Basement Find - Newbie Who Doesn't Know Where to Start

[toxcrusadr]

I don't think you should worry about tube replacement until the rest of the unit is functioning properly. Entirely possible all the tubes are good, but chances are there are bad capacitors, or about to go bad, just from sitting.

BTW if you take these to a shop, either remove the tubes and let them use their own tubes to test it, or casually let them know you want to make sure they take good care of the original tubes and not to mix them up with their own. Shops have been known to 'accidentally' swap valuable vintage tubes for cheaper ones.

I'd get it all fixed up and if you don't prefer the sound, you can sell it for plenty and buy something you do like. Nothing to lose.

 

[gadget73]

second not worrying about tubes just yet. They're quite possibly fine. They do not deteriorate from sitting like the other parts do.

 

[Basement]

Alright, small update. https://imgur.com/a/TVBsFGF

I ordered some parts today. Holding out on tubes. Would appreciate your thoughts on how I go about determining if I should be brave enough to trial with the tubes. The Mullards seem in good condition (beyond the labels falling off), and the reaming rectifer ant 7199s seem hard to replace as well? Also, in general, should I be concerned with the old resistors?

After ordering I got in a speaker mood so I opened up the SP200s. Caps appeared good, surrounds and cones as well, so I hooked them up to my Marantz SR1100. Sounded pretty good. I noticed the speaker grills are bowing a bit. Is there a safe way to flatten them again?

Decided to try out the BSR turntable and had limited success (lots of hum on phono, auto advance to next LP broken, drive motor disengaged (but I can still hear it moving).

Also provided some pictures of my old setup - curious as to your opinions on the lofi!

 

[8xlaxx]

Would love to see your amp and gear pics but my Malwarebytes Premium is killing off your links immediately.

Anyway, you could upload pics directly?

 

[gadget73]

most record changer problems are caused by grease that has turned to glue. Cleaning and re-lubricating them almost always fixes it. Sometimes they also need a new idler wheel though.

 

[Basement]

Another update: https://imgur.com/a/0temWtA

Its recapped. New feet. New RCAs. New bias kit. New stereo/mono switch. Diode. Appreciate your thoughts on if I can/should try putting in the tubes and make a dim bulb to try it out. Part of me wishes I tried before replacing the capacitors.

To make ordering easier, I quickly used the list from here https://www.hifizine.com/2010/06/restoring-dynaco-st-70/ however I now have 2x unused .22mfd caps. I've seen that Bob Latino and others use the larger caps but I can't figure out why 2. Ideas as to what they were going for? Also the parts list 4x 1.0uF but I'm not sure where these were going to be used either and didn't order them.

 

[Yamariv]

Another update: https://imgur.com/a/0temWtA

Its recapped. New feet. New RCAs. New bias kit. New stereo/mono switch. Diode. Appreciate your thoughts on if I can/should try putting in the tubes and make a dim bulb to try it out. Part of me wishes I tried before replacing the capacitors.

To make ordering easier, I quickly used the list from here https://www.hifizine.com/2010/06/restoring-dynaco-st-70/ however I now have 2x unused .22mfd caps. I've seen that Bob Latino and others use the larger caps but I can't figure out why 2. Ideas as to what they were going for? Also the parts list 4x 1.0uF but I'm not sure where these were going to be used either and didn't order them.

Awesome work on the resto! Can't wait to hear how those Mullards sound!

Any tips on changing out the caps on the PCB board? I'm about to change mine out..Did you solder suck the old solder then install the caps or just push them through the hot solder?

 

[Basement]

Cleaned it up a bit, put the tubes in. I'm very tempted to make a dim bulb tonight and trial it. Somebody knowledgeable convince me otherwise. https://imgur.com/a/xaNBMHz

 

[Basement]

Awesome work on the resto! Can't wait to hear how those Mullards sound!

Any tips on changing out the caps on the PCB board? I'm about to change mine out..Did you solder suck the old solder then install the caps or just push them through the hot solder?

It is pretty straightforward. I didn't have suction or any braid but had no troubles just using the old solder and adding more as appropriate. My advice would be to not touch it once placed. The traces are fairly easy to pull up inadvertently.

 

[Markoneswift]

Cleaned it up a bit, put the tubes in. I'm very tempted to make a dim bulb tonight and trial it. Somebody knowledgeable convince me otherwise. https://imgur.com/a/xaNBMHz

Definitely do a DBT first before you power up - I've made the mistake of powering up on line voltage with unknown kit and sometimes it didn't go too well ! You should have really tried a power up before recapping etc, because you could find that there are other more serious issues. Oh well, a bit too late for that now but love your enthusiasm

 

[Markoneswift]

It is pretty straightforward. I didn't have suction or any braid but had no troubles just using the old solder and adding more as appropriate. My advice would be to not touch it once placed. The traces are fairly easy to pull up inadvertently.

