The results of heat on PCB mounted tube sockets...

HeeBGB · Post by **HeeBGB** » Tue 08/09/05 4:26 pm

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Mr_dB · Post by **Mr_dB** » Tue 08/09/05 5:00 pm

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malt · Post by **malt** » Tue 08/09/05 5:06 pm

ok , i was planning to by a soldano
many years ago , so a rang the shop who was selling them.

Me: hi , i what to by a soldano

shop: sorry we stopped selling them

Me : why

shop: they keep falling apart.

Me : i thought they were god amps

Shop : no almost all the amps had loose thing in them and we are tired of fixing them.

So i guess things havenâ€™t changed in the soldano world

PMK

bamboo · Post by **bamboo** » Tue 08/09/05 9:11 pm

I've messed with an Astroverb a few times and thought they had a pretty cool sound...and the reverb is a plus. So, I always had a "back burner" interest in picking one up someday.

Thanks for sharing the pics. I would have figured that Soldano would have had a better answer for you...I know that I'd be bummed about that, too.

jetson · Post by **jetson** » Tue 08/09/05 10:31 pm

I could see this thread developing from the end of a 50 foot PCB. By far one of the most entertaining, and civil discussions to date.
On the one hand, we have pics of a seemingly distressed PCB in a localized area of known high heat dissipation. Some believe this to be an inherent flaw in the design. The manufacture will tell you it is a normal consequence of operation. We also know that the amp still functions as advertised and â€œsounds greatâ€

dotfret · Post by **dotfret** » Wed 08/10/05 3:35 pm

The most effective solution to this problem that I ever saw was in an old spectrometer from around 1960. Polythene spacers moulded to accept a socket sitting on top - looked like gearwheels with big teeth. Heavy gauge wire linking the socket to the board, acting as a heatsink. Spaced the socket about 0.75" off the board. Those sockets were still good after 20 years of continuous operation five days a week, but in the interests of accuracy the thermionic sections were scrapped out and replaced with solid state stuff.

s2 · Post by s2 » Mon 08/15/05 7:05 pm

Here's an oddball experience for you. I received an old Blues Jr to mod from about 1995. It was heavily used and the steel chassis was even discolored around the power tubes, so you could say this 10 year old amp has seen a lot of time with the power switch in the ON position. So I expected to find the PC board holding the tube sockets in very poor condition especially since the tubes are pointing down. Much to my surprise, there is absolutely nothing wrong with that board. No discoloration and no damage to the wave soldered pins. Nothing. I'm willing to bet it could go another 10 years at the very least. It's too bad really. Now it's a Marshall!

chriswu101 · Post by **chriswu101** » Mon 08/15/05 7:12 pm

Are you sure it was the original circuit board? Could it have been replaced?

s2 · Post by s2 » Mon 08/15/05 8:23 pm

The circuit board is dated (it is actually a '96). I'll take some pics as soon as I find a new battery for my camera.

dotfret · Post by **dotfret** » Mon 08/15/05 9:18 pm

I'll bet it's either a green glass board or a dark brown phenolic - don't say it's a red one?!

s2 · Post by s2 » Mon 08/15/05 9:44 pm

Green.

allynmey · Post by **allynmey** » Mon 08/15/05 9:45 pm

This might be of some interest to readers of this thread. I just got these little beauties at antique electronics. They should have sufficient heat dissipation for my new JA PCB Build! Add that to the fact that it will be a head build and the heat will rise away from the socket. I'll keep everyone informed. I'm waiting for my Chassis from JA. My Mouser order will be in tomorrow. Check it out.....

s2 · Post by s2 » Mon 08/15/05 9:51 pm

You know, I've been looking at that pic again in more detail. I'm not convinced that board is damaged. It looks more like extra flux has repeatedly been heated over time and discolored. I'd have to look at it under a magnifier to be sure, but...

dotfret · Post by **dotfret** » Mon 08/15/05 10:08 pm

I don't completely understand the rationale behind this (which is sad, considering I'm an industrial chemist who knows high polymer chemistry) but I can say that very old dark brown phenolic PCBs stand the heat best, but a lot of those died because they were formed on a paper/card base. The lighter brown melamine boards had a tendency to "tracking", but were thermally resistant. The glass-filled boards come in green, yellow and red, which is also the order in which they resist heat from sockets. I have seen the tracks come off the board and the joints go dry before the green ones discolour, but the others are not as good.

jetson · Post by **jetson** » Mon 08/15/05 10:56 pm

i am willing to bet the farm that if ALLYNMEY builds a JA PCB incoperating the [extenders] that he acquired, his chances of having a heat distress problem on his PCB are reduced to about nill. NOT to imply that they are required by any means! its like flood insurance when you live at the top of the mountain.
i have also seen the [moulded spacers] that DOTFRET refers to in his entry. i was at a USAF SAC base and use to hang out with the guys that kept our radar running. EVERYTHING was tubes! talk about heat! all this gear ran 24/7 untill the russians came. well they never did, but i wish i had all that mil-spec sh-- now.

Post by **zaphod_phil** » Tue 08/16/05 5:19 am

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