Search found 6 matches

by intercept
Thursday 10th Jul 2008, 1:53
Forum: CB Radio Repair and Troubleshooting
Topic: Maycom EM-27 flashing channel digits
Replies: 11
Views: 15827

Thanks - there are definitely some semiconductors labelled Q3 on the board. I'd managed to get the datasheet of Rick's preferred Sanyo equivalent (below), but that doesn't give the case markings. I've just scoured the component drawers in the lab at work and found 3 types of varicaps, BB405B, BB505B...
by intercept
Wednesday 9th Jul 2008, 12:02
Forum: CB Radio Repair and Troubleshooting
Topic: Maycom EM-27 flashing channel digits
Replies: 11
Views: 15827

What is the voltage each side of R102?
8.02V and 7.91V (on the Q100 collector side)
by intercept
Wednesday 9th Jul 2008, 11:18
Forum: CB Radio Repair and Troubleshooting
Topic: Maycom EM-27 flashing channel digits
Replies: 11
Views: 15827

Goop now removed, the board is as in the new photo. You can test the VCO, by checking the voltage at the junction of R107 and R108 the voltage should go up has you go from channel 1 to 40 TP1 has constant 2.67V regardless of channel selected if it not check the voltage at the Base of Q100 the voltag...
by intercept
Wednesday 9th Jul 2008, 9:45
Forum: CB Radio Repair and Troubleshooting
Topic: Maycom EM-27 flashing channel digits
Replies: 11
Views: 15827

Goop

Am I right is suspecting that the PLL components are beneath the wax in the photo?
by intercept
Wednesday 9th Jul 2008, 9:32
Forum: CB Radio Repair and Troubleshooting
Topic: Maycom EM-27 flashing channel digits
Replies: 11
Views: 15827

Thanks Gents, I'd have a look at the levels in the PLL, but it appears to be buried in the waxy goop used to prevent fiddling with the pot-cores. Any tips on how to remove it? Additionally, what lettering is on the varicaps? I can't see any semiconductors with 251 on them... Rick - in another thread...
by intercept
Monday 7th Jul 2008, 6:53
Forum: CB Radio Repair and Troubleshooting
Topic: Maycom EM-27 flashing channel digits
Replies: 11
Views: 15827

Maycom EM-27 flashing channel digits

Hi I'm hoping that someone here has seen and fixed this before... My previously fine vehicle mounted Maycom EM-27 has stopped working. The displayed symptoms are that the channel number digits now start flashing a few seconds after channel selection, and there is no reception or transmission. Volume...