Just some general tips for this kind of work - use an appropriately sized (clean) iron, don't spend too long heating the joint (this is the main cause of trace lifting), don't rock the components back and forth on the board (this puts downward force on the connections to the traces - another cause of them lifting), do try to get a 'solder sucker' - they're really cheap and really effective, do use rosin core solder which helps to clean the joint, do clean up any additional flux if used.

Good luck

 

[Basement]

Definitely do a DBT first before you power up - I've made the mistake of powering up on line voltage with unknown kit and sometimes it didn't go too well ! You should have really tried a power up before recapping etc, because you could find that there are other more serious issues. Oh well, a bit too late for that now but love your enthusiasm

Any thoughts on a DBT protocol? How worried do I have to be about the tubes? If I am worried - do I have to purchase all the tubes or just the EL34s?

Agree with trialing before recapping - though I was going to fix it regardless. Would've been fun to hear as is with just the selenium rectifier and bias caps replaced.

Thanks in advance and agree with your advice!

 

[Yamariv]

Cleaned it up a bit, put the tubes in. I'm very tempted to make a dim bulb tonight and trial it. Somebody knowledgeable convince me otherwise. https://imgur.com/a/xaNBMHz

Wow OP, that thing cleaned up great!! What did you end up using to polish up the metal? Any tips on removing the slight surface rust on the transformers? Amazing transformation for sure!!

 

[Yamariv]

Just some general tips for this kind of work - use an appropriately sized (clean) iron, don't spend too long heating the joint (this is the main cause of trace lifting), don't rock the components back and forth on the board (this puts downward force on the connections to the traces - another cause of them lifting), do try to get a 'solder sucker' - they're really cheap and really effective, do use rosin core solder which helps to clean the joint, do clean up any additional flux if used.

Good luck

Thanks, very valuable tips! That's what I'm worried about when I swap caps, don't want to overheat anything and lift any traces on the stock board. Would you solder suck first, then reheat quickly to remove the old caps?

 

[Markoneswift]

Thanks, very valuable tips! That's what I'm worried about when I swap caps, don't want to overheat anything and lift any traces on the stock board. Would you solder suck first, then reheat quickly to remove the old caps?

Yes, that's what I would do. Clean the old solder as effectively as possible and then I gently heat the pads while gently pulling upwards on the component to free it from the board. Make sure you note any polarity of caps etc, even if it is noted on the boards. Often, the board marking can be wrong so note what is actually installed AND the value. Even the service manuals can be wrong, because often there are 'revisions' to components that are not updated in the SM.

 

[Dandy]

Also the parts list 4x 1.0uF but I'm not sure where these were going to be used either and didn't order them.

I agree. I can’t see why they are on the parts list.

 

[electronjohn]

Unless they've undergone some catastrophic event, the 7199s in your amp should be fine. Dynacos (and others that use them) do not subject them to much stress...they operate at lower voltages and currents compared with the outputs, and even at 50+ years of age they still do the job. You can always get 6GH8 to 7199 adapters and run 'GH8s to preserve the 7199s for the future. 6GH8s were ultra-common in 60s color TVs and quite inexpensive.

 

[Basement]

Any thoughts on a DBT protocol? How worried do I have to be about the tubes? If I am worried - do I have to purchase all the tubes or just the EL34s?

Thanks in advance and agree with your advice!

Wow OP, that thing cleaned up great!! What did you end up using to polish up the metal? Any tips on removing the slight surface rust on the transformers? Amazing transformation for sure!!

I scraped the big parts with small flat head, the rest was less rust and more of a glue. Used a bit of Googone appears to have done the trick.

I wiped everything down gently with 70% IPA (wish I had more concentrated stuff available for this task) and then followed up with a light auto polish for the nickel. I used qtips to try to get in between the letters as best as I could. Finally I used armourall on a rag to add a shine (recognizing full well that it will make this incredibly dusty).

 

[Basement]

Unless they've undergone some catastrophic event, the 7199s in your amp should be fine. Dynacos (and others that use them) do not subject them to much stress...they operate at lower voltages and currents compared with the outputs, and even at 50+ years of age they still do the job. You can always get 6GH8 to 7199 adapters and run 'GH8s to preserve the 7199s for the future. 6GH8s were ultra-common in 60s color TVs and quite inexpensive.

Any thoughts about the 5AR4 and the EL34s? Not sure how cautious I should be. I'll go ahead and make (or more lazily order) a dim bulb and start slow for 2 hours and then progressively increase. I just don't want there to be any real risk to the tubes. If there is a real risk than I'd rather spend the 60 bucks for some JJ E34Ls or similar.

 

[tom3]

Do a search on the dim bulb test. Been too long for me but you power it up with no tubes, then some, then if all good put the rest (rectifier?) in. Start with a lower wattage lamp, then go up. Etc.

Had that Pioneer reverb unit years ago, was not impressed with it, tinny sound and very little delay. Gave it away, might have a couple tube in it that have value though.

The Sansui SP200s are probably a real good match with that amp. Those wood grilles are pretty delicate, I'd leave them as is.

Quality never goes out of style, and you have some quality components there.