Hello fcaton, good luck on repairing this amp. There seems to be a reoccurring pattern with bad capacitors. If there is any chance you can post a copy of your schematics or service manual that would be much appreciated. Also anyone else that could possibly post the repair manual - service manual and or schematic that would really be helpful.
Thanks, Steve
Thanks, Steve
Hi Steve,
Here is the schematics I have. Looking more losely, I should measure the bias on the far right (bias check) and RB should be the bias resistor. Correct?
The last thing to know is how much it should be set to.
I'll also check the capacitors as I now have a capacitor meter.
François
Here is the schematics I have. Looking more losely, I should measure the bias on the far right (bias check) and RB should be the bias resistor. Correct?
The last thing to know is how much it should be set to.
I'll also check the capacitors as I now have a capacitor meter.
François
the supply capacitors are very weak...20 mF per rail should do it,
using four 10 mF condensators..
using four 10 mF condensators..
Here is some info on adjusting the bias on a Hafler Transnova amplifier:
http://www.hafler.com/techsupport/pdf/LIT11383_TRM8-1_man.pdf
See pages 11, 17, 28 and 29 for the theory of operation, schematic and bias adjustment procedures. A couple of notes:
The schematic on page 18-19 has the wrong component designators. When adjusting the bias, they refer you to remove the amplifier from the heatsink, then tell you to connect a loose brown wire from the transformer to the IEC input socket. I assume this is a ground connection, that has been broken once the amplifier is no longer in contact with the heatsink. Irrelevant for us.
With respect to the TA1600, it appears that R136 adjusts the bias current. My guess would be in the 75ma range given that the 75W amplifier in the Hafler monitor gets adjusted to 100ma. R8 is to adjust the CMRR of the amplifier.
Here is another manual for the P1500/P3000 which appears to be nearly identical to the TA1600. It has a schematic and more theory of operation than the monitor manual above:
http://www.hafler.com/techsupport/pdf/MAN1461C_P1500_P3000_man.pdf
http://www.hafler.com/techsupport/pdf/LIT11383_TRM8-1_man.pdf
See pages 11, 17, 28 and 29 for the theory of operation, schematic and bias adjustment procedures. A couple of notes:
The schematic on page 18-19 has the wrong component designators. When adjusting the bias, they refer you to remove the amplifier from the heatsink, then tell you to connect a loose brown wire from the transformer to the IEC input socket. I assume this is a ground connection, that has been broken once the amplifier is no longer in contact with the heatsink. Irrelevant for us.
With respect to the TA1600, it appears that R136 adjusts the bias current. My guess would be in the 75ma range given that the 75W amplifier in the Hafler monitor gets adjusted to 100ma. R8 is to adjust the CMRR of the amplifier.
Here is another manual for the P1500/P3000 which appears to be nearly identical to the TA1600. It has a schematic and more theory of operation than the monitor manual above:
http://www.hafler.com/techsupport/pdf/MAN1461C_P1500_P3000_man.pdf
I Just repaired a TA1600 that has the same bad surface mount cap issue as the 1100 I previously repaired. replace the caps. amp works great....
Hi everyone,
Thanks for the great info. I just adjusted the bias to 75mA as advised by Jack. It seems to be good.
The next step for me is to learn how to adjust the CMRR, but I am not too sure of how it is done:
"Use a sinewave generator set to 1 volt output at 1kHz. Connect the generator signal output to the tip and ring of a 1/4" plug and ground to the sleeve". As I am using the RCA inputs does this mean I just have to send in a 1Khz signal? 😕
Or am I missing something? The rest is quite clear.
Thanks for any info or help!
François
Thanks for the great info. I just adjusted the bias to 75mA as advised by Jack. It seems to be good.
The next step for me is to learn how to adjust the CMRR, but I am not too sure of how it is done:
"Use a sinewave generator set to 1 volt output at 1kHz. Connect the generator signal output to the tip and ring of a 1/4" plug and ground to the sleeve". As I am using the RCA inputs does this mean I just have to send in a 1Khz signal? 😕
Or am I missing something? The rest is quite clear.
Thanks for any info or help!
