Harman Kardon AVI-100 Receiver

[JEWilson]

Seems to have issues with IR receiver (eye) in the unit

The part is a Hitachi TEMT5380 according to the service manual
Can't find these
This is a 38kHz part
Have been able to find a datasheet for TFMT5xxx - seems to be (newer) revision
These are TEMIC
Is TEMIC now Vishay or Atmel?

The remote commander control handset appears to be ok

Suggestions on a replacement for the eye

[redwire]

Re: Harman Kardon AVI-100 Receiver

It's really rare for an IR-receiver module to fail. What is it doing? The remote is almost always the culprit (worn buttons, loose connection, pop or food inside it), or interference problems from bright lighting, fluorescent (electronic) ballasts, CFL lamps or even LCD TV backlights and 3-D TV's (to sync glasses)!

As I remember, the optoelectronics went ->Siemens/Telefunken Temic->1999->Vishay.
You probably have a Temic TFMS 5380 by Telefunken/Temic Semiconductor. They are very good performing modules, need one capacitor to filter power (you did check it?). Nothing obstructing the Rx window? Vishay keeps obsoleting them and changing the part numbers on these so it is hard to track down: TFMS5380->TSOP1738->TSOP1138->TSOP31438

I don't know what modulation scheme HK is using. There is NEC, Sony, RC5, Thomson, Sharp, Mitsubishi etc. which sets the module's AGC. I found one source saying HK uses NEC encoding, which means the module would cross to a Vishay TSOP31438. There are some TSOP1138's still available.

[JEWilson]

Re: Harman Kardon AVI-100 Receiver

Thanks for responding

Well.. well.. well

Seems the IR is ok.
Did originally test this under flu tubes in the kitchen.

However...
This unit is going into protect at slightly high volumes say 9.45 - 10 pm
Odd.

I did check all of the O/P for main L & R out of cct. - these test ok
I replaced the O/P for the centre and rear - transistors and drive.

Maybe the speakers (small Sony midi hifi unit types) are difficult to drive
Unlikely as they state 6.5R - the O/P is nominally rated for 8R speakers

Protection mutes the O/P and puts unit in standby - this is working.
Suspect this may be a cap problem symptomatic of main lytics and/or
power rail distribution lytics.
I did have to replace the motorised vol control lytic caps as this was not
working but is now (post replacement).

Suggestions?
Seems HK units have issues with lytics in the protection cct.

[redwire]

Re: Harman Kardon AVI-100 Receiver

The protection circuit typically looks at heatsink temperature, output current and output DC offset (I'm not sure about the AVI-100 without a schematic to look at).

Run it with no speakers connected (no output current, runs cool) and see if it trips again. If it does, then I would guess the electrolytics on the protection cct low-pass filter are low in value, esp. if it (false) trips during music with a lot of low bass.

Or check the amp's output voltage once warmed up, it should be under 50mV DC offset but bad coupling capacitors (electrolytics) can let a little DC into the power amp and trip the prot. cct.

The multichannel AV amps run pretty hot and they must be hard on the caps.