output Transistor. With lesser transition frequency frequency as mentioned detailly above
I used 60W bulb tester , can I use 200W bulb ?
At this point , before installing the new IC , just want to know what are the consequences of using a output Transistor. With lesser transition frequency frequency as mentioned detailly above
Sorry but at this point you are just rambling in the dark - no tool, no method.
If you want to the forum members to help you then the first step would be sharing your measurement results - both for the working and defective channel.
On working channel , I get voltages exactly as per the Schematic on PA IC ,
In defective channel I get all pins 47V
These results observed by swapping the PA0016 from working to the defective channel
In defective channel I get all pins 47V
These results observed by swapping the PA0016 from working to the defective channel
Your post remains somewhat obscure - did you get 47V on all pins in defective channel with the IC from the working channel placed there?
Yes ., and I also measure 40V on all three pins of Final Transistors and driving transistor , I Desoldered them (Final T's and Driving T's) , but still I get such voltage
It's DONE !!!
I have fixed it , the reason for voltage appearing on all three pins of Output final Transistors was , a small Transistor (C1845) near PA ic is shorted , after replacing it all voltages good and I got sound !
And I get pop and mute of sound for some seconds when I increase volume faster which I think is result of using 20Mhz transistor in place of 30Mhz ., but when volume increased slowly thers no problem.,
So basically these are components I replaced...
1.2 * A2151+C6011( alternative for A1265+ C3182 pair )
2.47 ohm resisotrs, 100 ohm resisotrs, 260ohm,
3.4* 0.33ohm
4.C1845 transistor
5. The PA0016
Thanx for ur involvement @madis64
I have fixed it , the reason for voltage appearing on all three pins of Output final Transistors was , a small Transistor (C1845) near PA ic is shorted , after replacing it all voltages good and I got sound !
And I get pop and mute of sound for some seconds when I increase volume faster which I think is result of using 20Mhz transistor in place of 30Mhz ., but when volume increased slowly thers no problem.,
So basically these are components I replaced...
1.2 * A2151+C6011( alternative for A1265+ C3182 pair )
2.47 ohm resisotrs, 100 ohm resisotrs, 260ohm,
3.4* 0.33ohm
4.C1845 transistor
5. The PA0016
Thanx for ur involvement @madis64
