Altec 707 Receiver - phono preamp not working

[musicook]

Hi. I'm new to this forum and generally new to home audio. I've spent the weekend playing with my vintage gear. I replaced the capacitors in my Altec 19's and ran a ground wire across the four lugs in the crossover. I acquired this Altec tube receiver last year and had it serviced locally. It all sounds great, but has some hiss. I went to try a turntable through the phono inputs, and it is low volume as if it is plugged into any of the other inputs. The turntable works through another vintage receiver. I was wondering if there's anything I can check or try before bring it back in for servicing.

Thanks.

65379

[Earl K]

Welcome to the LHF .

I think you'll find that for something like this 55 year old receiver , you'll need to find a tech who's really into the history of the specific piece .

Sadly, I've never seen anyone here ( at LHF ) display any working knowledge ( about servicing these old things ) .

Good Luck with your quest !

:)

PS ; I poked around Google a bit and found your home theatre/performance space .
Nice Build! https://community.klipsch.com/uploads/gallery/album_139/tn_gallery_58328_139_152356.jpg (https://community.klipsch.com/index.php?/gallery/album/139-musicook-home-theater-build/)

[musicook]

Thanks. The house concert/home theater is still a work in progress. But I like the big University Classic / JBL horn combo.

[Wagner]

What cartridge were you using?
I'd also like to see a tight shot of the front and rear panels (where I can read everything); can't find much on line for this one

What handles gain for the PHONO, 12AX7? (should be two (2) of whatever ALTEC used, L&R obviously). Tuner section the same? If they are, or if you have some known good extras, try swapping them out

The problem with many of these oldies is that everything is always on, even when it's a section not in use; not very good for tube preservation!

Every Fisher I have ever overhauled that had a completely dead 12AX7 had it in the PHONO section; maybe we'll get lucky and yours are just extremely tired

Is the sound you are able to hear correct (EQed)? Just low in volume? Do you know the history of the receiver? (that some tech didn't re-purpose those inputs?)

The front panel layout of that receiver is very reminiscent of Stromberg-Carlson with all those slider switches and their placement; Bogen too. Those switches are often a weak link for giving cause to suppressed levels, especially any "monitor" or taping related function ones if you have them

Do you know who actually manufactured that receiver or is it truly an ALTEC product?

[macaroonie]

It might be geared up for a ceramic cartridge. Typically higher output than current types. What is the cartridge you are using ?
Or now that I think about it you wouldn't be using a moving coil cartridge , in which case you will need a step up transformer to get the small voltage stepped up to what the input needs.
A pic of your rear panel would be handy , and your 'needle '

[Wagner]

I found some good photo shots
This example just like yours?:
http://www.hifiplaza.co.kr/bbs/zboard.php?id=review&page=2&sn1=&divpage=1&sn=off&ss=on&sc=on&select_arrange=headnum&desc=asc&no=77

[Wagner]

It might be geared up for a ceramic cartridge. Typically higher output than current types. What is the cartridge you are using ?
Or now that I think about it you wouldn't be using a moving coil cartridge , in which case you will need a step up transformer to get the small voltage stepped up to what the input needs.
A pic of your rear panel would be handy , and your 'needle '
If the photos I posted (linked to) are indicative of his machine, the PHONO section jacks are clearly labeled "MAG"

[Wagner]

It might be geared up for a ceramic cartridge. Typically higher output than current types. What is the cartridge you are using ?
Or now that I think about it you wouldn't be using a moving coil cartridge , in which case you will need a step up transformer to get the small voltage stepped up to what the input needs.
A pic of your rear panel would be handy , and your 'needle '
I must be on your "ignore" list; that, or there's an echo in here :bouncy:

[musicook]

I found some good photo shots
This example just like yours?:
http://www.hifiplaza.co.kr/bbs/zboard.php?id=review&page=2&sn1=&divpage=1&sn=off&ss=on&sc=on&select_arrange=headnum&desc=asc&no=77

Thank you. This is the same receiver. I'm not at home now to take additional photos. I have a couple cheap turntables. I'm currently shopping for one. When I plugged it into the Altec, on phono, it was very faint. When I plugged the same turntable into a Sansui 9090 - it was plenty loud.

I have box of tubes for guitar amps, so I should have some new 12ax7s to try. I know I have some 12ay7s.

