sleekspeed22 Posted January 6 Share Posted January 6 I have a Sansui AU-2900 connected to JVC KD-V100 (cassette deck) and JVC L-F210B (record player). The Aux is often connected to iPad headphone output. The Aux levels are fine. But the Phono and Tape monitor are way too loud... even at 0 volume. Is this a problem with the Amp and how it's handling the inputs or is it the signal output from tape deck and record player? What should I measure to check? voltage? I need to buy a replacement fuse. Where should I look? local store in Canada? Online? I'm new to these so please feel free to share troubleshooting advice. Link to comment Share on other sites More sharing options...
Ian McP Posted January 6 Share Posted January 6 schematic will help a technician find any fault https://www.hifiengine.com/manual_library/sansui/au-2900.shtml 1 Link to comment Share on other sites More sharing options...
VanArn Posted January 6 Share Posted January 6 The reference output level for the Ipad is approx. 1 volt. This level will overload the Aux input of the Sansui which has a sensitivity of 130 mV. A 12 dB attenuator pad fitted to a connecting cable from the Ipad to the amplifier would fix this problem*. The cassette deck should be disconnected from the amplifier to verify if the turntable is working correctly. If the sensitivity is now as it should be then the amplifier is O.K. I would then advise re-connecting the cassette deck and making sure that one set of leads go from the amplifier's 'Tape Play' sockets to the 'Line O/P' sockets on the cassette deck and the other set of leads go from the amplifier's 'Rec Out' sockets to the 'Line In' sockets on the cassette deck. * You could also adjust the gain of the Ipad using the menu. 1 1 Link to comment Share on other sites More sharing options...
stereo coffee Posted January 6 Share Posted January 6 (edited) 7 hours ago, sleekspeed22 said: I have a Sansui AU-2900 connected to JVC KD-V100 (cassette deck) and JVC L-F210B (record player). The Aux is often connected to iPad headphone output. The Aux levels are fine. But the Phono and Tape monitor are way too loud... even at 0 volume. Is this a problem with the Amp and how it's handling the inputs or is it the signal output from tape deck and record player? What should I measure to check? voltage? I need to buy a replacement fuse. Where should I look? local store in Canada? Online? I'm new to these so please feel free to share troubleshooting advice. The speaker fuses are 3.5 amp rated . https://www.grainger.ca/en/category/fuses/electrical/c/2199 You will need to identify their size and rating. Popular sizes are 3AG and M205 , and ratings can be fast blow or slow blow Sansui's information just provides the amperage rating and lists the fuses as parts F 853 and F 864 with board markings so a visual check internally of your AU2900 will be needed to replace with the same part. Remember to DISCONNECT power at your power point before opening the cover , and replace cover before powering again. If the replacement fuse holds it will be indicating that the fault likely was with speaker leads. so check your speaker leads firstly Edited January 6 by stereo coffee 1 Link to comment Share on other sites More sharing options...
sleekspeed22 Posted January 21 Author Share Posted January 21 looks like hifiengine.com isn't taking new registrations? anywhere else I can get the schematics and docs? I checked my fuses and they seem to be ok. Guess the problem is elsewhere. Any suggestions on what to check with my multi meter? Link to comment Share on other sites More sharing options...
stereo coffee Posted January 21 Share Posted January 21 (edited) 50 minutes ago, sleekspeed22 said: looks like hifiengine.com isn't taking new registrations? anywhere else I can get the schematics and docs? I checked my fuses and they seem to be ok. Guess the problem is elsewhere. Any suggestions on what to check with my multi meter? There are 5 fuses, when you have checked them did you confirm 0 ohms or no higher than 0.3 ohms across each ? . Multimeter probes can be assessed for their own resistance by touching probe to probe, and the each fuse is similar displaying a resistance of probe + fuse resistance ( very little resistance ) + probe. You can check all the fuses with a multimeter set to ohms without power applied. Do that first There is a manual here: https://elektrotanya.com/sansui_au2900.pdf/download.html Sansui as you will find seem to suggest their output stage is less prone to faults, in which case the fuse condition , and present condition of operation will assist to diagnose. ie Is the amp running ? Are you running the phono input with a turntable cartridge ? A ipad output is likely to be too high in level. If so you can turn it down to nearly off , when connecting to the Sansui. levels expected are per the image Edited January 21 by stereo coffee 1 Link to comment Share on other sites More sharing options...
sleekspeed22 Posted January 22 Author Share Posted January 22 Thanks! @stereo coffee. I'll download and read over in the next couple days. The fuses are showing 0 ohms. I only have audio on the right side... both on speakers and headphones. Any thoughts on what to check next. Link to comment Share on other sites More sharing options...
