Akai GX-365D Loud "Wind" Noise

[MikeDC]

Hi, I picked up an Akai GX-365D at auction this weekend for $111 and was very excited to get it home and plugged into my system. I threaded a tape through and powered it on and was pleased that it started playing immediately. Unfortunately, it also has this loud rumble, that sounds like wind noise, that begins when the unit is turned on and is independent of the tape playing. Also, it got much worse as the unit warmed up, and I could watch the right hand VU meter start bouncing. The rumble seems to be only coming from the right channel.

This is my first reel-to-reel, but have read through other posts on the forum and have seen mention that this unit often needs to have it's transistors replaced. Could bad transistors be the likely culprit?

I'm a new member to audio karma, but have found your site very useful over the years for fixing a variety of issues.

Thanks in advance for any assistance.

Best, Mike

 

[audiojones]

Hi and welcome!

Yes, that model is loaded with those nasty 2SC458 transistors and you are describing their failure mode to a T. Of course you should start by cleaning all contacts and switches, also make sure all plug-in circuit boards are firmly seated and the card contacts are clean. Try it in both directions to rule out the head reversing contacts too, but my money is on failing transistors in the amp.

If the trouble turns out to be the transistors then KSC1845 is a suitable replacement that is easily available (if you're in the U.S. that is) if you are up to the task of repairing it yourself. If you go that route just watch the pin orientation, also bear in mind that this might not be a good job for the beginner as many AKAI decks of this vintage have no silk screening on the PC boards to help with component placement so you'll need to refer to the schematic. Replace 'em all, don't leave any in there or you'll be back.

 

[MikeDC]

Hi Audiojones, Thanks for your response and the information. I was afraid that would be the case. I am quite a novice at audio repair, my "expertise" rests in using contact cleaner, and replacing belts and fuses, which happily brings back a lot of older equipment. . I was able to find a copy of the service manual online, so I'll take a look and see if I can figure it out. It's in overall great shape cosmetically and the motor seems to be running fine. Be a shame to just leave it alone. Maybe I'll have to find a tutorial on reading schematics and a quick youtube on soldering basics.

Thanks again.

Mike

 

[audiojones]

If you go that route a cheap transistor checker from eBay will help a great deal. It’s a good easy way to identify the base, collector and emitter legs and the polarity / parameters of the transistors you remove and install. Following the schematics is pretty straightforward once you understand all the symbols and values. Once you know which leg leads to which component by following the board trace you can easily check your work. It’s a good idea to do this even if you have a silkscreen printed on a circuit board because sometimes they can have typos. Pay very close attention to how components are installed before you remove them, do them one at a time and don’t go by the component values in the service manual (very often component values are changed during production).

 

[MikeDC]

I found transistors on mouser.com. I see they have ksc1845FTA. Seem similar, but with a spread wire configuration. Assume these would still work? Thanks again.

 

[MikeDC]

I think I just answered my own question. They have the same datasheet attached for both varieties, so assume they have identical specifications.

 

[audiojones]

TA is just the packaging style. TA indicates taped on a roll, BU indicates bulk etc. I usually buy them on the taped roll but either is fine. Buy a bunch of extras, they come in handy for many applications and quite a bit of gear from that era uses them.