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  • #16231
    markk900
    Forum Participant

    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

    #16234
    Sterling Spurrell
    CVRS Member

    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.

    #16238
    Rick
    CVRS Member

    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.

    #16241
    markk900
    Forum Participant

    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.

    #16648
    markk900
    Forum Participant

    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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