Need help with restoration of Technical Pro HB1502U Hybrid amplifier

[onedumbquestion]

I couldn't figure out how to disconnect this connector and there's another like with more pins than this one As you can see I pried the nylon up and that left the pins exposed still hanging on Prying under the pins didn't seem to have any effect Also I need to identify whatever missing part/bracket held on the front panel jacks I found it laying loose inside

 

[rjenkinsgb]

I couldn't figure out how to disconnect this connector

I don't think that is a removable connector.

Some gear uses pre-assembled wire harnesses that have things like that which look similar to plugs or sockets, but just hold a set of pins in the correct arrangement for soldering to a circuit board.

A bit like this example, for ribbon cable:

Sometimes the fixed part is just at one end of a wired link and there is a removable connector at the other end, but not always.

That amp is a very cheap unit for it's claimed ratings (eg. $139 new), so cost-saving in manufacturing is to be expected.


The connector board appears to fit PCB upwards just below the power switch, from pictures I've found.

There are holes in the base of the case around there, visible in your photo.
Do they line up with holes in the PCB when it's in place? If so, it most likely just had tubular spacers and screws through the lot.

 

[Nigel Goodwin]

It's not a plug and socket, just a soldered in connection, often this is used at one end and the other 'might' have a plug and socket, but sometimes both are soldered.

Basically it allows the use of component insertion machines, and flow soldering - and makes a much more reliable connection than just soldering the ribbon cable through the board (as it gives support to stop the wire breaking off).

From a service point of view it's a real pain in the bum though, even if one end is pluggable, it's often hard to tell which it is.

 

[Nigel Goodwin]

Just a quick 'extra' - I had a look at the user manual (which rather nicely gives a schematic) - why is it called a 'hybrid' amplifier?, as there's nothing hybrid about it?.

Circuit wise, it's quite crude and simple - and obviously can provide nowhere near it's claimed output.

From the power supply voltages (assuming little or no voltage drop) it 'should' be able to provide 150W per channel to 8 ohms, or 300W per channel to 4 ohms. However, even at that, I doubt it would survive long as it only uses single pairs of output transistors, which are rated at only 150W maximum dissipation.

The fine old 2N3055 was rated at 115W, and was good for 50/60W output amplifiers - but if pushed to 100W reliability would be very poor, so usually two were used in parallel (so back to 50W each pair).

 

[onedumbquestion]

I think this is a class d amplifier

 

[Nigel Goodwin]

I think this is a class d amplifier

Then you think completely wrongly, it's a standard old fully complementry class A/B amplifier - haven't you looked at the schematic?.

 

[rjenkinsgb]

I think the "Hybrid" bit may be from the feature combination - tuner, mic PA, media player etc.

Nigel - what manual did you find? The only circuit I could see is a single page which shows the basic stereo stuff, no tuner, USB input or surround channel amps?

 

[Nigel Goodwin]

I think the "Hybrid" bit may be from the feature combination - tuner, mic PA, media player etc.

Nigel - what manual did you find? The only circuit I could see is a single page which shows the basic stereo stuff, no tuner, USB input or surround channel amps?

That was the only bit I have as well, but the main amps are A/B, and the entire device looks rather old fashioned and 'crude'.