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

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

deleted

tubetwang · Post by **tubetwang** » Wed 08/17/05 11:22 am

I used boards when first exposed to d.i.y. hi-fi tube building 5 years ago.
Was complete newbie then. Apprentice buider today.

Some boards were junk and some were great (Uncle Ned's (Triode Electronics) Shannon Parks's (diytube.com). I built 5 or 6 amps using boards (Dynaco ST-70 and ST-35). I may turn them into Dumble's and pay off the morgage.

But step on it long enough (tweak, re-tweak and re-re tweak) and you start having problems. The kind of problems that most newbie want to avoid...(but left alone, it does a great job).

Pcb's are great for newbies and others who want an easy build.

Today, i'm the proud owner of a point to point (rat nested and long hours) AA761 Champ, 2 x MA1, 3 x 5C3 Deluxe, 5B6 Bassman + wood and metal shop. I do not think i'd be there without that first pcb, Tino Zottola, Internet community, Freedom 50 and all the tube amp's books and videos purchased through the years.

PS. Interesting IAG boards at Partsconnexion.com (no flux problem on those...)

PS.. i would like to thank my 9 year old and fiance for putting up with me and believing in my talent...(':roll:')

scottosan · Post by **scottosan** » Fri 08/19/05 11:20 pm

jersey_aaron wrote:"DISCLAIMER: This is not intended to start a flame war >> It's informational only."

Not when the title of your post is "The results of heat on PCB mounted tube sockets...".

One board in one Soldano amp does not represent EVERY PCB with on-board tube sockets. Its ignorant to even remotely assert that. There are dozens of PCB guitar and hi-fi amps with tubes mounted on the board that have been around since the 1960's that are fine. There are also poorly manufactured guitar and hi-fi PCB amps that have failed miserably.

Posting a picture of a poorly manufactured PCB with a meltdown and shouting "ALL PCB'S ARE BAD!" doesn't prove anything, except that your particular Soldano Astroverb had a poorly manufactured PCB. But at least now we know you're a troll.

How many PCB have you had to replace components on? Seriously? The main problemis that the traces can peel away form the board due to heat form desoldering even with the most experienced techs.

Post by **zaphod_phil** » Sat 08/20/05 4:44 am

tubetwang wrote:Pcb's are great for newbies and others who want an easy build.

And trust me, there's nothing wrong with either of those...

jersey_aaron · Post by **jersey_aaron** » Sat 08/20/05 7:51 am

>How many PCB have you had to replace components on? Seriously? The >main problemis that the traces can peel away form the board due to >heat form desoldering even with the most experienced techs.

How many boards have you worked on that were designed by us? After over a dozen re-solders on several components on our PCB, not a single trace has lifted.

Most people only have experience with PCB's for mass produced products. Most of them are made cheaply and soldered by machines. But a well designed board will not exhibit the typical problems of mass production (i.e. boards made for cost savings).

scottosan · Post by **scottosan** » Sat 08/20/05 8:06 am

jersey_aaron wrote:>How many PCB have you had to replace components on? Seriously? The >main problemis that the traces can peel away form the board due to >heat form desoldering even with the most experienced techs.

How many boards have you worked on that were designed by us? After over a dozen re-solders on several components on our PCB, not a single trace has lifted.

Most people only have experience with PCB's for mass produced products. Most of them are made cheaply and soldered by machines. But a well designed board will not exhibit the typical problems of mass production (i.e. boards made for cost savings).

Your boars have not been around long enought to show signs of aging and natural chemical settling that occurs in all electronocs, PTP or PCB. What is the thickness of your boards? did you use 1oz. copper clad? Regardless how well you design the board, certian componts will/can fail. IF a diode goes on a PCB, its usually a mess, screen resistors, the same. I am not saying your product is bad, it just the nature of PCB. Not to mention the whole premise that a newbie will learn alot more when they have to learn how to layout components and see how they interact with each other. If I was to PCB DIY, then I would go a step furhter and etch my own board.

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

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