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Problems with Technics 858 8-tracck

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mrtickle

Member
Joined
Jul 9, 2003
Messages
30
Location
Belgium, Germany
I have a Technics 8 Track 858 with the "green meters". But it started to have some problems recently. Maybe someone of you has an idea what could be the problem.
When I got the unit it worked fine after some cleaning and replacing a spring used for changing the channels. After that I didn't use it for quite some time until I got some new Q8's. But now there is a problem. Once I plug in the power cord the drive starts running even without a tape inserted. The meters do light up although not fully, it is more like a faint glow.
I hope it is only a minor problem as the unit is cosmetically still very beautiful.
So, if anybody may have an idea would could be the problem I would really appreciate any help.

Thanks
Michael
 

Quadwreck

Moderator
Since 2002/2003
Joined
Jul 9, 2003
Messages
1,123
Location
Portland, Oregon
It sounds like the activation switch on your tape player is stuck, most likely a result of a jammed mechanical piece. I recommend cleaning all the inner mechanical parts and relubricating. If the problem remains, the switches may need cleaning or replacing.
 

jberger

Member
Joined
Sep 6, 2010
Messages
42
Any suggestion for parts sources for an RS-858US (besides another RS-858?)?

I'm looking for one bulb to go behind one of the meters (green meters); it's a rubber-sheathed bulb in a housing about 3/4" x 1/2". Any ideas on the part number (if someone has a service manual), or a parts source, or at least specifications?
 

jberger

Member
Joined
Sep 6, 2010
Messages
42
I rescued this unit from a garage sale, and gave it a good cleanup, replace the motor mount grommets, ordered new belts, sanded out the scratches on the top of the faceplate with 600 grit sandpaper (thank goodness for solid metal faceplates!), and repainted the rest of the case with hammertone black. I'll refinish the side panels, put in the belts, and align as best I can.

However, the unit does not play the left rear track on a quad tape. When I adjust it's volume control, I hear some amplifier hiss at high levels, so I think it's working from there, and I think I got some hum when i touched a screwdriver to the connections on the head (I think it was this track, but now I'm not positive; will have to go back and check). Is it possible that this track on the head is bad? Or is it more likely wiring?

Someone above mentioned a spring for the head-change mechanism, which would help it out; any suggested sources/part numbers for these?

I did find a 6v bulb that I retrofit into the rubber housing; it's slightly dimmer, but it does light up. I think either Pioneer or Kenwood used these rubber bulb housings for receivers in similar years, so I'll keep searching.
 

8trackman

Senior Member
Joined
Jun 24, 2010
Messages
212
you managed to snag a nice deck, mine had problems as well, mine wouldn't give me back my tape or turn on, I guess they all have some mechanical issues

once its working good, you will enjoy it

good job on restoring it as well, I am afraid of scratching it
 

JoeR

New member
Joined
Mar 5, 2011
Messages
4
Hi all! I'm new to this forum. Does anyone got information on how to open a Technics 858DUS? Please help. Thanks.
J
 

jberger

Member
Joined
Sep 6, 2010
Messages
42
As I recall, I had to take off the bottom panel (about a half-dozen screws) and remove it. Inside, there were four larger recessed screws (two on each side) that fastened the main chassis to the chassis for the cover and sides. Remove those, and the top and sides will lift off as one assembly.
 

JoeR

New member
Joined
Mar 5, 2011
Messages
4
As I recall, I had to take off the bottom panel (about a half-dozen screws) and remove it. Inside, there were four larger recessed screws (two on each side) that fastened the main chassis to the chassis for the cover and sides. Remove those, and the top and sides will lift off as one assembly.

Thank you very much. I'll try that.
 

jberger

Member
Joined
Sep 6, 2010
Messages
42
My RS-858 saga continues. It has never given me output from the left rear channel when in 4-channel mode (there was amplifier hiss); putting it into 2-channel mode, I got output, which got me checking upstream. C1 on that channel was microphonic (tap it, and you get sound in the outputs); I replaced it, but had the same symptoms. Since this is just after the tape head, I tested the resistance of all of the channels of the head (from the circuit board end, not the head), and I got an open signal on the bad channel. Worst case would have been an open circuit on the R/P head, and I figured the chances of finding a quadraphonic 8-track record/play head were very slim; however, a close inspection with the magnifier revealed a broken red wire at the head on the bad channel.

I spent the rest of the evening repairing the connections (the broken one, and the ones that had to be removed to get to it). To put it in perspective, soldering these wires was like having sixteen wires coming off of one face of a sugar cube. It was much easier once I removed the head block from the transport. As I put it back into place, I noticed a solder bridge shorting across two terminals, so I touched it with my hot iron, only to have two wires pop loose. I hate it when that happens! By then, it was too late at night to start over, so that'll be something to do this weekend.

I'm still trying to track down the tape counter belts for this and my Sony TC-854-4.
 

Q-Eight

2K Club - QQ Super Nova
Since 2002/2003
Joined
Sep 30, 2003
Messages
3,079
Location
Castlegar, BC, Canada
Try cleaning, wiggling, cycling the 2-Channel/4-Channel selector button. My most recent 858 has the same problem, one channel (I think it was back left, come to think of it!) would not play. Cleaning, cycling and wiggling the button got my four channels up and running.
 

dauQula

Well-known Member
Joined
Aug 13, 2004
Messages
172
Location
Midwest
Great suggestion. A good soaking with a deoxidizing contact cleaner, a lot of cycling, and my rear left distortion cleared up. As the two channel position cuts off the rear speakers, it follows that a pair of clean contacts in the 4-channel position are needed. Would also advise not to try to remove this switch. discovered a mechanical assembly on the bottom that prevents switch activation in record mode. This is a nightmare to reset once the switch is unfastened for easier cleaning. Now all I need is to find is replacement bulb for one of the VU meters.
 
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