[Wagner]

Thank you. This is the same receiver. I'm not at home now to take additional photos. I have a couple cheap turntables. I'm currently shopping for one. When I plugged it into the Altec, on phono, it was very faint. When I plugged the same turntable into a Sansui 9090 - it was plenty loud.

I have box of tubes for guitar amps, so I should have some new 12ax7s to try. I know I have some 12ay7s.

No need for photos now if the ones I linked to are an accurate reflection of your machine; was only interested in seeing if your machine had a level adjust and it appears not to be the case (some of the oldie goldies do)

Try swapping out the PHONO tubes and exercising the mode select switch and all others as well; you might get lucky; easily overlooked by a "tech" if he didn't test/clean for all the inputs and easily oxidized/dirty if the receiver spent a long time sitting at only one selection (most of these I run across spent the last decade or two of their lives doing radio only duty)
I don't know if you feel comfortable with it or not, but it wouldn't hurt to give all the switches a shot of DeOxit; might save you a trip back to the shop

Be sure to verify what's in those spots before any swapping; I was only assuming 12AX7s as that was a very common one for those spots during this period; haven't run across a tube compliment or a "free" schematic to look at

How much of a service has it received?

[musicook]

It received a cleaning and one light and one cap was changed out. The invoice says all tubes checked out good. The FM coils is bad, but did not replace since the part was not available.

I uploaded diagrams to my profile. There are so many tubes - I don't know which one is the phono section tube.
6539465395 (http://www.audioheritage.org/photopost/data//500/medium/altec707Diagram2.jpg)

[grumpy]

I'd expect V12 or 13, but can't read the schematic.

[Wagner]

Agree with grumpy, but I am GUESSING based on what I can see

The schematic won't enlarge, only the photo. That is the first vintage tube amp I've seen in a long long time that did not have "ID" screened or painted on the chassis

Regardless, look at the schematic, you should be able to see the section groupings.

Swap from known working circuit to non working PHONO; just pull and swap 2 and 2 and be careful to return the tubes to their former spots if nothing changes

Especially the radio section (make sure it eventually gets back what it started with)

[musicook]

Thanks. I tried swapping v12, v13, v14 with new tubes and it didn't work. The volume is faint.

[musicook]

Thanks. I tried swapping v12, v13, v14 with new tubes and it didn't work. The volume is faint.

I don't see anything on the schematic labeled phono. I tried uploading it to photo bucket to see if it is viewable in the higher resolution.

http:// (http://<a href=&quot;http://s1083.photobucket.com/user/crxyz/media/IMG_2870.jpg.html&quot; target=&quot;_blank&quot;>http://i1083.photobucket.com/albums/j393/crxyz/IMG_2870.jpg</a>)http://i1083.photobucket.com/albums/j393/crxyz/IMG_2870.jpg (http://s1083.photobucket.com/user/crxyz/media/IMG_2870.jpg.html)

[Wagner]

I'm not going to strain any more trying to look at this
Look at page 4 of your schematic, see the selector switch?
I can see that it does have a legend for the switch
Follow the indicated selector switch terminal to the tube and there you have it (PHONO is shown as #2, I can make that out)

The chances of BOTH L&R PHONO gain tubes being bad simultaneously is fairly slim; still it's where you start and stranger things have happened (always do the simple stuff first)

I strongly urge you to give that selector switch and all the tape related switches a shot of DeOxit or similar and exercise them, no matter what the tech said

Do you have this thing open?

But before you do anything else: DOUBLE CHECK ALL the mode switches on the front; it wouldn't be the first time a goose hunt began because all the 1950s type switches weren't in the right place...................or missing pre to amp jumpers on a '70s receiver.............that faint sound you're hearing may just be bleed through because something's not turned on or off as it needs to be

[musicook]

Thanks again for all of the advice. I opened it to change the tubes, I shot dexoit, I've tried the other inputs with the record player and it still doesn't work. So I guess I'll plan a visit to a repair shop - maybe a different one this time.

[Wagner]

Thanks again for all of the advice. I opened it to change the tubes, I shot dexoit, I've tried the other inputs with the record player and it still doesn't work. So I guess I'll plan a visit to a repair shop - maybe a different one this time.Take a good look at the RCA jackes with the turntables RCAs inserted; make sure there is good contact with the center pinAlso, check the PHONO RCAs jack shell(s) (grounds) for continuity to the chassis before you give up