Bush 82CL squealing

[Radio Scotland]

My old Bush 82CL has started squealing on reception of strong signals, It clears up if i rotate the radio. I'm thinking the AGC Capacitor.





Here is a clip of the radio in action.

https://www.youtube.com/watch?v=nRfx...ature=youtu.be

[Radio Scotland]

P.S... I'm pretty sure its not QRM it's picking up as my other radio's aren't receiving it

[Graham G3ZVT]

If you haven't done so already, replace all the electrolytic capacitors.

Don't forget there are a couple on the back of the chassis.

while you have the chassis out, take the opportunity to treat the wave change switch with some switch-cleaner.

[Radio Scotland]

Originally Posted by rambo1152

If you haven't done so already, replace all the electrolytic capacitors.

Don't forget there are a couple on the back of the chassis.

while you have the chassis out, take the opportunity to treat the wave change switch with some switch-cleaner.

No iv'e not recapped it, My problem with shotgun recaps is the price of them. I know i'm sounding like a tight scot But when i look on ebay it seems to be multiple amounts of the same values for sale. When a radio has varying values it soon adds up, Never seen mixed value bags for sale.

Band switch has been cleaned.

Cheers

Jay.

[Radio Wrangler]

I'm a little careful about where I buy electrolytics from. There are some dodgy components floating around, so I choose reputable brands and get them from an accredited distributor, usually Farnell or Mouser.

Pulling something apart is a fair amount of effort and I don't want to have to do it all again just because I saved a quid spread over all the capacitors. I thake the do-it-once low risk option.

Howling means feedback. So decoupling capacitors are likely suspects, and here you do not need to be picky about the right values, you can usually go up in value a fair bit and see no problems.

David

PS, I'm a Yorkshireman and Yorkshire is effectively twinned with Aberdeen Remember the ancient joke that copper wire was invented when someone dropped a penny midway between a Yorkshireman and an Aberdonian? In both Yorkshire and Aberdeen, we like to describe ourselves as 'Careful'.

[jonnybear]

Langrex will do 10x 100uf 25v you only need four for £1.65 free delivery

https://www.ebay.co.uk/itm/25V-100uF...AAAOSwDg5depKi

and these 10uf 25v X 10 you only need three and are avaliable for only £1.19 free delivery. so for £2.84 you will have enough to repair two Bush 82CL.

https://www.ebay.co.uk/itm/10-x-10uF...MAAOSwb69Zu6CD

Have purchased from both these vendors in the past all good components.

or you could recover some of these values from an old tv chassis or satellite receiver.

John

[Radio Scotland]

Thanks for the advice & links regarding capacitors, My post regarding capacitor prices was more in line with doing bulk recaps. Replacing waxies ect. Not one off radios, Well i have the bush stripped down, Am i right in thinking C10,C22,C23,C25,C27 Are the electrolytics ?

'Can't see any polarity markings and i'm working from a schematic for an earlier version. The one that uses OC Transistors. Mine uses AF-117, Seems to be slight differences in the layouts.

I did notice a broken hunt cap, The one that couples the signal from the base of TR1 to the band selector


RadioWrangler. You heard about the scotsman who dropped a pound coin ? When he bent down to pick it up it hit him on the back of the head

[ms660]

Originally Posted by Radio Scotland

Well i have the bush stripped down, Am i right in thinking C10,C22,C23,C25,C27 Are the electrolytics ?

Electrolytics = C22, C24, C25, C26, C28, C29, C30.

Lawrence.

[Radio Scotland]

Originally Posted by ms660

Electrolytics = C22, C24, C25, C26, C28, C29, C30.

Lawrence.

Cheers.

I need to source the correct schematic

[ms660]

https://www.service-data.com/section.php/1068/1/tr82cl

Lawrence.

[Radio Scotland]

Originally Posted by ms660

https://www.service-data.com/section.php/1068/1/tr82cl

Lawrence.

Cheers

[Radio Scotland]

The broken cap is marked .01 i take it thats .01 uf as in 10.000 pf ?

[Radio Scotland]

Am i right in thinking the 7 electrolytics are 4 x 100 uf & 3 x 8 uf ?

[ms660]

Originally Posted by Radio Scotland

Am i right in thinking the 7 electrolytics are 4 x 100 uf & 3 x 8 uf ?

Yes.

Lawrence.

[Radio Scotland]

Originally Posted by ms660

Yes.

Lawrence.

Cheers lawrence i'll order some up, 8 uf isn't a preferred value these days so i'll go for 10 uf, Should i replace the small black hunt caps ?

[ms660]

Originally Posted by Radio Scotland

Should i replace the small black hunt caps ?

If they are leaking I would replace them if it were mine, that's because I don't like leaking capacitors full stop......But I think opinions might differ depending on the circuit function and the fact that they are not subject to high voltages in a transistor receiver.

Lawrence.

[Radio Scotland]

I'll replace the broken one and leave the others if performance is ok,


Jay.

[HamishBoxer]

Black Hunts are not the best news these days.

[Stylo N M]

Hi Radio Scotland.

In reference to your question in post #12 yes 0.01uF is 10,000pF and it can also be described, or marked as 10nF nF is just another way of describing thousands of pF.

Paul

[Radio Scotland]

Originally Posted by jonnybear

100uf 25v you only need four

10uf 25v X 10 you only need three


John

Sorry john just noticed you had already mentioned the amount and values needed. I Must have been half asleep when i read your post this morning lol.

Thanks for the info regarding the .01 caps paul


As for the hunts would it be ok to replace them with ceramic caps ?

Jay.