Akai cr80dss strange trouble - please help!

[Quadgirl]

Hi, everyone! I'm back with a crazy problem on a QB restored deck, no less! UGH!
Alrighty – I hope someone can help here. This is my most recent trouble area with my quad system. Granted, it has been a couple of months since I last played a Q8, but I had not previously noted this situation. My system, briefly, includes a QB restored 9001, a QB restored akai cr80dss, a technics quad deck (unrestored), marantz cd-400, two dbx 400s and two dbx snr-1s and turntables not having any trouble. Well, today on my QB restored akai, I noticed virtually nothing from my left rear channel. So, I spent hours to troubleshoot. I played the same tapes on the technics and had good four channel music. So I changed out cables, to no avail. Finally, I turned the 9001 to fade to rear and then only left rear where I continued to mess with cables. I even swapped between the front and rear dbx 400s to make sure they weren’t the problem (they weren’t). Well, I had to turn volume up a bit and heard hiss on the line out (rear) with left and right channels plugged in from akai to dbx 400. Very interestingly, I found that when I removed the left channel cable (from either line out on akai or “from line out” on dbx 400), the hiss was gone and I could get very, very faint sound, but no hiss. So, I have left that one cable unhooked from the 400 for now. Bottom line, the akai left rear out is malfunctioning. The final thing I have observed in messing with it all day is that upon first turning on the akai, the needle showing what’s happening with the channels for the left rear actually moves (but no indication on 9001 or at the speaker itself that there is music playing in it) kinda haywire-ish and then it settles to no movement at all. Please advise if you have any suggestions whatsoever. I’d be willing to try anything since this was to be my warhorse of a q8 deck and I wasn’t supposed to worry about it like I do the others. Also, I did try different brands of Q8s and really did swap out cables and as I said plugged the left rear out into the plugs for the front dbx 400 to confirm lack of anything playing in it. Hope y’all are enjoying the holidays even as I write this. Thanks in advance.
Quadgirl (Laura)

 

[JonUrban]

This may be a shot in the dark, but if the heads got out of alignment, maybe they are "missing" a channel. Does the same thing happen on track one AND track two? If it is, then this isn't the problem.

I remember I had thought that I had adjusted my heads once, and I adjusted them clear off of one channel!

Probably not your problem, but worth a shout.

 

[Quadgirl]

Thanks for the idea, Jon. Alas, the same problem is on tracks one and two. And I forgot to mention that I've only had the deck since this summer (a new restoration), so kinda doubtful that heads out of alignment, though that would be a better problem to have, I think. I'm still perplexed about the fact that I just turned it on again today and for a bit the needle for the channel that is out goes to the far right and sticks for awhile. Seems like some kind of electrical something going on, or the fact that I have the one cable dangling to prevent hiss. Well, again, thanks for trying! I'll keep ya posted if anything changes. Happy Thanksgiving!

 

[geotex]

Unless you have the test equipment and knowledge to actually do board-level testing, and inject an audio signal to find the trouble area, it sounds like a trip back to your technician is in order.

 

[spenceo]

Hi Laura,

Geotex is probably right. Sounds like you have been through the cabling and other components, to rule them out. Looking at my schematic of the cr80dss, I suspect you problem would be on the pre-amp board. If you work on your own electronics, I could start you off with a few good starting points for troubleshooting.

Spence

 

[Quadgirl]

Thanks spenceo and geotex. I sure wish I had some knowledge or training as I'd love to be able to work on my own stuff. I wish there was a quad 101 fix it yourself class - I'd take it in a heartbeat! But, while I'm not scared to take off the cover of electronics, I wouldn't even know where to start and wouldn't want to mess anything up. It seems from responses that I have exhausted the troubleshooting I'll be able to do, so will have to bother QB about it - hate to bother him since I know he is perpetually busy, but maybe he can guide me somehow here. I am lucky enough to have another unrestored akai I can put back into the chain, but am just frustrated that my newly restored unit is already having a problem. This hobby can be irksome at times! Anyway, thanks to all who offered suggestions and I do appreciate having some confidence that I have done about all I can. One more question if anyone is still reading, should I go ahead and plug in that one cable just to be sure I'm not messing anything up? The hiss won't be so noticeable when I'm not fading to just that channel for isolation purposes. Just curious - feel funny having one cable not hooked up. Alrighty - thanks again!
Laura (quadgirl)

 

[geotex]

Most inputs normally have a blocking capacitor to protect against a dc voltage, and you are only working with a preamp output, so no high rail voltages to worry about. On the down side, you are still only getting 3 channels, so you might want to unplug the other rear channel and use the unit in stereo mode until you pull it out of your system for repair.

