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JVC QL-A7 with speed issues

Matt Mincer

Matt Mincer

Active Member
Hey all,

A guy brought me a QL-A7 and said it will work fine for a while but will speed up to super-fast after running for a while. So far, I haven't been able to recreate the problem but I'm wondering if it's a known issue or if there's something I should be looking at?

Thanks
Matt
 
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Matt Mincer said:
Hey all,

A guy brought me a QL-A7 and said it will work fine for a while but will speed up to super-fast after running for a while. So far, I haven't been able to recreate the problem but I'm wondering if it's a known issue or if there's something I should be looking at?

Thanks
Matt
Click to expand...

It is a known issue for the 71 81 & 101 family of motors. But it has more to do with the fact that the tables are 40 years old by now and that takes a toll after years of use and moving around.

I have the same problem. Still to this day. I have isolated it to a specific location on pcb. I thought it was a bad capacitor but it’s a poor solder joint. I have to slightly tap it at the location and mine is good for months of playing. I had similar issues years ago and it was a connector contact that was going bad. Maybe due to corrosion or vibration when moving homes.

If you have it happen again you might want to take off the bottom metal cover and check all of the cable connections , look for any leaky capacitors and look for any open traces or suspicious solder joints. I was about to ship it to a tech that has repaired a few of these models but he asked me to check the cable connections and look for cracks in traces or bad solder joints. Said bad caps were not always the problem.

I don’t think it’s the ic chip or anything like that. Most likely a few of the things mentioned above.

Good luck with finding out what is wrong with yours. I’m betting It is something other than a bad chip.

DR

PS. This just happened again to my QL A7 about 6 weeks ago. Fingers slipped dropping the dust cover down too hard enough to jar some poor connection. I tapped pcb lightly and it came back to normal instantly. Been fine ever since.
 
Did you check the topics about fixing the TT-101? Maybe it could help your turntable desertrat748.

They're still trying hard to work propperly those turntables!
 
Snuck said:
Did you check the topics about fixing the TT-101? Maybe it could help your turntable desertrat748.

They're still trying hard to work propperly those turntables!
Click to expand...

I’m being lazy and avoiding taking the pcb off to repair cold solder joints (I think I know the location) or replacing the troublesome caps.

I’m now almost certain that it is the solder joints at two different caps. But I have it running perfect now so I’m fixing the drooping counter weight issue first. That issue (drooping cw) was temporarily fixed and now I have parts for a more permanent fix.

So many repairs going on for me right now. Fisher 500c getting updated mods. BDM1 modified bugle2 preamp build has to finished with its latest mods. I just purchased another board for a different preamp build with headphone amp board. A Wyn Preamp.

I have so much going on right now that I’m just trying to button up one at a time. And I’m just trying to get over Covid on its first week and first time catching it. Just took the wind out of my sails.

- DR
 
It's not being lazy, it's preparing to make it in a good mood! :D

At least, everything is ready for its maintenance so its fine. Waow, yes, lot of projects, please post about them ! Mods can be very interesting since vintage amps were very nicely made, only age and technology of the chips/vacuum maintenance are their drawbacks.

Please recover well from Covid, I wish you the best !!
 
Snuck said:
It's not being lazy, it's preparing to make it in a good mood! :D

At least, everything is ready for its maintenance so its fine. Waow, yes, lot of projects, please post about them ! Mods can be very interesting since vintage amps were very nicely made, only age and technology of the chips/vacuum maintenance are their drawbacks.

Please recover well from Covid, I wish you the best !!
Click to expand...

I have the Fisher mods posted up under the Fisher thread. It’s near the bottom of all the main topics that are listed on ak. Towards the end well past topic threads like turntables.

Guys on that thread are top notch! Very helpful and informative. The only reason I was successful and able to perform such.

Lots of pics of my progress. Particularly helpful if anyone else has the same needs. I also posted up some pictures of the wooden case repairs. I received the Fisher 500c in a few pieces instead of one unit. I was able to repair it and it looks great. Almost undetectable for 3 out the 4 separations of the wooden pieces. I don’t even notice it now unless I’m looking for it.

The preamp mods are posted up by another AKer who figured it out. I merely tagged along and duplicated the build. Posted up by “The best preamp under $1000” It took a turn for awhile as another AKer has his own version of the old diy preamp that has been going on for years. But lots of good info there and I have purchased the boards to build one of those. I will be able to compare soon. I’m still making mods for the original pa. It’s probably the best thing that I ever did to enhance my vinyl experience. Wish I started with the preamp first and then gone from there.

Back to work,

DR
 
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