I cheated and it was successful

[Transistorized]

Yes I cheated today. Not on my wife but I had to operate on Goldie.

As you guys know I pulled Grand Master C out and stretched its legs. Everything was going smoothly while playing a tape but then out of the corner of my eye I thought I noticed something odd. It looked as if my tape run indicator hesitated. Now fully engaged I am now up close and keeping a watchful eye on it.

Could it be that I imagined it......Hell NO!!! I can't ever get that lucky! :annoyed: Sure enough its freezing up every now and then. Tape counter is working great though.

All I can think about is how I am not looking forward to tearing this thing down to bare bones to look things over but also knowing full well that this is going to drive me nuts unless I fixed it. Pulled the back off and looked at all the work that lied ahead of me. I started brainstorming. Hmmm. Might be a stretched belt. Looks like much of it is under the circuit board for the lower deck. Next I opened the cassette door. Hmm. Enough room to fish the belt out around the spindle.

Ok....Attack mode. Lets cheat!!! Loosened the lower deck board and folded it out of the way. With the help of a pick and my assorted new belt assortment I was done in 15 minutes flat with a fresh replacement belt.

Guess the belt had stretched just enough to not turn the tape run indicator pulley correctly. She's all good now. A picture of me squirming the belt past the front cover of the box housing inside the cassette bay. This really is a better way to go IMO. Beats the alternative. Easier than I thought and much better than labeling wires and making a career out of it...

 

[Will]

cool!

 

[Superduper]

There's a good chance that simply operating the deck for extended periods will correct it. The problem is that with extended non-use, the belt takes on a somewhat permanent oval shape. The counter belt is supposed to be a bit loose so as to not introduce drag onto the system. Normally this is not a problem, even with very loose or stretched belts. But when they get set in the oval form, then it could stutter or even go into permanent slip mode (typically when hardened). Continued use, if caught early enough, might eventually restore the belt enough to perform satisfactorily again.

Ever heard of square tires? That's something that happens when a car sits for extended periods of time causing tires to develop a flat spot and go thump thump thump when you drive. So yeah, rubber belts do that too.

 

[Transistorized]

There's a good chance that simply operating the deck for extended periods will correct it. The problem is that with extended non-use, the belt takes on a somewhat permanent oval shape. The counter belt is supposed to be a bit loose so as to not introduce drag onto the system. Normally this is not a problem, even with very loose or stretched belts. But when they get set in the oval form, then it could stutter or even go into permanent slip mode (typically when hardened). Continued use, if caught early enough, might eventually restore the belt enough to perform satisfactorily again.

Ever heard of square tires? That's something that happens when a car sits for extended periods of time causing tires to develop a flat spot and go thump thump thump when you drive. So yeah, rubber belts do that too.

Very true. I have seen that happen as well.

That belt had stretched slightly but not enough to where I thought there should be an issue. The new belt wasn't but just a tad smaller. What I noticed more about this one is the belt was slightly hardened and looked shiny or glazed. So far so good. I was hoping and praying it wasn't the control box going out. That would be hard to find.

 

[hemiguy2006]

Hopefully you wont be due for a full re belting soon.
Mine are gone and I cant even get my deck door open because the play head is engaged.
not looking forward to fixing that one!! I have'nt played a cassette in it in over a year

 

[floyd]

Hell I followed the old Al Bundy advice, marry the TV and leave your wife at Sears.

 

[Lasonic TRC-920]

Nice simple repair. Way better than pulling the whole thing apart. But to not have the feature working would drive me nuts too.

My Clairtone 7979 has a similar display. There are a row of lights above the deck that light one at a time as the tape plays, some times skipping and lurching forward. Not sure why it bugs me, but it does.

Like Superduper said, I need to use it more!

Do you have a belt installation tool? Makes life soooo much easier for jobs like this

 

[caution]

But when they get set in the oval form, then it could stutter or even go into permanent slip mode (typically when hardened).

 

[Transistorized]

Has anyone had the carbon trace unit go bad? Should I keep one on hand or this this very uncommon?

When I say carbon trace I'm talking about the box that sends power to the LED light bar with the pulley.

 

[caution]

I know at least one member here has had a problem with worn tracks, not sure it was ever resolved. So yeah, if someone parts out a box, snag it. No guarantee one from a parts box resets the clock, but if you are ambitious enough you could experiment with conductive inks, paints, and epoxies. It's possible there's a blend with similar/greater durability as the original carbon.