 

[Quadgirl]

Hi, again. I'm following up with more info. Last night I decided to also play dts-encoded quad discs to see how they would fare. Interestingly, found weak rear left channel as in the akai. The only commonality would be connection through dbx400s. Anyway, this morning checked all cables to sansui for tightness and such. And, this is a b*&^h to do with the tight 9001 fit in my Lovan rack! All were good. Checked and played some more dts quad and found something very interesting. When I swapped between front and rear dbx400 units on the monitor input left and right channels (the ones that go to the sansui from the 400s), I found that plugging what had been the connectors to the rears to the front dbx 400 that I had whopping good rear channel sound in both the left and right rear! I mean equal volume-wise when moving sansui dial from left to right rear! So, unless I'm missing something, and I could be losing my mind after all this time bending like a pretzel to get to the back of the gear to test all things connected, it seems like the sansui is doing its job getting info to the rear channels (when hooked into the other dbx400), so even though I have doubts about the akai because of the lack of needle movement (when I keep left and right both plugged in despite low hum when faded only to that channel - seems the erratic far right needle movement must have been caused by having only one of the cables attached), it also played fine in the rears with the swap between dbx400 monitor inputs. So, both dts quad and akai were able to get rears making music when run through my dbx400 that is otherwise hooked to front channels. So, now I think I have a bad plug on the "monitor input" on my dbx 400x unit (the other is a dbx400 and I had just assumed the x meant even better!). Does this seem right to y'all? If anyone is still following my latest saga! The technics deck, though, has been unaffected (playing all four channels just fine) and it seems like it would still be affected if it was the monitor input plug. This just gets more confusing. But I am absolutely certain of what I heard when swapping the plugs - no doubt a bunch more sound coming to speaker when plugged into the front dbx unit and clearly hum and/or low level faint sound when put back to the rear dbx. Has anyone had one of these things go bad? I don't mind buying another, but would like to know if there are trouble spots on the units. Also, what is the difference between 400x, 400 and 400xg if you know. Thanks for bearing with me through this long post and I continue to seek any input, however much a shot in the dark. I'm feeling like my findings are getting crazy, but I guess it is possible that there is a simultaneous problem, with the akai needle even though that channel now has been made to work by reversing front and rear plugging ins on the 400x to 400. Anyway, if you have any suggestions, information, etc. please post. The more I investigate, the dumber I seem to sound here! One more confounding tidbit: I did only just put the snr-1s into the ever growing vintage quad chain of toys Wednesday, but just cannot fathom that they would be creating any part of this problem. They are just routed to the processor 1 loops of 400s while the marantz cd-400 is routed to the processor 3 loop. Well, that's all I know. Thanks in advance!
Laura (quadgirl)

 

[JonUrban]

OMFG! Sounds like you have a frustrating "puzzle" on your hands. You may have to unplug everything and start over.

Have you tried headphones on the AKAI? That should prove that it's either good or bad.

Or you could try this...............

 

[The Quadfather]

Dear Laura:
I got confused trying to read all that in my hungover state, but I will try to help you with the Akai. First, you cannot rule out the possibility of two unrelated problems in two separate pieces of equipment. Having said that, I will concentrate on the Akai. You say you have no meter movement when playing a tape. There are two possibilities:
1 The channel is not functioning.
2 The channel is functioning, but the device or cable it is connected to is shorted.

I will discuss number 2 first. The meter is positioned in the circuit as the last thing in the signal chain, so that it will kill if the output is shorted by a bad cable or jack on either the Akai or on something it is connected to. To verify this, unplug the outputs on the akai and play a tape. If the meter movement is apparent, then reconnect. If the act of connecting kills the meter movement, then you probably have a bad cable or a short in the equipment being connected to the Akai.

Now for number one. Disconnect the Akai to remove any extrernal factors. Still have no meter movement on the bad channel when playing a tape? Try this. PULL THE TAPE OUT. switch rapidly between record and play several times. Put the machine in play mode, and play the tape. Is the meter movement apparent? If not, then it will have to go to the shop. If the meter is now moving in a normal fashion, then you probably have a dirty Record/Play switch. Remove the cover and use silicon contact cleaner to clean the long switch that the record button mechanically links to. Operate the switch while cleaning to dislodge dirt. Do this by punching play and record alternately. Inject the cleaner using the straw that came with the can into any opening in the switches (I think there are two of them). If this does not solve the problem, it's back to the shop.

Other problems can be a bad record play switch (bad news) or a bad chip, or a bad capacitor. I know Quad Bob restored the unit, but new capacitors are known to fail also. If the record/play switch is bad, about all you can do is to take out the switch and jumper the unit for play only or install a relay board to handle the switching functions. I hope that is not the problem. Also, the chips are pretty hard to get, but not impossible. If this is the problem, I can tell you where to get them. Always use a tape you don't like when performing these tests. It is easy to make a sequential mistake and record a blank spot on the tape. Good Luck and Happy Listening!

