Tascam 238 Transport Stop

[SkywaveTDR]

To keep this site alive with new things I thought I would ask if anyone else has seen the transport stop randomly in the 238. I have two units that are supposedly doing this one with a complete power supply rebuild so it will not be bad caps or diodes as in the previously found 122 diode failures.
This is not an everyday occurrence but two units makes me think that it is going to be seen more in the future.
I have to guess that it is a 10V cap or a 16V Marcon on the face plate control board at this point but until I am able to resolve these problems then I will not know for sure.
The cassette in switches were Deoxited and worked but maybe they need to be burnished. the counter seems to also reset so that might be it.
Any experiences in even other models would be helpful.
It seems that with age the lower grade parts such as Marcon caps start to make themselves known as in the shorted ones I found in a Tascam 48. I did change all 16 ( 2 per audio card) of them and no problems so far.
Marcon 220uFd 16V have also been found shorting in Z6000 and Z7000 decks.

 

[Caveman]

My 238 does that, frustrating to say the last. I read on another site it’s some kind of sensor in the well that needs to be cleaned. I cleaned everything still shuts off. Counter resets too.

Maybe this helps.
https://www.youtube.com/watch?time_continue=145&v=tUOhe2dPE1E&feature=emb_title

Also trk 7 and 8 horrible crosstalk don’t have jig from tascam for head alignment, is it something a person could monk with without that jig?

 

[SkywaveTDR]

As far as tape path is concerned that head structure as it is should not be moved past the original position and the edge track will get worse due to wear edge in the head. The tracks are extremely close together and why would anyone not expect crosstalk under these conditions- you should consider the format of 8 track on cassette tape before making complaints of cross talk. Also record rap music or heavy bass is also going to jump boundaries more than regular music not to mention the levels they use are absurd anyway. Some common sense which seems to be lost in this generation still has to be used.

 

[SkywaveTDR]

If a counter resets and I have a 238 on bench now, then if it is not the caps on the control board which I changed all of them yesterday, it is related to a power supply item failing under heat- my unit stopped only after 5 passes of a 90 minute tape in record but it still stopped. Now come the fun of finding out which supply, cap or diode is failing under heat stress. There is no measurement for this or maybe a storage scope is required.

 

[-mjk-]

Reminds me of the can of Freezit on the bench at Dad's TV shop.

 

[Caveman]

Thanks skywave but I’m well aware of narrow track width of the 238. I’m not talking about normal expected crosstalk and bass always goes on outside tracks. I’m talking HORRIBLE crosstalk.

The amount of cross talk between 7 and 8 is such that whatever level 7 is 8 is almost even. I cleaned path, switched out all cards for giggles. Same.
Screw it, into the shop.

My stop counter reset issue gets better as 238 warms up. Maybe hairline crack somewhere. This guy thinks sensor too. I cleaned mine, I’ll let my guy know what you’re thinking. There goes my 238 for several months. Lol https://238pro.com/repairs/

 

[SkywaveTDR]

Maybe there is a broken solder joint or something shorting the two channel busses together at the main board. These things can be tricky to fix and some days I find 10 V caps on the cards which I change to 16V on sight. The 238S is not fixable due to no documentation anywhere.

 

[Caveman]

I’m thinking same. Trk 4 is between 7&8 on the other half of split head but if alignment issue 4 should be funky too. Plus overnight issue.

Thanks for 10v to 16v tip. I’ll make note on wo when I drop it off at the shop.

Let us know how the stop issue works out.

 

[SkywaveTDR]

There has to be someone else working on these out there besides me. The issue is that there are three unit here that like to stop intermittently due to who knows what reason.
Russ in NJ suggested the cleaning of the detector switches. These are not the open type switches as used in other equipment but closed microswitches and of course they could still be the problem but they handle sucj low current unlike the Pioneer RT909 that they are not likely to be bad- I shall clip a shorting lead on some and see if this helps if not then it is maybe a rotation sensor issue or circuit of that type. Things were a lot more simple when they used magnets and reed switches as they almost never failed.

 

[SkywaveTDR]

This Denis Petrov guy does not have a valid E mail address as I have tried sending to him and it bounced.

