| ECM |
I'm repairing a few orion amps. A 250 HCCA, 225 HCCA, and a 275 SX.
All three of them have shorted outputs and shorted power supplies. I have on order irf3205's to replace the smps60n06 fets in the power supply. Must any changes to the gate resistors be made?
For the outputs, I ordered original 2n6488/91 parts, so no changes made. I'll be replacing all mpsa06/56 drivers since I have plenty in my parts bin. I'll order mpsu07/57 if needed.
What is the rail voltage on these amps? I'm assuming the 275sx has the highest since it makes the most power at 4 ohms followed by the 250 and the 225. Can I replace the rail caps on the 225 with 35v versions of higher capacitance? I will keep the 50 volt versions on the 250 and 275.
Thanks, |
|
|
| Perry Babin |
They all use 10 ohm gate resistors so no changes will be necessary. Don't forget to check the 10 ohm resistors between the A56 drivers and ground in the power supply.
As long as the voltage rating on the capacitor is equal or greater than the originals, they will be OK.
If you don't know the rail voltage, find the Zener connected to the base of the 2n6488 standing vertically in the power supply. The rail voltage is ~1v greater than the Zener voltage.
If you have a couple of good FETs, solder one in each side of the supply and power it up (after removing the shorted outputs). Then you can measure the actual rail voltage. |
|
|
| ECM |
Thanks Mr. Babin. With the fets installed, each resistor was measuring right at 10 ohms. I was thinking I would need to replace them with 63 ohm resistors to use the irf3205. Maybe I was thinking MTX power supply.
My plan is to strip all the fets and outputs, wipe down the board and replace the drivers. These amps are relatively old and one has minor corrosion, hence the wipe down. This will make it easy to fire up the amp with minimal fets to measure the rail voltage.
The 275SX is actually in a 225 case and an attempt at converting it to a 225 is next, but before I start rewinding toroids and adjusting rail voltages, I want to get it working first.
I have most parts on order. In the meantime, I can start stripping the boards down.
What's a good replacement for the double sided tape used on the transistor claps? I was thinking something along the lines of weather strip instead of double sided tape. That stuff is difficult to remove. Some transistors cracked when I removed the aluminum bars, but those were the ones that were shorted because once I took them off, all the shorts were gone. :xeye: |
|
|
| Perry Babin |
I use double-sided tape but I don't remove the backing so it can't stick to the transistors. When you burn the amp in, you need to re-tighten the clamps several times as the amp heats up and the tape compresses.
You could try to find some high-temp silicone rubber. http://www.mcmaster.com/ part number 93755K51 (or something on that page) should work well but I've never tried it.
To clean the boards, you can put them in the diswasher (don't use heat to dry them). I spray the boards with 409 and use a low pressure, pressure washer. Use compressed air to force the water from under the caps and ICs. If it's a warm day, set them in the sun to dry.
You can remove the pots before washing or flush them with contact cleaner after washing. |
|
|
| ECM |
I already have a couple rolls of double sided tape so I'll use that with the back on. I thought about doing that, but I figured the wax paper used for backing wouldn't hold up.
Dishwasher to clean boards? I never would have thought of that, much less actually done it. At work we have some really potent contact type cleaner which dries damn near instantly. It leaves the parts cold as it dries, which sometimes leads to condensation. I have used this stuff to clean smaller boards and it does a good job, but it tends to eat away at certain plastics and removes markings off some components. |
|
|
| ECM |
I pulled all the parts off the circuit board of the 275sx and cleaned it up a bit. The input power inductor is toast and I have some magnet wire on order to rewire it.
There are 4 main caps in the power supply primary. Two 1000uf 35V from b+ to ground BEFORE the inductor and two 3300uf 50V from b+ to ground AFTER the inductor.
Is there a reason why orion chose 35v and 50v caps for these locations? I was under the assumption that these were the smoothing caps, but those are on the audio side of the board and consists of 4 1000uf 35v caps and a couple smaller ones.
I'm thinking I can replace the 1000uf primary caps with 2200uf 25V units and the 3300uf caps with about 5600uf 25v caps as well. Is there a reason I shouldn't do this?
The board is pretty much bare at the moment so these mods should be fairly easy to do. The mpsa06/56 drivers in the PS have been changed already and the 10ohm resistors to ground all check ok. |
|
|
| Perry Babin |
All else being equal, higher voltage caps generally have lower ESR and will run cooler when there is significant ripple current. When you choose replacements, choose caps with the lowest ESR/impedance you can find. You should also use caps rated to operate at 105C (on the primary side of the power supply).These have worked well for me.
http://dkc3.digikey.com/PDF/T073/P1417.pdf
If you can't find a source for the 3300@50v axial caps, Radio Shack generally has them. I don't like buying replacement parts from RS but I haven't had any problems using these for repairs.