François
Francois,
No. To adjust the CMRR (Common Mode Rejection Ratio) you must apply the same signal to the - and + inputs at the same time. When the circuit is nulled perfectly, none of this 1kHz signal will be passed along to the amplifier power stages.
No. To adjust the CMRR (Common Mode Rejection Ratio) you must apply the same signal to the - and + inputs at the same time. When the circuit is nulled perfectly, none of this 1kHz signal will be passed along to the amplifier power stages.
Hi Jack,
Thanks a lot for your help. It makes a lot more sense now. Just a quick further question, just to make sure I am not overdoing things.
The Hafler plays quite well at the moment (no bass problem) but I have a quite audible background noise even without an input signal.
Am I right in thinking that adjusting the PSSR I may get rid of that noise? Thanks again for helping me out.
François
Thanks a lot for your help. It makes a lot more sense now. Just a quick further question, just to make sure I am not overdoing things.
The Hafler plays quite well at the moment (no bass problem) but I have a quite audible background noise even without an input signal.
Am I right in thinking that adjusting the PSSR I may get rid of that noise? Thanks again for helping me out.
François
Unplug both inputs to the amplifier. If the noise out of the speakers is now gone, then you either have a ground loop or your preamp has too much noise for the input sensitivity of the Hafler.
If the noise from the speakers is hiss, improving the CMRR won't help. You just have something in the system limiting the s/n ratio. In this case, probably the input sensitivity of the Hafler is not matched to the maximum output level of your preamp. Just turn the input level controls on the Hafler down until the hiss is acceptable.
If the noise from the speakers has hum or buzz (harmonics of the 60Hz hum frequency), then you have a ground loop problem.
If you are using the RCA inputs, the CMRR probably isn't giving you any benefit. You need to use the balanced inputs to get an advantage of the high CMRR.
To correctly connect the unbalanced input of your preamp to the balanced input of the Hafler, see the link below:
http://www.jensentransformers.com/an/an003.pdf
Build a cable as shown in fig 2.1. Note that you MUST use a cable that has three total conductors (two plus the shield). DO NOT short pins 1 and 3 together at the Hafler end of the cable. This will cause noise. Since the Hafler doesn't have an XLR input, but a TRS input, you will need to connect Shield to the shield of the TRS, HI to the tip and LO to the ring.
If this doesn't completely fix the hum or buzz, you can try removing the pin 1 connection at the XLR/TRS end of the cable. If your preamp and Hafler are at the same ground potential from the 3-pronged power cords, this may reduce the hum/buzz some more. If they are not at the same ground potential, it will probably just make tons of noise.
If the noise from the speakers is hiss, improving the CMRR won't help. You just have something in the system limiting the s/n ratio. In this case, probably the input sensitivity of the Hafler is not matched to the maximum output level of your preamp. Just turn the input level controls on the Hafler down until the hiss is acceptable.
If the noise from the speakers has hum or buzz (harmonics of the 60Hz hum frequency), then you have a ground loop problem.
If you are using the RCA inputs, the CMRR probably isn't giving you any benefit. You need to use the balanced inputs to get an advantage of the high CMRR.
To correctly connect the unbalanced input of your preamp to the balanced input of the Hafler, see the link below:
http://www.jensentransformers.com/an/an003.pdf
Build a cable as shown in fig 2.1. Note that you MUST use a cable that has three total conductors (two plus the shield). DO NOT short pins 1 and 3 together at the Hafler end of the cable. This will cause noise. Since the Hafler doesn't have an XLR input, but a TRS input, you will need to connect Shield to the shield of the TRS, HI to the tip and LO to the ring.
If this doesn't completely fix the hum or buzz, you can try removing the pin 1 connection at the XLR/TRS end of the cable. If your preamp and Hafler are at the same ground potential from the 3-pronged power cords, this may reduce the hum/buzz some more. If they are not at the same ground potential, it will probably just make tons of noise.
Hi Jack and thanks again!
I'll do the tests you suggest.
Also, and that may be of importance, I use this passive promitheus preamp:
Reference TVC
There is a provision for balanced XLR output, but I never used it because the hafler uses TRS.