 

[Caveman]

There’s a guy in nyc if nyc is still there, he’s a tascam tech or was says he’s the king of 238’s or something to that effect, I’ll try and find his info. Big Matt on YouTube does 238’s too but his main focus is rtr machines.
Oops yeah Dennis is one of the guys I was thinking about.

A bypass of that sensor would work as long as I stay awake to push stop lol

 

[Caveman]

Skywave, I sent denis an email he got right back to me denis@238pro
He thinks mainboard short crack etc too. Fast turn around but he might only work on 238’s not getting bogged down with old akai rtr cams and stuff. I have a d150 needs cams if you know anybody making new cams. I thought that little rtr sounded amazing when it worked.

 

[SkywaveTDR]

Yes, it seem the E mail link I copied had a space in it that did not belong. Denis is now added to my fellow Technician folder on E mails and so he seems to be a good source for fixing these decks. With all the work that is out there, we need all the help we can get- there seems to be more guys bailing out of the business faster than I can train new guys. Maybe I should start a Training institute but that all cost money and time.

 

[SkywaveTDR]

There was a guy on Tapeheads forum that was making Akai cams- I don't know the longevity of him making them but the ones he showed were a lot more durable than the junk Akai put into their decks. I suggest you do a search or post a question over there- I am no longer a person that goes there anymore myself.

 

[Caveman]

Thanks I’ll head there. I found some on eBay a yr or so ago shoulda bought some.
My usual guy is so backed up he’s had 2 414’s of mine in his shop almost two years! He gets a lot of high end stuff in and jumps them ahead of me. He can’t get any kids to work and learn. I don’t know if they even teach ohms law anymore, I think they teach em keyboard tricks and how to unplug plug lol

 

[SkywaveTDR]

Well I got a response from Russ at New Jersey Factory Service and Denis and both had said to spray the switches and then locating those pin switches behind the mode motor I sprayed them on 3 different units that had the problem and it took care of the stopping issue. So in my case I take the transport out take off the cam motor and then get the spray tube of Deoxit on the switch and give it a spray. Then exercise the switches a couple of dozen times. Those yellow Deoxit tubes get me mad each time I use them- what a dump idea on such a product.

 

[SkywaveTDR]

I had a complaint of terrible cross talk on a 122 Mk II deck. It turns out the cassette guides were lose and so I have to take the door down to get the driver in there and then lacquered the screws when they were tight. This then required a whole alignmnet job with the M300A jig which I did with magnification and precision. After the azimuth was done I recorded a signal on one track and it did not bleed over at all even to -57dBU at which the tape hiss was here. Now he 238 has more narrow tracks but a mis-alignment of the heads might be the source of the problem is some one just started turning screws- just because there are guides on the heads they do not correct for any wrong head position and will either damage tape or cause it to skew until the head is put back into the right position. Lesson learned was to not take the plastic guides in the cassette holder as being tight and correct for granted. Time to get the M300A out. The crosstalk was hear also in the side A to side B of the tape turn over- this was even greater than the crosstalk between channels. After the alignment I heard no signal on side 2 from the deck recording of base on side 1 at all.

 

[Caveman]

I’m trying to limp thru a couple of projects on 238 for a client, it’s going out for service as soon as I’m done using it maybe sooner. I took cover off, pulled cards, used a very powerful light and magnifier looking at cards connections moving wires around gently, nuthin. Put back together no crosstalk. I had those cards out before and moved them around hoping to eliminate or trace crosstalk issue still had it, bad. If it comes back it’ll go right out for service otherwise it’s going as soon as I’m done with current projects. It’s something I missed and needs to be fixed properly.

I sprayed switches sensor area a few times. I didn’t run it long after putting it back together but short time I ran checking crosstalk in play/record it didn’t stop and reset counter. Either way it’s going out to have a thorough going over including head alignment if needed. I’m probably going to buy a spare 238 so I have a back up when needed, mine is a little beat up. I have 20 yr old clients insisting on recording entire albums on cassette including mixdown. It’s like a cult or something, these kids are releasing cassettes like in the 80’s. It’s like a badge of honor if they used cassette for entire album. lol I don’t mind at all, using the 238 is fun when it behaves