stereo coffee Posted January 22 Share Posted January 22 12 minutes ago, sleekspeed22 said: Thanks! @stereo coffee. I'll download and read over in the next couple days. The fuses are showing 0 ohms. I only have audio on the right side... both on speakers and headphones. Any thoughts on what to check next. If you reverse the input cable, does the fault now swap to the right side and left side as good ? If so then fault is likely the cable, and if so check the RCA by undoing the collar and re soldering what may be a broken wire there, or replace the cable . Sansui use a switch for speakers, see if rotating the switch regains the non functioning channel. As speakers and headphones are not going on one channel, and fuses are intact, most likely is a fault at the input, so report back with channel swap, and try another cable. If there is a fault with the power amplifier it will invariably show as DC offset in varying degrees. You can check DC offset using a multimeter from speaker negative to speaker positive, measuring DC volts, anything over 0.03V is indicative of a fault Link to comment Share on other sites More sharing options...
sleekspeed22 Posted January 22 Author Share Posted January 22 @stereo coffee thank so much for your suggestions. Troubleshooting: Left: no audio, Right: audio working... for both headphones and speakers In each of these test I turn the know from Power Off to Speaker Off (to hear headphones) 1. test the inputs source and cable - I reversed the inputs as suggested (no change... still only right channel) then I kept the cable plugged in the ipad headphone jack and pulled the connections from the amp. plugged into another amp... both left and right channels work 2. then I plugged the rca cables from the ipad to Phono (reduced the volume to min... switched to matching source and turned on and the volume was still pretty loud. Still only on right 3. then plugged ipad into Tuner and switched to matching source and turned on and the volume was very low. Still only on right. I also tried flipping the rca plugs but still only sound on the right 4. then plugged ipad into Tape - Play and switched to matching source and turned on and the volume was very low. Still only on right 5. when adjusting volume (quickly up and down) I hear some scratching on the left in the headphones Does this give any more clues? What did you mean by: Sansui use a switch for speakers, see if rotating the switch regains the non functioning channel. Which switch should I rotate? Balance? changing balance didn't have bring back left. I rotated back and forth the other knobs and treble also produces a tiny bit of static but only on the right. Link to comment Share on other sites More sharing options...
stereo coffee Posted January 22 Share Posted January 22 48 minutes ago, sleekspeed22 said: @stereo coffee thank so much for your suggestions. Troubleshooting: Left: no audio, Right: audio working... for both headphones and speakers In each of these test I turn the know from Power Off to Speaker Off (to hear headphones) 1. test the inputs source and cable - I reversed the inputs as suggested (no change... still only right channel) then I kept the cable plugged in the ipad headphone jack and pulled the connections from the amp. plugged into another amp... both left and right channels work 2. then I plugged the rca cables from the ipad to Phono (reduced the volume to min... switched to matching source and turned on and the volume was still pretty loud. Still only on right 3. then plugged ipad into Tuner and switched to matching source and turned on and the volume was very low. Still only on right. I also tried flipping the rca plugs but still only sound on the right 4. then plugged ipad into Tape - Play and switched to matching source and turned on and the volume was very low. Still only on right 5. when adjusting volume (quickly up and down) I hear some scratching on the left in the headphones Does this give any more clues? What did you mean by: Sansui use a switch for speakers, see if rotating the switch regains the non functioning channel. Which switch should I rotate? Balance? changing balance didn't have bring back left. I rotated back and forth the other knobs and treble also produces a tiny bit of static but only on the right. Try testing with another source, other than the ipad .ie a source that is RCA to RCA like a Tuner or a CD player (but don't use the phono input with line level sources - even at low level the level is way too high ) .to see if Left restores. The reason for this is there are differences of how the sometimes 4th connector on a 3.5mm connector are used. see: https://www.head-fi.org/threads/3-5-mm-jacks-4-vs-3-conductors.689100/ The speaker selector switch is the first knob on the front panel on the left Link to comment Share on other sites More sharing options...
sleekspeed22 Posted January 22 Author Share Posted January 22 Some more testing as @stereo coffee suggested. I plugged in a JVC tape deck with RCA output (connected to tape play jacks) and left source selector at Aux and selected Tape Monitor and it's still only playing sound on the right for speakers and headphones. also switched to Tuner with Tape Monitor selected and same result. only sound on the right. Link to comment Share on other sites More sharing options...
stereo coffee Posted January 22 Share Posted January 22 (edited) 36 minutes ago, sleekspeed22 said: Some more testing as @stereo coffee suggested. I plugged in a JVC tape deck with RCA output (connected to tape play jacks) and left source selector at Aux and selected Tape Monitor and it's still only playing sound on the right for speakers and headphones. also switched to Tuner with Tape Monitor selected and same result. only sound on the right. Observing the schematic from the Left Speaker output positive to the power amp output for Left channel, test for continuity, which can be done with power OFF . You should have close to zero ohms. If though its open circuit then trace to find where continuity ceases , A handy reference is to then compare to right Test once the cover is back on and power applied for DC at the Left speaker output as mentioned beforehand where each channel should have no appreciable DC offset. Edited January 22 by stereo coffee 1 Link to comment Share on other sites More sharing options...
Recommended Posts