If you're going to reuse the old inductor core, you should scrape it smooth and dip/coat it in epoxy. |
|
|
| ECM |
I already cleaned the inductor core up since it was all crusty from over heating.:hot: Should I wind it and dip it or dip it before winding?
For capacitors, I have a few on hand and a few on order of different ratings and voltages. If I can fit a higher uF cap, I'll give it a try. If they blow up, I'll use originals. I didn't pay much attention to the esr when I ordered the caps. I was having a hard enough time finding the right size since I couldn't source any locally (I now live in Cyprus).
FYI, I installed two fets and the rectifiers and the sucker powered up just fine without the input caps. I installed a jumper where the inductor would normally be and the PS buzzed a little, but I didn't have any caps installed in the primary side. It was a really faint whine. I measured the rails at +/- 29V. This is for the 275SX.
Also on order are a few strips of high temp silicone to replace the double sided tape.
This hobby gets expensive fast. A few fets here, some outputs there, it all adds up. Of course, I'm ordering enough **** for 3 amps. The 250 alone uses 18 fets in the PS. |
|
|
| Perry Babin |
| I would coat the core before winding it. |
|
|
| djQUAN |
| quote: | Originally posted by Perry Babin
I would coat the core before winding it. |
then coat it again after. ;) |
|
|
| jol50 |
| quote: | Originally posted by ECM
This hobby gets expensive fast. A few fets here, some outputs there, it all adds up. Of course, I'm ordering enough **** for 3 amps. The 250 alone uses 18 fets in the PS. |
This sounds more like a restoration than a repair, but should be some very nice amps when done. What do you do write down all the parts, or do you have the schematic for them? |
|
|
| ECM |
jol50, yes, it does sound more like a restoration.
I bought all three amps non-working. On all three, it seems the output section shorted, then took out the PS.
Instead of just replacing the shorted parts, I'll be replacing them all since they were all subjected to the same abuse that caused the shorts in the first place.
I don't have a schematic for them, but folks on this forum are more than willing to help out. Especially Perry Babin.
I have repaired amps on and off for about 12 years and I have been lucky enough to be able to repair all but one (it was an Xtant).
I plan on keeping these for myself, so I'm going all out on the repairs. I plan on installing better power supply fets, larger caps, etc. It probably won't make a sonic difference, but it gives me peace of mind. |
|
|
| jol50 |
I have not done that much of this, but I do one part # at a time on the board so I don't screw something up. Just wondered what you do if you take a lot of things out at once...or the proper way.
Maybe some time I would do a project like that, the broken amps I have now are newer and not that good except for the alpine 1002 I posted about. Unfortunately it is a little beat up on the outside. But then I don't worry if I can't fix them either. Trying to get a little HK that might need a workover, that would be a nice little amp I'm told...if I can fix it. |
|
|
| ECM |
I write down all the component locations before removing them. In the orion amps, like half the board contains power supply fets so it's no biggie to remove all of them at once. Before I remove the outputs, I make a quick reference sheet with component part numbers and locations.
Sometimes, if i get an amp that is missing parts, I'll try to match up the missing parts with the parts on the other channel. that usually works for me.
Ampguts is a good website with lots of internal pictures that you can use for reference. If all else fails, you can ask on this forum. |
|
|
| ECM |
I'm still working on the 275SX. I epoxied the inductor core and rewound it. No shorts between any of the coils or to the inductor core itself (I made a small dmm probe incision to the metal on top of the core).
I replaced the capacitors on the power input side and installed a couple fets. It worked, but made a faint whine. I installed all 10 fets and it still works, but it is still making a faint whine. Is this normal? I recall someone on this forum said the toroid will make noise with no load and that they could actually hear music coming from it.
I'm going to install a pair of outputs per side and go from there. I'm at work, so I don't have a speaker handy, but I'm curious to see the amp work.
Even though I am getting +/-29V on the rails, the power light does not come on. I haven't tested the LED so it might be burned out.
Quick side note: My "faulty" DC power supply works just fine. It just doesn't like MTX amps. With the orion amp, it maintains a steady DC output. |
|
|
| jol50 |
I see, yes I know ampguts well. I could send them some pics too.
At least it is running. Had one amp I could hear static from the toroid, the rest I don't. Many have culk globbed under them, looks like for deadening...yet some don't.