François
I'll do the tests you suggest.
Also, and that may be of importance, I use this passive promitheus preamp:
Reference TVC
There is a provision for balanced XLR output, but I never used it because the hafler uses TRS.
François
Hi guys,
Sorry for the bump from obscurity. I don't really have any experience with electronics, but I have had a TA1600 for about 5 years now, and it's had this problem for 4 of them.
The first time it happened, it was still under warranty, so I got a new one. The second time, they quoted me $170 to repair it, and seeing as I only paid $130 to buy it in the first place, I turned them down.
After a little experimenting, I discovered that I could restore the bass and mids in the problematic channel by inserting a TS adapter into the jack so that it lifted the first two contacts and just barely touched the last one. The sound was still a little distorted, and I lost control of volume in that channel, but as long as I had a (sorta functioning) preamp for volume control, I could live with it.
Then, about two years ago, the other channel went out. I could treat it the same way, but honestly, it wasn't worth the distortion and annoyance (the adapter would fall out of position every time I touched it).
Anyway, I would be very grateful if you could help me out - does it sound like I need to replace certain caps? Does my story give you any clues about which ones to try first?
And most importantly, does this sound like a repair that someone with limited electronics experience could hope to do himself, or should I just save up for a more reliable power amp and deal with crappy sound in the meantime?
Thanks!
Sorry for the bump from obscurity. I don't really have any experience with electronics, but I have had a TA1600 for about 5 years now, and it's had this problem for 4 of them.
The first time it happened, it was still under warranty, so I got a new one. The second time, they quoted me $170 to repair it, and seeing as I only paid $130 to buy it in the first place, I turned them down.
After a little experimenting, I discovered that I could restore the bass and mids in the problematic channel by inserting a TS adapter into the jack so that it lifted the first two contacts and just barely touched the last one. The sound was still a little distorted, and I lost control of volume in that channel, but as long as I had a (sorta functioning) preamp for volume control, I could live with it.
Then, about two years ago, the other channel went out. I could treat it the same way, but honestly, it wasn't worth the distortion and annoyance (the adapter would fall out of position every time I touched it).
Anyway, I would be very grateful if you could help me out - does it sound like I need to replace certain caps? Does my story give you any clues about which ones to try first?
And most importantly, does this sound like a repair that someone with limited electronics experience could hope to do himself, or should I just save up for a more reliable power amp and deal with crappy sound in the meantime?
Thanks!
I am curious if any of the gurus here have any ideas on how to bring this affordable amp up to audiophile level.
Hi there,
Today I got a TA1600 with "buzzing" one or both channels. No input signal applied, just a pair of headphones to do a quick test.
Eventually fiddling with the power supply input(by means of a variac) I found out that this "audiophile amp" is simply too sensible to voltage fluctuation.
In fact, lowering the power input voltage to 226Vac, the buzzing sound appeared. As soon as the supply was at 230 or slightly more volts, the amp worked just fine.
I measured the auxiliary supply from the transformer to be 2x15Vac when 230V are input. With this voltage we get some 19Vdc at the input to the two linear voltage regulators... I think this is a little bit on the low side to have the 317/337 stabilize the output. They need at least 5V(Vin-Vout) difference to operate properly - at least according to their datasheet.
So a mere 2V are not enough and thus we get the ripplety-rip power supply directly to the input section(current source) of the amp and this is afterwards faithfully reproduced at the output.... I'll try to replace the 317/337 with some low-dropout regulators(perhaps from Linear). The correct way to solve the problems would however be replacing the power transformer with a type which has a greater output voltage at the auxiliary winding. Say some 2x17-20Vac.
Oh, where did I read something about the input power tolerance +5%/-10%(240Vac/207Vac)?
Cheers,
Today I got a TA1600 with "buzzing" one or both channels. No input signal applied, just a pair of headphones to do a quick test.
Eventually fiddling with the power supply input(by means of a variac) I found out that this "audiophile amp" is simply too sensible to voltage fluctuation.
In fact, lowering the power input voltage to 226Vac, the buzzing sound appeared. As soon as the supply was at 230 or slightly more volts, the amp worked just fine.
