Akai GX4000D - does it need a new play head?

[62vauxhall]

I put up this same question on tapeheads.net but thought I'd increase my chances of an opinion by posting here.

Found a near mint black face Akai GX4000D for nearly nothing. Discovered no playback on left channel but proved it records by playing a recording it made on another deck.

Head surfaces were spotless, cleaned them anyway and no residue came off.

Putting the deck in Play and touching the head terminals with a metal probe produces hum equally in both channels so signal is getting through the electronics.

My conclusion is that the playback head has an internal fault or poor solder connection.

Am I right?

The solder connections on that head look pretty solid.

 

[BubbaH]

Have you tried cleaning the track selector switch?

 

[62vauxhall]

No, did not. Firstly because there doesn't seem to be a way to spray inside it and second, because i was able to produce hum on each channel by touching the head's terminals, it made me think that switch must be OK if that signal was getting through the playback amplifier to headphones plus making both meters register.

I would like to know though, what the best method is for getting cleaner inside that switch.

 

[VintageShadow]

You can try by inverting the wires between channels in the head, so if the channel is shot the other one will play the actual dead channel. In this case you'll need another pb head for sure



Sep.

 

[TheDutchOwner]

The fact that you got it for nearly nothing already worries me.

 

[orange]

Have you tried cleaning the track selector switch?

It's not a Crossfield deck, it's strictly two channel, four track stereo and in this case I would try the MONITOR switch first (clean and isolate any faults) and the level pot of the affected output and report back.

 

[62vauxhall]

You can try by inverting the wires between channels in the head, so if the channel is shot the other one will play the actual dead channel. In this case you'll need another pb head for sure



Sep.

Just tried that. I left the shield alone and swapped the signal leads to the head and still no output from one side. Plenty of signal by touching each lead but since from only one side of the head, I guess it's toast.

 

[62vauxhall]

The fact that you got it for nearly nothing already worries me.

It was a complete crap shoot = as is, where is. Skids of old audio gear with questionable functionality. But for $10, I thought it was worth a shot. Got a Teac too for the same price but haven't tried it out yet. The Akai was a lot lighter and easier to handle so I looked at it first.

 

[laatsch55]

Gary for 10.00 you did not get close to being hurt. What's the number on the head, any part numbers you can see?

 

[62vauxhall]

Gee, fancy running into you again. You hang around here often?

No number visible. There probably is one but the head would need to come out of the base to see it. The Service Manual quotes two numbers for the playback head HP307087 and P4-241E but I don't know which is the actual part number.

This deck is not a priority. I was going to wait until done with amp so I have some clear space to start on a reel to reel. I've had a Teac A3300 for about a month that I also got for cheap. Not $10 but not huge money and I'm pretty optimistic about it. Reasonably sure I'll just be changing the belt (already have it), cleaning, lubing and spraying the pots This is the deck I would use, at least for a while anyway.

I should not have gone unattended to that garage sale. In addition to that Akai R2R, I came away with yet another Teac (A2300S) also for $10 but I have no idea what's wrong with it. The only thing I think I know is that mechanically it's good.

I met a tech a few weeks ago who lives nearby, actually visited his garage/shop. He's quite prolific with reel to reels judging from the number of them I saw. His main gig is overhauling and maintaining those humongous overhead projectors. He spoke of reasons why and circumstances where they're experiencing a renaissance - quite interesting.

I was going to ask him if he had any interest in this Akai, maybe as a trade for a couple of Teac 7" metal reels if he has any.

Even though it's bottom of the line, this Akai is in really nice shape - other than the playback head. It's black which was not that common, the pinch roller shows barely any evidence of use and it still has the speed change sleeve that I doubt was ever off it's holder. Everything's tight and it does record well on both channels. For the most part, the pots are even quiet.

 

[laatsch55]

Yeah, I could pop up anywhere......

Excellent trading material then...

 

[62vauxhall]

I started reading threads on other forums and became less and less sure that the playback head was bad. There were frequent references to a particular transistor in Akai decks, 2SC458, that were notorious for going bad. Did a little Q&A on Tapeheads.net, learned of a substitute called 2SC2240, found those at a shop this morning, put all 14 of them in and by damn, the deck works again. .

Probably only had to replace a couple but if those 2SC458's are as bad as people say they are, I thought ridding the board of all of them was the a good idea.

The investment has climbed to $21.85. Now just have to bolt it all back together.

 

[NavLinear]

I started reading threads on other forums and became less and less sure that the playback head was bad. There were frequent references to a particular transistor in Akai decks, 2SC458, that were notorious for going bad. Did a little Q&A on Tapeheads.net, learned of a substitute called 2SC2240, found those at a shop this morning, put all 14 of them in and by damn, the deck works again. .

Probably only had to replace a couple but if those 2SC458's are as bad as people say they are, I thought ridding the board of all of them was the a good idea.

The investment has climbed to $21.85. Now just have to bolt it all back together.

Great job Gary - I'm glad you were able to get this R2R back up and operational.