Synq Digit 2K2 Class D 2200W Amplifier Needs Repair : Protect & Limit LEDs on

A Customer brought two of these Synq Digit Amplifiers to repair. This has one channel with Signal, Limit and Protect LEDs all stuck on. Let's see if we can fix it.
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[@LearnElectronicsRepair]

*Guys, I have info from the supplier who sells these modules. The Power Module 101 is the same for both amplifiers. The Amplifier Modules 101A and 101B are for the left and right channels respectively. I checked on the 3K6 and one module has the marking partly obscured by paint but I do have a 101A and a 101B. So I can use these to test and hopefully repair the 2K2 amplifier. As both the other amplifier modules are just marked 101 I think I will order a pair 101A/101B for that one. Just to be sure. The only thing i can think is different with the two modules is when you run the amplifier in bridge mode one must invert the audio signal, but it doesn't do that in stereo mode*

[@chrishartley1210]

Translated from a Dutch website: This Synq Digit 2K2-02 + 101B Amplifier PCB for the Synq Digit 2K2 is supplied including a 101B amplifier module . The same amplifier PCB is used for the left channel and the right channel. However, the switching frequencies of the modules mounted on the PCB do differ (between left and right). This "A" or "B" information can be found on the bottom of the small plug-in PCB. If it is not there, check whether a switching frequency is stated (with a marker). If it is above 300, it is an "A" module. If it is below 300, it is a "B" module. If it is no longer possible to determine which module it is, replace them both to be sure (for example by ordering 1 extra. That agrees with what you were saying about needing a pair, but just like other information it doesn't say which is which. You can check for an A or B on the underside if it is there, or a frequency marker.

[@LearnElectronicsRepair]

@@chrishartley1210 Thanks for the info Chris. There are no distinguishing markings on those modules unfortunately

[@bittertruth6575]

can you not compare the pinouts on the 3 modules side by side like you did for the working and non working power modules for the 3k6? That should give you an indication of which ones an A and which are Bs

[@chrishartley1210]

@@bittertruth6575 They are electrically identical, the only difference is the frequency. I would guess that if both modules were the same then any tiny variation in frequency could cause harmonics between the channels, particularly in bridge mode, which is prevented by using different frequencies.

[@BkR090]

Why the difference in freq though???

[@winlose3073]

Thank you Mr. Richard for your continuous informative posts!

[@followthetrawler]

If I had to guess I would think the 101B is a revision that corrected the 101A overheating in all that. potting compound - I bet electronically they are the same, however I'm not being paid to fix it so I completely understand your caution!

[@Dutch-linux]

I agree on this statement

[@Simon-mz7sf]

I agree to play it safe too.

[@ralphj4012]

There's a listing on ebay which suggests that the 101A is for channel A and the 101B is for channel B, implying, perhaps, that there is a difference (throws entire salt cellar over shoulder).

[@bittertruth6575]

Surprised to see you place your multimeter on the heatsink there Richard whilst the amp was powered up especially since the heatsinks can often times have high voltages on them. Makes me appreciate the lengths you go to to provide a good repair lesson. Please be careful though.

[@andygardiner6526]

Isn't the module on the main PSU board the 101A? If so does the schematic show the devices to be the same pinout?

[@Harsesis86]

Can you attempt to open up/fix the 101 module?

[@RobbiePohlmann]

Cant hurt to gather more info before plugging anything in.

[@sivoltage]

Dont risk it. Who knows whats going on inside those black boxes.

[@Dutch-linux]

At least this has a better schematic then the crap harmon kardon sub shit thing !!!

[@Karthor.]

I wouldn't risk it either too much unknown