You can always kick it up a notch. Once it fails and you develop that burning desire to make it perfect again forever and ever, draw it up in CAD and order a new board. Costs a bit more to plate copper with something appropriate for use as switch contacts, but it would never wear out after that!

 

[Superduper]

I thought we were talking belts, what is this carbon trace box?

 

[caution]

Transistorized, I found the link. https://boomboxery.com/forum/index.php/topic/25117-static-noise-on-tape-play-bad-caps/

 

[Superduper]

Eric, is that carbon trace box like a rotary switch but runs all time? What is the contact made of? Would making a copper pcb result in even more wear? Carbon is a natural lubricant. In fact, graphite is used to lubricate locks all the time. But metal to metal, and the copper traces will have ridges too which I imagine will get worn off first. A PCB copper traced version on the face of it, seems like it will last forever, but I'm not so sure. Still, it may be the best way to give it new life if the original carbon traces are gone but definitely a think oil or other lubricant is recommended to reduce wear from the metal-metal contacts.

 

[caution]

The standard plating for PCBs that use copper for contacts, such as a PCI card, is 50 microinches of a gold hardened with a bit of cobalt that is electroplated over a 200 microinch nickel barrier to prevent gold-copper embrittlement. As long as the brushes are still smooth and not cockeyed and jagged, it will outlast the box. This is in contrast to electroless nickel immersion gold (ENIG), a full-body plating process used for PCBs and is a pure, soft gold that is applied using a galvanic process that replaces nickel atoms, and tops out around 8 microinches.

 

[Superduper]

The standard plating for PCBs that use copper for contacts, such as a PCI card, is 50 microinches of a gold hardened with a bit of cobalt that is electroplated over a 200 microinch nickel barrier to prevent gold-copper embrittlement. As long as the brushes are still smooth and not cockeyed and jagged, it will outlast the box. This is in contrast to electroless nickel immersion gold (ENIG), a full-body plating process used for PCBs and is a pure, soft gold that is applied using a galvanic process that replaces nickel atoms, and tops out around 8 microinches.

Uh... well, I'm sure you are right although I know nothing about the coatings or actual plating. I only know I design the PCB's on my computer using PCB software, send the files generated by the software to some company in china, pay $$$ and a few months later, a box comes with custom PCB's already made up. Guess we will just need to trust the chinese manufacturers to do them up "standard."

 

[caution]

Heh, standard is fine, but you're right, extra plating makes the unit price skyrocket unfortunately, in small batches. That standard solder coating may work well enough I suppose.

Not sure how China compares but there are quite a few US shops that ship within a week that are somewhat reasonable.
Assuming it's about 1"x1.5", Sunstone will ship a single board for $36 (or 2 for $42, 5 for $60, 10 for $90...)
Pentalogix will do one for $25.
ExpressPCB will do a fixed size of 3.8x2.5" for $51 that you could slice apart on your own, and get six for that price.
And so on. Depending on your needs, what you can live with/without, it's possible to find something that works.

 

[Transistorized]

Transistorized, I found the link. https://boomboxery.com/forum/index.php/topic/25117-static-noise-on-tape-play-bad-caps/

Very interesting indeed. I have been fortunate to not have my control box fail (knock on wood). The pads look large enough to where it almost looks as if you could massage the fingers to glide on a different section of the pad where the material is good, follow a new path and get out of the bad (groove).

I'm sure with all the hours I put on my boxes each year I will need to reference this again one day

Thanks Caution

 

[Transistorized]

I had to do this again today on Goldie. Ive been trying to use a belt that isn't so snug but it keeps slipping and the tape run indicator stops and goes. Annoys me. So, I had to install a tighter belt and the FF and Rew are really suffering but I've got to have my tape run indicator

 

[caution]

Did you secure the end of the tape run pulley shaft to keep it straight?

 

[Transistorized]

Did you secure the end of the tape run pulley shaft to keep it straight?

Hi caution. I need to do that. I had seen where you (or someone) had used a washer to help nudge the rear spindle shaft towards center. I guess all those years of playback causes the shaft to oblong the hole and cause drag.

I ended up using a SBS8.9 which some say is too tight but that's all I had.

Its back together now but I will likely remove the lower deck PC board soon to gain access and see about giving that a try. Its struggling way worse than with the other belt. Almost doesn't FF to the end of a C90 much less than Rew. Rew is now about 3/4 tops on a C90