Newbie with a Rogers 4622 – looking for help with disassembly

[markk900]

Hi all – first post here in a long long time. I have been lurking for years, and am a newbie to the actual work. With Covid I finally decided to tackle the Rogers 4622 we have.

Removal of the radio from the cabinet was straightforward, but I have a question about the next step. The band selector and internal transformers (T1, T2, T3) are mounted to a subframe as you can see in the picture attached. The frame is only held with 5 screws (4 on the front face and one on the top), but there are numerous connections from the switches and transformer, most of which are very hard to access. In the group’s experience is the best plan of attack to desolder connections from components on this frame ( as few as possible) and remove it; or is there a better plan?

If indeed the best approach is remove the frame, is it simply a matter of taking great care to get at desoldering connections in awkward places? As an example at least two connections go through the chassis top to the base of the tuner; neither end is very accessible for the purposes of desoldering the lead to allow removal.

On the trivia side: this radio has been in the family since new; the speaker/field coil connections were attached with wire nuts (which seemed bogus) but the nuts were ceramic so perhaps that was the way they came? And in the photo you will notice someone has added an external antenna connection (brown wires at the bottom) but the way they did it seems to me at least to be quite sketchy! Of the caps we can reach all have tested within spec but we expect to replae the paper/wax ones anyway. the “we” is my adult son (who is a electronics whiz and a ham operator) and myself.

Anyway, long post and thanks for any advice you can provide.

Mark

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[Sterling Spurrell]

Not sure about how you would approach the caps but they all need to be done before applying power to the radio. Looks like most can be done without do any taking apart the chassis. Patience is a very much needed part of antique radio repair. Hope all works out for you and you get lots of use from your family radio.

[Rick]

I’d try to avoid taking out those IF transformers and that sub chassis if possible. This looks like it will be a very tough radio to get at everything.

The Electrolytic capacitors may cause you troubles if you just plug the radio in, so as Sterling says be cautious until you deal with them. Unfortunately it looks like the connections to the electrolytics are under the two cans on the left of your picture. That big yellow 10 MFD cap in the centre of your picture looks like a replacement so someone may have already replaced one of them, hopefully they’ve disconnected the old one and not just bridged the new one. If you are lucky and can see the wire(s) that go to the terminal on the bottom of the electrolytics you could maybe snip them and put your new cap somewhere out of the way and connect it to your snipped wires.

You can take your chances with a “Dim Bulb” on the power to protect the transformer from possible shorts and try powering up the radio, but that does not give you any protection from future shorts if the electrolytics are not replaced, if you do choose to leave the old ones connected, then add a fuse, still not a great solution but better than leaving it as is.

[markk900]

Thanks for the advice folks. We’ll take it slowly to begin with and see how things go. I will admit that as the radio sat in a family member’s living room for decades that is has been turned on in the past few years with no smoke…. however we’ll proceed without any new powering on until we are done.

[markk900]

Hi all – its been a couple of months but to be honest I was pretty intimidated by the prospect of diving in to this project, but I spent a lot of time studying the chassis and finally got up the gumption to dive in (taking copious notes and photos).

I was able to desolder a number of connections that bridged between the subassembly with the IF transformers on it and was then able to withdraw it from the chassis. Whew!

First picture is the liberated transformer frame.

Second is the chassis underneath the frame – lots of caps in there to test/replace. Also lots of the fabric covering wire is quite brittle – will have to replace some of that. Does anyone have a good source for fabric wiring or do people just go modern?

Third picture is the original chassis layout diagram from the owner’s manual. I found that my radio has a big modification – instead of one stacked cap (C25/26) there are now two cylinder caps….see 4th picture.

Now to catch my breath and get ready to tackle the rest of the chassis.

Mark

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[markk900]

Hi all: long delay in updating as to be honest I was totally intimidated by the task. So I let things sit for a couple of months while I gathered the courage to tackle this. As an aside I also love vintage guitar amps and watch a couple of the great youtube channels on amp repair…..I must say that it gave me a bit of confidence to take this on.

Anyway, I spent a bunch of time scoping out the layout. As mentioned earlier, there is a transformer section in the middle combined with the band selector switch which clearly needed to come out in order to get at basically *anything* in the radio. So I looked for and (i hoped) identified all leads coming out of that section that went anywhere else….the section is held in by 5 robertson screws so I knew it was intended to be removed. There was also a weird (non-original) selector switch that had been added – it seems to allow the selection of an external antenna and it needed to come out as well. Armed with a notebook, pencil, flashlight and soldering iron I got to work.

Happy to report success (so far!) Here is the main chassis bereft of its transformer section:
[img]https://i.imgur.com/4XpKNl5.jpg[/img]

I took careful notes about everything I removed and photos to remind myself where things went. I must say this radio was NOT designed for easy servicing – sure I am not an experienced radio tech but so much is hidden behind or underneath other components when it was clear there are pieces that are supposed to come out as a unit. In any event I got the transformer section out:

[img]https://i.imgur.com/2rwnjg5.jpg[/img]

I also discovered a modification that the factory made after the original chassis layout was documented – the chassis layout available online (which matches the one on the original owner’s manual I have that I got with the radio) has two caps in a cylinder (C25 and C26), but in reality these appear to have been separated and are two distinct – here’s the layout diagram:

[img]https://i.imgur.com/sqIHRvv.jpg?1[/img]

And here’s the actual chassis:
[img]https://i.imgur.com/njyUA02.jpg[/img]

Anyway, just wanted to share the adventures of a newbie!

[Dan Walker]

Your images did not appear on the post.
Dan in Calgary

[Ralph Spracklin]

He Dan

I made some changes to Mak’s links. They worked for me. As they were in the post they were dead linls. I have not yet tested them as the apear in this reply. I will again test them after I SUBMIT

https://i.imgur.com/njyUA02.jpg%5B/img

View post on imgur.com

Ralph

• This reply was modified 2 years, 2 months ago by Les Dickson.
• This reply was modified 2 years, 2 months ago by Ralph Spracklin.

[Ralph Spracklin]

Hi Dan
Mark’s links are dead links, Here I have corrected those Links. They work for me!

< https://i.imgur.com/sqIHRvv.jpg?1%5B/img >
< https://i.imgur.com/njyUA02.jpg%5B/img >
Ralph

[Ralph Spracklin]

Sorry Guys, now rhe IMGUR.COM seems to have gliches, as images appear and then dissappear???
Ralph

[Ralph Spracklin]

Hey Dan
Those links Posted by Mark were dead links. I have corrected them and they work for me.

View post on imgur.com

]https://i.imgur.com/njyUA02.jpg[/img

Regards
Ralph

[Ralph Spracklin]

Hello Mark

Hopefully the assembly was designed with long enough leeds, that once the five retaining screws were removed, the complete assembly would be able to be lifted out far enough to access what ever you needed to get at. And that should also allow you to remove the rivits for those three cannisters. Maybe Dan, who has lots of radio experience, may have another suggestion.

Ralph

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