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Akai GX 400D SS need replacement motherboards

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OlallaBay

New Member
I bought this tape deck in about 1980... almost new. Recently I took it to a repair guy here in Seattle area to get it working again... he said it has a couple of cracked motherboards, and will need to find one for parts. Wondering if any of you have an old GX 400D SS in the bone yard for parts?
 
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Tape recorders do not have motherboards. That is a component in a computer. I'd be suspicious of someone who doesn't have a good command of the correct terminology.
 
If you post a pict we can tell you if it's fixable. Most of the old boards are fixable, you'd need a replacement if some obsolete IC was broken. But most crackled boards can be fixed, usually easily.
 
steerpike2 said:
Tape recorders do not have motherboards. That is a component in a computer. I'd be suspicious of someone who doesn't have a good command of the correct terminology.
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I assumed he was referring to the main system control pc board in this unit. Then again, it also has a servo control pc board, a power supply pc board, a direction pc board, a rec amp pc board, an osc. pc board, a speed and eq. sw pc board, a volume pc board, a dummy quadrasync board, a selector pc board, and a headphone pc board... With all these, I can see how a donor unit would be useful, but how do boards get cracked to begin with in a deck that was purchased almost new?
 
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Thanks for your interest! This I don't know. The tech who has it now said the "motherboard" is a "22 pin" and that another one that he has for parts is developing a crack as well. I purchased the unit in Hawaii as a young man and recorded several projects there, moved to Washington in "86 and continued using it until the late 90's when I made the move to digital. It sat in the corner until a couple of years ago when I decided to start using it again. Tracks 3 & 4 didn't work at all, tracks 1 & 2 were VERY muffled sounding even after head cleaning and demagnetizing. Not being a tech, I don't know the inner workings. Just hoping to find a unit to cannibalize.
 
I don't think you need another unit. Fixing the board should be possible if you didn't drop the unit from a 1st or 2nd floor...

I'd wait before buying a 2nd machine until yuu upload some picts, or ask your tech to detail exactly what is broken and why is not possible to repair it.

Regards
 
These may be the 22 position card edge connectors your tech needs to repair your unit. These are also available in a double readout (44 position) version. These are the type of connectors that circuit boards often plug into in tape decks to connect them to the rest of the circuitry. This may be what is cracked in your unit since this is a common type of failure as these connectors age.

http://www.alliedelec.com/cinch-50-22a-20/70152836/
 
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I would think he was talking about the P.B. Amp. and Rec. Amp P.C. boards in this unit. There are 2 of each (front and rear) and each is a 22 pin board. You'll find them on pages 8-10 in the service manual.
 
Yes, I agree but the problem description provided by the tech has changed somewhat after further discussion. Is the problem with the circuit board (card) or the card edge connector that the card plugs into? As has been stated in a previous post, a cracked card can usually be repaired but repairing a cracked card edge connector is not likely to be an effective long term solution. Replacement connectors of the type required for this application are available from the vendor whose link I posted above.
 
OlallaBay said:
Thanks for your interest! This I don't know. The tech who has it now said the "motherboard" is a "22 pin" and that another one that he has for parts is developing a crack as well. I purchased the unit in Hawaii as a young man and recorded several projects there, moved to Washington in "86 and continued using it until the late 90's when I made the move to digital. It sat in the corner until a couple of years ago when I decided to start using it again. Tracks 3 & 4 didn't work at all, tracks 1 & 2 were VERY muffled sounding even after head cleaning and demagnetizing. Not being a tech, I don't know the inner workings. Just hoping to find a unit to cannibalize.
Click to expand...

I've fixed a few of these (very complex) decks and have never seen a "cracked board" (?) , unless of course they were damaged by mishandling, or the recorder has been dropped. Some trough hole pc tracks continuity can be problematic but these are no "cracks" and can be easily fixed. Regarding the dead tracks it's very easy to swap the two plug-in PB amp boards at the bottom of the deck to check if the problem follows the boards. Try to replay a 4-track pre-recorded tape in the 4 channel (quadro) mode: you should have a signal at the 4 outputs, with two tracks sounding backwards. Don't forget that in 2 channel (auto-reverse) mode the rear outputs (2 & 4) are automatically muted by the logic circuitry. The most likely cause for two missing tracks in 2-channel reverse mode is the PB head switching relay (TECK-36) located on the (impossible to reach) sync selector switching board. This relay can also be responsible for intermittent or degraded sound at playback. Replacing this relay is a very tedious task as most of the machine must be dismantled to gain access to it. I also had failures of the LD3141 PB output amp IC's which are unobtainium... Again, due to the many possible modes the circuit switching/routing path in this deck is quite complex and hard to follow, going trough many switches, connectors, boards,... which all could be intermittent (dirty,oxidized) and must be cleaned. This is typically a work for a qualified and experienced tech only. Most of the 400D SS I've serviced had multiple faults and as far as I can remember never an easy or speedy job.
 
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