DSP-61 failures in Sony DFP-D2000?

[Tom Ostertag]

Hello everybody,

As I have been working on fixing up an SDDS system (2000 series) for use in my screening room, I have noticed a failure mode of the DSP-61 boards now on two different processors.

On both units, after running for 10-30 minutes, I noticed a burning smell. One of the units displayed an error, but the other did not. Upon shutting them down and checking all boards with a thermal camera, both had a very hot (over 200 degrees F) IC on the DSP-61 board. The smell seemed to emanate from there. The specific IC location was different on both (IC91 on the first, and IC88 on the other), but the custom Sony chip model was the same. One unit had a reader connected, and the other was just powered up on the bench.

After letting them cool, both systems still boot up, but the previously hot ICs still run hot, albeit only 10-20 degrees hotter than the surrounding ones. The first board now has two dead audio channels (L and LC meters pegged). The second appears to behave normally on the panel, but I have not put audio through it yet.

Both units have recently recapped and tested power supplies.

I have four more units that were briefly tested to boot up, but I'm reluctant to swap boards until I'm reasonably certain I'm not doing something to fry them.

Anyone seen this failure mode before? Are the DSP-61s and/or these ICs just prone to burning up?

I'm relatively adept at hot air SMD rework, so I could always try swapping chips on two dead boards if I get really bored or desperate!

Thanks!

[Marco Giustini]

My experience with SDDS is very little - and I have a 3000. I do have the D3000 maintenance manual with schematics but unfortunately those chips are not listed there.

Let me see if I can source the 2000 maintenance manual, it would be nice to have a block schematic to find out what those chips do before you swap them around!

[Carsten Kurz]

On the german forum, someone recently diagnosed audio decoding errors to bad thermal contact on the AD-111 board, which causes the board to overheat after a while. The guy, though, mentioned that he found out about this issue on film-tech.com, so you may already know about that specific issue.

[Tom Ostertag]

My experience with SDDS is very little - and I have a 3000. I do have the D3000 maintenance manual with schematics but unfortunately those chips are not listed there.

Let me see if I can source the 2000 maintenance manual, it would be nice to have a block schematic to find out what those chips do before you swap them around!

I have the D2000 service manual, so I'll give the schematic a check tonight. Since all the chips in question have the same numbers, I'm assuming they don't have any hard-coded programming and are probably initialized on bootup. This is Sony though, so who knows!

[Tom Ostertag]

On the german forum, someone recently diagnosed audio decoding errors to bad thermal contact on the AD-111 board, which causes the board to overheat after a while. They guy, though, mentioned that he found out about this issue on film-tech.com, so you may already know about that specific issue.

Assuming that's the daughterboard on the decoder board, I know that's prone to failure as well. I've already ran into one dead one. Perhaps at this point it's a good thing to check and/or replace the aging thermal paste. Good thing to be aware of for sure, so thanks!

[Marco Giustini]

If you share it here - or somewhere - we can also have a look

[Tom Ostertag]

Definitely! Will do.

Thank you.

[Tom Ostertag]

It doesn't totally fit on my 11x17 scanner, but here's the relevant page of the schematic. I may re-scan it in higher resolution, but it's better than nothing for now.

I'll do a bit more studying of the manual and see if I can find anything else that might shed some light on the ICs' roles, and check the parts lists to see if there's any difference between these 14 chips.

[Carsten Kurz]

A 'CX' chip designation typically identifies a SONY chip (who would have thought this). Mostly, banks of identical ICs like this are memory, DRAM, SRAM/Cache RAM. Two pins are named 'CAS' and 'RAS', that usually is associated with DRAM. CX02705AQ. I can't find a datasheet, but I found another Sony circuit diagram using this part, and it is indicated as DRAM there as well, and is connected to a DSP there.

[Tom Ostertag]

This is interesting. I looked at the chips again, and the number is CXD2705AQ, not CX02705AQ. That returns not a complete datasheet, but some pinout information, which I've attached here.

They're calling it a "digital audio signal processor". I found a more complete datasheet for the CXD2507AQ (the 5 and 7 flipped), and that was a Sony DSP for CD players. Could be related, could not.

The unused pins appear to be address and I/O for external RAM.

Who knows how the DFP is utilizing these. Maybe Sony was repurposing parts developed for another application. I'm still thinking that swapping chips from another unit shouldn't be an issue though.

But for now, I'm content with playing the board swap game. I just was a bit concerned when two boards in a row failed in nearly identical ways!

[Carsten Kurz]

Hmm, you are right, the RAS/CAS goes TOWARDS an external DRAM. A BANK of 14 DSPs?

[Marco Giustini]

I recently fixed a PS3 power supply and that too had a Sony part for which I found a similar datasheet, looked like someone had reverse-engineered the chip a bit! Typical Sony.

Tom, does the service manual have a block diagram? It might be a better start than the schematic.

I see the chips are arranged in blocks of four. Checking the middle block, the input is EQ12 which is fed to both top chips on pin SIA (Serial Input A). What seems to be the output goes from SOA (Serial Output A) to the bottom chips SIA again. The last chip - bottom right - gets inputs from two of those chips on SIA and SIB and outputs EQ03 and EQ04. Wondering if those are the DSPs used for the EQ.

Did you check your 5V rail on your 2000?

[Marin Zorica]

Few times now I did run into similar problems where DSP/mcu ic's are overheating and drag more current than normal, but they still do work until they overheat too much and than start to reset or to behave strange. I can be with something around it, but mostly problem was in ic itself as there are no I/O lines with high current demand. Three year ago I have problem with industrial AC inverter where logic unit did drag around 0,3A instead 0,1A as stated. Since there is around 10 of them it did trigger protection on 24V power supply while unit itself still did work.........only solution was to add bigger PS and it works after for some time now......i know that manufacturer did not know any solution for problem as unit is obsolete, and they do probably agreed it has to be something with component aging. Here is hard to check it as all DSP's are on same power line, except you exchange them for some know good one.

[Mark Gulbrandsen]

There was a long time period when Sony could not deliver any SDDS parts at all. I think during that time they were integrating other product lines parts into the pro parts division. Then one day parts started showing up that were ordered a year or more in the past. By then I had replaced most of the Sony 2000's with CP-650's and the Sony's just sat in each booths junk pile.