Ran the alpine with one power mosfet in bad ch and it lives too. It is like two amps in one, so looking at the other channel is like a mirror even in power supply. |
|
|
| Clipped |
you may want to check the current draw when hooked up to the supply, i think most SX series amps have 36 volt rails and most hcca's have 22 volt rails....
the 225 and 250 i worked on in the past had 22 volt rails
and the 2150sx i worked on had 36 volt rails.
29 volts sounds low. |
|
|
| ECM |
clipped, i think 36v would be high for a 75 watt/chan amp. I will double check the regulator zener to verify the value. The current draw at idle is very low...maybe 1/2 amp or so. This is exactly what the owners manual states. I'll be installing the rest of the outputs today and connecting a speaker to it.
I'm surpirsed the 250 has a rail voltage of 22v, the same as the 225. I'm led to believe 29V is about right for the 275 since the power supply caps are rated to 35V and I don't think the designer would run the rails at 36V with 35V caps. BTW, did you ever convert the 225 to 275 after all?
jol50, i was thinking along the same lines as you about the toroid. I'm going to put some epoxy on it to secure any loose coils that may exist. It's a very faint whine/buzz that is probably not audible once the bottom cover and side panels are installed. |
|
|
| Clipped |
hmmm.... good point and a good thing i didnt convert the 225 to a 275 if the rail voltage is indeed 29 volts...be sure to let me know, once you read the zener.
i was really surprised too when i measured the rails on the 250,
i guess after this i just assumed the 275 was 36 volts, as the 2150 is 36volts.
i still havent done the conversion yet cuz i havent had a need for it yet, my newest craze these days is finding good donor subs then rebuilding them to hit harder...ive found a few good gems out there, in need of a little tlc ,different spiders and epoxy in the right places. |
|
|
| ECM |
http://www.diyaudio.com/forums/show...threadid=113663
In this post, the rail voltage for a 275hcca is 29 volts. The difference between a 275sx and hcca is the current delivery. The hcca uses more fets to deliver more current, but the rail voltage is what determines the power output, in this case 75 watts per channel. So I'm pretty confident the power supply in my 275 is working as it should.
All fets have been installed along with all the outputs and the amp is working like a champ. My power supply delivers no more than 5 amps and I'm using a pair of 4 inch speakers to test it and the amp sounds great. At moderate volume, it draws about 3 amps and hits 4amps on musical peaks.
Offset voltage at the output is 18mv and 11mv per channel.
I'm not going to call this a success until I use a proper power supply or battery to fully burn the amp in with some better speakers.
Thanks to all who pitched in and helped me fix it. I'm waiting on some parts before I can start repairing the hcca amps.
Clipped, what kinds of subs to you repair? do you wind the voice coils too? |
|
|
| Clipped |
that link you posted is for the 'G4' series amplifiers, the:
"Digital Reference' 275hcca
and
275 sx
are two completely different amps...as far as the digital reference series goes...the 'G4' took on a completely new design.
i repair all kinds of subs, sub designs are basicly all the same, except for differential drive motors, but even still, it is the same concept.
whenever i come across an odd size voice coil such as 3.5" if i cannot find the replacement coil, i wind them myself.
youd be surprised how similiar in performance a $500 sub is to a $50 sub...main differences are in marketing and soft parts.
as long as the magnet is strong enough and the coil is of optimum size as well as good metal composition of the top plate.
the soft parts can be replaced and mass added for the sub to peform at desired resonance....i say resonate because air resonates...
manufacturers are going backwards these days, they add multi level spiders lowering the efficiency...why use 2000 watts to put out the same spl as an efficient 500watt sub? |
|
|
| jol50 |
| Lol! That is why I want to try a pyramid again...the old one, the 'original paper' one they are coated blue now and about the cheapest ones they have. Back in the day I ran 4 10s on an old school 2x60 or 2x75 and they hammered at 2 ohms. Now I have 4 12s at 420wrms and I am not so sure it does much better. It will hit 30Hz easier and the subs are not near xmax at that wattage....but for all the hassle/power/weight I just don't see the point of it. These are all IB setups. There is about 10dB difference between the infinity and the pyramid (10 more), if they measured both right. You can only go to xmax running IB anyway, so power handling is not really an issue. Yes the pyramid did wear out after a couple/few years, if they are still made the same as 20yr ago but don't know if they are. |
|
|
| Clipped |
youd be surprised how much a sub can change by simply changing the spider...
really though, power handling is the toughest factor to conquer, most subs ive fixed had a failure at the joint where the voice coil wire is bent 90 degrees from the coil, to the run to the tinsels.
the sharp angle results in a bottleneck of heat transfer, just unwind it a bit and make the angle smoother.
the other failure is when the voice coil becomes unwound do to heat, ....just coat the coil in epoxy and it will stay wrapped around the former....5 minute epoxies work just fine, ive taken torches to coils with epoxy coatings and they never burned or melted.
im so glad i started experimenting, ive saved hundreds maybe even thousands of dollars....i'll never go mainstream again. |
|
|
| ECM |
Clipped, yes the 275hccaG4 and 275SX are two completely different beasts, but the point I am making is that the rail voltage determines power output. In this case both the 275hcca and 275sx are 75 watt per channel amplifiers with identical rail voltage.
