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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc.

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Old 25th Jul 2021, 6:37 pm   #1
Tink-GB
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Default 1979 circuit board Hitachi Stereo Radio Cassette Player

Hi Re-posted in correct area now...

I've essentially finished repairing a Hitachi TRK8080e where the wiring was completely pulled from the circuit board now all connected...bar one.. the power-on diode..l
One male pin is missing leaving a disc.on the circuit board....the voltage remains thankfully.
Anyone know where to get some replacement pins, if possible? Presumably it snapped off when being pulled but I didn't really want to solder the wire on to it, else would have to de-soldered if anything else goes pop after a soak test.... Thanks all.
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Old 25th Jul 2021, 7:37 pm   #2
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Default Re: 1979 circuit board Hitachi Stereo Radio Cassette Player

Hello and welcome to the Forum.

A photo would help to better understand this.

David
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Old 25th Jul 2021, 7:45 pm   #3
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Default Re: 1979 circuit board Hitachi Stereo Radio Cassette Player

I meant to have also asked, is it an actual pin or is part of the said diode ?

David
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Old 25th Jul 2021, 8:12 pm   #4
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Default Re: 1979 circuit board Hitachi Stereo Radio Cassette Player

Welcome! Yes, post a picture (choose 'Go Advanced' below the reply box, and upload the image there. It will be resized for you) and no doubt someone will be able to tell you exactly what it is.
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Old 25th Jul 2021, 8:13 pm   #5
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Default Re: 1979 circuit board Hitachi Stereo Radio Cassette Player

Looking at the parts list on the schematic it looks like the mains rectification (bridge rectifier) diodes/diode assembly is mounted to some sort of tag board.

David
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Old 25th Jul 2021, 8:39 pm   #6
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Default Re: 1979 circuit board Hitachi Stereo Radio Cassette Player

Here you go guys...soz...
First attachment shows the area concerning p11, with the pin missing unlike p12...female connectors are on my red and black wire going to the diode akin to the yellow leads in the shot.

Its the ac power-on leads in question so is firing 5v AC into a red diode directly (the second picture) which has also blown I think now...never seen one of those...goodness knows how to replace that...

P11 has the missing pin ...should be like P12...to connect a 5vac led
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Old 25th Jul 2021, 10:50 pm   #7
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Default Re: 1979 circuit board Hitachi Stereo Radio Cassette Player

Quote:
Originally Posted by DMcMahon View Post
Looking at the parts list on the schematic it looks like the mains rectification (bridge rectifier) diodes/diode assembly is mounted to some sort of tag board.

David

The schematic covers the 8080E and the E(BS) variants, both of which have different circuits for the LED, my own E model being the upper circuit of the two, ie without the black wire going to the power distribution board
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Old 25th Jul 2021, 10:57 pm   #8
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Default Re: 1979 circuit board Hitachi Stereo Radio Cassette Player

Well that is a lot clearer.

Masses of various contact pins available online, no idea type or size of yours.

Personally I would just cut off the female connector and carefully solder to the pad on the board or make a suitable pin using soldered cable strands or a suitable sized pin obtained from a spare cable connector.

Loads of LEDs online, just need to find one suitably sized and voltage rated, may need to play around with the value of current limit resistor R601 to get the LED brightness optimum.

David
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Old 26th Jul 2021, 12:32 am   #9
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Default Re: 1979 circuit board Hitachi Stereo Radio Cassette Player

I use this kind of thing for Veroboard construction. Not too expensive to test out. Cricklewood are a popular supplier around here, and they do answer the 'phone if you have a query. They have red LEDs too, though it looks like your one has a shallower domed shape than normal. I'm not sure if that's critical. Other sources will be found if you do a search for PCB Terminal Pins or similar. Alternatively, as David says, solder the lead if you're not desperate to keep unplugging it!
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Old 26th Jul 2021, 2:58 pm   #10
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Default Re: 1979 circuit board Hitachi Stereo Radio Cassette Player

If those pins are too thin you can always use a pair of pliers to reduce the diameter of the connector as it's not going to be connected to anything else. A large red LED should do the trick - observe the polarity.
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Old 29th Jul 2021, 10:59 am   #11
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Default Re: 1979 circuit board Hitachi Stereo Radio Cassette Player

Thanks Guys for the suggestions, a new pin soldered and LED working.

New problem!

Now back together and soak tested for only an hour each (Radio & Tape/PB/Rec etc), it seems something has popped somewhere.

Symptoms:

1) FM Radio signal bleed of a station from 102.3 right through 108 MHz whilst tuning upwards, when I hit the actual station frequency it tunes in correctly at 107.9 with no sound of any other station close by as it should. Almost like the sensitivity is too great, increasingly more so when aerials are extended.
(i.e. I start hearing the station that should be at 107.9Mhz at 102.3Mhz + cutting across others in the range until tuned to 107.3). Only happens at this end of the frequency range. 88 to 102 is perfect, (LW, SW and MW no issues at all). I therefore cannot tune to any stations in between this range.

2) Annoyingly now, when any motorised control of the cassette player is pressed, the right channel now pegs out the VU meter (sometimes clicks or pops first) before a high pitch whine through the right channel only.

BUT this is only when in stereo mode. When switched to Mono the right channel operates with the left correctly.

Any experience of this fault?
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Old 31st Jul 2021, 1:12 pm   #12
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Default Re: 1979 circuit board Hitachi Stereo Radio Cassette Player

Any funny business involving random buzzing, whining and oddness on the VU meters on a cassette unit of that era is going to be a dirty record / replay switch, the long narrow switch which is operated when you press the REC button.

Take out any important tapes and either defeat the record protect lever with your fingertip or insert a blank tape and vigorously 'exercise' the record switch about 100 times. If the nature / sound of the fault changes every time you press and release the record button, the switch is your culprit. If so you can try running switch cleaner down inside it and repeatedly operating it to clean it, or you can carefully desolder, dismantle, clean, reassemble and fit the record switch.
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Old 31st Jul 2021, 7:39 pm   #13
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Default Re: 1979 circuit board Hitachi Stereo Radio Cassette Player

Many Thanks Sirius, got some Servisol Super10 and applied it to out all the pots, switches and the play/record switches; and as you said, not a pop bang or whistle.

I have also solved the tuning issue by shielding the aerial wires and routing them both differently.

Many thanks all again for all replies, kudos to you all.

Until next time, Tink.
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