Dumont RA-110 from ETF

[Kamakiri]

Managed to get this set in the silent auction for $20


The bad news: 19AP4 is toast

The good news: Cabinet has had a decent amateur refinish job and the knobs were sitting inside a coffee cup tucked between the picture tube and chassis.....but that's not all!

After giving the chassis a once over, I'm convinced this was a working set that had a picture tube failure. The recap job here is artistry. Whoever did this job used some funky 2 x 50 uF 500V UK manufactured caps and mounted them neatly in the chassis. Not really any info out there on them, they say FAC/RD37DUK 95-42.

They make everything look so neat, in the midst of what would be long terminal strips of caps mounted on the chassis if I were the one doing the job. Even the disc caps are all new.

Also, there's a funky relay underneath, with one wire labeled COIL. A quick glance shows that the wires go between the power transformer and the twin 5U4s. Could be some type of surge surpression that someone built in, like a soft start circuit?

Anyway, I'd love to shake the hand of the man who did this work.....

[init4fun]

I'm just about 99% positive that you will find that relay is a "field repair" replacement of a Dumont factory supplied item .

I'm less sure as to it's exact functioning , but my guess is that it was to protect the CRT from being phosphor burned in the event of a sweep failure ?

[Kamakiri]

I don't have a schematic to be able to say. I just can't recall ever seeing anything like this in any set I've ever had my hands in.....

[pearsonk]

The relay was standard fare for Dumont/Crosley sets. 5000 ohm coil.
Usually bad and often just bypassed. 6AL5 activated. I recently replaced
two.

[rca2000]

Originally Posted by Kamakiri

Managed to get this set in the silent auction for $20


The bad news: 19AP4 is toast


.....

WIll it not wake up at all? On say 8-9 volts--will is give decent emission--or is it just "dead"?

[Steve McVoy]

The RA-110 manual is on our site.

[maxhifi]

Those are guitar amplifier filter caps... manufacture stopped around 2001 or so, but they were common in Marshall and other british made tube amps.

[hi_volt]

So, what is that tube mounted underneath the chassis?

[Kamakiri]

Originally Posted by rca2000

WIll it not wake up at all? On say 8-9 volts--will is give decent emission--or is it just "dead"?

That's the odd thing. Powered it up on my tester, 6.3V, and let it warm up for a minute. Walked away for a sec, heard a quiet SNAP, and the filament went dead

Never had that happen before.

[Kamakiri]

Originally Posted by Steve McVoy

The RA-110 manual is on our site.

Thanks Steve, I was actually reviewing the DuMont service notes and find it odd that they claim that the RA-110 and RA-103 chassis are basically the same, especially since the RA-110 has a separate HV chassis. But since I've never had my hands into an RA-103 before, I can't really say.

[Kamakiri]

Originally Posted by hi_volt

So, what is that tube mounted underneath the chassis?

It's a 6AL5....

[jr_tech]

Originally Posted by Kamakiri

That's the odd thing. Powered it up on my tester, 6.3V, and let it warm up for a minute. Walked away for a sec, heard a quiet SNAP, and the filament went dead

Never had that happen before.

Sorry to hear, that is typical heater burn-out for a very gassy tube... likely the 19AP4 was pretty much "up to air" when you got it. How do the getters look?

jr

[Tony V]

I have the same set in blonde. I picked mine up on Ebay for $10 and like yours had a dud crt. I picked up a tested like new crt for $75. The set was recapped in the recent past so I tried it and it works well except that it needs a new focus control. The winding of the control is burnt in the "sweet" spot so I cant get the raster as sharp as it could be.

[tvdude1]

I have a crt if you decide to keep it.

[Kamakiri]

Oh, I'm keeping it, believe me

Might have one lined up, but if not I'll definitely let you know