The Quadfather

 

[Quadgirl]

Thanks Quadfather! I was hoping you'd chime in. I am about to try your methods, but wanted to say hey and thanks! And, Jon - ha! Yes a migraine is in store, but I'll choose to drink through it!! And, geez, shoulda thought of headphones, so will try them, too. Thanks so much - got something to go on now.
Laura

 

[Quadgirl]

Okay - now we're getting somewhere. I tried the headphones (only one jack and you switch between front and rear). Sound coming through, but hissy in left rear (as in playback through system). So, tried quadfathers number one try and disconnected the output cables from the akai, popped in a tape and low and behold, meters all work! Yeah - lesser of two evils! So, now I know I wasn't losing my mind when I swapped cables at the dbx 400 level (substituted rear cables in front dbx box jacks for monitor inputs) and then got sound to come from both rears. I hope I am correct in that there is a problem with the 400xdbx at the monitor input jack. Having swapped out numerous cables yesterday, I believe that is it. There is only one unit on ebay and I'll bid, but in the meantime, if there are any more troubleshooting tips or fixing tips to pursue, I'd love to hear them. Thanks for helping. Progress is slow, but happening! Thanks again (and to Jon for the levity!!).
Laura (quadgirl)

 

[The Quadfather]

Hey Quadgirl:
Yeah, it sounds like the input to the DBX is shorted. If you have an ohm meter and know how to use it, you can check that. To do this, set the ohm meter to the lowest scale, and zero the meter. Then plug a stereo patch cord into the DBX monitor inputs where you had the Akai connected. hold the negative lead to the chassis and the positive lead to the center pin of the cable for the good channel. On that scale, it probably will read open or around 1000 to 1500 ohms, depending on the input resistance. Then move the positive lead to the suspect channel. If the reading is near or at zero ohms, or is signifigantly lower, then you have found your problem. The input is shorted. Send it to the shop, or get a replacement. Happy Listening!

The Quadfather

P.S. In some cases if the short is beyond a coupling capacitor, it may not register a short on the ohmmeter. But it will still kill the signal just the same. That's because an ohmmeter uses direct current to measure with and a capacitor blocks DC. It passes the alternating current signal quite easily right to the short. Of course by this time you're probably pretty sure about it anyway.

 

[Quadgirl]

Thanks again, Quadfather. I do have a multi-meter thing that I never really learned to use. It is digital, so not sure I zeroed things out very well, but I understood about the stereo cables and what lead to touch to what. When I held the probe thing on the good jack's cable, numbers circulated and landed on 219.6k ohms. Now that is a good deal higher than I expected, so don't know what I did wrong. Then went to the bad jacks cable (still making sure to hold the black lead on the chassis) and on that pin, the numbers just kept circulating and the meter kept going from kohms to mohms and on and on - never really settled. Then, I probably did mess something up (but, hey, didn't get electrocuted!), because now in repeating the test, I can get nothing to move on the multimeter - just shows .0L on either cable's pin. Still, I think it is something with that dbx unit's jack and will know for sure when I win an auction for another one. Also, because I'm impulsive and didn't want to wait before playing with the multimeter (always did want to measure stuff with this thing! only used it once years ago when quadbob was walking me through some tests on the 9001 pre-restoration and even then I managed to get something to start smoking in the unit!), I didn't ask whether I was supposed to have the units plugged in and all, so I did have the dbx and really everything on. Maybe that was the problem. Anyway, sorry to be so clueless on this - I sure wish they taught even just how to use the multi-meter in school, then I'd have a practical skill. Thanks again for keeping on top of this and helping. Looks like you stayed up late, though!! I'll pm you sometime - would like you and your wife to come over next time you are in or near Columbia. Well, gotta go. Talk to you later. And for others out there, if there is any information about testing/measuring/fixing vintage stuff for dummies, please point me in the direction! Thanks!
Quadgirl

 

[The Quadfather]

Hey Quadgirl:
It sounds like you have the problem pinned down anyway. So don't worry about the meter. It's always a pleasure to help. I appreciate the invitation but I don't know when we will get to Columbia, SC. Maybe a future concert? We were planning to go to Richmond but instead we wound up in Philadelphia as I was sent to transmitter school. We turned a business trip into a vacation. We flew there, so there was no opportunity to visit points in between. But we did get over to Gettysburg to see the site of the turning point of our nation's defeat. I had several Philly sandwiches while I was in Philadelphia, and noticed that the Philadelphians do not put bell peppers in the sandwiches. So I must conclude that the South has improved the philly sandwich by including this ingredient. Philadelphia is a beautiful city, but it's full of bums. The left wing marxists were having a march there. I hope you do well on Ebay looking for your DBX replacement. Good Luck!

The Quadfather