Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems DSP life expectancy

If instructions were simple, it would be appreciated if these could be posted.

But if they are not, in light of potential component shortages, is prevention now better than trying the cure later if/when the failed bits are no longer available?

This work done in a preventive measure, will require less tedious soldering and possibly trace/run repairs.

I would like to eventually post some pictures and tutorial, but as of now, I'll simply supply in text.

As long as this is done in prevention and the dreaded "hot" is not apparent or the unit has not completely stopped passing audio, this should not take longer than 45 minutes.

Parts needed: 2x 680 ohm load resistor

You will replace the existing load resistor with new. If you have wire wound resistor in place, purchase the nomenclature specified on the device, or use the mentioned 680 ohm. It doesn't matter which is used.

Remove the seven outermost screws holding the back panel electronics to the cabinet. The power supply can stay put unless you wish to pull it as well.

Peel the back panel back lightly from top and lift just a bit to expose the connections. There will be one connector (molex) from the power supply to the input section on the back panel (****BE VERY CERTAIN TO NOTE THE ORIENTATION, IT IS NOT IDIOT PROOF AND IF PUT ON BACKWARDS WILL CAUSE DAMAGE***)

Once the power cable is removed, remove the flex cabling from the silver tin can that connects to the display. (****you will see a red line on the cable***be sure to note its orientation or you will not have lights***again, it is not idiot proof and can go on either way.

The third connection is the audio umbilical cord from the amp section. It pulls directly out and it is idiot proof. (only goes in one way)

Now that the back panel is free, set it in a well lit area. You will notice the amp section in the center, and a tin can to the right. Between the amps and this tin, and the edge of the pcb, you will find to load resistors standing vertical. These are to the left of a blue and black mute wire section. They will be located near a two voltage regulators and varying caps. Again, you may recognise either load resistors or wire wound type. They should show signs of heat and look rather "used". If they look BURNT, you may encounter some difficulty in removal.

Remove the corresponding screws that hold the tin can to the back panel. This depends on the rev how many there are, but this will allow more play on the wires coming from underneath to the amps.

Once you have the DSP board visible from under the can, you can check for popped caps or raised cap lids on the caps located on the DSP board. Raised caps are indicators of failure or failing. Your unit may be working with these, but this shows they need to be changed. This part is jsut visual inspection at this point.

Flip the back panel over or stand it tall and remove the Three screws in the center of the electronics that correspond to the amp section. this will allow you to lift the board up and check the underside.

You will want to check the lines/traces/runs that connect the eyelets for the mentioned load resistors. If they look badly burnt, you have difficulty removing the solder and eyelet will be damaged.

I suggest adding a little new solder to the eyelet for each resistor on the top side for a good re-flow. I suggest using wicking to remove the solder from the bottom side. Do not attempt to remove the resistors without removing the solder or until they will come freely out without the soldering iron. Be careful not to use too much heat either as it will cause the trace runs to lift.

Once both have been removed, insert new resistors(orientation on a resistor is not important- no polarity). Solder from top or bottom until there is uniform flow with the rest of the board.

Visually inspect the surround caps for lifting or popping tops. In most general cases, nothing else should be needed in the preventive stage. The load resistors generally cause the faults. The surrounding voltage regulators 2x 337 and 317 have been known to defect, but again, probably wont need replacing in prevent.

If there aren't any sound anomalies, there shouldn't be any reason to measure components on the amp side. The amp generally either works...or it doesn't, and in most cases rarely ever needs repair.

The good news is aside from this resistor issue, the 5K is rock solid. When this is taken care before damage, the unit should rock on for some time. The problems come when the resistors go bad and take out other components...

Assembly is easy enough. Place the three amp screws back into the back panel. Place the tin back atop the DSP board and make sure all wires are routed without pinching.

Place the back panel atop the power supply and attach the molex in the correct noted direction, plug in the umbilical to the cabinet from the amps, and then connect the display cable with the red wires in the noted orientation.

Place 2-3 screw in the back panel and test power for lights and then audio. If no lights, you have the display cable on wrong. If no audio, you forgot to plug in the umbilical . If the power pops and sparks and scares you brown in the pants, you hooked the psu up improperly and did not note the correct orientation.

This is not a difficult task and can be done in no more than 30-45 minutes.

If you have questions, feel free to PM and send pictures as well.

Awesome. Added to the wiki: http://www.meridianunplugged.com/wiki/index.php?title=DSP5000

Thanks for the tutorial.

At what age do these tend to fail? Or at what age could they start to fail?

I always cut the part out first. Then heat the lead from the back side and pull it out from the component side with needle nose. Then I use a solder sucker on the component side and heat on the back to clean it.

Thanks Marc. I wondered if the statistics was a factor as well. This forum has been up for 12 years and I don't recall seeing any DSP speaker stand out from the crowd on failures (even with those statistics). Expect perhaps DSP-33's occasionally (possibly again because I think Meridian sold a lot of those).

The most common failure (on the forum) is the Tweeter. A few cases of transformer hum. Occasionally D1 input goes while D2 still works (probably due to user error). Overall a pretty good track record (on the forum) if you consider it includes multiple amps, DAC and the speaker. And they are very serviceable.

Curious what parts are obsolete that there is no subsitute for, I might want to stock up

SupreM,

awesome...thanks for the info.

Can one really tell? I have often wondered about this. While I think actual failure of the woofer/driver/amp is immediately obvious -- what of the parts that slowly decay/degrade with time? I know caps can degrade, what else is in there that just slowly degrades with time? I guess the real question is. If I took a 10 year old 5000 and one that was brand new, would it sound the same? I don't know the answer.

George, you must live in an enormous domicile!

/Marcus

Fantastic info! Thanks John

Hmmm, I had to look that one up. Still not sure what you meant

But they are not in one place, 3 addresses actually.

2 at work (listening right now actually, fiddle music of course)
2 in fiddle practice room (2-3 hours every evening google Amazing Slow Downer)
2 in vacation home (also used for fiddle practice)
2 rears in HT
2 spares in boxes since I have such a large dependence on them.

Most of them were around $1000.00 a pair. 3 sets are hooked to TASCAM US-144mkII Preamp ($130.00) off a computer. 2 pairs are 24/96 but I notice zero difference with that. Room/Placement impacts their performance way more. It just happens the older 18-bit ones sound the best by no small margin because of room/placement.

The D1-D2 issue is a hex inverter on the DSP board. This is the second most likely fault with the 5K after the load resistors.

I can't say at what age or usage the load resistors fail. Anywhere from serials 100-400...It's not uncommon.

A quick visual inspection can tell you whether it is time or not.