I measured the auxiliary supply from the transformer to be 2x15Vac when 230V are input. With this voltage we get some 19Vdc at the input to the two linear voltage regulators... I think this is a little bit on the low side to have the 317/337 stabilize the output. They need at least 5V(Vin-Vout) difference to operate properly - at least according to their datasheet.
So a mere 2V are not enough and thus we get the ripplety-rip power supply directly to the input section(current source) of the amp and this is afterwards faithfully reproduced at the output.... I'll try to replace the 317/337 with some low-dropout regulators(perhaps from Linear). The correct way to solve the problems would however be replacing the power transformer with a type which has a greater output voltage at the auxiliary winding. Say some 2x17-20Vac.
Oh, where did I read something about the input power tolerance +5%/-10%(240Vac/207Vac)?
Cheers,
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The smart way to fix it might be to change the resistor on the adjust pin (R29, R30) to regulate at a lower voltage.
But before I did that, I would change the two 470µF filter caps, C3 and C14, and check all four diodes in CR10.
But before I did that, I would change the two 470µF filter caps, C3 and C14, and check all four diodes in CR10.
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Looks like the lack of bass issue with these TA1600's is a common problem. I'm having the same issue - one channel lacks bass and is putting out 1/3 less power than the other. I'm seeing that a lot of people did recaps, but others only did some components. Is there a good place to start or is it worth it to just change all of them?
It's been a while since I've been on this thread but I wanted to follow up and add another strange observation I came across.
I was able to find a second TA1600, this time for only $50 because it was "as is". It turns out that this amp was in perfect working order and did not exhibit the bass issues of the first one.
Lately I have been using both inputs as a temporary solution to being able to play both my turntable and my computer my monitors. The only issue is that connecting the 1/4 automatically disables the RCA jack. While experimenting with this, I discovered that putting an unbalanced input jack halfway in to the first insert contact turned each channel volume into an almost "treble/bass" control. I know this isn't the right way to use the amp so I'm not going to continue using it like this (even if it does seem to allow a fix for the lack of bass issue), but does anyone know why or how this could happen?
I was able to find a second TA1600, this time for only $50 because it was "as is". It turns out that this amp was in perfect working order and did not exhibit the bass issues of the first one.
Lately I have been using both inputs as a temporary solution to being able to play both my turntable and my computer my monitors. The only issue is that connecting the 1/4 automatically disables the RCA jack. While experimenting with this, I discovered that putting an unbalanced input jack halfway in to the first insert contact turned each channel volume into an almost "treble/bass" control. I know this isn't the right way to use the amp so I'm not going to continue using it like this (even if it does seem to allow a fix for the lack of bass issue), but does anyone know why or how this could happen?
I know... an old post...
If anyone has the schematic for the TA 1600 amp, I could really find a use.
After 12 years, my amp woke up with no bottom...lol
I do a bunch of electronic projects when necessary...and now it is necessary again...
Thanks, Mike
If anyone has the schematic for the TA 1600 amp, I could really find a use.
After 12 years, my amp woke up with no bottom...lol
I do a bunch of electronic projects when necessary...and now it is necessary again...
Thanks, Mike
Hi All,
I have the same issue unfortunately. One channel works perfectly fine but another has no bass and has approx. 1/3 of volume. Made recap of two 10uF and two 100uF - without any changes. Waiting for two 470uF and two 4700uF (instead 3300uF) but multimeter sais that removed capacitors are ok... Likely recaping won't solve the issue. So, maybe someone already has solution how to fix this issue?
Many thanks in advance
I have the same issue unfortunately. One channel works perfectly fine but another has no bass and has approx. 1/3 of volume. Made recap of two 10uF and two 100uF - without any changes. Waiting for two 470uF and two 4700uF (instead 3300uF) but multimeter sais that removed capacitors are ok... Likely recaping won't solve the issue. So, maybe someone already has solution how to fix this issue?
Many thanks in advance
And yes, for all who is still finding a schema, pls, refer to this PDF - http://www.hafler.com/pdf/archive/TA1600-schematic.pdf
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