Periodical Change Of Belts In This HARMAN/KARDON Tape Deck Model HK300XM
This Tape Deck had visited me in November, 2022 for overhauling and replacing its belts. You can see my earlier report of this in the following link:
https://jestineyong.com/overhauling-mechanism-of-harman-kardon-cassette-deck-hk300xm/
This revisited me in July, 2024 (after more than one year!) with the complaint tape not turning. I opened the set and cleaned it as usual. Saw broken belts.
I have already explained how extremely difficult it was to replace the belts in this set and how crude the circuit and wiring was inside the set in my earlier article, which also has more images. You can have a look at what we need to do to access the capstan wheel assembly:
The four control board has to be unscrewed and kept to one side ensuring that no wires break. The cassette door, front panel and cassette support plate all has to be removed to get access to the belts in the collection wheel, gear wheels, counter etc. Then we need to use a long screw driver and unscrew the bottom two screws and slightly turn loose the top two screws to insert the belt from underneath between the plate and screw lugs.
Then using a U shaped tool pull it from top through the gap ensuring that the belt stays put on the capstan wheel and then roll it over the pulley of themo tor. As you can see, this has two motors; one for the capstan and another for Collection, FF and REW functions. The entire mechanism works on solenoid controlled by ICs. I had to really struggle to put the flat belt in its place as it was slipping quite often. Then tightened the screws and replaced the control board and fixed it properly, re-inserted three connectors from the mechanism to the control board. Then replaced the belts in the front, placed a cassette and played. It was working perfectly well. Here, you can have a look: (I used headphones to listen to the music. The speed was perfect)
After allowing the set to work in this condition for several hours, I fit the front panel, for which again I had to struggle a lot as there wer many switches that had to be properly inserted to the slots, failing which it might break. Then fixed the knobs back in its place taking care that the markings on the knobs were properly synchronized with the markings on the panel.
Then continued the playing and tried all the functions such as REW, FF, Play & Pause. I never tried Record as the cassette belonged to the customer and I did not have a blank cassette to try it. But keeping the switches pressed on the cassette loading case, without a loading a cassette, I pressed the record a few times so as to enable cleaning of the switches for any fine dust collection. Mission accomplished with satisfaction getting added to the collection:
This article was prepared for you by Parasuraman Subramanian from India. He is 74 years old and has more than 30 years’ experience in handling antique equipment like Valve Radio, Amps, Reel Tape Recorders and currently studying latest tech-classes conducted by Kerala State Electronics Technicians’ Association. He has done graduation in BBA degree, private diploma in Radio Engineering and retired as MD of a USA company. Presently working as Consultant to Hospital and other institutions.
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You may check on his previous article on Replaced IFT With Imported In PHILIPS Valve (TUBE) Radio Model MAJOR
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