I picked up a Hitachi TRK-9150 ghettoblaster that looked great from the outside but had a few obvious problems. The radio worked, but the volume control crackled badly, the cassette transport didn’t move tape, and the small LCD clock display didn’t show anything. It was also missing some foam on the back, and one of the speaker cables had been patched with a rough wire extension.
The first look showed just how loaded this thing was. It had FM, shortwave, and medium wave, line in, phono in, line out, multiple mic inputs, a loudness switch, balance, bass and treble controls, and even detachable speakers with built-in contacts so they could slide onto the main unit without separate wires. Around back there was also a 12 to 15 volt DC input, battery compartments, and a voltage selector, so this was clearly built to do a lot.
Testing confirmed that the tuner section was alive right away. FM and AM came in, but the controls needed cleaning, and the tape deck had the classic belt problem where the motor ran but the tape didn’t move. Rewind and fast forward also wouldn’t stay engaged. The LCD clock still looked dead at that point, and the light function didn’t seem to do much during the initial check.
Getting inside wasn’t too bad once the back came off and the speaker and antenna connections were unplugged. The whole center assembly slid out, and from there I could get a better look at the tape mechanism and the wiring. I first tried approaching the belts from the back board side, but after getting far enough in to see what was going on, it turned out the easier path was from the front of the mechanism.
With the transport opened up, I found the belt arrangement and replaced what I could from my parts supply. I also removed a small panel to get at the potentiometers and switches, then sprayed DeoxIT into the controls and worked them back and forth to clear up the crackling. While I was in there I found a broken wire on the erase head and soldered that back, then cut out the ugly speaker cable extension and rejoined the original wires with solder and heat shrink.
One of the replacement belts was narrower than the original, so I did a quick test before buttoning everything up and ran into another fault. The capstan pulled tape across the head, but the take-up reel wasn’t collecting it, which immediately made a mess. I traced that to a loose, wobbling pulley in the take-up mechanism and secured it with a small amount of super glue, which got the transport moving again.
The cleanup took a while because there was dust and grime packed into every corner. I used glass cleaner on the larger surfaces, a lot of cotton swabs for the tight spots, and isopropyl alcohol on the tape path, heads, capstan, and roller. I also cleaned corrosion from the battery terminals with white vinegar and a toothbrush, removed the old disintegrating foam from the back, and scraped off the leftover adhesive.
I went ahead and added a Bluetooth receiver so the line input could be used wirelessly. There wasn’t a 5 volt rail available where I needed it, so I tapped the roughly 20 volt DC supply and used a small switching regulator to bring it down to 5 volts for the module. The plan was to mount the Bluetooth board behind the battery cover, but direct installation introduced ground loop noise into every mode, so I tested it from an external battery and ordered an isolation board for the final install.
With fresh AA batteries in the clock compartment, the LCD came back to life and the timer functions worked again. In the end, the radio worked, the cassette deck played, the scratchy controls cleaned up, the Bluetooth input sounded good, and the only remaining tape issues were fast forward, rewind, and a permanent belt replacement still left to do.
— Aaron
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Timestamps
00:00 – Intro
01:37 – First Look
11:00 – Testing
13:45 – Disassembly
19:15 – Repair
22:11 – Cleaning
24:29 – Bluetooth Mod
27:36 – Final Tests
40:31 – Wrap Up