Sony XM-2252-HX issues

[Johnny Dior]

This is the old, solid red color amp line from the late 90's roughly.


Anyways, it seemed to be an OK amp despite running HOT at a 4 ohm bridged load when it was powering a 10" Alpine R and 12" L5, dunno if it's tiny fan was working or not to be honest. I had the switches correctly set for the 4 ohm load.


I stopped once to fiddle with the freq. settings and used a small screw driver to change the LPF and at the same time it occurred a very HARD fault that took out one of it's 40 amp fuses and I believe took out the main 80 amp on the 12v cable (happened some time ago).

Oddly enough, nothing burnt internally that's visible despite the fact it dimmed my car briefly before the 80 amp blew, and despite having dual power supplies, the other channel won't work even on the high current setting. The on-board diagnostic lights will eventually point to the "offset" light IIRC.

I can't connect a heavy 12v source to it as it'll pop the same 40 amp fuse again (2nd one remains OK).

Is there a way to test the board in this scenario? Amp is very spartan internally and interestingly enough used Nichicon FG caps throughout and would like to get it working again, though it seems all the outputs are discontinued.

 

[Perry Babin]

Does it only draw excessive current 'after' remote voltage is applied?

 

[Johnny Dior]

If I replace the blown fuse, then only connect 12v+ and neg (spare car battery), it won't do anything.

If I then connect rem., it'll blow the fuse.

If I instead connect a low amperage 12v+ source (like a small milliamp 12v+ ) it won't pop the fuse, and will power up the diagnostic lights briefly before showing the offset light.

 

[Perry Babin]

If the offset LED lit, it could mean that you have a shorted output transistor. Have you checked them yet?

 

[Johnny Dior]

Good call Perry. Found some open faults on the left channel. Are there modern alternatives to the Mitsubishi FX50SMJ (2 9403) and FS70MJ (2 9402) ? I'd need 4 of each to keep everything matched.

Are you familiar with these amps at all? Noticed each channel has it's own pot on each channel right next to the FX50SMJ. Is that some kind of bias pot?


BTW, Are the links in your signature your sites? Very helpful info in there.

 

[Perry Babin]

I don't know if there are alternatives. I think you'd have to try what you find that's close and then test to see if there are any problems. Be aware that any you find on ebay are likely to be counterfeit.

VR101 and VR201 are bias pots. Email me if you want the service manual and updates.
[email protected]

The sites in the sig line are mine (3 of 5, links to others are on the site below).

 

[Johnny Dior]

Your sites are very helpful. Nice to see someone care enough about the field to take a few minutes (or possibly a few years in your case ) to share the knowledge.

If alternatives could be procured, the service manual would be helpful, and I'll take you up on that if parts ever turn up.

Are you familiar with any other amplifiers (Sony or otherwise) that ran these outputs? Thinking I might be able to find something that's beat up, or open the available options of possible donors, probably for less than actual parts would cost if they even existed. Yeah, I'm aware of the Chinese knock-offs. Makes you wonder why a knock-off purse gets the FBI involved, but proprietary electronics components are utterly ignored and sold on ebaiyt and others.

 

[Perry Babin]

I think it would be the other way around for most people. As far as I know (could be wrong), this is the low amp in the range of amps that used these transistors. You may be able to sell it for quite a bit for those wanting to repair the xm-7527, 7547 and 7557.

The buyers are the only ones losing on the counterfeit parts. The original manufacturer no longer makes them so they have no reason to fight (not in competition with the counterfeits).

 

[Johnny Dior]

This is a rather large A/B 2 channel, probably weighing close to 10 pounds. It supposedly did 225w @4 x2; 330w @2 x2; and 600w bridged, then did same wattages at the low ohm/high current settings.

From a quick look, it retailed for something like $450 when new, so it had to be upper fringe of mid-tier for the time, plus it has the odd high voltage or high current configuration, and the interesting diagnostics, but I'm not partial to it. Got it as it was old and was curious what these were like.

I'll just sell it off then for someone looking for parts. Otherwise it'll end up a wall hanger

 

[Perry Babin]

The last 7557 I see that sold on ebay went for $435 with shipping. MSRP was $800. The difference between a working and non-working 75xx may be as much as $200. If you have no attachment to the amp, selling it may be a good option.

The HX designation was for the amps with the high current/voltage option. There were several.

 

[Johnny Dior]

I'll sell it off. It has Muse, Fine Gold, dual toroids, nothing is physically destroyed as I can tell.

Are you positive that 5 channel Sony uses the same outputs at some point of the amp? Maybe the single sub channel? Just want to be sure, as it can be included into the description, but I know nothing about these amps other than what I know about mine, which boils down to it's specs and what's easily visible on the board. Would like it to go a good home that'll either repair or use everything possible as parts.

Thanks again!

 

[Perry Babin]

Here are the two service manuals. The 7527 and 7547 also use those outputs.

http://www.bcae1.com/temp/sony - XM-2252.pdf

http://www.bcae1.com/temp/sony - XM-7557_Car Power Amplifier SM.pdf

 

[Johnny Dior]

Thanks Perry. Wasn't questioning you, just didn't want to post an incorrect desc. if that 5 channel has a bigger following and someone bought this and I was wrong.

 

[Perry Babin]

No problem. I make plenty of mistakes. Now you know definitively.