A friend purchased a used, repaired XTR2500.1DZ that was reported to have an intermittently shorting output inductor. It was tested at purchase time and he actually used it lightly for a few days until I vhad time to look inside.
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The amp is operating normal but the one area of concern is the bipolar output filter capacitors. There are board markings for six capacitors which I believe should be 22uf 250v , but there are only five capacitors in these spots. To make it worse,, three are 22uf250v and the other two are 10uf/250v. Bipolar caps are difficult to find around here, so it appears that they scavenged. What they could.
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Will these mismatched 22uf and 10uf capacitors cause any problem if he continues to use the amplifier lightly until the proper replacement
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The amp is operating normal but the one area of concern is the bipolar output filter capacitors. There are board markings for six capacitors which I believe should be 22uf 250v , but there are only five capacitors in these spots. To make it worse,, three are 22uf250v and the other two are 10uf/250v. Bipolar caps are difficult to find around here, so it appears that they scavenged. What they could.
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Will these mismatched 22uf and 10uf capacitors cause any problem if he continues to use the amplifier lightly until the proper replacement
If they all are in parallel, it isn't a matter of matching but of total capacitance.
If the total capacitance is lower than it should be it means that the LC filter cut-off frequency is higher than it should be, meaning there's a bit more noise at the output.
It might change the sound but should not be bad for the amp.
Jan
If the total capacitance is lower than it should be it means that the LC filter cut-off frequency is higher than it should be, meaning there's a bit more noise at the output.
It might change the sound but should not be bad for the amp.
Jan
Could the caps be in two different output filters?
Some amps object to having insufficient output capacitance. Others do not. The ones that do, generally make it clear that they will not operate with too little capacitance.
I have used 10uF 250v mylar/film caps in place of 10, 22 and 33uF bipolar electrolytics (one 10uF per location) and only 2 amps (that I can remember) had a problem.
Some amps object to having insufficient output capacitance. Others do not. The ones that do, generally make it clear that they will not operate with too little capacitance.
I have used 10uF 250v mylar/film caps in place of 10, 22 and 33uF bipolar electrolytics (one 10uF per location) and only 2 amps (that I can remember) had a problem.
I believe all 6 caps are connected across the secondary ground and the positive speaker terminal. We are going to have to order the six 22uf 250v bipolar/no polar capacitors as we can't source them locally.
I specifically need to know if it would be ok for the amp to operate with 3 10uf 200v and 2 22uf 250v capacitors installed until the correct parts arrive? I don't fully understand what the mixing of the cap's specs is actually doing but I do know that there would only be 5 caps instead of 6, so he would not be abusive with the output..
Also, I am placing an order from Arrow as they are the only ones with 2SA2121 in stock but I am having difficulty selecting the correct capacitors because they are not specifying bipolar/nonpolar. Can someone identify the correct 22uf 250v bipolar caps from Arrow for me...
I specifically need to know if it would be ok for the amp to operate with 3 10uf 200v and 2 22uf 250v capacitors installed until the correct parts arrive? I don't fully understand what the mixing of the cap's specs is actually doing but I do know that there would only be 5 caps instead of 6, so he would not be abusive with the output..
Also, I am placing an order from Arrow as they are the only ones with 2SA2121 in stock but I am having difficulty selecting the correct capacitors because they are not specifying bipolar/nonpolar. Can someone identify the correct 22uf 250v bipolar caps from Arrow for me...
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In a class D amp. the carrier (rail-rail oscillation) has to be blocked. The inductor provides a high impedance to the carrier. The capacitor(s) on the speaker side of the inductor, pull down the carrier to try to reduce it as much as possible. The more capacitance, the more the residual carrier is reduced. With some amp/speaker combinations, you probably couldn't tell if there were no caps but it would give the amp very bad specs and would look awful on the scope. If the amp plays normally with 5 caps, replacing them probably won't make a difference. You should replace them, especially if this a repair you're being paid for.
The only possible damage to the amp (assuming that it plays normally) would be a risk of burning out the series resistor/capacitor network that's across the speaker terminals of some amps.
It's difficult to find reliable replacements for those 10/22/33uF BP electrolytics. That's why I use film caps.
The only possible damage to the amp (assuming that it plays normally) would be a risk of burning out the series resistor/capacitor network that's across the speaker terminals of some amps.
It's difficult to find reliable replacements for those 10/22/33uF BP electrolytics. That's why I use film caps.
I might get the six capacitors to replace C352-C357 tomorrow. Can you please confirm what the values for C351 and C359 should be as I am unsure what is in there is correct and I will like to try to get those at the same time. Thanks
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They have no writing on them. They both appear to be identical, and they are both across the + and - speaker terminals, just like the six radial bipolar caps that I am replacing. They look exactly like what you sent me the link to. I am not sure how accurate the capacitor tester is on my Sonometer VC9808, or if I am using it correctly, but when tested it reads 1.24uf. Sorry for the upside down pics.
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The other film cap measures 1.2uf also. Should I try to swap one of them out for a 10uf, if available?
I am not certain that 22uf is the original specs for this amp's bipolar radial caps, but that is what was in there and also what was reported in another thread on here. Should I go back with 22uf for the 6 radial spots, leave one of these 1.2uf film caps, and try to get a 10uf film cap for the other spot? Or should I just leave the two 1.2uf film caps alone?
I am not certain that 22uf is the original specs for this amp's bipolar radial caps, but that is what was in there and also what was reported in another thread on here. Should I go back with 22uf for the 6 radial spots, leave one of these 1.2uf film caps, and try to get a 10uf film cap for the other spot? Or should I just leave the two 1.2uf film caps alone?
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