I too have wondered why people buy 3000watt subs with 83dB efficiency when they can get the same output with lower power higher efficiency subs. Maybe it is the HUGE rubber surround or the thick paper cone that you can stand on. Or maybe it's the chrome flames that make people buy them.
I just picked up a 1st gen 425HCCA for $130 bucks off ebay and three busted Xtant 4180's for the same price. My shed will be full pretty soon. Maybe after the holidays I will start getting rid of some of my amps...here is a list of what I have.
2-Orion 275sx
2-Orion XTR275
1-Orion 225HCCA
1-Orion 250HCCA
1-MTX 2160
1-MTX 4160
1-ADS PH15
And these are just the amps! I have speakers and other **** too. |
|
|
| Clipped |
if you find a dead 2150sx, send it my way!
i thought power output was determined by both voltage and current output divided by the ohm it goes into. :confused: |
|
|
| ECM |
Yes, power is a function of voltage and current (P)ower=I(current)*E(voltage). Ohms law states that if voltage remains constant, then current is determined by the load I=E/R.
That's how HCCA amps make lots of power. "E" remains constant, but "R" is lowered by connecting many speakers in parallel, and "I" therefore increases. Going back to P=IE, if "E" remains constant, but "I" increases, then the "P" also increases.
In a typical amplifier, the rail voltage is constant. Due to amplifier inefficiencies, the rail voltage must be a little higher to make stated power. Also, every time you half the load, the amplfier does not exactly double power, again, due to inefficiencies. To make up for this, the manufacturer raises the rail voltage until it makes stated power into a given load. For example, the 225HCCA is designed to produce 400 watts into 1 ohm mono. At 2 ohm mono, it probably makes 220 watts and at 4 ohm mono, something like 140. In 4 ohm stereo, maybe something like 40 watts.
So making 75 watts into 4 ohms will require the same exact voltage, regardless of make or model.
Do you check ebay regularly for 2150SX amps? I see them come up every now and then, but those huge amps usually come with a hefty price tag. |
|
|
| Clipped |
ebays too far from me...check out my flag ;)
then why do the 225 and 250 hcca's both have 22 volt rails??? |
|
|
| ECM |
I was wondering the same thing as you. The 225 and 250 should not have the same rail voltage. I'm thinking it should be around 25V, not 22V. I'll find out once I get working on the 250. I'm waiting on parts.
No ebay in Thailand? A while back, I saw some dude selling three brand new 225hcca's on ebay and I think he was from Thailand. My co-workers visit Thailand every chance they get!
|
|
|
| Clipped |
we can buy things but the shipping and import tax is outrageous. unless the seller overseas declares the item a 'personal item' or 'gift'..the guy you saw selling them might have been 'sqguy' he use to be a part time writer for 12 volts magazine, thailand.
every 2150sx i come across is DOA do to installing below 4 ohms mono...i dont even test them before buying anymore, i know something will be wrong with it. :hot:
most of the 225hcca's over here are starting to have problems with the muting circuit, the epidemic started about two years ago....a snip here and a snip there and voila! its working again. :D those jfets in the circuit are extremely hard to find, i found like 12 of them once and they were all defective.
friends visit thailand often ehh? i wonder why lol... ;)
im pretty sure the 250hcca has 22 volt rails, could be wrong though, never know... |
|
|
| ECM |
which jfets are you talking about? the mpsa06/56 or the mpsu07/57?
On all three amps, I went ahead and changed the 06/56 jfets in the power supply section before installing the power supply fets. If you need some, I'm sure I can send a handful your way as a "gift." I get them pretty cheap.
On the 225 these are also used on the output side and on the 250, they use the 07/57 drivers. Are these the ones used in with the muting circuit? |
|
|
| Clipped |
^^^ what Perry said...
thanks for the offer though, as far as those A05, A056's those little things are like roaches in my room, wherever i look there seems to be one laying around with twisted legs, kinda like a dead roach laying upside down... |
|
|
| ECM |
Clipped, send me an email.
gherrera1 at netzero dot com |
|
|
| Clipped |
| email sent.....errrr i dont know what to put as a subject though... |
|
|
|
