HH Scott 340B parts list/rehab

Well, since I got sidetracked into test equipment, a friend's dad had given me an old Amprobe RS-3 Ultra clamp meter a while back, and since I was already in cleaning/testing mode I dragged it out and it works perfectly! (If he ever had the accessory ohmmeter attachment it's long gone, but no big deal.) So I've gone from having no clamp meter and deliberately buying a Simpson one a while back to now having three... the Simpson, the old Amprobe, and a newer digital Amprobe that I salvaged from the recycling pile at work (how it got there, I have no idea... I actually let it sit a week before picking it and told the warehouse guy someone might come looking for the pile of meters I'd made, but after a week I figured I'd better take them before they got hauled off. Some other good stuff in that pile too...)
 
got an email from Tom @ Hayseed, he actually got my previous email and caps are in the pipeline, maybe shipping Thursday, now I'm all motivated again...
 
And they still haven't shipped yet so nothing to report. Did get another email from Tom, apparently they made the 4x20/500 cap twice and weren't happy with it either time so they're holding off until they get a new shipment of materials in for it. In one way I'm disappointed but in another it shows they really are testing this stuff which makes me happy.

Question: I did, before I packed everything up for the holidays, replace the power switch contacts and put it back in place. I was trying to plan my moves re: installing an alternistor to preserve the "new" repaired switch, I noticed that the power cable within the unit appears to be shielded. Any recommendations for a similar shielded cable that I could use to jump over to an alternistor? Probably 16/2 shielded, would need to be rated for at least 120VAC

thanks!
 
You can put the thermistor on the transformer side of the switch if that makes wiring it easier. Not familiar with the particulars of the Scott's wiring, but somewhere it has to connect from the switch into the transformer, and I expect it does so on a terminal strip. You can put the thermistor there. Just make sure it has plenty of room around it, they get hot.
 
I got it, it's just that apparently Scott felt it necessary to use shielded cable for the run from the switch to the fuseholder... is it really necessary to maintain that and if so what do I use? Don't have a ready source of shielded wire in bigger than 18AWG solid
 
They likely did it for hum control. If they used it, there is probably a reason for it. I'd try to find somewhere else to locate the thermistor that doesn't require changing the original power feed-in wiring.
 
I can do it very easily , there is some vertical metal making a partial shield around the outputs... I just would need a short run of 16/2 and since the original wiring to the power switch was shielded I was thinking that whatever I added should be as well.
 
gadget73 said:
I own four of them, three here at home and one at work. I can only use 2 at a time here at home just because of a lack of test leads, but I have used both, plus at least one of my other meters to monitor stuff. Having an extra working meter is just not a bad idea IMO.

If you can make use of the glass, I'd be happy to send it your way. Its living in a dead meter that isn't worth fixing. Quite honestly I'm pretty much stocked up on 260 parts, with the exception of needing to buy myself one more set of test leads so my extra series 7 is complete and usable. I'm well into a state of "too much crap", so I'm doing my best to not bring anything else in at the moment.
Click to expand...

I haven't forgot about this just haven't had time to deal with the 7M. I sent an enquiry to Newark over the holidays and need to call them to see if I can get the parts I need to fix it as I didn't have part numbers for everything I needed.

This all may be back burner though. Just pulled the trigger on ANOTHER 260-8P on eBay for $26 and change shipped...?!?!?!?! need another meter like a hole in my head, was really searching for a set of replacement leads, but holy hell... that'll make a nice gift for someone if it turns out to work OK. When someone is selling $50 bills for $20 apiece you just buy them, right?
 
I hear you.

You can cheat and "make" shielded wire by twisting the leads together, then wrapping them with a grounded lead. It probably can be found in small quantity, I just don't happen to know where.
 
gadget73 said:
I hear you.

You can cheat and "make" shielded wire by twisting the leads together, then wrapping them with a grounded lead. It probably can be found in small quantity, I just don't happen to know where.
Click to expand...

I've once replaced an unobtainium shielded wire with a single wire, one bare lead on top wrapped in aluminium foil, all of this with heat shrink around...
 
No updates sadly... my can caps finally showed up, but between being sick, company from out of town, dealing with an unfixable Jeep, a close friend having brain surgery, and most recently being out of town for the weekend, I haven't touched the thing :/

Someday I will have a free weekend and actually pick up a soldering iron in anger I promise!
 
No worries, man! You have to deal with life as it comes. Sorry to hear about the travails and best wishes all around.
Dave
 
Well crap. Ish. Old a$$ thread, back from the dead.

I thought it was two Christmases ago I was planning on fixing this thing but it was actually three, which is why I took it to a local tech beginning of this year. He's finally looking at it (has a backlog as you can see) and told me that the reason the power switch was all burned up was that one of the HV diodes was shorted, not the multi section can caps as I suspected.

if there are no other problems, and I'd spent another hour troubleshooting it past what I did, I could have been listening to it all this time... but at least it's gonna come back all working.
 
Wouldn't be surprised to find both a bad diode and a bad cap, and at that point its a chicken and egg sort of problem. Bad caps causing high current load could kill them, or maybe it just went bad because sometimes things happen. If it didn't immediately blow the fuse and dumped a bunch of AC into a cap though, that won't do the caps any favors.
 
Oh, it'd vaporize a fuse if I'd been dumb enough to power it up in its original state. Dead short.

I'm just anxious to hear it. It's so goshdarned pretty, and my Pilot 654 in unrestored condition sounds good, and I basically told the guy to treat it like his own and left it with all the parts I bought. Plus this one has mostly Telefunken tubes for it save for the outputs which some miscreant stole so they're a matched quad of Tung-Sols from Jim McShane.
 
As I was searching for stuff for my scott LT110 tuner. I found this old thread, I demand satisfaction. IMG_20210821_202055.jpg :banana::biggrin:
 
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